F-head consuming a LOT of oil, help!

Hi all,

I picked up a 62 CJ5 a couple months ago and have been working on the weekends to get it up and going. Hopefully to be able to do some mild Moab stuff as well as do some more fun camping stuff with it. Made a complete new wire harness, new mastercylinder, wheel cylinders, shoes, etc.

But it's consuming a LOT of oil. Like 3-4 quarts in just an hour or two of driving.
If I let it idle or downshift downhill for a bit (high manifold vacuum situation), THEN hit the gas to take off a huge cloud will come from the exhaust. At no other time is anything noticeable from the tailpipe.

So first instinct was to replace the intake valve guide seals. Put in new o-rings, old ones looked fine, but changed them anyway. Made no difference.

When I had an airline hooked up to the cylinders to keep the valves up while I replaced the seals, I could hear a little bit of bubbling in the radiator. Okay, bad head gasket. I replaced the head gasket because it was obviously bad, and hoped that maybe oil from the push rod tubes was also leaking to the combustion chamber.

With the head gasket changed, the smoke has been reduced and the engine runs much better (less cutting out, etc), and the plugs are not fouling out anymore. Before the plugs would be 'wet' with oil when I removed them. At this point, the plugs are dry, but running rich. So, progress.

So then I thought maybe oil was pulling through the breather, and into the intake (the rubber boot connecting the oil bath to the carb was oily inside). So I removed the hose, leaving the breather connected to the oil bath. I need to clean the oil bath, because I had to reset my idle mixture with it removed. Plugs are now showing a good burn as well, so the oil bath is restricting quite a bit right now. I'll take some time to clean that out for sure. But, it is still burning a LOT of oil. If I sit there and rev it over and over again, I can get a huge cloud of burning oil out the tailpipe.

But it is still burning as much oil as ever, needing me to top off the oil as often as always. I've made progression the amount of smoke, and how well it runs (It is actually running pretty good now.).

Any ideas what I may be missing? Compression is 115, 125, 120, 120 when warm. Looking in the spark plug holes with the engine off, the chamber looks 'dry' like the plugs are now. My neighbor is going to bring his small probe camera home from work so we can really get a look at the inside of the chamber for clues.

New intake valve guide seals, head gasket, and removed the crankcase ventilation from the equation. I'm hoping someone familiar with these F-heads will know what I'm overlooking. I don't want to have to take 3-4 gallons of oil with me anytime I want to go do a weekend trip in it.

It does seem to burn more fuel if I drive around at about 3000-3100rpm (close to 50mph). Low RPM crawling around seems to buy me more time on oil consumption.

Any help appreciated. I'm running out of ideas!

 

Oh yea, here she is:



Soon as I get this oil thing figured out, I'll be onto 'outfitting' it better for the trail. Engine and drive train will stay stock (I'm diggin it), but will make new bumpers, ad a winch, highlift jack, a set of MT's, etc. One thing at a time though, got to get this engine to ease up on the oil consumption first. :?

 

The vacuum pump (combination fuel pump) diaphragm may have failed in a way that sucks crankcase oil to the intake manifold.

Busted rings have been common in my F-heads, but your compression readings seem passable.

Good luck!

Pete

 

I just replaced the fuel pump with the non-vacuum port type. The old pump had nothing attatched to the vacuum lines. Is there something there I should be checking for that a previous owner may have done?

I noticed the hardline coming off the manifold under the carb, but didn't follow where it went to. Maybe I should go out there real quick and check out where it is going?

 

I put some oil in the first cylinder that showed 115 and it bumped up to just over 120.

One thing I just went out and looked at. There is a hardline off the intake manifold. Mine goes down around the front of the motor, and connects to the lower valve cover. It all 'looks' factory, but makes sense that it would just be pulling oil from the side of the motor and sucking to the intake manifold. Is this how it's supposed to be, or has somebody done something wrong to this motor at one point?

If it is connected wrong, what is supposed to be connected to what? If it is correct, what the heck is the purpose behind it?

 

Interesting. I would have thought the 1/2" breather line off the oil filler tube would be adequate? No? I might try disconnecting it and sealing both off and take it for a test drive tomorrow to see if anything changes. Otherwise the curiosity will kill me.

I'll re-do the compression check tomorrow after work. Dry and wet after I get it fully warmed up again and post the results.

 

I've hinted at it to the wife for Christmas. Keeping fingers crossed. lol

 

That hard line should go to your PCV valve which is hardware mounted to the side cover above the fuel pump.:hurrican:

 

This is the leak down tester I made out of common stuff I had laying around. I would try to do a leak down test.

http://www.earlycj5.com/forums/showthread.php?t=58684

 

Well, made real progress tonight.

Something must be wrong with the PCV system, because by closing that system, the jeep is no longer burning oil. Wondering if there is a deflector or something behind that lower valve cover that is missing or something that allowed all that oil to be sucked up into the intake past the PCV. Very odd, but that was the source of the oil I have been burning.

I cleaned out the oil bath filter, re-installed it, unhooked the PCV hard line to the intake and plugged both ends. Fired it up, re set the idle speed and mixture and went for a drive. Night and day difference now. Any smoke at all is very faint, possibly just residual in the exhaust maybe.

Went for a drive around, got it fully warmed up for a while. Got back to the garage and pulled the plugs. They look fantastic. a nice light brown/tan on the porcelain, excellent burn going on. Would have done a compression check, but dinner was ready and I wasn't about to break my golden rule, "Happy Wife, Happy Life". lol

Really happy with it for now. I'll do some more driving on it next weekend and make the sure oil consumption is really under control. No more smoke, and the plugs look fantastic, I'm feeling pretty optimistic about it at this point.

Now to fix that exhaust leak under the drivers seat. That's getting loud and annoying, lol.

Thanks for the help everyone!

 

Pretty normal there.

I think what I'll do is install a PCV valve into the upper valve cover with a splash guard to keep oil spray from directly going into it. That way I can still get some cross-flow through the motor to help remove any moisture and contaminants better.

 

i think that the orignal pcv valve is stuck in the fully open postision, just my $.02, and by the way thinking that willys was the first to have a pcv system

 

Makes sence, first to be production designed to go under water (?)