Coolant Expansion Tank Full of Engine Oil?

[sboxstergirl]

Has anyone experienced coolant expansion tank on a 99 Boxster with a 2.5L engine filling with engine oil? It appears to be a pretty severe concern as the coolant tank is completely full of oil and the oil level is low.

If the engine is started, oil will begin flowing out of coolant tank as it appears to be pressure fed. There is no smoke from the exhaust.

Is there anything common here? Head gasket, oil cooler, cylinder cracked, etc...

I don't see any coolant on the oil dipstick, just oil in the coolant tank but I have not drained the oil yet....

I will perform further diagnostics to try and locate concern.

Does anyone have a schematic of the coolant and oil passages in this engine?

Please let me know if you have experienced this concern and what you did to resolve it.

Thanks!

:o

[Cassiebox]

Yikes - that is definitely not good news at all sboxstergirl.

There are some well known issues w/ the M96 engine including blocks which were re-sleeved or have a porosity problem. Best advice I can give you is to not drive it until you figure out the source of your problem. Hopefully it something minor [fingers crossed for ya]. You might want to find a good indy mechanic (who's very familiar w/ the M96 engines) to investigate further.

Best of luck

[sboxstergirl]

well, I had a chance to go out and drain the oil and no signs of coolant in the oil.

I also pressurized the cooling system and it is not leaking into the crankcase.

Does anyone have an oil passage and coolant passage diagram?

Any other thoughts were the oil could be coming from?

Head gasket?

Cracked or damaged cylinder?

What other components share oil/coolant that would be pressurized by oil or possibly combustion?

Are any of the cylinders close to the oil passage or coolant passages?

I really would like to determine where the root cause is prior to removing the engine.

I may pressurize the oil passage and see if I can determine where the leak is.

Please respond if you have something that comes to mind.

Thanks again!

:huh:

[wvicary]

There have been a few cases of a freeze plug falling out in the camshaft area and oil coolers failing.

[Brad Roberts]

SB? where are you located? I'd like to see this and document it :)

If the engine was running fine, I'm willing to bet it is a casting plug from the heads (most people call them freeze plugs, but in fact they are just casting plugs that allow the foundry to empty the sand/whatever after the forging/casting process)

Not an easy fix, but not too bad!!

Let me know! If you are in Santa Barbara, I can be there on Wed this next week.

B

[Brad Roberts]

Are any of the cylinders close to the oil passage or coolant passages?

The cylinders are surrounded by coolant at the top near the head.

B

[JFP in PA]

Has anyone experienced coolant expansion tank on a 99 Boxster with a 2.5L engine filling with engine oil? It appears to be a pretty severe concern as the coolant tank is completely full of oil and the oil level is low.

If the engine is started, oil will begin flowing out of coolant tank as it appears to be pressure fed. There is no smoke from the exhaust.

Is there anything common here? Head gasket, oil cooler, cylinder cracked, etc...

I don't see any coolant on the oil dipstick, just oil in the coolant tank but I have not drained the oil yet....

I will perform further diagnostics to try and locate concern.

Does anyone have a schematic of the coolant and oil passages in this engine?

Please let me know if you have experienced this concern and what you did to resolve it.

Thanks!

:o

I have to say that I’m a bit apprehensive about finding oil that is separate from the coolant (e.g.: not a milky emulsion) in the coolant tank……… Normally, if there is a leak between the two systems, it shows up as a foamy emulsion, not just oil by itself. And as you have said you ran a pressure test, the correct diagnostic for such a situation, and not observed leakage, I would become even more circumspect that there is a real issue.

Suggest the following:

1. Remove the oil from the coolant tank using a siphon.

2. Top off the coolant mix, adding a coolant UV dye indicator (available on line or at many full service auto parts outlets).

3. Top off the oil to the correct level.

4. Run the car for a few days, monitoring the oil and coolant to see if any emulsion starts to form or the oil returns.

5. If no emulsion (or oil) is seen after several days, check an oil sample from the dipstick under a UV light source, looking for the presence of the UV dye.

6. If after these steps, you see no emulsion or signs of the dye in the oil, assume that somehow, oil was added to the coolant tank by mistake…..

Edited March 1, 2009 by JFP in PA

[Sputter]

It kinda makes me wonder if somebody topped off the oil via the coolant tank. It wouldn't be the first time i've heard of it.

