Disappearing coolant after overheating = blown head gasket?

[kwayocu]

Originally Posted by kwayocu

I am having the exact same problem. plenty of fluid, no heat, car heats up quickly to the red, but strangly after a few miles of hwy driving it normalizes. I had the water pump change last year after the plastic impellor broke. Just change themostat and bled the system. Back to no heat and overheating car. Let me know what you discover.

Ok so I went ahead and bled my coolant system last night in about 10 degree weather. Earlier i poured coolant in the tank, got home (about five miles) no problem. Parked on an incline and removed the radiator cap and open the bleed valve. I poured about a 3/4 of a gallon of 50/50 in until the air bubbles slowed down almost to a stop (will repeat today). As I was doing this i noticed a good amount of steam coming from the Thermostat Housing no where else... I took a closer look and saw just a drop of fresh coolant underneath the housing. I think that maybe my slow leak is allow air to get into my coolant system an allowing the coolant to evaporate. I will be replacing the theromostat/housing again (did this two weeks ago) and let you know. BTW my car ran perfectly this morning 22 degrees and I had very hot air!

[Rich]

Something else to check for is the connection from the pipes that go to the heat core and the plastic tubes used to connector the hoses to the engine.

http://www.realoem.com/bmw/showparts...68&hg=64&fg=15
See part: 4

When I had my old engine I kept losing coolant (while driving round Europe one summer). No water to be seen under or in the car. Took it to a BMW garage they did a leak test and said it was the head gasket & probably a cracked head!! €3000+ please... I nursed the car home and swapped the engine. (was planning to do that anyway this just moved the deadline up)

Anyway, after the swap I had the same problem with the new engine! Long story short I found out that the water was leaking out into the space between the engine bay and cabin (where the heater sucks in air) It was leaking just enough to not go down the overflow pipes, therefore making it looked as though the water was going into the engine.

2 x 50p O rings fixed the problem, would have felt very silly if I had let BMW fix the engine when there was nothing wrong with it

Its worth a checking, no guarantee this is the problem but its easy to check.

[marko]

also, check or just replace the 2 plastic coolant connectors - they are a frequent cause of coolant leaks.
In fact, my car has just started leaking excessively from one of them (as the temps droped).

# 9 on this:
http://www.realoem.com/bmw/showparts...61&hg=11&fg=15

& # 1 on this:
http://www.realoem.com/bmw/showparts...58&hg=11&fg=10

[christophbmw]

how much coolant have you put in it so far? do you need to put in 1/2 a gallon ever 20 miles (like you said) a lot, or did you just have to do that a few times? also, have you found out what made it overheat in the first place? im having similar problems when the car idles for extended periods.

[kwayocu]

I have not needed to put in any more coolant since. You may need to burp the system which has been mentioned a few times, I tried it out----very easy---.

I made sure the car was at an incline with the nose pointing up (inclined driveway will suffice) then open up the bleed screw and radiator cap. Pour in coolant up to the fill line and wait for only coolant to come out of the bleed screw.

I was able to get the air out of the system that way and everything is working great.

I did have an issue with the car overheating in the past, typically if i was driving in the city or idle. I found that the car would get down to normal temps with highway driving. Like many others on this fourm, I found that i was the plastic impeller in the water pump that broke and did not allow the car to get coolant.

You may also want to change the themostat. In any case both are easy fixes that will save you thousands in the long run if you seize your engine.

Hope this helps!

[christophbmw]

Originally Posted by kwayocu

I have not needed to put in any more coolant since. You may need to burp the system which has been mentioned a few times, I tried it out----very easy---.

I made sure the car was at an incline with the nose pointing up (inclined driveway will suffice) then open up the bleed screw and radiator cap. Pour in coolant up to the fill line and wait for only coolant to come out of the bleed screw.

I was able to get the air out of the system that way and everything is working great.

I did have an issue with the car overheating in the past, typically if i was driving in the city or idle. I found that the car would get down to normal temps with highway driving. Like many others on this fourm, I found that i was the plastic impeller in the water pump that broke and did not allow the car to get coolant.

You may also want to change the themostat. In any case both are easy fixes that will save you thousands in the long run if you seize your engine.

Hope this helps!

thanks for the info. the first time it overheated (almost went into the red) i changed the water pump and the thermostat. bled the system (put 2 gallons in it!) and it ran fine for 2-3 weeks. last night while in the drive through (i usually don't go to fast food drive troughs but a buddy was visiting and that's where he wanted to go) the car overheated again and this time it blew the plastic expansion tank . i personally think it has something to do with the electric fan because not once did i hear it come on.

[Eric]

Hi, sorry to have dropped out - stopped driving the ti and switched to my pickup because I got tired of pouring in coolant (it's gotta be bad for something in there). Since I wasn't being aggravated by it I stopped checking this discussion (short attention span). I can't pull the head until the spring (no garage + Maine winter = wait).

I'm confident the heater core's good.

I'll change all the plastic tubes and seals when I pull the head, which I've got to do because of the compression variation.

The only new piece of information is that after I drove her around a bit a few days ago, with an ambient temp around 10F, when I stopped, I glanced back at the car and saw a trickle of steam rising from the grille. I opened the hood, and, of course, couldn't find a source, other than the radiator in general, so it would seem I need to replace that, too. Any advice about what to get or to avoid. I've seen them seemingly reasonably priced on eBay, but one wonders if that's always a good idea...

Thanks,

Eric

[Eric]

I fixed it.

No big deal, unless you live in New England, where, this year, it started raining as soon as it got warm enough to go outside, and kept up until 2 weeks ago, and in addition, as in my case, you've got no garage.

I got the head off, measured it with the proper equipment, found it was about 0.009" high (head surface moved away from the block surface) in between #2 and 3 cylinders, tapering back toward normal as it got to the edges (a "cupped" shape with no significant twisting).

I had a family friend with a machine shop deck it.
Interestingly, he pressed it as straight as possible before machining it, pointing out that the thickness (from the valve cover gasket surface to the head gasket surface) hadn't changed, so just taking off material would leave the head still with a curved shape which could cause clearance problems with the cam bearings.

I cleaned and reassembled it in the customary fashion, with all new seals, gaskets, and water lines throughout.

During its time off the road, the Idle Control Valve had seized up, but I was able to disassemble it and free it, which I will post about separately.

Only other problem was that the valve cover gasket seated wrong it that one place you can't reach to check, RH side, farthest back, under the spark plug wire guide, causing an oil leak onto the exhaust manifold and an audible pressure leak that also screwed up the idle. When I put it together the second time, I actually had to get under the car to see whether it was seated properly, as there was no other way to see or feel it.

Many, many thanks to Dave (-45056) for all of his assistance, without which I might have made some bad mistakes.

And thanks, also, to all of the other posters who thought about my problem and offered advice.

If anyone contemplating pulling their head has any questions about my experience, I'd be glad to answer them.

- Eric