What advice should we provide when a newbie asks for help with a blown E39 engine?

In responding (yet again) to a blown engine thread today:
- 2001 528i engine

I got to thinking that we should be more efficient about helping these people.

It seems, lately, about once a week, someone writes to us with anguished stories of a potentially 'blown' E39 engine (or, more often, a blown cooling system which they want to fix piecemeal for cost reasons).

What should we tell these people that will help them make the major decision they're facing?

The intent of 'this' thread is to POINT people to it for a comprehensive answer.

Hopefully, we can provide:

• Test procedures (heads, block, valves, cooling, gaskets, etc.)
• Cost analysis for repairs (sell, junk, rebuild, repair, etc.)
• Suppliers (rebuilt engines, parts, tools, etc.)
• DIYs (head gaskets, resurface heads, replace engine, etc.)
• ? anything else they need ?

In looking at the past dozen (or so) previous 'blown engine' threads, here is the advice that I've come up with, so far, that I think we can point others to (based on my input to this thread - where the OP, unfortunately, disappeared after we did all that work to help him):
- 525i BIG problems!

Originally Posted by bluebee

Here are the details I dug up for you ...

Overheating a BMW E39 engine is the most common cause of blown head gaskets, cracked heads, warped blocks, cam seizures, contaminated main bearings, coolant-caused hydrolock, & piston, ring, & valve damage in the BMW E39, particularly those with the aluminum block (1) (2) (3) (4).

If you think you might have a blown head gasket, you don't have many options (the solution would have been to not to let it happen in the first place), especially since, by some reports, only 1 out of 20 aluminum engines are rebuildable after exhibiting symptoms of a 'blown head gasket' (which may be a misnomer of sorts given that the problem is usually a warped block and/or a cracked cylinder head, in which case, it's time to replace the engine (1) (2)).

But, if it is 'just' a head gasket you need, these are your options:

• Replace just the head gasket (not likely this, alone, will work on E39s with aluminum engine blocks)
• Repair the engine, machine the valves, grind the head, repair the pistons, fix bolt holes, etc. (as needed)
• Replace the engine (often the lowest-cost solution overall)
• Sell the car (and cut your losses)

Now ... maybe ... just maybe ... your head gasket is not blown ... (if you're lucky) ... and your head isn't cracked ... (doubly lucky) ... and your block isn't warped (triply lucky) ... but, nobody here at the other end of a keyboard can actually tell you that.

You need to run some basic tests:

• Cooling system pressure test
• Cooling system exhaust-gas "geyser test" (1)
• Cooling system exhaust-gas "analyzer test" (1)
• Cylinder compression tests, wet & dry (1)
• Cylinder leak down test (1)

Here are references for pricing out parts and labor & for finding a mechanic:
- BMW phantom diagrams (1) & nominal prices by part number (1) labor rates by zip code (1) (2) (3) where to find a good mechanic (1) (2) & finding a specialty BMW indy in your area (1)

Bear in mind, the entire BMW cooling system is a time bomb to overhaul the cooling system in any case.
- Complete cooling system overhaul recommended parts list (1)

Don't believe me. Believe these pictures:
- Pictorial look at typical E39 cooling system failure modes (1)

When this time bomb goes off, if you don't immediately STOP driving the vehicle, the engine can easily become toast. Again, don't believe me. Believe these people from these representative threads:
- 525i BIG problems!
- Major Decision - replace head or buy "new" engine
- E39 528i Engine removal/replacement
- Overheating and water loss
- Replace head gasket or replace engine
- E39 528i Engine removal/replacement
- E39 540i low compression
- Possible blown head gastket, but no mix of oil/water yet
- Blown 528i update.....New motor advice & subsequent Engine swap advice....528i
- Advice on getting new cylinder head assembly.
- 2001 528i engine
etc.

