Yellowish goop on inside of oil cap.....

[Rinn69]

Short version. Changed my oil today, and when I open the oil fill cap, there was some yellowish goop on the inside of the cap. Cleaned it out (didn't think of saving some or a pic---dumb, I know) and proceeded with the oil. Oil looked fine, no "milkshake of death".

Long version with details. About 2-3 months ago, I had an overheating light that came on, then went off 5 seconds later....came on again about a minute later, same short duration. I Was only a block from home, so I popped the hood, and the overflow tank was low. Got some antifreeze, added it, and all was good. Checked the coolant level the next day, and it was down....then I noticed a drip from the bottom of the overflow tank, and also saw there was dried coolant on top of the tank, so I ordered a new overflow tank and radiator cap and installed a few days later. Had to keep adding coolant since I didn't have the tool to "burp" the cooling system. All was good. A month and a half ago, I took a 2000 mile round trip down to Louisiana with no issues. Checked the coolant level a few times, and had to add some periodically, maybe a cup or so each time. Then I changed to oil today with 44% oil life left, about 5000 miles on it and did notice a small amount of steam or smoke coming from the oil fill since I drove it around to warm everything up. I don't drive it very often, 1 or 2 times a week, usually short trips--10-15 minutes one way. It may sit for 4, 5, 6 days in the garage, with no use.

Thoughts ?? Diagnosis ??

EDIT---- Clarified a few things in my next post below.

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[Figarou]

Short version. Changed my oil today, and when I open the oil fill cap, there was some yellowish goop on the inside of the cap. Cleaned it out (didn't think of saving some or a pic---dumb, I know) and proceeded with the oil. Oil looked fine, no "milkshake of death".

Long version with details. About 2-3 months ago, I had an overheating light that came on, then went off 5 seconds later....came on again about a minute later, same short duration. I Was only a block from home, so I popped the hood, and the overflow tank was low. Got some antifreeze, added it, and all was good. Checked the coolant level the next day, and it was down....then I noticed a drip from the bottom of the overflow tank, and also saw there was dried coolant on top of the tank, so I ordered a new overflow tank and radiator cap and installed a few days later. Had to keep adding coolant since I didn't have the tool to "burp" the cooling system. All was good. A month and a half ago, I took a 2000 mile round trip down to Louisiana with no issues. Checked the coolant level a few times, and had to add some periodically, maybe a cup or so each time. Then I changed to oil today with 44% oil life left, about 5000 miles on it and did notice a small amount of steam or smoke coming from the oil fill since I drove it around to warm everything up. I don't drive it very often, 1 or 2 times a week, usually short trips--10-15 minutes one way. It may sit for 4, 5, 6 days in the garage, with no use.

Thoughts ?? Diagnosis ??

If the oil looks like oil (and not milkshake), just clean the cap and call it a day. More than likely you just haven't been running your vehicle enough. You need to take it out and completely get it warm which will burn off any moisture which might get into the crankcase. Moisture is a byproduct of the combustion process and will get into the crankcase. If you don't get the oil hot enough through usage, the yellowish foam can collect in the oil cap.

 

[puckdodger]

My first instinct is that this is not a good situation, primarily because you had to continue to add coolant. I would think the proper amount of coolant to add on a 2000 mile trip would be zero. But as @Figarou said it may just be condensation building up from not a lot of time at full operating temperature.

 

[MarioCart]

I've seen this goop before.
At the time I don't believe I had a coolant leak issue, but it'll always be on the back of your mind, especially if you're adding occasionally. I wasn't adding any, so I slept good at night believing it was just condensation and a high humidity environment.

Its moisture in a general sense, time will tell if its detrimental or not.

 

[Jason B]

If your truck isn't driven at operating temperature for several minutes, moisture is never driven out of the engine, so you may see a little accumulation on the cap.
Just keep an eye on it and don't become this guy:
(1) 98k and cracked gasket, told I need new engine | 2019+ Ford Ranger and Raptor Forum (5th Generation) - Ranger5G.com

 

[jeez]

Coolant has to go somewhere.....It's not a 'used' by the engine. If there isn't any drips under the vehicle, it's in the engine and going out the tailpipe. You'll see some white smoke out of the tailpipe and/or goop being generated. Small amount won't give you the milkshake of death, but you gotta know it's going somewhere.

 

[airline tech]

The yellow sludge may be just normal condensation build up from short trips.
But with coolant loss along with that, it needs to be investigated further to ensure that it is normal.

Frequent adding of coolant is not normal, I would pressure test the system and let it sit pressurized for 30 minutes or so, as I suspect a small leak is still present, possibly Head Gasket or EGR Cooler. Pressurize to 21 PSI and ensure it holds.
If pressure drops and no external leaks are noted, then it is internally leaking somewhere.

The most likely will be a Head Gasket or EGR Cooler, leak.
EGR Cooler will be dumping into the exhaust.
Head Gasket will be dripping down the cylinder walls and can be seen if you pull the plugs and borescope the cylinders.

I would at the very least pressure test the system an ensure it holds pressure, mainly to confirm was the Degas Bottle (Reservoir) the cause of the leak or was it a secondary leak created by another unseen leak.

Note: If the system does have a small leak, the system will never reach full system pressure with engine running, this is the benefit of a pressure test, you can pressurize it to full system pressure of 21 PSI.

 

[Rinn69]

@puckdodger @airline tech @jeez

First and foremost---THANK YOU for everyone's input !!!!!!

Just to clarify a couple things due to my poor writing, clouded with thoughts of a costly repair bill, I didn't have to add any coolant on the 2000 mile road-trip.

When I check the system, it's always a day, or a few days after I drive it, so it's had time to cool completely. When I open the reservoir cap, there has always been pressure that I slowly allow to vent....takes 10-20 seconds to do so.

My thinking is that since I didn't "burp" the cooling system with a vacuum device, there are / were some air pockets/bubbles that remain in the system, hence, the need to add coolant when it does burp some air into the reservoir tank ?‍ The amount I had to add has been decreasing over time.

Also, no smoke from that tailpipe and no drips on the floor or engine bay since I replaced the reservoir tank and cap.

 

[NotBudule]

I would check for coolant in the oil , either dye or the little test strips ...

 

[Grandaccess]

I changed my coolant about 15k ago, never checked it I glance over at it if the hood is up LOL, and still hasnt gone down a drop? no foam or gas in the oil "yet"

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