oil fill cap problem

[djnineball]

looked under the hood today and noticed some oil spots on a couple of the hoses and the valve cover. found that the oil fill cap had twisted loose and was just sitting there. i have the plastic valve cover because the metal ones i found online required drilling and tapping to mount and it has the plastic oil cap. it is not threaded, it's a twist in place type.

anyone encountered this and know of a solution? i twisted it down back in place but now i don't have any faith in it staying in place. AMC 258 i6 / 4.2l if it matters.

 

[JR74CJ5]

Normally if your oil level is good and you're getting oil out the filler, you've got some crank case pressure not venting through the pcv valve I believe...

Have you checked the pvc valve to make sure it's not clogged?

I have a AMC 304 so my fill tube is quite a bit taller and different for sure...

 

[djnineball]

Normally if your oil level is good and you're getting oil out the filler, you've got some crank case pressure not venting through the pcv valve I believe...

Have you checked the pvc valve to make sure it's not clogged?

I have a AMC 304 so my fill tube is quite a bit taller and different for sure...

it's not an engine problem, it's the oil cap itself. it is not a threaded cap, it is held in place by two tabs similar to our gas caps. it is not a super tight fit once in place and due to engine vibration it eventually slides around to where the tabs come out of the "lock" position and the cap just sits there in place.

 

[Torxhead]

I installed a rubber o-ring under that rubber washer, and it seems to seal it pretty good. Also, I still have that oem valve cover.

 

[djnineball]

I installed a rubber o-ring under that rubber washer, and it seems to seal it pretty good. Also, I still have that oem valve cover.

good idea. where did you put the oring, under the large lip (the part that makes contact with the cover itself)?

 

[WHATROAD]

JR's point about the PVC valve is worth exploring. It sits near the oil fill towards the firewall on the AMC 258 i6 / 4.2l . I change mine often as it does seem to plug. My oil filler cap is a simple plug in affair without a catch. no problems so far with that set up. I did change to an aluminum valve cover some years ago. I was afraid of the fire danger from the old plastic one. Good luck!

 

[Torxhead]

good idea. where did you put the oring, under the large lip (the part that makes contact with the cover itself)?

Between the plastic cap and that rubber sealing washer. Checking or replacing that pcv valve sounds good also.

 

[gert]

Between the plastic cap and that rubber sealing washer. Checking or replacing that pcv valve sounds good also.

Thats a pretty good idea I wish I knew about years ago. I was going to suggest replacing the cap because the rubber flattens over time and you no longer get the seal you once had which is what sounds like has happened to djnineball

 

[djnineball]

well based on subsequent posts i have determined my problem - there is no rubber sealing washer. all i have is the hard plastic plug, nothing else. as i said even when in place it is not a tight fit and can easily move around while the engine is running/vibrating. i'll swing my my flaps and grab an oring on the way home today.

Thats a pretty good idea I wish I knew about years ago. I was going to suggest replacing the cap because the rubber flattens over time and you no longer get the seal you once had which is what sounds like has happened to djnineball

nope, impossible. it's a new engine and the cover is brand new as well. i just never got the oring/washer.

Between the plastic cap and that rubber sealing washer. Checking or replacing that pcv valve sounds good also.

see above. it's brand new, maybe 600 miles on it.

 

[Hedgehog]

The engine has been rebuilt, much is new on it. Why not get a new cap as well?

 

[djnineball]

The engine has been rebuilt, much is new on it. Why not get a new cap as well?

it is a new cap, along with a new valve cover. it just did not come with the rubber gasket/oring for the cap apparently.

 

[Hedgehog]

Hmmmm - no oil seal, how odd. I probably wouldn't have noticed either.

 

[Lumpy Grits]

Don't forget to re-torque the headbolts at about 1000-1200 miles.
I would NOW put a wrench on ALL of the manifold nuts.
LG