For a head gasket DIY, you might try these:
- BMW Head Gasket Replacement, Pelican Technical Article, by Wayne R. Dempsey
- Journal: M54 Head Gasket Replacement & Other Stuff Too
- M62TU Head gasket/ Timing guides journal
- DIY This! One Person M54 Cam Removal
- Replacing the M54 head gasket (1)
- Replacing the 540i cylinder head (1)
- (Note: I need more and better DIY links.)

The basic cylinder head gasket DIY procedure is outlined below:

• Raise the front of the car to gain access to drain plugs
  • Drain engine oil (probably contaminated with coolant)
  • Drain coolant (probably contaminated with exhaust gases)
• Remove radiator viscous fan clutch & fan assembly
  
  • This job is easier if you purchase two recommended tools
    
• Remove the radiator & the attached expansion tank assembly
  • Optional: Flush (or replace) the radiator & replace all hoses
• Remove both drive belts
  
  • Optional: Replace with new
    
• Remove the water pump & thermostat unit
  
  • Optional: Replace OEM plastic impeller waterpump with an aftermarket metal impeller design
    
• Remove the ignition coils from the head & remove the spark plugs
  • Optional: Replace with new
    
• Remove the valve cover to access the head bolts
  • Check for head bolts yanked out of their threaded holes by force!
    
• After using the special camshaft alignment tool, remove the camshaft
  • You 'can' replace the head gasket without removing camshafts
  • But, head resurfacing requires camshaft removal
    
• Remove the intake manifold (to access the cylinder head)
  • Optional: Consider replacing your knock sensors after removing the intake manifold
    
• Remove the VANOS unit (to access the cylinder head)
  • Optional: Replace the VANOS seals while you're there
    
• Remove the camshaft position sensor (CMP) from the cylinder head
  • Optional: Replace the crankshaft position sensor (CKP) while you're there
• Remove the lower timing chain tensioner to loosen the chain on the camshafts
• Disconnect the VANOS oil line (to access the cylinder head)
• With a special tool inserted into a hole in the engine block & flywheel, lock the engine at top dead center (TDC) for cylinder number 1
  
  • This is to accurately time the camshafts when you reassemble the engine
    
• Remove the cylinder head bolts hidden under the camshaft with a special Torx socket tool
• Enervate all electrical connections and heater core hoses innervating with the cylinder head
• Disconnect and loosen the exhaust manifold
  
• Remove the cylinder head
  
  • Tie off the timing chain so it doesn't fall into the block
  • Remove the camshafts prior to sending the head for reconditioning
    
• Send the cylinder head to a machine shop for resurfacing
  • Don't forget to save the oil pressure check valve on the bottom of the cylinder head
    
• Have the machine shop check for cracks in the cylinder head
  • A crack will cause any new head gasket to fail!
  • Cracks 'can' be repaired by the machine shop
    
• Have the machine shop measure, lap, and grind the valves
• Optional: Have your fuel injectors cleaned & 'matched' (1)
  

Note: While the parts are off the car, you may as well:

• Do a complete cooling system & belt-drive system overhaul
• Replace your VANOS seals
• Replace your camshaft position sensor (CMP) and your crankshaft (CKP) position sensor
• Replace the valve cover gasket (VCG)
• Replace your spark plugs
• Replace the oil filter housing (OFH) gasket
• Send your fuel injectors out for cleaning (1)
• Consider replacing your knock sensors (once the intake manifold is off)
• Consider replacing your oil pressure check valve (on the bottom of the cylinder head)

Good luck. Keep us informed.

Unfortunately, even after all that 'help', the OP of that prior thread simply disappeared. Sigh.

Anyway, undaunted, we should still strive to help those that are worth helping (you don't always know ahead of time who is worth our valuable time and effort).

Here's another writeup I made for the following thread that might help others in dire need:
- Replace head gasket or replace engine.

Originally Posted by bluebee

To the team:
Please tell me what I missed in this attempt at a quality response?
And, why aren't there more head gasket DIYs?
Please improve the "typical scenario" below as I don't have the technical expertise to write this important paragraph!

