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It is beginning to feel like my '01 330ci's cooling system is posessed :loco:. Last winter I had an expansion tank failure that resulted in the car being severely overheated and placing stress on an otherwise weak head gasket :facepalm: I took my car to a friend who works at an Indy shop that specializes in imports - most specifically euro cars. The head was pulled and sent out to a machine shop where they said it was "very, very, slightly" out of spec - they milled it back and I had the gasket and entire cooling system refreshed. The car runs terrific now and sounds better than it has for quite some time, but I can't seem to get past the car either overheating or overflowing the expansion tank. I'm confident it's not a bleeding issue, I've bled the car over 20 times according to the popular posts with the front raised and the heater on set to 91 at the lowest fan setting... Not a single bubble. I've even bled the car over a 24 hour period just to make sure that there wasn't any air bubbles trapped in the heater core or one of the hoses. There are no signs of coolant in the oil, nor exhaust in the coolant.

To date, I've replaced:
  1. Radiator
  2. Expansion tank
  3. Thermostat (twice)
  4. Waterpump (twice)
  5. Upper Rad. Hose
  6. Lower Rad. Hose
  7. Lower coolant temp. sensor
  8. Heater inlet pipe (below intake)
  9. Fan clutch
  10. Expansion tank cap (twice)

Signs and symptoms are:
  • Expansion tank overflows the cap when coolant reaches temp and purges.
  • The car can hold a stable temp (once for abput 45 minutes!) without overflowing, but overflows the cap within 100 yards of being driven.
  • Zero system leaks until car "boils over" expansion tank cap.

Things I've checked are:
  • Fan clutch is operable
  • Thermostat opens\closes
  • Waterpump will push a steady stream through expansion tank weep hole
  • Pusher fan works like a champ
  • Good flow through new radiator
  • Upper radiator hose is expanded when thermo. opens
  • Lower hose gets warm after tank purges

I've also checked for blockage in the heater core valve, nothing is evident and the car's heater will kick out some seriously warm air at operating temp.

ANY educated guesses are appreciated at this point...
 

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Discussion Starter #2
Really? No cooling gurus out there interested in taking a stab??? One mechanic is saying that a cylinder sleeve may have slipped - I think that's doubtful as the engine is running like a top...
 

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xAP,

Well, you're not making it easy...almost everything is off the books.

Up until the end of studying your efforts, I was thinking water valve, and noticed the lack of certainty you had about it. It's also bringing coolant from the engine. I'll toss up a realoem diagram to get you in the neighborhood.

Some basics...fill the ET so the balls straddle the top of the filler neck. There are too many cooling posts. I say this when I think of it...because I know of all the different styles there are of bleeding.

I've changed my thinking on that in the last few months for bleeding after partial work on the system...but we'll say you've bled.

Look into the water valve. I don't know how it's set up internally, but I know it works both heating and engine cooling. It will undoubtedly shut off the heater core when it can, I don't know if the engine cooling hose just passes through directly, but I'd think there would be a valve there for whatever reason.

Sorry, I'm totally making this up because I don't want you hunting me down with Apache!

Work everything other than the 'maybe cylinder sleeve' issue.

Other basics--after market therms really bad; electronics fail all the time

In all this, could belt be slipping? Bad tensioner, not really driving WP as you think.

Did you install underdrive pulleys, AM WP...anything else however unrelated you might think it is.
If you were messing with AE or installing a horn from a fireengine under your hood, now would be a good time to fess up! :lmao:

Did you do something like not drain coolant and add one of the few really wrong coolants that could gunk up a system? Low odds, but it's possible.

Tensioners, other pulleys hanging up, and you're noticing it in your WP? Guess.

When cool and level, start with the level where I said.

Then, with heater on high, fan on low, three red dots, start the car, rev to 4000 rpm for 20 secs. and turn it off.

Check the level...adjust as necessary and report back.

If level is too high, remove coolant, don't let the cap 'level' coolant for you.

Okay...that's a bit of homework for you! Sorry! Report back and I or someone will help.

BTW, even though I did a lot of guessing, that's what a lot of it will be! I like proximate causes, and without getting you pissed, you have to consider the work you did/had done and the parts you used.

You've got a few things you can work on before considering it was something in this rebuild you had. But, I will say, those who take on that work, generally only do so because they know what they're doing. It's a lot of work!

Oh, finally, I hope the shop that did this would be fine with you asking them to look at it...unless, of course, bridges have been burned!

Okay...sorry for the long post...I have that problem--others too, but we'll let you discover them as you 'consider the source'! Which here, you absolutely should...except for me. I'm like the only trustworthy one in the whole bunch here...well...there might be 20-30!
 

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Sounds like you've done everything except replace the expansion tank filler cap. Those can break and not do their job causing it to spew coolant.
 

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You need to pressure check the system, the kit is very affordable and relitively easy to perform. It usually includes dye that indicates the exact location of the leak under ultra voilet light. Just my two and a half cents worth...
 

