Tempest

Hi guys,

Still feeling my way around my 1990 S4 Shark, as I have now owned it for just about 3 months. Fixed quite a few electrical gremlins, had a full service done by a local Porsche specialist, changed the alternator myself (old one had noisy bearing).

The local Porsche specialist is still to change all the auxiliary belts (trust his tensioning tool more than my own belt tensioning skills), change the tranny oil after having changed a seal on the tranny. Still need to change the coolant, too, but had a coolant leak during the first service visit, which I thought might have originated from the water bridge. The mech cleaned everything out around the water bridge, and it wasn't leaking. He suspected the water pump, even though this had been changed about 3 years and about 6000 miles ago, according to receipts from the PO. The leak was visible from the front of the block area, dripping onto the ribbed section of the oil pan.


Now to my problem:
There are no more traces of the coolant leak. The ribbed setion of the oil pan is dry after each journey. I do not need to top up coolant any more.

So far so good, but immensely suspicious about this.

Recently checked the coolant reservoir cap after a 90 mile journey and for the first time spotted the dreaded white milk! Cleaned it out, drove the 90 mile back home, same again! Checked the oil filler cap and channel, all nice and clean, well oily, of course, but no traces of milky coloured substances. Dipstick is clean, too.

It's a 1990 S4 with separate oil cooler located at bottom of radiator (not integrated into the radiator). Did a block test on the coolant reservoir and the fluid stayed nice and blue, suggesting no headgasket leak.

Having spoken to my mech this morning he started mentioning the dreaded words cracked head! The car's done 80000 miles. He was going to come back to me after he had done some research into the likelihood of this happening on 32 valve heads. He mentioned it was a problem on some mid 80s (16 valve) heads.

What do you guys think? Is there a link between no more coolant leak and the milky deposits in the coolant reservoir cap? Am I looking at a knackered engine? Bit scared now.

Tempest

NoVector

Tempest - I'm not sure what you mean by a "block test on the coolant reservoir". Do you mean the mechanic pressurized the cooling system at the reservoir cap and detected no leaks? Or, did he do a leak down test on the engine cylinders to see if there were bubles in the reservoir? Funny you mention you have an external oil cooler as the internal oil cooler in the radiator would have been my first guess if you're not losing pressure with a leak down test.

Is it running hot and/or any white smoke clouds; or, did it get hot when you were having the radiator fluid leak? You could also look at your spark plugs to see if any are steam cleaned.

It could be a leaking transmission cooler too BUT that would be unlikely.

daveo90s4

If it's not using water it's pretty unlikely to be a cracked head I'd have thought. Maybe the car has done lots of short trips and this is the first decent drive to get it all up to operating temp and all the condensation out of the system maybe?

I'd be inclined to keep a close eye on the oil colour, the coolant level and colour and also the temp gauge reading and keep driving it.

With a bit of luck you're worrying about nothing :-)

Mike Simard

Someone culd have put in some stop leak product. I don't know what you have in the UK but 'BarrsLeak' is common here and could settle in and make a milky look for a while. You may even see gook inside the reservoir. Chin up mate!

heinrich

You are getting oil in the coolant, no 2 ways about it. You have a transmission fluid cooler on the right side of your radiator. That is the usual suspect.

Your coolant in front of the engine is almost always caused by a water pump. If I were you, I'd do the water pump and tbelt before driving much more. Even without this leak, I would have.

Taking both pieces of probably unrelated info into consideration, it could remotely be that coolant is making or was making its way through a bad head gasket, into oil, and simultaneously out at the front of a head. But I would say very remote.

Go with the simple, obvious, most likely possibilities.

Start with a tbelt wpump job and pull the Rad ... have it properly pressure tested especially at the lone side tank.

heinrich

Omigoodness Mike, both gook AND chin in one post... Sheesh man, slow down on the slurs ;-p

the flyin' scotsman

If I remember correctly isnt it a little damp in England?

Mongo

My money's on that radiator.

Lizard928

That wont cause oil to get into the coolant. It could cause this in the oil, but not visa versa.

Monitor your oil consumption carefully and see if you are consuming any oil.