To the OP:
We're very sorry to hear about this issue. The main problem is that the BMW cooling system is a time bomb. If not periodically overhauled (about every 6 years or 60,000 miles), the cooling system "will" leak in multiple places ... (see pictorial reference here). If you drive for even a few minutes with an overheated engine, the aluminum heads warp & crack, often causing bolts to pull out of the aluminum block E39s (some E39 blocks are, thankfully, cast iron and are less susceptible to this common problem), and other internal damage to the engine (valves, cylinder walls, piston rings, etc.). This is bad. Very bad. The cost for parts is nothing compared to the labor rates involved. Half the engine needs to be removed. If you "suspect" this problem, you really need professional advice with the engine being TESTED! Your options are to replace the parts (expensive), replace the engine (expensive), or buy a new vehicle (expensive). Plus the car will be out of service a minimum of a couple of weeks realistically. Did I mention you really must get professional advice from someone who has the engine to test in front of them? Good luck. And, please keep us informed as to your progress, if for no other reason, so that we may advise the next person who follows in your footsteps.

We get this question about once a week:
- 525i BIG problems!
- Major Decision - replace head or buy "new" engine
- E39 528i Engine removal/replacement
- Overheating and water loss
- Replace head gasket or replace engine
- E39 528i Engine removal/replacement

The problem is this is like asking a forum "I think I'm having a heart attack ... what should I do?". You may be in serious trouble; so you need professional help. Up 'till now, this was my standard response (1).

o 1997-1998 6-cyl M52 engine: iron block, ferrous-liners?, aluminum head
o 1999-2003 6-cyl M54 engine: aluminum block, non-ferrous liners, aluminum head
o 1994-2005 8-cyl M62/S62 engine, aluminum block, non-ferrous liners, aluminum heads

However, I'll try to consolidate the questions from those last few threads to come up with a more standard (i.e., artificial intelligence) approach for improved efficiency.

For quality control, I would ask subsequent posters to help us hone this questionnaire below...

To the OP:

1. What happened?
   • Who was driving (i.e., reporting what happened)?
   • Did the car overheat?
   • How long did you drive it overheated?
2. What is the vehicle?
   • What vehicle (i.e., engine) do you have?
   • What is the age, miles, condition?
   • Do you (really) want to keep the car?
3. What is your situation?
   • Can you afford the few thousand dollars to spend on the fix?
   • Do you have (or want to have) the appreciable skills to DIY?
   • Can you allocate the weeks-long downtime while it's being repaired?
4. What symptoms do you have now?
   • Do you have white smoke in your exhaust?
   • Is your engine running rough or not at all?
   • Are you losing coolant?
     • Is it visibly leaking?
     • Is your dipstick oil somewhat milky?
     • Does your oil or exhaust smell somewhat sweet?
5. What tests have you run?
   • What are your wet/dry compression pressures? (1)
   • What is your cylinder leak down results? (1)
   • What is the cooling system pressure test result?
6. Have you had a professional price out your options?
   • Comparison cost of a replacement vehicle = ?
   • Installed cost of a replacement engine = ?
   • Labor rates for a replaced head gasket = ?
     • Warning: "Head gasket" costs often escalate due to unseen issues like the bolts ripped out of the aluminum heads or damaged rings, cylinder walls, or valves, etc. Pad accordingly!
7. If you decide to fix the engine yourself
   • Remove the head, check for warp & cracks & check bolt holes for threads & check cylinder walls, pistons, rings, & valves for scoring and pitting
   • Here are the DIYs (note to self: why aren't there more headgasket DIYs?)
   • - Journal: M54 Head Gasket Replacement & Other Stuff Too
     - M62TU Head gasket/ Timing guides journal
     - DIY This! One Person M54 Cam Removal
8. While you're at it, replace a few other maintenance items
   • Vanos seals
   • CCV, ICV, & DISA valves
   • All cooling system & belt-drive system parts

If the OP is a newbie, which often is the case, then these links below should help with pricing:
- BMW phantom diagrams (1) & nominal prices by part number (1) labor rates by zip code (1) (2) (3) where to find a good mechanic (1) (2) & finding a specialty BMW indy in your area (1)
- Where to get a new engine for your E39 (1)

I just did some research and found plenty of advice to cull through for newbies faced with this problem.