[sboxstergirl]

Brad and JFP- Thanks for the thoughts and here is current the situation:

-There is definitely milky substance in the coolant tank as oil mixed in the cooling system. Majority of fluid was oil.

In other words no coolant in the crankcase but crankcase only had 3 quarts of oil when I drained it.

- I used a wet/dry vacuum to extract the oil/coolant mix from the coolant tank and extracted several quarts as the tank began to overflow with the engine running and cap off.

This is the reason I'm thinking the oil cooler or a pressure fed passage is allowing oil to enter the cooling system. Oil pressure is higher and overpowering the cooling system. If both sytems were equal pressure I'm sure I would have found the crankcase mixed with coolant too.

-Dye is a good idea and I do have access to dye.

-I am going to pressurize the oil galleries via oil pressure sending unit passage and pull the coolant hoses to expansion tank and see if there is pressure in the cooling system. If there is I will need to follow the hose back to the engine to determine where the leak is.

- Is it possible for the oil cooler or head gasket to leak into the cooling system?

- The engine runs normal and I'm afraid to run it for any length of time as oil leak seems to be constant and fairly large.

I am still looking for a diagram of oil and coolant passages to see if there are any passages close to each other.

Do the expansion plugs in the heads seal coolant or oil?

I will keep everyone posted after I run my next test.

Thanks for your suggestions and keep them coming!

:D

[sboxstergirl]

Guys, just to confirm there was no oil added to the cooling system by mistake.

The issue is occuring internally inside the engine.

:rolleyes:

Keep me posted with your thoughts.

Thanks!

[wvicary]

The casting/freeze plugs in the cylinder are in the coolant passage.

[sboxstergirl]

Well I have good news and a major relief at least for the wallet.....

I removed the small hose from the oil cooler and the milky oil/coolant mix began seeping from the oil cooler. I removed the oil cooler, poored a soapy water solution into the coolant ports and applied 60 psi air pressure to the oil passages. Bubbles galore!

I will try and send pictures and a small video if possible.

Does anyone make a retrofit cooler or larger more efficeient cooler to replace the factory cooler?

I may make a block adapter and add an external cooler to keep the oil cooler.

Please let me know if there is a company with such an adapter and cooler.

Thank all of you that replied! :renntech:

Now it's time to get busy and clean up the mess.

:)

[Brad Roberts]

I like to install the BoxsterS oil cooler. It is taller than the stock 2.5 and is just about the same price. It will come close to the intake hose, so just slide a piece of rubber fuel line "split" over one edge of the cooler. The intake hose will not touch, but it is VERY close. This is what we do on ALL of our 2.5L BoxsterSpec cars :)

BoxsterS on the right stocker 2.5 on the left!

B

[Brad Roberts]

Now that I think about it.. if you want to go back stock.. I have a lot of them laying around off of good running engines! Tell me were to send it!

Oh.. and I have never seen one fail :)

B

[JFP in PA]

Now that I think about it.. if you want to go back stock.. I have a lot of them laying around off of good running engines! Tell me were to send it!

Oh.. and I have never seen one fail :)

B

We have. but it isn't a "common" occurance........ A cooling system pressure test usually catches it when it does happen.

[JFP in PA]

Well I have good news and a major relief at least for the wallet.....

I removed the small hose from the oil cooler and the milky oil/coolant mix began seeping from the oil cooler. I removed the oil cooler, poored a soapy water solution into the coolant ports and applied 60 psi air pressure to the oil passages. Bubbles galore!

I will try and send pictures and a small video if possible.

Does anyone make a retrofit cooler or larger more efficeient cooler to replace the factory cooler?

I may make a block adapter and add an external cooler to keep the oil cooler.

Please let me know if there is a company with such an adapter and cooler.

Thank all of you that replied! :renntech:

Now it's time to get busy and clean up the mess.

:)

Jake Raby and LN Engineering make a spin on oil filter adaptor that allow the addition of an air/oil cooler that is used in conjunction with the OEM water/oil unit. Suggest going to the "S" version of the OEM unit first; water/oil units have the advantage of warming up the oil under cold starts. If you are to add a second air/oil unit, you will also need to add a thermostatic valve in the air/oil system to limit oil movement to the cooler until it warms up.........

[Brad Roberts]

Yep. The LN parts work well :)

B

[tstover]

I have the exact same symptom with my 2002 Boxster S. I just discovered tonight what looked like a "coffee" stain on the driveway. Turns out it was dripping from the coolant overflow. The coolant tank is filled with the same sludge. The oil is low (beneath the dipstick), but there is no sign of the same sludge on the the dipstick or oil fill cap / tube. It may be the same problem as the engine was running great, although I haven't started it since I discovered the problem.

