Linus

Hi all,
My '83 928S2 has developed a very nasty illness. After five minutes driving the temperature reaches the red light area. Stop the car and smoke/steam comes from header tank and it boils over. What comes out is a light brown "mess" which seems to be more oil than water, oil level on dipstick also falls. The car feels well down on power but the engine runs smooth and does not stall. Now I've got a nasty brown oil/water emulsion everywhere, especially in the oil filler, air distribution chamber, header tank etc.
Question is does anyone recognise these symptoms immediately ? I have to suspect head gasket or oil cooler inside radiator (heat exchanger) but how to determine which ? How about cracked cylinder head ? Any other ways oil / water can mix to such an extent that oil boils out of the header tank ?
Any ideas much appreciated.
Paul (South London) <img src="graemlins/crying.gif" border="0" alt="[crying]" />

John..

Sounds like a bad head gasket at the minimum, or a cracked cylinder head. First and foremost, stop running the car altogether. Getting coolant in the oil can make the main and connecting rod bearings junk in no time flat. if the leak is bad enough, you might also lock up a cylinder, sinc the water can not be compressed.

You should drain everything, and refill the oil with some fresh oil....might be best to fill and redrain to get rid of any coolant down there.

Then remove the coil wire so the car can not start.

Remove all of the plugs and turn the engine over to clean out each cyliner.

Then use a compression tester to see which cyliners are leaking. It is best to use a bleed down tool.

If you run it like it is, you will be sure to ruin the engine.

Normy

It could be a bad head gasket or a cracked block..

[yikes!]

But most likely it is a failure of one of the coolers in your radiator. Porsche uses the radiator to cool the oil- there are heat exchangers in the end tanks that routinely rupture and cause the mess you've described. You should probably not drive this car until you are sure what is wrong.

Question: Does your oil look like coffee with cream? This would indicate water in the oil...if so DO NOT START THE ENGINE!

[Don't ask how I know about this~]

-A simple compression test can tell if you have a bad head gasket or a cracked block. Many auto parts stores will lend you a tester.

Good luck!

Normy!
'85 S2 5 speed

Linus

Thanks for the replies guys. It's as I suspected but now have to track down the exact reason.
Yes Normy the oil on the dipstick looks like coffee with cream. I am not running the engine. Does this symptom suggest something extra to you ??
Any ideas about testing the heat exchangers ?
I don't think a compression tester will spot a cracked block :-)

Thanks again
Paul

928 U.K.

hi
i had the same symptons as you it ended up being the cooler on the rad. common problem. new rads are £1000 from AFN i put a new cooler in front of the aircon rad to isolate the water from the oil
i am putting a new cooler for the auto tranny on at the moment as this one has also split and ruined my auto box which is out at the moment

easy check take out the rad and squeese a hose in one end of the cooler and block off the other end if water appears in the main rad its the cooler!

cheers

Tim 84 s2 auto

onthedge928s4

hey don`t jump the gun yet I agree with the guy who suggested the oil cooler is bad very common!
just don`t run the caryou have to test the oiler cooler i don`t know of a good way but i assume you can disconnect the oil lines and pump air into the lines and look to see if the rad bubbles
up the you know .there is probably a better way out there .but by all means don`t jump the gun .. good luck i`ll be watching for the final determination

Greg86andahalf

Linus

Here's how I did a quick test on mine.

Disconnect the upper and lower radiator hoses. Leave the other lines connected. Take a bicycle inrertube from and cut out two pieces, one with the valve stem on it. Fit one piece the lower radiator port with a hose clamp to seal it. The other piece with the valve stem is fitted to the top port with a hose clamp. The object it to presurize the radiator with an tire pump and listen/look for leaks. Put enough air in the system for the innertube to swell a small amount, then remove the pump and seee if there is any leakdown. You may even hear air or bubbles in the block as you pump the air in. Don't over-fill the radiator, just create a bubble in the innertube.

This is a "quick and dirty" test, but remember, there is more PSI in the oil cooler than in the water cooler, and heat expansion can show leaks that cold metal won't.

You should probably take the radiator to a shop for testing, tanking and repair. Be clear with them that you have coolant in the oil and want a test first to determine cross-contamination of the coolers before they do any work.

My shop redid the radiator on my request, but when I asked if it had leaks before they started, I never got a clear answer.

HTH
Greg

Normy

I don't know....

Y'all need to hang out on High Street, or the nightclub known as "Heaven" near Picadilly Square....

BUT you SHOULD NOT DRIVE YOUR CAR!