Here, for the record, are more blown engine references to cull solutions from for a newbie faced with this big decision:
- Engine is apart
- Anyone have info/advice for DIY head gasket repair on 2003 525i E39?
- Breaking BMW E39 528i
- 1989 535i help please
- Head gasket done but still overheating ahhhh
- bad bleeding or blown head gasket
- Overheating and water loss
- SH!* blown head gasket!! question..
- Very confused about this over heating thing
- Add me to the "overheat" club
- 2.8 L e39 528i engine for sale
- Choc milk coolant
- I Need Immeadiate Help

Would this fluorescent-dye test work for testing whether an engine has a major problem?
- Bad electric thermostat causing rough or fluctuating idle-

Originally Posted by BigCo540i

*UPDATE *
Rough idle solved. Just got her back from the shop and everything is running great. They put florescent dye in the oil and coolant that will light up with a certain type of light if any leaks were to appear. 2 year 24 month warranty on the work.

The inside of my engine was really clean with no sludge and hardly any wear on the cam lobes and chain guides. Synthetic has done its job for 150k mi.

A few weeks ago, I felt badly about the fact that people were coming in (more and more) with symptoms of a badly heated cooling system suspected of damaging

and we didn't have a comprehensive answer for them that outlines ALL their options.

Since then, I've spent probably ten to fifteen hours on compiling the last two dozen recent ruined-engine sad stories (of suspected blown head gaskets, cracked heads, warped blocks, cam seizures, contaminated bearings, coolant hydrolock, or piston, ring, and valve damage) into a comprehensive set of options & recommendations and put it all in keyword rich sentences in the bestlinks.

Note: For example, here are the last two dozen known ruined-E39-engine stories to learn from:
(1) (2) (3) (4) (5) (6) (7) (8) (9) (10) (11) (12) (13) (14) (15) (16) (17) (18) (19) (20) (21) (22) (23) (24).

But, a new option came up today, thanks to Franka in post #23 over here:
- E39 (1997 - 2003) > I Need Immeadiate Help

You can read his suggestions over there; this is the suggested product and here is a testimonial, of sorts.

Bluebee, I'd be curious to know where the cognoscenti on this site rank Bars Leaks in the matrix of options. For instance, for a blown head gasket, where the engine had only overheated briefly, my first reaction would probably be to replace the head gasket before I tried Bars Leaks and only use Bars Leaks as a last resort. But the more I think about it, the more it seems like it would depend on whether I was looking for a short-term or long-term solution. The intriguing thing is, Bars Leaks might also work for the longer term. Does anybody have statistics on how long the Bars Leaks solution holds up?

Originally Posted by bobdmac

Does anybody have statistics on how long the Bars Leaks solution holds up?

I too would love to know the answer!

BTW, after reading more than a few dozen sad stories, I just now created this set of tentative links to help the NEXT inevitable person who writes in with a suspect blown engine due to overheating.

As always, BETTER links are always welcome!

- Summary advice to provide users who suspect a major engine repair due to overheating (1) & how to test an engine for blown head gasket, cracked heads, a warped block, cam seizures, contaminated bearings, coolant hydrolock, or piston, ring, or valve damage (1) (2) & a well researched reusable response to a particular user with a blown engine (1) & what questions to ask when severe heating-related damage is initially suspected (1) & what E39 engine swaps are most recommended (1) (2) (3) & how to lift & remove the engine (1) & where to obtain a new or rebuilt replacement short block or long block (1) (2) & why the E39 engines are so prone to heat-related damage in the first place (1) & real-world results from people faced with similar blown engine problems from which this advice came from (1) (2) (3) (4) (5) (6) (7) (8) (9) (10) (11) (12) (13) (14) (15) (16) (17) (18) (19) (20) (21) (22) (23) (24) (25).

