Yellow foam under oil fill cap

I was changing my front valve cover gasket today and I saw this under the oil fill cap.


I didn't drive my car that much this winter, so it could be that I didn't heat the oil enough to burn the condensation. I am due for an oil change, so is there anything to worry about? I am also low in coolant, so I need to find where it is leaking to. Are they related?

Thanks for the help.

98riv wrote:

I was changing my front valve cover gasket today and I saw this under the oil fill cap.


I didn't drive my car that much this winter, so it could be that I didn't heat the oil enough to burn the condensation. I am due for an oil change, so is there anything to worry about? I am also low in coolant, so I need to find where it is leaking to. Are they related?

Thanks for the help.

It would be well worth the expense or labor to have a cooling system pressure test done while the engine is Cold and Hot, to rule out a coolant leak internally.
You mentioned changing the valve cover gasket, what does the rest of the cover and valve train look like.

Rickw wrote:

98riv wrote:

I was changing my front valve cover gasket today and I saw this under the oil fill cap.


I didn't drive my car that much this winter, so it could be that I didn't heat the oil enough to burn the condensation. I am due for an oil change, so is there anything to worry about? I am also low in coolant, so I need to find where it is leaking to. Are they related?

Thanks for the help.

It would be well worth the expense or labor to have a cooling system pressure test done while the engine is Cold and Hot, to rule out a coolant leak internally.
You mentioned changing the valve cover gasket, what does the rest of the cover and valve train look like.

The valve cover and valve train don't show any of the yellow substance or any other kind of foam. The valve cover was dirty on the inside (old oil stuck to the top). The rockers and everything else looked fine.

I also changed the LIM gasket about two years ago to the new metal gasket, so it shouldn't be leaking there.

Something caused this yellowish snot.
Had you used some kind of coolant system flushing product before the winter.?
And where did the coolant go to.?
I would start with the coolant system pressure test to find out where the coolant is going and if you can't find the source of the leak then perform a coolant system flush with one of the brand name flushing products to get rid of the snot that may be in the system and try a pressure test again.
I find the best way to get a complete flush is to remove the thermostat and reinstall the housing with no stat, put in the flushing product with water, let it run until warm / hot for a while, change RPM's to help get it moving thru the system and then drain it.
Put in fresh water and do it again, drain, then install either old thermostat if you know it's good or just put a new one in. I recommend new.
Refill sysytem, let it get up to normal operating temps and then do a pressure check and look for leaks or pressure bleed down. If you can't see anything coming out externally then triple check your dipstick and drain your oil, looking for the water or coolant in the oil.
Good Luck

Rickw wrote:

Something caused this yellowish snot.
Had you used some kind of coolant system flushing product before the winter.?
And where did the coolant go to.?
I would start with the coolant system pressure test to find out where the coolant is going and if you can't find the source of the leak then perform a coolant system flush with one of the brand name flushing products to get rid of the snot that may be in the system and try a pressure test again.
I find the best way to get a complete flush is to remove the thermostat and reinstall the housing with no stat, put in the flushing product with water, let it run until warm / hot for a while, change RPM's to help get it moving thru the system and then drain it.
Put in fresh water and do it again, drain, then install either old thermostat if you know it's good or just put a new one in. I recommend new.
Refill sysytem, let it get up to normal operating temps and then do a pressure check and look for leaks or pressure bleed down. If you can't see anything coming out externally then triple check your dipstick and drain your oil, looking for the water or coolant in the oil.
Good Luck

I didn't use any kind of coolant system flush. Don't know where the coolant went. I don't think it is burning it because the exhaust doesn't have a sweet smell and the exhaust isn't while smoke. It seems like a slow leak. I haven't filled it up since probably last March or so. I think I had originally filled it up in between the hot and cold marks on the reservoir. There is probably a half inch or so coolant left in the lower part. I know the coolant shouldn't be leaking. It seems like it is always lost some coolant. More so when I had the LIM gasket leak. Can I rent a pressure tester from Autozone? Also, could it be evaporating in the coolant reservoir tank (maybe the cap isn't sealing all of the way properly)?

For the past year or so I really have cut down on the driving with my car. In the winter, it was common for it to not have warmed up all of the way before I reached my destination. It would have been better if I would have let it warm up more. I'll have to check out Autozone and see if I can rent a pressure tester.

Driving the car and not allowing it to reach normal operating temperature will eventually cause "snot". As you said, the condensation that builds up doesn't have enough time to evaporate and eventually builds up. Change your oil, clean that snot, and keep an eye on it. I wouldn't do anything just yet. Just drive it and check......

Even after replacing the LIM gaskets, there are still some coolant passages prone to leakage. The ports from the LIM to UIM with the throttle body coolant have been known to leak. If it were leaking, though, I would expect that coolant to be sucked through the intake and burned off, but it could go anywhere.

If you haven't lost that much coolant (1/2") in the overflow tank, I wouldn't worry about it that much.
Or did I mis-read what you said. You haven't driven it enough to know what is normal or just evaporation. The cap in the overflow tank is vented to the atmosphere, so consider that .
Flush and fill for the season and have it pressure tested when you can and start your analyzing over again.
Drive it some more and see what your losing during normal usage of the car.

Rickw wrote:

If you haven't lost that much coolant (1/2") in the overflow tank, I wouldn't worry about it that much.
Or did I mis-read what you said. You haven't driven it enough to know what is normal or just evaporation. The cap in the overflow tank is vented to the atmosphere, so consider that .
Flush and fill for the season and have it pressure tested when you can and start your analyzing over again.
Drive it some more and see what your losing during normal usage of the car.

I wasn't sure if the coolant could evaporate out of the reservoir tank or not. I will keep an eye on it and pressure test it if it gets worst.