1995: Normy takes a job in Puerto Rico. All the Bacardi I can handle, which is NONE, is at my beck and call. I bought a Fiat Spyder convertible for airport use.

-A convertible was perfect, considering my apartment fronted the Caribbean Sea, and the car was 16 years old at the time. The owner showed me the dipstick...Cafe Au Lait, he said that the head gasket was blown. I was attracted to the European nature of the car.

I purchased the car, drove it to San Juan, and within a few weeks, switched the head gasket...to no avail. Despite my correct job...

Correct from the manual... I pulled the head, changed the gasket...to no avail. The engine's bearings had been damaged, almost instantly according to my friends who routinely race cars.

The engine's oil had been milky. Sir, I recommend that you NOT drive your car if your oil looks like this! If it looks like Cafe Au Lait, I'd ask myself how my children's transportation needs been exposed to this... then I'd ask myself about whether my finances can deal with a sick 928. And if, like me, you still can deal with a sick shark....

Then by all means park the bitch!

N!

Linus

Have now diagnosed the fault - I have a leak between the oil cooler and the radiator. Used the bicycle inner tube method to prove the fault. The radiator appears in real good shape so I'm surprised it has done this. "Design fault" comes to mind!
Question:
Is the oil cooler really necessary - has anyone simply looped the feed line back into the return from the block? Seems to me that for track days etc. the cooler would be needed but normal driving?? Maybe I'm missing something, the oil would also warm up quicker from the water?
Question 2: Has anyone replaced the oil cooler with an external one. If so where from and what about the piping?
OK I'm also trying to save some money but if I replace the radiator I'm going to be paranoid the new one will do the same!
Grateful for any responses.

Paul
'83 928S2 <img src="confused.gif" border="0">

Greg86andahalf

Linus,

Good job finding the leak!

The radiator may be able to be repaired for a somewhat reasonable price. I would pull it out (not a big job) and take it to a radiator shop for evaluation and an estimate.

I think that oil cooling is very important in the 928. I can't help you with the external cooler idea, I havn't done it.

Once you're ready to put things back together, you're going to need to be careful to get the crankcase clean of as much coolant as possible. I hope some people chime in with the best way to clean things up. Below is what I would probably do, unless someone gave me beter advice.

A guide might be: using standard motor oil as a flush, replace oil filter, fill and drain the crankcase a number of times without starting the engine. Once the drained oil looks clear, replace filter again, add proper amount of oil, run car for one minute, drain oil into clear pan, checking for coolant residue. Replace filter again, refill oil to proper level. Run car for a couple of minutes, repeat drain and oil filter change. When the oil looks good on the dipstick, drive car 10 miles or so to get it to full temp, then change oil and filter again. If oil looks clear, you're probably good to resume normal driving. I would watch that dipstick daily and change oil and filter once more at 100 miles.
BTW that's six oil filters and many gallons of oil.

There may be an eaisier way, but I'd be real careful to get all of the residual coolant out of the crankcase.

Greg

Randy V

Many early model 928s have had the oil cooling deleted at some point in their past - including my '79 auto - with no negative effects. My car runs very cool without oil cooling.

It is a simple procedure to remove the oil cooler lines and install plugs in the engine block and the radiator.

In fact, if I'm not mistaken, oil cooling was completely deleted by Porsche in the S4 and later models.

The auto trans must have the cooling lines remain intact however.

By deleting the oil cooling loop, you can install the less expensive replacement radiator that does not have the integrated oil cooling system.

Look for a used radiator from a late model 928 with relatively low miles - all model years are interchangeable.

Greg86andahalf

Randy,

If he removes the cooling loop, could he simply clean his radiator real good, plug the oil cooler line inputs, and run the radiator he has?

Greg

Randy V

Probably - it would require cleaning the oil cooler loop as well, since it has been breeched.

I'm not sure what the long-term effect of coolant leaking into the closed oil cooling loop would be, but this approach would get him back on the road relatively inexpensively until he can locate a replacement radiator.

Linus

Thanks a lot for all the input.
I've taken the rad out and off to a specialist who is going to put a new oil cooler into it.
Randy V: Thanks for your reply but you state plugging the oil ports on the block - surely this will place a total block in the oil flow !? I thought of taking the outlet pipe and fitting it back to the return port. I don't know the internal flow diagram for the oil system as it's not in the repair manuals (unless I've missed it).

Best regards,
Paul

Greg86andahalf

Randy,

Just to clarify (my description was bad).

I meant to plug the radiator's inputs. The cooling loop would either feed into itself or be removed and the block plugged.

Sorry, I was so vague.

Greg