For the cross-linked record, this sad blown-engine story has a nugget of useful information for those (like I was) who didn't know there is an 'oversized head gasket' we can put on our engines:
- E46 (1999 - 2006) > depression between the #5 & 6 cylinders

Originally Posted by wddanie

I can see from the invoice that they used a normal .7mm thk head gasket (11-12-7-501-304) and not the oversized 1 mm thick gasket (11-12-7-501-305).

For the record, there is good advice on how to test for a blown engine due to overheating over in this E46 thread today:
- - E46 (1999 - 2006) > Lost Cause? I need blunt honesty here...

Originally Posted by moneymike

Ok guys awhile ago i was having overheating issues...it was actually my brother...so the upper radiator hose blew...car over heated & he drove it for 10+ miles while overheated...at stoplight car cuts off...he restarts...drives about another mile & cat cuts off again...this time wont restart...tries a few times & finally it restarts...drives another .5 miles to destination & as pulling into driveway hears a rapid knocking...once the hose was replaced & coolant returned the car has been running...no knocking...no real issues but it has started gradually running worse...is there any tests to know for sure if there is internal damage?

The good news is that a lot of good advice resulted which the OP of this E39 thread can quickly benefit from.

For example:

Originally Posted by floydarogers

The chances are slim. I'm amazed that you're not losing coolant. Nevertheless, here's what you need to do:
1) Flush the coolant. Look at it; if there is oil or other contaminants, you're toast.
2) Pressure test the cooling system. If it doesn't hold pressure, there's a leak somewhere. Not losing coolant VOLUME isn't a guarantee of the engine being intact.
3) Change the oil - it was under incredible stress as it was the only thing cooling the engine. It's toast. Again, inspect the old oil, filter and drain plug. If there are metal shavings-bits-filings, you're probably toast.
4) Do a compression test. Do a leak-down test. This will show if you have bad rings/cylinders or burnt valves.
5) Have someone check the oil pressure (you need a real guage and hose to connect to the system.) If low or high, may indicate bad bearing or turned bearing (which is the likely noise heard when pulling into the drive - might also be bad kingpin.)

If all that looks "ok", you may be ok. The operative word is "may", as these engines don't like being overheated AT ALL. However, it's not unheard of to hear of abuse like this and having them last for some time. The engine's lifetime has been adversely affected at the minimum.

Originally Posted by jvr826

Contact Blackstone Labs, get an oil test kit sent to you, and collect a sample and have it analyzed. If you are in a hurry to change the oil, collect the sample prior to receiving the kit. You need a warm engine and a clean vessel with a cap, open the drain plug and let it flow for a few seconds (5-10), then duck your vessel into the stream and collect 3-4 ounces. They will let you know the percentage of coolant in the oil, if any. I suspect you'll find quite a bit.

You are in the denial phase of grief. Soon comes acceptance. You'll want to throw money at your engine, but listen to the experienced folks. It will save you time and money in the long run.

Originally Posted by SJBimmer

That is great advice all around. Unfortunately for the people who don't listen, the first time they realize that they were wrong is after they have spent a lot of money having the head re-milled, buying a new head gasket and then trying to put it all together. They go to torque the new head bolts and they pull out like butter. Time serts MAY solve the problem, but if they don't, all that money, that could have been put towards a replacement engine, has been wasted. That is when extreme frustration occurs, and they sell what might have been a salvageable car, spew all sorts of obscenities about BMW's, and vow to never buy another one.

Originally Posted by Variocam

Lots of great comments here, but I especially agree with jvr826's about the oil analysis. They are very cheap, and will give you a wealth of information as to whether the engine has suffered major damage. You should definitely tell them in the "comments" section of the submission form about the overheating episode, so they can pay special attention to the aspects of the analysis that might pertain to to the impact on the oil of overheating.

