Getting the head cleaned/cut. Some warpage going on there and some coolant leaks. Waiting to hear if he found any cracks. Damn thing was a bear to pull off with all the crap attached to it.
Anyway, look at the scale and crap on top of these pistons. Shop guy does engines for the BMW Stealer in Charlotte and told me to stop burning 87 octane because it puts huge thick carbon deposits all over the place.
That was my reaction when I took the head off. Unbelievably disgusting. Don't think I've seen that since the carb days. No more crap gasoline for me. That avg $1.40 savings at the pump for an 8-10 gallon fillup costs more down the road.
166,500 and some change. Had to pull the head cause I couldn't find the source of a coolant leak after replacing the reservoir. Glad I did because the head was warped. Tech put the straight edge on there and pulled out his feeler gauge.... it slipped under there with ZERO resistance at the highest tolerable thickness gauge.
Getting it pressure tested and cut. Hopefully, he won't find any cracks, if he does and can fix it, fine. If he can't fix it, guess I'm saving up for a new head.
No, but I believe it's a lower quality gasoline and the crap that is in it that may be responsible, that and the fact that my CCV had peanut butter pouring out of it when I removed it.
Happens all too frequently.
Do you think there is a possibility those heavy combustion chamber deposits happened during the overheating episode?
Went and got a wire brush attachment for my drill. Pretty fine wires, and if I don't put too much pressure on it, it shouldn't take off any appreciable metal. I'll put each cylinder at TDC before I do it and use a vacuum to suck out the mess.
Actually, that is the plan. Mask off the cylinders with the pistons not at TDC, scrub and vacuum at the same time. I've done something similar on other engines I've rebuilt, mostly chevy's.
Costco (also amazon dot com) sells a fiberoptic camera for $130 (similar to colonoscope that doctors use to look at bowel).
This camera has multiple purposes. it allows to inspect engine pistons etc. etc.
- Octane 87 does not do this.
- The common causes of carbon build-up on top of the pistons:
a. Mixture too rich
b. bad spark plugs create incomplete combustion
c. Oil consumption, in your case it could be a blocked CCV.
Yeah, I figured the CCV had something to do with it, even though no usual CCV symptoms show. I don't know, this guy rebuilds engines and heads for Hendrick BMW in Charlotte. I'm going to heed his rant and never use 87 again in either E39.
Actually, despite my appreciation for people who use the recommended fuel in their cars, higher octane burns at a *lower* temperature than lower octane. Additionally, "proper" high-octane gas (i.e. gas that isn't ethanol blended to achieve the octane rating) gets there with higher levels of aromatic compounds that will increase carbon build-up if the car isn't built for it***8230;and whether or not our cars are is up for debate, but they're not super-high compression engines.
Actually, despite my appreciation for people who use the recommended fuel in their cars, higher octane burns at a *lower* temperature than lower octane. Additionally, "proper" high-octane gas (i.e. gas that isn't ethanol blended to achieve the octane rating) gets there with higher levels of aromatic compounds that will increase carbon build-up if the car isn't built for it….and whether or not our cars are is up for debate, but they're not super-high compression engines.
Just got back from dropping off my camshaft raceways and caps at the shop, and this is almost exactly what the owner told me word for word. He said that regardless of the octane ratings, the lower octane fuels produce more carbon which coats everything and.... this is important.... clogs the tiny passageways and sensors in the emissions sensors. Said that BMW engines were not built to withstand long time use of low octane "cheaper" fuel.
Either way, I'm gonna stop being cheap and start using higher grades of gasoline. For a 10 gal fillup, what am I saving by using 87? Maybe $2.50? $3.00? About $12-15.00/month? Is it worth it?
BTW, this old guy who does work for the dealer is a BMW schooled tech. Now, I know how we all feel about them, but either way..... I'm sure that using a better cleaner fuel will not hurt me.
Mine looked exactly the same when I pulled the head for a HG job. I suspected a coolant to cylinder 6 passage way leaking very small. The car never really overheated but would warm up with sprinted driving. I used roll-loc disc and sea foam, I then followed that with carb cleaner to get in the piston skirts with compressed air to blow it out. The compressed air helps a lot. Also after you will want to change your oil to get out any cleaner that seeped past the piston. 10k later and my car is great.
This post goes toward validating the argument AGAINST using low octane fuel vs recommended high octane. I always use 9X grade and some tried to argue in favor of 8X. Lower octane gas is less stable than high octane (under pressure). Pressure exerted on 8X by the pistons may prematurely ignite the 8X crap-gas (aka knocking). Our engines correct for the premature ignitions by changing the timing (prevents knocking). yet people STILL try to argue in favor of using crap-gas based on science that has ZERO to do with the reason BMWs require high octane fuel. BMWs have a high compression ratio as with most "performance" cars. Higher the compression the more likely 8X will ignite prematurely which is then corrected by throwing off the engine timing to compensate.
Crap-gas misfired timing WILL impact your fuel-air mixture. Which, in turn, CAN lead to more carbon buildup over time. As for the rest of the unrelated information, nothing promotes using 8X octane beyond people trying to drive an executive level car on a shoe string budget.
THANK YOU for this post as a picture says 1000 words. Not just because it validates my stand, more so because it is very educational for us all.