Is there anyone that has the procedure for removing the oil cooler? I would like to check this out before panicking about head gasket, cracked head, new engine, etc.

I will drain the oil to check it out in the next few days when I have a chance.

[JFP in PA]

I have the exact same symptom with my 2002 Boxster S. I just discovered tonight what looked like a "coffee" stain on the driveway. Turns out it was dripping from the coolant overflow. The coolant tank is filled with the same sludge. The oil is low (beneath the dipstick), but there is no sign of the same sludge on the the dipstick or oil fill cap / tube. It may be the same problem as the engine was running great, although I haven't started it since I discovered the problem.

Is there anyone that has the procedure for removing the oil cooler? I would like to check this out before panicking about head gasket, cracked head, new engine, etc.

I will drain the oil to check it out in the next few days when I have a chance.

If you have access to a Bentley manual, the cooler removal is covered in detail. First, jack up the car and remove the rear belly pan. There is a small 5 or 6 MM plug on the bottom of the engine that was covered by the pan, this is the coolant drain plug; remove it with a container than can hold 5 gallons (yes, you read correctly), of liquid. Remove the coolant cap in the rear trunk to facilitate draining. When the coolant drain slows, pull off each of the large hoses just in front of the coolant plug, these will drain the radiators. When the coolant drain is complete, replace the drain plug with a new sealing ring (a few cents at the dealer) after putting a light coating of anti seize on the plug threads. Torque drain plug to 7-11 Lb Ft. Reattach coolant hoses. Replace belly pan. Couple of useful tricks:

1. As you are fully draining the system, this is an excellent time to replace the factory 185 degree thermostat with the LN Engineering 160 degree unit. We have had excellent results with this swap, lowering around town coolant temps by 15-18 degrees.

2. Get the “-03” version coolant cap and replace you current unit. For a few bucks, it prevents major headaches later.

You need to open the engine bay, pull the air intake tube from the air filter box to the throttle body, and the cooler is exposed and ready to remove. Couple of tricks:

1. When the cooler is unbolted, do not move it, but lift it in a level position and slide a plastic bag under it to catch any residual oil and coolant still inside (there is a lot of both retained inside the unit and it will get all over if it drains while you are pulling it).

2. Wipe down the sealing area and always use four new (two sizes) o-rings.

3. If you are a 2.5/2.7 base engine, do not use the cooler for that engine, get the “S” model (996-107-025-57, about $200 from a good dealer). The “S” unit is more than twice the size of the base factory unit and will give you much better heat transfer.

4. Replace the Allen head fasteners and torque to 7 Lb Ft.

5. Replace the factory spring hose clamp on top of the cooler with a quality screw type.

6. On some models (but not all) there will be a close proximity between the new cooler and a hose; if you have that, just use a small section of split hose as a “sacrificial” wear protector. Again, not all models need this.

7. While you are in there, this is a great time to replace the air filter…….

8. Consider doing your poly rib belt as well at this time if it is anywhere near due, for $24, it is cheap insurance.

Button everything back up; you often find the throttle body end of the air tube can be a ***** to reconnect, but it does go back on. Refill the cooling system using the factory coolant premixed 50/50 with distilled water (ONLY; again, for less than a buck a gallon, distilled water is cheap protection); again the Bentley has instructions for this if you do not have access to a vacuum fill system, but using the vacuum system makes the refill a 5 min. no-brainer, and even pretests the system for any potential leaks. Unfortunately, the Porsche OEM vacuum fill system sells for over $500; but the company that makes them for Porsche is in Canada and sells the same unit, but with adaptors to fit anything from a Porsche to a lawn tractor for less than $100; so it is a good “buddy group buy” if you don’t want to spring for one yourself, but they really are handy for anything with a cooling system……..

[tstover]

Thanks JFP!

I drained the oil last night and it looked pretty good. No sign of coolant that I could see. So hopefully it is the same problem that sboxstergirl had.

I will make another post (hopefully with some pictures) when I get further into it.

[crwarren11]

Tstover, looks like you might be right as you responded to my other post about intermix problem. I will follow the instructions above to replace the oil cooler, but probably not until next week as I need to order the parts and stuff. Just curious if you got a chance to take any pictures or detail the procedure any more? Thanks!