But to get the maximum bang for your troubleshooting buck, I would do the following:

1) Warm up the engine
2) Do a compression test. If this shows an obvious problem like, well, low compression in one or more cylinders, stop, and start searching for a replacement engine
3) If the compression looks OK (not sure what the spec is, but the readings should all be within about 5% of each other across all the cylinders), drain the oil, and fill the oil sample vessel after letting it drain for a few seconds, like jvr says (the idea is to take the sample about midway through the drain), send the sample out for analysis, and pray.

For the record, I added that useful thread as recent example #41 to the list below for others to benefit, as always, by the virtue of incrementalism:

- Summary advice to provide users who suspect a major engine repair due to overheating (1) (2) (3) (4) & how to test an engine for a blown head gasket, cracked heads, a warped block, stripped head bolt threads, cam seizures, contaminated bearings, coolant hydrolock, or piston, ring, or valve damage (1) (2) & what are the major factors in deciding whether to rebuild the engine, replace the engine, or sell the car (1) & a DIY for replacing the I6 M54 head gasket (1) (2) & replacing the V8 M62TU head gasket (1) & why these engines are so prone to heat-related damage in the first place (1) & welding the crack between cylinder #3 and the water jacket on the exhaust side (1) & what engine swaps are most recommended (1) (2) (3) & where to obtain a new or rebuilt head (1) replacement short block or long block (1) (2) & how to lift & remove the engine (1) & real-world results from people faced with similar blown engine problems from which this advice came from (1) (2) (3) (4) (5) (6) (7) (8) (9) (10) (11) (12) (13) (14) (15) (16) (17) (18) (19) (20) (21) (22) (23) (24) (25) (26) (27) (28) (29) (30) (31) (32) (33) (34) (35) (36) (37) (38) (39) (40) (41).

I'm gonna stop the reference list at 50, as shown below:
- Summary advice to provide users who suspect a major engine repair due to overheating (1) (2) (3) (4) & how to test an engine for a blown head gasket, cracked heads, a warped block, stripped head bolt threads, cam seizures, contaminated bearings, coolant hydrolock, or piston, ring, or valve damage (1) (2) & what are the major factors in deciding whether to rebuild the engine, replace the engine, or sell the car (1) & a DIY for replacing the I6 M54 head gasket (1) (2) & replacing the V8 M62TU head gasket (1) & why these engines are so prone to heat-related damage in the first place (1) & welding the crack between cylinder #3 and the water jacket on the exhaust side (1) & what engine swaps are most recommended (1) (2) (3) & where to obtain a new or rebuilt head (1) replacement short block or long block (1) (2) & how to lift & remove the engine (1) & the most recent real-world results from the last 50 people faced with similar blown engine problems from which this advice came from (1) (2) (3) (4) (5) (6) (7) (8) (9) (10) (11) (12) (13) (14) (15) (16) (17) (18) (19) (20) (21) (22) (23) (24) (25) (26) (27) (28) (29) (30) (31) (32) (33) (34) (35) (36) (37) (38) (39) (40) (41) (42) (43) (44) (45) (46) (47) (48) (49) (50)

5BMWers

Sorry bout your motor,,I just replaced my motor in my touring,,,Total cost of having it done was about $3500. installed... I searched the internet for a long block and ended up with a better deal locally,,

If the motor was well taken care of I would think about repairing it,,, I think most BMW owners go waaaay to long between oil changes,, Finding a good quality used motor is not easy or cheap,,

I could guess the three most common reasons for a blown E39 engine are overheating (by far), DISA, and hydrolock.

On that third topic, hydrolock, this thread opened today has some useful information:
> E39 (1997 - 2003) > Squealing brakes and Rough Idle

Originally Posted by Topaz540i

this is a common problem. the drain tube in the cabin filter clogs leading to a brake booster sucking water. Many people have experienced catastrophic engine failure due to hydrolock.

