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Oil filler cap

schmiedel

NAXJA Forum User
I replaced the oil filler cap of my 1988 4.0 XJ one month ago, but it doesn't seem to seal properly, so I have minimum oil leaks. Since I drive alot in dusty environments, my valve cover is a mess, I can clean it up but after a while it'll be a mess again. I know Jeeps are famous for having this kind of oil leaks, in my case I don't have any blow-by, so it's only the oil cap that doesn't seal properly. What kind of oil filler cap do you recommend?

Any experiences with OEM/aftermarket ones that have worked well?

Regards
 
I just replaced mine also and the new one works great. I got it at Autozone for about $4.00. If it still wont seal, you might go to the hardware store and get a thin rubber washer to add to the cap. This should create a tighter seal.
 
I have a 98 with the ratchet screw in type. Stant makes replacement ones.
 
I was considering to build a washer, the cap I have is made of rubber, but it doesn't feel like it pressures to the valve cover. If it doesn't improve and I don't find a washer in the proper size, I'll cut one out of a sheet of foamy. :D

It would be great to find one that has a spring with a washer or something similar to a radiator cap, that would do the best possible job.
 
The original cap should have threads that screw it tight to the valve cover. If its just a rubber plug type cap, I think you have the wrong one. Mine screws down and creates a nice seal.
 
schmiedel said:
I replaced the oil filler cap of my 1988 4.0 XJ one month ago, but it doesn't seem to seal properly, so I have minimum oil leaks. Since I drive alot in dusty environments, my valve cover is a mess, I can clean it up but after a while it'll be a mess again. I know Jeeps are famous for having this kind of oil leaks, in my case I don't have any blow-by, so it's only the oil cap that doesn't seal properly. What kind of oil filler cap do you recommend?

Any experiences with OEM/aftermarket ones that have worked well?

Regards
Get a valve cover off of about a 93 to a 95 XJ or ZJ. They have a better style oil cap but still not the stupid ratcheting one that breaks all the time, plus they have larger CCV orifices which helps blowby(even though you don't have it). Anyway I'd give that a shot but it's just my personal opinion.
This is a 93's in my 90.
ResizedVC2.jpg
 
Had the same problem. Put a small layer of rtv around the opening on teh valve cover. Acts like a rubber seal. Problem solved.
BSD
 
schmiedel said:
This looks great, the oil cap seems much better. However, are the Renix and the HO valve covers identical in the bolt pattern and the gasket?
I know for a FACT the bolt pattern stayed the same throughout all the years. However, in I believe 96(I know it wasn't 95) Jeep went to a ratcheting style oil cap that sucked as well as what I understand to be a "stamped" gasket that is like $40.00 to replace, even at the auto parts stores. If I were you, I would get one from a 93-95, 91 and 92 were a slightly updated design but the CCV lines had janky fittings on the actual valve cover. I'm VERY pleased with the way mine looks and performs honestly.
My .02
-Collin
 
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