Oil cap looks moist. Should I be worried? - 986 Forum - The Community for Porsche Boxster & Cayman Owners

CharlesE · 03-06-2021, 08:04 AM

I'm changing the oil in my 99' boxster and I noticed taking the oil cap off was hard. Then when I got it off there was a weird moist oil residue on the top of the filler and the cap looked wet. Should I be worried?

CharlesE · 03-06-2021, 08:27 AM

Also the oil that came out looked fine. The dipstick looked normal. But I think my AOS might be going bad.

911monty · 03-06-2021, 08:40 AM

How do you drive your car? Lots of short trips that barely get engine warm? Looks to me like engine not getting hot enough to cook off water vapor. As far as AOS get a manometer and check.

CharlesE · 03-06-2021, 08:44 AM

Quote:

Originally Posted by 911monty

How do you drive your car? Lots of short trips that barely get engine warm? Looks to me like engine not getting hot enough to cook off water vapor. As far as AOS get a manometer and check.

Just came from a long drive on the highway so it usually always gets up to temp. Is it possible the cap is going bad in letting moisture in.

911monty · 03-06-2021, 08:52 AM

Quote:

Originally Posted by CharlesE

Just came from a long drive on the highway so it usually always gets up to temp. Is it possible the cap is going bad in letting moisture in.

The cap would show as an air leak. As engine cools water will condense inside the case. When you say usually always gets up to temp do you mean you get it to 180 deg and drive for 20 min or more or just gets there and then shut down.

If you are not short driving it then you may have other issues.

JFP in PA · 03-06-2021, 10:49 AM

Quote:

Originally Posted by CharlesE

Also the oil that came out looked fine. The dipstick looked normal. But I think my AOS might be going bad.

If your AOS was going bad, the sump vacuum level would be too high, which would help get rid of the moisture. Your problem lies elsewhere.

Gilles · 03-06-2021, 11:37 AM

Quote:

Originally Posted by JFP in PA

If your AOS was going bad, the sump vacuum level would be too high, which would help get rid of the moisture. Your problem lies elsewhere.

Not enough driving, or perhaps too many short trips..?
.

BrantyB · 03-06-2021, 05:04 PM

Quote:

Originally Posted by Gilles

Not enough driving, or perhaps too many short trips..?
.

I'm in this camp

JFP in PA · 03-06-2021, 06:14 PM

Quote:

Originally Posted by Gilles

Not enough driving, or perhaps too many short trips..?
.

Possibly, but the water could be coming from an internal source as well.

CharlesE · 03-06-2021, 06:28 PM

Quote:

Originally Posted by JFP in PA

Possibly, but the water could be coming from an internal source as well.

I drive it alot and i dont drive slow so i know its gets warm enough. I did notice a really slow coolant leak but I dont know where its coming from I just see the level drop every month or so. Could this be a factor?

Jager · 03-06-2021, 08:30 PM

Quote:

Originally Posted by CharlesE

I drive it alot and i dont drive slow so i know its gets warm enough. I did notice a really slow coolant leak but I dont know where its coming from I just see the level drop every month or so. Could this be a factor?

First thing I thought of when I saw the photo is a coolant leak into the oil system. The residue under the oil cap is not normal. Hopefully it is something simple like the Oil Cooler.

pilot4fn · 03-06-2021, 09:53 PM

Depends also of the climate you're at.
We used to have 'normal' 20-30 years ago that if you do not get the car hot for a long time at least couple of times a week (if driven daily) during winter when the temps do hover between 30-0 F, then the oil cap looked just like on the OP's picture. Summer was never a problem.
Also, the coffee color stuff is so small amount, that makes me to believe the current colder weather could be the culprint of this - or very recently started small mix of water to oil.

blue62 · 03-07-2021, 07:22 AM

Quote:

Originally Posted by CharlesE

I drive it alot and i dont drive slow so i know its gets warm enough. I did notice a really slow coolant leak but I dont know where its coming from I just see the level drop every month or so. Could this be a factor?

First thing to do is pressure test the cooling system and see if you can determine why your coolant level is dropping and where it is going. Once you know the answer to where the coolant is going you will know if you need to be worried about the moisture on the oil filler cap or not.

CharlesE · 03-08-2021, 06:02 AM

Quote:

Originally Posted by pilot4fn

Depends also of the climate you're at.
We used to have 'normal' 20-30 years ago that if you do not get the car hot for a long time at least couple of times a week (if driven daily) during winter when the temps do hover between 30-0 F, then the oil cap looked just like on the OP's picture. Summer was never a problem.
Also, the coffee color stuff is so small amount, that makes me to believe the current colder weather could be the culprint of this - or very recently started small mix of water to oil.

This sounds like it could be whats happening. I did let the car sit for a week so I dont daily drive it. I'm not worried about it but I'll try to find the coolant leak to see if its a problem. Thanks!

blue62 · 03-08-2021, 09:07 AM

looking at your picture I see quite a bit of water droplets on the underside of the oil filler cap. Not good.
Also due to the fact that your slowly loosing coolant that makes the water droplets more suspect. So finding the reason for the coolant loose is rather important.

Things you can do:
Coolant system pressure test.
Test coolant system for presence of hydrocarbons, I think you can still get test kits for this at auto parts stores.
Send an oil sample out and have it tested for the presence of antifreeze.

CharlesE · 03-08-2021, 12:45 PM

Quote:

Originally Posted by blue62

looking at your picture I see quite a bit of water droplets on the underside of the oil filler cap. Not good.
Also due to the fact that your slowly loosing coolant that makes the water droplets more suspect. So finding the reason for the coolant loose is rather important.

Things you can do:
Coolant system pressure test.
Test coolant system for presence of hydrocarbons, I think you can still get test kits for this at auto parts stores.
Send an oil sample out and have it tested for the presence of antifreeze.

Do you have a link to the tool to use to pressure test our coolant tanks?

blue62 · 03-08-2021, 02:20 PM

Quote:

Originally Posted by CharlesE

Do you have a link to the tool to use to pressure test our coolant tanks?

Harbor freight carries a coolant system pressure tester for a reasonable price.
It will work on any system.

Gilles · 03-08-2021, 04:23 PM

Quote:

Originally Posted by JFP in PA

Possibly, but the water could be coming from an internal source as well.

Bad O-rings on the heat exchanger could be the cause for this issue as well..?
.

911monty · 03-08-2021, 04:24 PM

[QUOTE=Gilles;631655]Bad O-rings on the he heat exchanger could be a cause then, right?
.[/QUOTE

NO. This is physically not possible. 4 O-rings that contain pressures greater than atmospheric (oil at 15-50 psi and coolant at ~18 psi), cannot leak into each other separated by 2+ inches through the atmosphere @0 psi (14 psia) unless the O rings were gone and the leak was so bad they drained into the other from residual on the engine. But then I think the fluid on the ground would be hard to not notice.

Edit If I ruined a long standing joke like foglights then I apologize.

flmont · 03-09-2021, 08:21 PM

hopefully you have some oil that you could send out to get analyzed might help find the answer..