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Discussion Starter · #1 ·
My z3 overheated the other day and ended up melting the plastic part coming out of the back of the cylinder head. I replaced that, the hose, and the thermostat. I have an extra water pump but didn't install it yet.

The car continues to overheat....both while idle and driving.

Does anyone have any suggestions.... such as maybe temp sensor, how i can tell if my water pump is bad....any tips to diagnose the system.
 

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The hose coming out of the engine, going into the top of the radiator should be hot to the touch when the car is warmed up (watch out, its really hot). If not, then water is not flowing through the coolant system. That means the termostat is closed shut, the pump isn't pumping, or there is a clog.

If your coolant fluid level is always low, you have a leak, and that's causing the over heating.
 

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IF it continues to overheat, the water pump probably failed = no coolant circulating.

Did you melt the coolant manifold on the back of the engine ? or did it leak at the O-ring/flange??
If you melted the plastic manifold, you probably warped the head too....worst case scenario but not uncommon on the 4 cyl M-42/44's if they're driven a long time in the overheat mode. SRY
 

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Discussion Starter · #5 ·
update...still overheating

So far, I have replaced the coolant manifold on the back, replaced the water pump, replaced the thermostat, replaced the hose in the back that goes to the coolant manifold, replaced the two hoses to the radiator, and flushed the system.

The coolant manifold has a 'Y'. It first busted a whole in the middle of the Y. We patched that so that I could get the car home....During which the larger pipe into the coolant manifold busted off.

I have not seen any smoke coming out of the exhaust. I also have not noticed any moisture on the exhaust tips, they are very dry.

The blower in my car has not worked for a while...so I'm not even able to turn that on to assist with blowing off hot air.....I replaced the resistor but it still fails to go on. I'm currently testing the fan that goes over the radiator; I don't believe it's turning on.

At this moment I let the car idle until it was warm.....at which point i drove the car around the block a few times. After a few laps i noticed it began to go over the norm and heading to hot. I parked the car and it idled for a while longer without getting hotter (sitting right on the line). I then just turned off the car before it got worse. Oh....the top radiator hose remained cool until the car reached normal operating temp.....when it started to overheat the top hose got hot and the bottom hose remained cool.

I did not see any leaks anywhere at all. I keep checking the dipstick and I haven***8217;t noticed any water on it and the level oil is remaining steady.

How can in find out if I warped the head or need to replace the head gasket....if i did warp the head any idea what I'm looking at to fix it?

Any information would be appreciated...Thanks everyone for the input
 

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Discussion Starter · #6 ·
compression test results....any input?

I finally got around to doing the compressions test. At the moment the car can idle without overheating. Driving still causes it to overheat but if i park it it cools itself off slowly back to normal. The blower inside my car is not working, but when it does let anything in it's cool air, never hot.

So, the compression test. Here are the results
cyl 1: 161
cyl 2: 150
cyl 3: 151
cyl 4: 170
The numbers are all over the place. What could this mean? (I hope not what i think it could mean)

Things noticed:
  • after compression test cyl 1 was the only one that had some white smoke come out after i removed the testing hose.
  • cyl 1 socket had some oil in it, cyl 2 had less, cyl 3 has alittle, cyl 4 is in near perfect condition
  • sometimes during the compression test i heard a pop, not sure if this is normal
  • Needle was always on the rise during all of the tests
  • When complete, i tried testing cyl 2 again i got a 120, but i don't think the engine was turning as quickly plus the engine had now pretty much cooled off.

any ideas? Could my head be alright and I may just have a blockage in the heater core maybe?
 

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I finally got around to doing the compressions test. At the moment the car can idle without overheating. Driving still causes it to overheat but if i park it it cools itself off slowly back to normal. The blower inside my car is not working, but when it does let anything in it's cool air, never hot.

So, the compression test. Here are the results
cyl 1: 161
cyl 2: 150
cyl 3: 151
cyl 4: 170
The numbers are all over the place. What could this mean? (I hope not what i think it could mean)

Things noticed:
  • after compression test cyl 1 was the only one that had some white smoke come out after i removed the testing hose.
  • cyl 1 socket had some oil in it, cyl 2 had less, cyl 3 has alittle, cyl 4 is in near perfect condition
  • sometimes during the compression test i heard a pop, not sure if this is normal
  • Needle was always on the rise during all of the tests
  • When complete, i tried testing cyl 2 again i got a 120, but i don't think the engine was turning as quickly plus the engine had now pretty much cooled off.
any ideas? Could my head be alright and I may just have a blockage in the heater core maybe?
Head gasket. I have done them twice on M20's and just buttoned up one yesterday on my GF's Mazda. They usually blow towards the corners or in the front/back. How many miles are on this car?
 

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Discussion Starter · #8 ·
the engine has around 60k miles on it. I heard a new head gasket could cost alot to have put on. Could this definitly be my reason for overheating? I'm looking to maybe keep the car running somehow for a just a little longer, just enough time to get another car I can drive, then put this in a garage and work on it.

If cost is too high to get car running again without overheating I'm just going to have to junk it.
 

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Head gasket leaks don't normally cause overheating unless it's severe or you ignore it and let it taint your oil, which can potentially cause a lot of collateral damage. If severe, it might explain your problems; combustion pressure might be the cause of the problems you had with the 'Y' and other piping.