Do not even start the car until you get the water out. You risk hydrolock blowing your motor up. You may find more info on this at bimmerforums.com as this seems to pop up about once a month there.

Another blown engine today:

Originally Posted by larryshomework

Just found out my 530i has a cracked block. Not sure how the moisture got in the block but the damage is done.

I'm leaning towards not replacing the engine and selling the car. Overall the car is in great condition (except for the engine of course) and someone else may want to put an engine in or part it out. Details - 03 530i, non-sport, AT, 84K miles, gray with black interior.

Any idea how to get a price range on what it might be worth as is?

This is a thread designed for pointing people to who have unexplained (as yet) overheating.

To that end, this post today (from yet another why-am-I-overheating thread) is a diagnostic jewel:
a) Either air isn't moving ...
b) Or water isn't moving ...
c) Or air has replaced water.

Originally Posted by hh3uunp

There are a few reasons why he would over heat.

1. There isn't any air moving throw the radiator
2. Coolant is leaking out somewhere AKA head gasket
3. Coolant isn't moving AKA waterpump impellers

I suggest that you test the fan clutch first then the oil for coolant. OP it takes 2 seconds to do these tasks. Try them and get back to us

One test we should point users to is this one:
Who here has tested the E39 head gasket using an exhaust gas analyzer on the coolant?

Bluebee you are a machine. Admitting that I didn't read through all of your references I wanted to ask a question regarding a potential cause of head gasket failure. I have bought a few e36s and one e39 with blown head gaskets. They all had the iron block engines and in every case that I was able to talk to the previous owner they admitted to running 87 octane fuel. My indy told me that extended use of low octane fuel in these high compression engines will cause certain damage most likely to the HG. This seems consistent with my direct though limited experience. How much of a factor do you think the use of low octane fuel is to the seemingly common problem of HG failure on the M50/M52 engines?

Originally Posted by kmorgan_260

extended use of low octane fuel in these high compression engines will cause certain damage

You're asking the wrong person since I've been using 87AKI since I was still under warranty and my previous high-end cars were the same.

There is a discussion thread on the octane monetary considerations over here:
- What is the cost differential between 87 & 91 octane AKI (1)

And, just recently, there was a discussion on whether or not an engine could possibly show overheating simply due to the octane differences (all assuming that the knock sensors are doing their job by retarding the timing as needed).

See also:
- How to understand the piezoelectric knock sensor operation (1)

In short, it's my experience & understanding that the cause of the blown engines has nothing to do with the octane rating - and more to do with something else.

See also:
- How does the E39 fuel injection work (1) & what are the most often recommended fuel pump & fuel filter brands (1) (2) & a DIY for replacing the fuel filter (0) (1) (2) (3) (4) (5) (6) & a quick test for fuel pump operation (1) (2) and a DIY for replacing the fuel pump (1) (2) (3) (4) (5) & how to replace and service your BMW E39 fuel injectors (1) & details on replacing the 7.52X3.52mm and 9.2X2.8mm fuel injector o-rings (1) & the location of the K96 fuel pump relay (1) & where is the fuel system pressure test Schrader valve for the I6 (1) & where is the fuel pressure test point for the V8 (1) (2) (3) & where is the location of the fuel pump relay K96 (1) & cleaning (1) (2) & replacing the fuel sensor (1) & resolving blown fuses due to a stuck fuel filler door solenoid (1) & engine fuel & octane (1) & The Gasoline FAQ & top-tier gas stations (1) & how large is the fuel tank and reserve in the E39 (1) & what gasoline to use (1) & how much gas should be left to cool the fuel pump (1) & how to siphon the fuel out of the tank (1) & does spilled gasoline go into the charcoal canister (1) & how to replace the gas cap tether (1) & a reputed fuel filler leak into the trunk (1) & the P0455 diagnostic trouble code when the gas cap is missing (1) & what is the cost differential between 87 & 91 octane AKI (1) & what gasoline mileage should an E39 get (0) (1) (2) (3) (4) (5) (6) (7) & the truth about mpg calculation accuracy (1) (2) & E39 great mpg stories (1) (2) (3) & E39 awful fuel mileage issues (1) (2) (3) (4) (5) (6) (7) (8) (9) (10) (11) (12) (13) (14) (15) (16) (17) (18) (19) (20) (21) (22) (23) (24) (25) (26) (27) (28) (29) (30).