This post goes toward validating the areguement against using low octane fuel vs recommended high octane. I always use 9x grade and some tried to argue in favor of 8x. Lower octane gas is less stable than high octane (under pressure). Pressure exerted on 8x by the pistons may prematurely ignite the 8x crap-gas (aka knocking). Our engines correct for the premature ignitions by changing the timing (prevents knocking). Yet people still try to argue in favor of using crap-gas based on science that has zero to do with the reason bmws require high octane fuel. Bmws have a high compression ratio as with most "preformance" cars. Higher the compression the more likely 8x will ignite prematurely which is then corrected by throwing off the engine timing to compensate.
crap-gas misfired timing will impact your fuel-air mixture. which, in turn, can lead to more carbon buildup over time.
thank you for this post as a picture says 1000 words. Not just because it validates my stand, moreso because it is very educational for us all.
Carbon Buildup in combustion chamber has many many causes. The bottom line is:
- Gasoline leaves behind a tiny of carbon when burned. Do this experiment outside on your driveway: burn a small amount of gasoline, maybe 10-20cc in a small metal can, and see what is left behind.
- Oil leaves behind a lot of carbon when burned. Do the same experiment using 10-20cc oil.
Don't tell the enviromentalists you are doing this (j/k)!
2. Engine Oil somehow gets into the combustion chamber:
- Loose piston rings (unusual before 200K for M52/M54 engines)
- Loose valve guides (unusual before 200K for M52/M54 engines)
- Clogged CCV ---> #1 cause in M52/M54 engines
Made a little headway yesterday, scrubbed out three of the six cylinders. It's not easy to do holding a vac and the drill with the wire brush at the same time while trying not to strip the tape off of the oil and coolant holes that I plugged up to keep grit from dropping into.
Oil is already drained but I think I'm going to pour at least one quart into the top of the head when I get it back to clean up any errant dust I created out of the oil passages when I get it back on.
CCV ordered (OEM), new vac hoses and coolant temp sensor to be picked up tomorrow, cut to fit, and staged. Going to scrub the intake manifold real good and try to get any leftover oil out of the inside of it.
Should hear from the shop either tomorrow or Monday about whether or not they found any cracks. He inspected it good when I took it in and found no obvious signs of cracks, but still getting the pressure test done. I might have him look at one of the screw holes for the t-stat housing because I think the lower one may be partially stripped.
I'll be inspecting the camshafts with a bright LED light tomorrow morning to check for signs of wear. Remind me to tell the story of a Chevy cam I didn't inspect years ago and the resulting catastrophic failure 10 miles down the road after the rebuild (it was cracked).
In all of the engines I've ever rebuilt, I've never come across something like this. Trying to find a safe way to clean this filth up. Scale and crust at the top of the cylinder above the upper limit of the rings.
I think it's gonna be Scotch Bright pads and a little brake fluid. It's pretty soft so should come off pretty easily. Then, a razor blade and scotch bright to the mating surfaces. Ordering parts is going to wait until after I hear from the shop with a "Go" or "No Go" on the head.
Holy macro man! Never seen something like that. Anyways, GL with your rebuild. Imagine a 2000 e39 M5 with carbon buildup issue using that gasoline........
Yeah, it was nasty. Started cleaning out the intake today too. Plenty of loose oil in there so my guess is that the mess was mostly caused by the old CCV.
Yep, and I had always *intended* to replace the thing. Just been very busy and lack of motivation (and being cheap) since no outward symptoms presented themselves. I've never replaced it. Got the car in Miami in October of 04 and it had 109k on it. Has 166500k on it now. Runs smoothly, but it's about time the little things were taken care of.
To tell the truth, the oil consumption wasn't really that bad. I replaced the oil filter housing gasket about 6 months ago and that stopped the previous consumption issue I had. Since then, no real issues. I think I have put maybe a half pint of oil in there since.
I definitely agree with you that the CCV should be checked and replaced on a schedule. I feel guilty for not doing it before, but it's always been in the back of my mind that I should just go ahead and replace the thing.
Head is fine. It's been cut and cleaned up. Having him chase the thread holes for the bottom t-stat bolt (I think it was stripped). Still have to find the source of the leak. Possibly the warp was giving up some coolant under pressure. Hope that was it.
Going to clean up all 24 lifters, get my gasket kit, finish polishing the block surface, replacing all of the vac hoses, and get her back together.
Got a small round grinder to pull some of the crap out of the combustion chambers and the valve faces. Going to pull the valves when my gasket set gets here to replace the seals. Still trying to clean diagnose all 24 lifters. Have one with what seems to me is a "loose check ball" in the piston.
Quick question: There's the M54 engine lifter "issue" lately . brought up. Did you notice anything out of the ordinary"? Did you change them, or did you run the same? Did they look OK?
Not sure I understand..... I have an M52. I'm in the process of dismantling, cleaning, and reassembling the lifters. The only thing I see wrong is one of them has a fairly loose ball underneath the piston.
Couple more photos. Cam rails and a lifter in the middle of cleaning. Getting ready to run out and rent a valve spring compressor. Trick will be finding the appropriate one that will fit these valve springs. Going to pull the valves so I can replace the seals, clean the valves a little deeper, especially since the faces are still caked with carbon, then finish scrubbing out the combustion chamber.
Shouldn't need any shims, he said he didn't take much off the surface of the head when I asked him if I needed a thicker gasket. He didn't touch the combustion chambers and only cleaned the cam rail.
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