Should not be too difficult to replace the head gasket on a 1.9, though it's still a good few hours of work. White smoke is an obvious telltale sign that the headgasket must be replaced; it's not optional and you shouldn't be driving it until that's done. You'll also need an oil change after it's done, and I'd do a second shortly afterward (say 500 to 1000 miles). I'd send a sample of the oil that's in the car now to Blackstone Labs for analysis. If you had been doing this all along, you'd have likely known about the head gasket leak before it got bad. I known, hindsight is always 20/20, but it's one of the big reasons to do oil analysis at each oil change.
 

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Discussion Starter · #10 ·
Head gasket leaks don't normally cause overheating unless it's severe or you ignore it and let it taint your oil, which can potentially cause a lot of collateral damage. If severe, it might explain your problems; combustion pressure might be the cause of the problems you had with the 'Y' and other piping.

Should not be too difficult to replace the head gasket on a 1.9, though it's still a good few hours of work. White smoke is an obvious telltale sign that the headgasket must be replaced; it's not optional and you shouldn't be driving it until that's done. You'll also need an oil change after it's done, and I'd do a second shortly afterward (say 500 to 1000 miles). I'd send a sample of the oil that's in the car now to Blackstone Labs for analysis. If you had been doing this all along, you'd have likely known about the head gasket leak before it got bad. I known, hindsight is always 20/20, but it's one of the big reasons to do oil analysis at each oil change.
DWM, thank you for your input. My only issue at this moment with the car is controlling the overheating, otherwise it runs very well when I drive it around the block. But I will take your suggestion and stop driving it around. I ordered the oil test kit and will arrive soon. I'll be doing these for all my cars from now on.

I have no smoke coming from my exhaust tips but the white smoke from cylinder 1 after the compression test was alittle scary to see. It was hard to see so it may have happened to the other cylinders but didn't notice it cause the flashlight may not have been at the right position.

Is there anything anyone thinks I can do to maybe get the car running for alittle while, or my compression numbers say no way. I'm ok with paying to have the headgasket done if I can do something else while I'm in there to increase performance of my engine, something to make it worth while doing. Otherwise, if the cost of just replacing the gasket is $800 or over I'd rather just sell the hamman parts of my car and call it quits (I already spent 3k 2 years ago for this engine).

I live in Branford, CT. Anyone recommend any local mechanics? Currently I can really only drive the car for like 4 miles before I need to turn it off for and let it cool for 20 minutes. (that does not mean overheating that means i let it hit the max normal range)

Any input to help me save my Z3 from forced retirement would be great.
 

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Discussion Starter · #13 ·
think it's game over

I did some research and found that the M44 engine is very likely cracked or warped after overheating...in which case mine had done so pretty bad. That news along with the fact that if cyl 2 and 3 show low compression it's most likely a crack. Without access to a garage at this moment and the cost of a new head and labor being around $1400. It's going to have to be Game Over for the Z3. Hopefully the money I get for selling Hamann, Projector Z, and other parts will be enough to cover a beater.

If anyone has further suggestions in the CT area I'm still listening.
 

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Your compression numbers are within spec. It sounds to me like you're fishing for reasons to sell the car, in which case I've little advice to offer you. I will tell you it's foolish to jump to conclusions before the head is pulled. If it were me, I'd pull the head myself, take a good look and take the head to a machine shop. Aluminum heads can often be repaired and if there's no crack all you'll need is machining/surfacing and a new head gasket (preferably MLS so it's unlikely to happen again).

In terms of close to you for head work, I'm not sure. Maybe Kehl Technology in Northford. (203) 484-4808
 

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Are you doing the compression test with the engine running or the type where you just crank the engine? I use the crank method........ In order to tell if you have a cracked head, sometimes you can spray WD40 (generous amount) into the sparkplug hole and if its a crack you'll maintain the lower number, if it's rings the oil will fill the scratches and the pressure will go up. I've never had the head off my Z but I agree, in part, with Daniel.... it's not that hard to pull it before you junk it.
 

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1.9 Overheating

: popcorn: Did I miss something or did we go streight to head gasket/warped block, cracked block?

Try burping your system.... put it up on front ramps, turn heater to full hot (I know no fan) then bleed the system.
 

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On one of my E30's the gasket blew from the water jacket to outside. Caused over heating that could be controlled and then one day just poof , white smoke everywhere. I second the pull the head idea. These are easy engines to work on with the two piece intake.
 

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Check the radiator.

It has been my experience that the rad on the 1.9 causes lots of problems. The first time the issue was diognosed as a warped head due to overheating. NOT!!! There was a chunk of change wasted. The radiator was shot. Idleing it was fine, putt putting around in the first 3 gears it was fine too. Hit the freeway and there she went straight to hot. I just recently put the third rad in my car and will always put a new rad in when doing the cooling system maint.
 

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Fred is right, and I thought I had already posted that but it must've been during the nasty storms when my connectivty was being flakey. A minute after the thermostat opens, point an infrared temperature gun at various points on the radiator. If temperatures aren't fairly uniform, you need a new radiator. I'd still want the head off due to the white smoke and having overheated it more than once. If you need a new radiator, I'd call Max (www.oembimmerparts.com)

Blackstone analysis will tell you if coolant has found its way into your oil, but it might take a bit to get the sample kit (they don't seem to be consistent about it... two of my sets of four have arrived quickly, two have not).
 
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