Just changed oil in the truck today and found thick-ish light brown foam on the underside of the oil cap and down in the fill tube (for lack of better words). The dipstick is clean and parts look clean when I look down into the hole, but this brown gunk on the inside has got me concerned? I've never seen it previously. What is it?

Should I be worried?

Oh, about two weeks ago the engine inexplicably started to overheat (not into red zone), stayed hot for a few minutes. Radiator fluid was bubbling (not sure if it was boiling over) and then went back into normal range for no apparent reason after I shut the engine off and let it set a few minutes. Never did it again and has been holding steady ever since. Would this have caused foam build up? Is there some other underlying problem that I should be thinking of?

Details: '97 4.6L 4x4 & I use Mobil 1 synthetic oil.

Thanks in advance for any advice...Scott

 

Antifreeze. You overheated so it may be a cracked or warped head. May just be the head gasket though.

Sounds like a classic case.

Hopefully I am wrong.

Sorry

 

Are you loosing antifreeze/coolant? If there's a significant loss then your antifreeze/collant is mixing with your oil. Have your engine pressure tested to see if there's a leak, if there is then its probably due to cracked head or torn head gasket.

 

You've got either a cracked head or most likely, a leaking head gasket. Radiator bubbling and foam on the oil fill cap are the telling signs. You're in for major work. Depending on the miles of your truck, you can opt either to pull the heads (do a valve job and have them checked) or get another engine (if you have high miles). Mine had 185K when I experience your problem. I opted to pull the engine. In fact, I pulled it Friday night and am in the process of ordering a remanufactured motor. Best of luck!

I see by your profile you've already go a reman engine. I hope it is still under warranty!

 

Did your oil look normal? If you dont see any signs of water or antifreeze in the oil you drained out, you are probably just seeing condensation on the oil cap. When it gets cold you can get some condensation formed on the oil cap if the engine doesnt get warmed up fully, and you end up with that milky substance.

 

+1.

That funky stuff on the oil cap is nothing to worry about. If and when you OIL looks milky/watery it's time to worry.

 

+2 If its not in the actual oil, then its no big issue. Just a little codensation under the cap is actually a frequent seen occurance in all vehicles, not just fords.

 

Thanks for all your replies.

I've saved the oil to recycle it so I'll check it soon. I didn't notice anything funky about it while I was changing it, but I wasn't looking too closely either. I don't want to go thru another engine change any time soon.

I did notice that my electric fans are not kicking in. The engine has been staying cool without them except for that one time (didn't go into red zone tho) since it's been relatively cool around here. A quick call to Troyers and their excellent customer service quided me in my trouble shooting checklist since I've have lost my installation manual in the past two residential relocations. Will do that tomorrow as well.

Any more thoughts on the subject are greatly appreciated...Scott

 

So did you get the fans back online? And alot of times, the oring on the oil cap goes bad from heat exposure and thats where you'll get some condenstaion

 

Fix your fans and you should be fine. It is extremely unlikely the engine is in any way damaged (yet).

That brown crap is most often seen in vehicles that see mostly short-haul usage. The engine never gets hot enough for long enough for the moisture to fully evaporate out of the crank and get sucked out via the PCV system. When the engine cools, it condenses at the highest and coolest point.

The brown crap issue comes up every winter here on the forums.

Stev

 

I ran into that same situation a couple weeks ago when I changed my oil. I only found the brown sludge under the oil cap and the oil filler neck. I did not find any antifreeze mixed in the oil, nor was my antifreeze level low. More than likely it's just condensation in the crankcase.

 

the nasty looking stuff is nothing more than condensation. the dodge motors are esecially bad for it... just as any 318 or 360 owner.

 

I just joined the forum to research a problem with my son's '98 F-150 (4.6 w/63k miles) and stumbled on this thread.

When he changed his oil a couple of weeks ago, everything was fine, except for foam in the oil fill tube. Not much, just a "finger full". His truck is always outside (my Excursion gets the garage because it's bigger...). Before he moved out (yes, there IS a God!), he didn't have the problem. I'm guessing that because he only lives about a mile from work, he's not getting the valve cover hot enough to get all the condensation out? Before, his commute was 30 miles.

Regardless, it sounds like this is NOT a problem? Just wanted to make sure. There are no other problems. Oil's good, engine runs like a dream. Just this foam.

thanks folks!

 

Ditto to the second half of the thread. If it's JUST inside the oil cap, it's nothing to worry about. If it's in the engine oil, you'll know it when you drain it.

It sounds to me like the likely cause of the initial overheating may have been the fans not coming on.

For the record, even if it does get up into the red zone, the engine will switch over into limp-home mode. Gotta love fail-safe cooling.

-Joe