Cmcilm94

Okay, so last night I was at McDonald's sitting in the parking lot for about 30 minutes while the jeep was running, then when I pulled up to get my food it just out of nowhere has such a horrific misfire, like it sounded like it was going on 2 cylinders maybe, and then I pulled out onto the road and it did the same thing but I the throttle some fines and after about 30 seconds it cleared up... Before I went to McDonald's I did put some gas in it because it was almost on empty, and this morning I went to inspect and I noticed a petroleum jelly like substance on my oil filler cap... I don't really know what is going on here. My first initial guess is I bought some bad watery gas but I'm uncertain at this point. The coolant was low but that's because I recently did a complete flush and I am still letting the system bleed. Any ideas what's happening?

CR-Snow

What year is your truck? Any CEL's?

Cmcilm94

1999, and no, nothing. It was pretty Strange.

CR-Snow

My first thought was heat soak on the injectors.
But they usually heat soak after the truck has been running, it's hot, then you turn the truck and subsequently the fans off. This lets the fuel in the injectors get super hot then when you go to turn it back on after a short break, they'll misfire like crazy.

But this doesn't sound exactly like your situation.

As far as the petroleum jelly issue, have you checked the casting number on the side of your head? Take a look between #3 and #4 cylinders on the intake manifold and look for a 4 digit number. Hope it doesn't read 0331

Cmcilm94

First off, Thank you for your input and opinion as it is very much appreciated.

I went outside and gave it another once over and it appears that my heads casting number is 0630... But


I also thought to take a look between cylinder 3 and 4 with the cap off...



Yeap... I managed to get a pic before my flashlight died. There is another green blob right above it also that cannit be seen in the picture. This is right where all of the cracked heads usually report the missing coolant, but it's odd... Do they do this on this casting number?


Also, here's a picture of the cap, it was way worse but I knocked some of it off earlier.

CR-Snow

Well that doesn't look good at all. Definitely looks like there is coolant mixing with oil. I'm not an expert on these cracked heads but maybe something else is happening.

Someone correct me if I'm wrong but, you could be getting coolant into the oil from a bad head gasket. I don't know where the head gaskets typically fail on the 4 liters, but I suppose they could fail around an oil passage and let coolant in that way.

I guess a shop could do a leak down test to check.

Hopefully some folks with more knowledge will chime in. They almost always do. Good luck.