Wow, thanks for the informative reply. I will read through and attempt to sort out fact from urban legend!

This test will find a cylinder #3 crack:

Originally Posted by Metlic53

ok i called the tech and he explained, he pressured up the 3rd cylinder and water sprayed out the radiator cap. all other cylinders were fine

And this thread has pictures of a typical cylinder #3 crack:
> E39 (1997 - 2003) > 2002 525i Cracked head

Another similarly blown engine posted today:

Originally Posted by ironman27

I just had my second diagnosis on my car and it has a blown engine. Looking to sell as i dont have the money to pay for a used one. Excepting reasonable offers. The car is located in New Jersey.

Here is the saga of a recently hydrolocked M54 that is in the process of being rebuilt:

Here is another cracked head, with a successfully welded crack:
> E39 (1997 - 2003) > Another cracked head

Originally Posted by H2odiesel

I got the Head off on 12/21, and I was relieved to see no sign of Valve butter as I like to refer to the oil and water emulsion that is formed after running for a time with oil contaminated with coolant. Upon close inspection the typical cylinder three crack from exhaust valve seat to coolant passage is present. I've decided to have a local company do the repair. They said they do them frequently and warranty the repair for two years. There were also two sets of heads on the counter waiting for the local BMW dealer to pick up, which I felt was a good sign. I dropped the head off with cams still installed along with all of the studs still in place. The counter man reassured me they understood the proper cam removal procedure. I'll get it back repaired with a valve job and new valve stem seals, fully assembled for $550. I think that price includes a $50 off locals discount.

There is a steel washer under each head bolt, and after removing the head bolt you can fish the washer out on edge through the Bearing ledge that supports the cam shaft and lifters. Does anyone have a tip on how to best get these washers back in place when reinstalling the head? I was considering running the washers up to the machine shop and have them stick them down with some assembly lube in there recesses.

Originally Posted by H2odiesel

Update: I've had the repaired head on for about three weeks now, and once I tracked down a slight coolant leak from an inadequately tightened hose clamp, the engine has preformed well. I also did the vanos repair while I had things apart and I can feel a distinct difference when accelerating. Here is a pic of the repaired area. If you look closely you can make out a little of the welded material in the coolant passage.

See also:
- Summary advice to provide users who suspect a major engine repair due to overheating (1) (2) (3) (4) & how to test an engine for a blown head gasket, cracked heads, a warped block, stripped head bolt threads, cam seizures, contaminated bearings, coolant hydrolock, or piston, ring, or valve damage (1) (2) & what are the major factors in deciding whether to rebuild the engine, replace the engine, or sell the car (1) & a DIY for replacing the I6 M54 head gasket (1) (2) & replacing the V8 M62TU head gasket (1) & why these engines are so prone to heat-related damage in the first place (1) & welding the crack between cylinder #3 and the water jacket on the exhaust side (1) & what engine swaps are most recommended (1) (2) (3) & where to obtain a new or rebuilt head (1) replacement short block or long block (1) (2) & how to lift & remove the engine (1) & the most recent real-world results from the last 50 people faced with similar blown engine problems from which this advice came from (1) (2) (3) (4) (5) (6) (7) (8) (9) (10) (11) (12) (13) (14) (15) (16) (17) (18) (19) (20) (21) (22) (23) (24) (25) (26) (27) (28) (29) (30) (31) (32) (33) (34) (35) (36) (37) (38) (39) (40) (41) (42) (43) (44) (45) (46) (47) (48) (49) (50)