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Discussion Starter #7
Solved\Update - Thanks all for sharing your thoughts. I did a leak down test yesterday afternoon and it started out being fairly inconclusive....that is until I pulled the plugs. Got those suckas out of there and viola! Turns out there was the presence of coolant in cylinders #3 & 4. It was just a few drops, but it was enough to convenience me that I am probably getting exhaust gas in the coolant. During my HG job I had been proactive and had the head milled, but turns out that there still may be a chance that there was a hot spot or "wave" on the block. I'm looking into alternatives now, but I'll probably go the heart transplant route to ensure long term motoring happiness. Thanks again!
 

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I had a similar problem about two months ago,pressurizing water system from the third cylinder (2001 330ise),water spewing from expansion tank,misfiring on start up and steam coming from exhaust,i.d only bought the car a month or so before this and until this it had been running fine.There was copper grit like stuff on the expansion tank cap which to me looked like the previous owner had put radweld in it to mask the problem and get it sold.Looking for a cheap fix i tried some radweld in it with no success,I am a maintenance fitter by trade and mechanically minded so decided i would just research the job and do it myself as i do all my own mechanicing where possible,to cut a long story short i decided to try another magic potion in it first, i am as sceptical as the next man but i thought its a big job what have i got to lose? There was a lot of potions on the market some over £100 but i settled on a bottle of steal n seal at £30 on ebay.There were some videos on you tube about it which looked promising, thats why i picked it, and i didnt want to spend much more because to be honest deep down i didnt hold out much hope for success.I followed the instructions and ran with the spark plug out of the third cylinder,you have to bring to temp and then leave an hour to cool/settle,you are told to do this twice but i did it five times to give it the best chance possible.That was about 5 or 6 weeks ago and i,ve been checking every couple of days and it hasnt used a drop of water. I dont know how long this will hold and i,m not saying its a miracle cure, all i know is its working and if it goes again i,ll pour another bottle in before i start stripping cylinder head.Sure its worth a try if it could save you a small fortune.Hope you get it sorted,cheers...Just an update....27/9/11...car still running perfect and i,ve been giving it some welly, lol
 

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Here goes for my first ever post,,I had a similar problem about two months ago,pressurizing water system from the third cylinder (2001 330ise),water spewing from expansion tank,misfiring on start up and steam coming from exhaust,i.d only bought the car a month or so before this and until this it had been running fine.There was copper grit like stuff on the expansion tank cap which to me looked like the previous owner had put radweld in it to mask the problem and get it sold.Looking for a cheap fix i tried some radweld in it with no success,I am a maintenance fitter by trade and mechanically minded so decided i would just research the job and do it myself as i do all my own mechanicing where possible,to cut a long story short i decided to try another magic potion in it first, i am as sceptical as the next man but i thought its a big job what have i got to lose? There was a lot of potions on the market some over £100 but i settled on a bottle of steal n seal at £30 on ebay.There were some videos on you tube about it which looked promising, thats why i picked it, and i didnt want to spend much more because to be honest deep down i didnt hold out much hope for success.I followed the instructions and ran with the spark plug out of the third cylinder,you have to bring to temp and then leave an hour to cool/settle,you are told to do this twice but i did it five times to give it the best chance possible.That was about 5 or 6 weeks ago and i,ve been checking every couple of days and it hasnt used a drop of water. I dont know how long this will hold and i,m not saying its a miracle cure, all i know is its working and if it goes again i,ll pour another bottle in before i start stripping cylinder head.Sure its worth a try if it could save you a small fortune.Hope you get it sorted,cheers
This magic stuff can block your heater core and other critical passages that will cause you more problems then you started off with.
 

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radweld will block cores etc but steal n seal doesn,t work like that it is a liquid that only seals/solidifies in hot spots where extreme temperatures are being generated.Anyway to be on the safe side i flushed the system out before refilling with anti-freeze so theres no chance of any mishaps, thanks all the same.
 

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Glad to hear you figured it out. You might have a "selective" HG leak which only happens at higher RPMs or under higher combustion pressures. So when you idle it in the garage for 45 minutes it's fine, but when you start driving it, exhaust gases leak into the cooling system. You get overheating and the ET releases the extra pressure.

I haven't pulled an engine head, butr from what I've heard, another possibility is the head bolt threads in block won't hold torque. The block is aluminum so sometimes when these engines overheat, the bolts pull out of the threads, which means the HG can't seal properly. The answer is either to drill and put timeserts into the block, or get a new engine. However if this happened to you, a good shop would have noticed the problem when bolting the head back on. So maybe that's not the problem.

Solved\Update - Thanks all for sharing your thoughts. I did a leak down test yesterday afternoon and it started out being fairly inconclusive....that is until I pulled the plugs. Got those suckas out of there and viola! Turns out there was the presence of coolant in cylinders #3 & 4. It was just a few drops, but it was enough to convenience me that I am probably getting exhaust gas in the coolant. During my HG job I had been proactive and had the head milled, but turns out that there still may be a chance that there was a hot spot or "wave" on the block. I'm looking into alternatives now, but I'll probably go the heart transplant route to ensure long term motoring happiness. Thanks again!
 
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