Tempest

Thanks folks for the replies so far

Yes, it is a little damp here in the UK

You mean the radiator that runs along the top of the main radiator? Sits in front and at the top of the main radiator, with part number 92830702706 stamped on mine.

I used a colouring agent inside of a glass tube held on top of the coolant reservoir, through which you draw the hot air coming out of the coolant reservoir. If any exhaust gases are present the coloured liquid (blue) will turn yellow or green. It stayed nice and blue on mine.

That was going to be a next step, too, run some radiator cleaning stuff through, flush out and refill and test drive.

Tempest

heinrich

No, the radiator. Automatics have a side tank with a heat exchanger in it.

NoVector

Thoughts and prayers are with you. You'll soon find out if the POs dumped any stop-leak in there.

FWIW, there's a drain plug on each side of the block too.

Good luck! / Bruce

Tempest

Small update, just in case it may be helpful:

Removed the coolant reservoir, cleaned that out thoroughly, no more oil deposits, refitted reservoir, flushed through 2 buckets of water, letting it run out of the overflow hose (not yet connected to the reservoir), to clean the feed and overflow hoses. I know this is not a full flush (yet to do that).

Connected everything again, filled up with fresh coolant and drove around a bit.

Oil dipstick stayed clean, oil filler cap and neck stayed nice and oily, coolant level stayed the same, and initially no signs of milky deposits.

Took the 928 for a longer run yesterday (160 mile round trip), after first leg of 80 miles noticed the dreaded oily deposits on the coolant reservoir cap (this time tan to brown coloured) and indeed inside the reservoir where the coolant isn't in contact with the reservoir walls.

No oil floating on the coolant inside the reservoir. Oil level still OK, no milky deposits on the dipstick or inside the filler neck, coolant level still OK.

Oh, and no white smoke from the exhaust once engine warmed up. The coolant temperature gauge does settle at 90°C (194 F) and stays there, no matter how I drive it.

Had a chat with the mechanic where I had a service done now 4 weeks ago, and he told me that he had in actual fact looked at the ATF and apart from it needing replacing (dark colour) he noticed neither an abnormal level nor any coolant traces. So he's ruling out the radiator, and still likes to scare me with a cracked head.

So next up is a good flush of the coolant system, I guess :-)

Tempest

Tempest

Small update, just in case it may be helpful:

Removed the coolant reservoir, cleaned that out thoroughly, no more oil deposits, refitted reservoir, flushed through 2 buckets of water, letting it run out of the overflow hose (not yet connected to the reservoir), to clean the feed and overflow hoses. I know this is not a full flush (yet to do that).

Connected everything again, filled up with fresh coolant and drove around a bit.

Oil dipstick stayed clean, oil filler cap and neck stayed nice and oily, coolant level stayed the same, and initially no signs of milky deposits.

Took the 928 for a longer run yesterday (160 mile round trip), after first leg of 80 miles noticed the dreaded oily deposits on the coolant reservoir cap (this time tan to brown coloured) and indeed inside the reservoir where the coolant isn't in contact with the reservoir walls.

No oil floating on the coolant inside the reservoir. Oil level still OK, no milky deposits on the dipstick or inside the filler neck, coolant level still OK.

Oh, and no white smoke from the exhaust once engine warmed up. The coolant temperature gauge does settle at 90°C (194 F) and stays there, no matter how I drive it.

Had a chat with the mechanic where I had a service done now 4 weeks ago, and he told me that he had in actual fact looked at the ATF and apart from it needing replacing (dark colour) he noticed neither an abnormal level nor any coolant traces. So he's ruling out the radiator, and still likes to scare me with a cracked head.

So next up is a good flush of the coolant system, I guess :-)

Tempest

NoVector

It's great that you don't have white smoke or it's running hot. Unless you're having freezing temperatures, you could save some quid and refill the system with only water until you confirm what's going on. If you add coolant now, you may later have to drain the system for a head, radiator, head gasket, etc., money down the drain.

When my 84 trans cooler leaked, I definitely had transmission fluid in the coolant--but the goop was more of a frothy pink color--not brown.

Hopefully, you just have residual crap in the coolant from the PO. If your coolant flush doesn’t do it though, I think next I’d do a leak down test and look for bubbles in the overflow tank.