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Oil Cap Leak

N

nates94xj

NAXJA Forum User
Location
WA
Is there any solution for the leaky oil cap on a 4.0? I bought a new oem one, and that worked for a bit, then I tweaked the flanges to make it a little tighter, and that worked for a bit, but now it leaks a ton.

Which brings me to another question. How much oil is it possible to leak out the cap? I'm losing almost a quart every thousand miles. It doesn't smoke, and the only other leak I can see might be a small one on the front crank seal.
 
Sounds like you ahve a bigger problem than your 710 cap leaking. Have you checked the valve cover, rear main, behind timing chain cover?
 
I'm going to agree with Johnnie, and add that oil shouldn't be leaking from the cap (at least not enough to lose a quart of oil). I would guess that some part of the CCV (Crank Case Ventilation) system is plugged up, check the hoses that run from the valve cover to the intake and to the airbox. It sounds like you are building up pressure and there is nowhere for it to go but out the cap (and every seal that isn't sealing up tight).
 
Those caps are always a little loose feeling, even brand new.

However, I'm with Johnnie Walker, I think you need to service your CCV system, and be sure to check your air filter, it may be oil saturated.

When the CCV system isn't functioning correctly your valve cover/crankcase becomes pressurized and starts forcing oil out of the oddest places.
 
GrimmJeeper said:
I'm going to agree with Johnnie, and add that oil shouldn't be leaking from the cap (at least not enough to lose a quart of oil). I would guess that some part of the CCV (Crank Case Ventilation) system is plugged up, check the hoses that run from the valve cover to the intake and to the airbox. It sounds like you are building up pressure and there is nowhere for it to go but out the cap (and every seal that isn't sealing up tight).
Click to expand...

Great minds...

You beat me to it!
 
Crikey, you guys have some serious post counts! Thanks for sharing the wisdom!

I haven't had oil on the air filter for 50k miles. I cleaned the ccv system when I first bought the vehicle. I have replaced the rear main seal, oil pan seal, oil filter adapter seal, valve cover casket, and they are all bone dry except for a tiny bit of weepage on the front of the valve cover. There does seem to always be some oil on the starter, but I thought that was just from changing the filter? The car never drips oil on the driveway.
 
You should check the CCV a couple times a year. Run a stiff wire or drill bit through the port on the intake manifold, and the orifice in the rear of the valve cover, and make sure the vacuum line between the two is open.

As I mentioned earlier, those oil fill caps are a little loose even when new. It hasn't been an issue for me--at least not yet--but you could cut out a piece of old inner-tube to fit and "stack" the rubber washers for a tighter fit.

Good luck.
 
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