AMC V8 Oil burn issues

[IrishCJ6]

I'm looking for advise,
The 360 was using vast quantities of oil (<1 litre/100 miles), it only seemed to use it under acceleration and deceleration and clears when at a constant RPM, after doing a bit of research I figured valve stem seals seemed a perfect place to start. I have just replaced all 16 seals with new umbrella (nylon, white) seals. The old ones were definitely original they were all still intact however, some were very loose. I was hoping this would solve all the issues but I still notice smoke (oil) under acceleration and deceleration, haven't driven far enough to see whether the oil consumption has improved but was wondering if there was any other obvious places to get these symptoms. I know the rings are good as compression seems OK, and its not burning constantly as it would if it were rings. I changed the seals on the Jeep and used air to do so, I believe the valve seats/guides to be OK also as there was no leaking during the disassembly and reassembly of the seals/valves. I did read something about faulty PCV valves causing oil burn?
Anyone have any bright ideas.

 

[xena1]

I'm looking for advise,
The 360 was using vast quantities of oil (<1 litre/100 miles), it only seemed to use it under acceleration and deceleration and clears when at a constant RPM, after doing a bit of research I figured valve stem seals seemed a perfect place to start. I have just replaced all 16 seals with new umbrella (nylon, white) seals. The old ones were definitely original they were all still intact however, some were very loose. I was hoping this would solve all the issues but I still notice smoke (oil) under acceleration and deceleration, haven't driven far enough to see whether the oil consumption has improved but was wondering if there was any other obvious places to get these symptoms. I know the rings are good as compression seems OK, and its not burning constantly as it would if it were rings. I changed the seals on the Jeep and used air to do so, I believe the valve seats/guides to be OK also as there was no leaking during the disassembly and reassembly of the seals/valves. I did read something about faulty PCV valves causing oil burn?
Anyone have any bright ideas.

Sounds like a problem I had with oil getting sucked up into the PCV valve. I re-routed PCV hose from vacuum port on carb to fitting on base of air cleaner and problem was solved. Don't know what intake you have or intake gaskets you used, but mine was Edelbrock intake and carb.

 

[Torxhead]

Valve cover gaskets are another area where you can loose oil and it burns off before dripping to the ground.

 

[IrishCJ6]

Sounds like a problem I had with oil getting sucked up into the PCV valve. I re-routed PCV hose from vacuum port on carb to fitting on base of air cleaner and problem was solved. Don't know what intake you have or intake gaskets you used, but mine was Edelbrock intake and carb.

Mine is completely standard with the cast 2 barrel manifold and using the MC2100, have you any photos?

 

[Scooter402]

I had a major oil consumption problem in a 360 V8 I originally had in my CJ7 . Turned out it was the valve guides. I found this when I went to go change the valve seals after the PO told me he already did that, still not solving the issue. Hopefully that's not your problem, though.

 

[Saddle Tramp]

Welcome to the forum! My hat is off to anyone who drives an American V8 with the price of petro. Even though you state you are burning oil upon hard acceleration are you sure some of the oil isn’t leaking from the rear main seal or the valve covers? AMC motors are notorious for dripping the stuff. Having said that valve stems do come to mind. In the “olden days” fuel contained lead which was a great lubricator; once the lead was removed a lot of older engines experienced premature wear, particularly the valve steam guides. Not sure when they got the lead out in Ireland but it was the early 1970s in The States; depending upon when the motor was manufactured it may not have been upgraded for unleaded.

 

[IrishCJ6]

Welcome to the forum! My hat is off to anyone who drives an American V8 with the price of petro. Even though you state you are burning oil upon hard acceleration are you sure some of the oil isn’t leaking from the rear main seal or the valve covers? AMC motors are notorious for dripping the stuff. Having said that valve stems do come to mind. In the “olden days” fuel contained lead which was a great lubricator; once the lead was removed a lot of older engines experienced premature wear, particularly the valve steam guides. Not sure when they got the lead out in Ireland but it was the early 1970s in The States; depending upon when the motor was manufactured it may not have been upgraded for unleaded.

Thanks for the welcome, I've been around for a while just no posts, yeah petrol is expensive but its a weekend crusier thus not used much. Yes it does have a small leak from the rear main but not enough to leave marks on the ground overnight or even over a month. I though it may be going into the bellhousing however there are holes in this from previous owners neglect and thus you would see oil dripping from here also but nothing. Also it would be on the clutch by now and it hasn't so I don't think this is the cause. There was no major leaks from the valve covers either (replaced when seals were done) so this option is out. I'm going to do a compression test again to see if there is any issues here but it really doesn't smoke like a vehicle would with bad rings. I've ordered a new PCV valve and grommet so will install this and see that that helps.

If anyone is interested in my build then look here

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I tried to post this on the build forum page but it wasn't allowed.

 

[IrishCJ6]

So I'm still dumb founded with this issue, did a compression test today and got these figures

Cyl 1: 160
Cyl 2: 155
Cyl 3: 155
Cyl 4: 163
Cyl 5: 158
Cyl 6: 168
Cyl 7: 155
Cyl 8: 163

These were dry figures, I decided that seeing that they we so good there was no point in doing wet figures. So all are well above the 140PSI as given in the workshop manual, and there is less than 10% difference between highest and lowest figures.

So I'm still using oil about 0.5l/50km +/- (no speedo) and I have no leaks from the engine other than a small weep from the rear main and that doesn't leave marks on the ground, so where next? I have ordered a new PCV valve to check that off the possibility list.

Anyone got any bright ideas?

 

[Jimbos76cj]

I would change the valve seals.. they are cheap and can be done in the vehicle.

 

[hagar]

I would change the valve seals.. they are cheap and can be done in the vehicle.

He's already done that.
If nothing else, ditch the 15-40 for straight 30 wt.

 

[dunebuggy18]

Pull the PVC and see if the check moves easily by rattling it back and forth. If in doubt, it's a cheap part - replace it to eliminate the possibility that it is the issue. A clogged PVC can cause oil burn, oil leaks and major sludge build-up if it is bad and not repaired.

 

[phil8825]

Yeah I had that problem as well, my 360 just swallowed oil, I was to the point of refilling 1 quart every 100 miles. The engine ran like ****. Compression test showed i was pretty much running 4 cylinder .. Although my problem was a little different in that I was out of the country, jeep had been sitting quite some time, had a friend drive it and it turns out there was no oil in it. He stated it was banging and doing all sorts of things. Expensive mistake.. Engine is currently at the machine shop. Although im surprised it didnt fully seize, checked the dip stick when I got back, bone dry

 

[jdarg]

Valve cover gaskets are another area where you can loose oil and it burns off before dripping to the ground.

Pull the intake and make sure you have a valley pan gasket. AMC V8s will drink oil through the PCV if its missing.