Danton

Hi 951'ers,
A few days ago I noticed my car idleing strange upon startup. Having had this car for several years now I've pretty much been through it all. Now, I'm losing coolant and the oil filler cap has moisture but no froth and my coolant resevior does have froth in it. At first I thought blown HG, but after seeing the coolant resevior I'm thinking oil cooler seals or possibly both - God forbid! Is it possible to have froth in the coolant resevior from a blown HG? What test can I perform to verify what the culprit is? TIA!

Regards,
Danton
03' 325i
87' 951

hosrom_951

Do a leak down test........

Duke

Water in oil can be both HG/Oil cooler seals.
Oil in water is most likely be due to oil cooler seals.
Rough idle/running on 3 cyl. during startup can only be due to bad HG (except problems with fuel or ignition but we can probably rule that out here..)

As said, do a leakdown test or at least a compression test.
But if you end up doing the HG, do the oil cooler seals while you're in there since it makes the job soooo much easier!

Good luck!

Danton

I'll do a compression test today as I already have the tester. I'll post the results.

Thanks,
Danton

hosrom_951

DO A LEAK TEST, that would pin point a head gasket leak (if it is).

Peckster

A compression test probably won't show a slow hg leak, but it can't hurt.

Do a cold start, run the engine for a few seconds and then pull the plugs. One will probably be either very clean or sludgey, because of the water accumulating in that cylinder after the engine's turned off. If you pull the plugs, then turn the engine over you'll probably see water being ejected from the hole.

A leakdown test is better, but you probably won't need one to diagnose the hg problem.

I've got a slow leak back again myself, so I feel your pain. Never had oil in the res from an hg, but I quess it's possible.

Danton

I did a compression test and I got these numbers using the $50 Craftsman tester. 150-150-140-155. These numbers seem fine being within 10% of each other. Tomorrow I'll do a cold start and pull the plugs as suggested. If that doesn't shed more light on this then I'll get a leakdown tester. I've seen them online for $70- $110.

Regards,
Danton
03' 325i
87' 951

Laust Pedersen

$70- $110 for a leak down tester??
Try this reference instead.

hosrom_951

Danton: Was the engine warm?

Was the OIL warm as well (since the oil takes twice as long to reach normal temp. of the water).

Danton

Well it had been sitting for an hour before I did this. How warm does it need to be? I also found a leakdown tester locally and will do that as soon as I find time while trying to prepare for this damn hurricane. Imagine, a possible blown HG and a major hurricane in the same week? I must have pissed somebody off...

Regards,
Danton
03' 325i
87' 951

hosrom_951

Engine should be at normal operating tem (oil and water)

Make sure you got an air compressor for the leakdown test.

Tom M'Guinn

Also check for excessive moisture out the tailpipe. Mine literally spit water out the tailpipe (after fully warmed up) and had a lumpy idle. You can try putting compressed air in the spark plug hole without the leak down guages. If your coolant pressurizes, bubbles, or raises, you prolly have a dead gasket. The combo of rough idle and frothy coolant points to the HG. One wet or overly clean plug (#3?) would be all I'd need to see to seal the deal.

hosrom_951

Danton: After reading your post one more time, i am suspecting the HG. My 88 NA started really bad (3 clyinders not 4 fired) few seconds later, all four worked.

I was filling her up wil coolent daily, but got no white smoke in the tail pipe.......

I am suspecting the HG, since they are also responsible for oil/coolent mix.

michael2e

In my experience it sounds like a classic HG leak. Are you experiencing increased coolant system pressure? If you feel the coolant hoses around the reservoir do they feel really taught? Does the reservoir look like its gonna explode? You can get a coolant pressure tester to quantitate it. What happens is that a slight irregularity or poor seal by the HG allows combusiton pressure to enter the cooling system. When the car is shut off this pressure equalizes across the HG causing coolant to back flow into one or more cylinders depending upon the extent of the HG failure. A warped head/block from overheating can result in similar findings.You can actuallly see green if you pull a plug and shine a light in. Upon start up there is rough idle for a short while til the coolant is burned. Depending upon the amount you may see white smoke out the tailpipe. A leakdown test would identify this problem. My $0.02 worth, hope it helps