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Pukin' Oil
https://slantsix.org/forum/viewtopic.php?t=8371		 Page 1 of 2
Author:  Daddiojoe [ Tue Feb 10, 2004 7:26 am ]
Post subject:  Pukin' Oil
:x :x :x

This is an ongoing problem, and you've helped me with suggestions in the past, but it's still happening. I feel like there ought to be a simple fix that I'm overlooking--like a clogged breather on the underside of the engine or something.

I have a 1971 D100 pick-up. Engine seems to be original, with completely rebuilt head. Several months ago I checked compression and as I recall, numbers ranged from 110-140. This was before the head rebuild. I need to find where I wrote that info down, and probably check the compression again.


Here are the symptoms:

Oil puking out on the valve cover from around the PCV gasket, under the oil filler cap, and out and around the breather.

Oil puking out of dipstick filler tube, and when stick is firmly seated in the tube, from somewhere farther down on the left side of the engine.

There's oil on the frame and down on the inner fenders.

If I plug the breather hole on the valve cover to keep oil from puking out, and if the dipstick is firmly in its tube, oil pukes from somewhere else on the left side of the engine.


Here's what I've done:

Changed oil and made sure that the oil level is correct.

Found properly fitting dipstick in tube. That seems pretty sealed up.

Got correct PCV valve and checked hose to carburetor.

Rebuilt Carter BBD, making certain that all passages are clear.

Cleaned breather and used several different ones on the back hole of the valve cover. Currently using a breather with a hose that attaches back to the base plate of the open air filter I'm using. Doesn't seem to be puking a lot of oil up into the filter housing. Doesn't seem to be burning oil.

I recently installed a Melling stock pressure oil pump.


Random thoughts:

The PCV hose is hooked up to the carburetor where the vacuum will be strongest when its idling. It doesn't seem to be able to flow enough when the the throttle is open.

Is there some way my crankcase could be over-pressurized to make this happen?

The truck performs fairly well. In addition to the carb rebuild I had a two and a quarter inch exhaust installed. That seems to have smoothed it out quite a bit.

But it's still pukin' oil!!! :x :x :x :x :x

Thanks for your help, everbody,


Joe
Author:  Eric W [ Tue Feb 10, 2004 9:36 am ]
Post subject: 
Sounds like the exact symptoms I had with the original '72 engine in my car due to excesive blow by caused by bad rings. Your compression readings seem pretty good to be rings though. Maybe try an "open" breather (one with out the nipple to get more air flow) to see if more fresh air into the engine will help. Other than that, I don't know. Anybody else??
Author:  mnecaise [ Tue Feb 10, 2004 12:32 pm ]
Post subject: 
Quote:
The PCV hose is hooked up to the carburetor where the vacuum will be strongest when its idling. It doesn't seem to be able to flow enough when the the throttle is open.
This confuses me... The carb should have a PCV port, which will be a larger port around 3/8" (?) at the base of the carb and feeds directly into the manifold.

If you're feeding it into one of the small (3/16") vacuum ports, it'll never keep up.
Author:  Daddiojoe [ Tue Feb 10, 2004 4:44 pm ]
Post subject: 
MN----

Yes, it is hooked up to the PCV port. It just seems that due to feeding into the manifold beneath the throttle plates, there's going to be a drop in vacuum when the throttles are open. Of course I don't see any alternatives to doing it the way it's done, but it does seem to have a hard time catching up with the throttles opened.

Sorry to be obtuse,

Joe
Author:  bud L. [ Tue Feb 10, 2004 5:20 pm ]
Post subject:  ?
I suspect you have too much blow-by. Have you tried squirting oil in each cylinder and rechecking compression. If the compression significantly improves, the rings are worn enough to warrant replacing. You can, sometimes, minimize the blow-by by using thicker oil, and/or slowing down(lower revs).
Author:  steponmebbbboom [ Tue Feb 10, 2004 5:56 pm ]
Post subject: 
If you remove the breather, does the puking of oil stop?

Allpar did an article about modifying a late style breather with ABS or PCV pipe fittings to act as an oil catch basin. Im not sure where you would find it, but that might help. You need to manage all the air coming out of your engine if compression is normal. Sure do a compression check but if youre getting normal numbers, replacing the rings won't make a difference.

Does your fill cap also have a filter in it? Maybe that's plugged too. It could also be the incorrect PCV valve. Someone mentioned earlier about getting a PCV valve with an "A" suffix and having problems with it. Hope that helps.
Author:  argentina-slantsixer [ Tue Feb 10, 2004 8:12 pm ]
Post subject:  same here
I came to the same issue after rebuilding my never opened late 70's engine head. It came up throwing out oil and like hell and I started to notice oil consumption. Now that I've rebuilted it turned out that when I rebuilt the head, restoring valvle seats, milling .40 out and fitting hardened seats and new gaskets, the compression raised to a good level. As a result for this fact, a noticeable blow down started to happen (I'm writing blow down instead of up 'cuz the blowing goes to the carter, then it goes up thru the PCV and the oil cap) I started to have oil pouring out on air filter element, the PCV started to causing carb gagging when cold running, never was able to tweak rite the idle, the dipstick was dripping oil, all over around. When I opened the engine, i had no compression rings (they were cracked due to heat? age? worn out?) the cyls were all badly scratched and they were oily... don't wait till your engine smokes out oil if you have auto trans.... will never smoke like a manual tr car. I can only understand it were running 'cuz it's a /6!
Author:  mnecaise [ Wed Feb 11, 2004 5:34 am ]
Post subject: 
Naw, you weren't being obtuse, I was just confused....

Sounds like you've got it set up right. I'm tending to agree with the others; sounds like bad rings leading to blowby. If you had weak rings to begin with and put a newly rebuilt head on, it may have finished them off. As the others have suggested, check your compression.
Author:  Daddiojoe [ Wed Feb 11, 2004 7:07 am ]
Post subject: 
The filler cap is just a flat type. No filetr or anything. I've got a three hole valve cover. When I remove the breather it just lets out more oil/gasses.

I'll check the compression this weekend. Kind of worried about what I'll find.

Thanks for everyone's suggestions and I'll keep you posted,


Joe
Author:  argentina-slantsixer [ Wed Feb 11, 2004 6:31 pm ]
Post subject: 
:cry: I think you'll need a complete rebuilt :cry:

same here :evil:
Author:  Michael_Cuda [ Thu Feb 12, 2004 2:32 am ]
Post subject: 
You should do a wet compression test. Ill give a quick walk threw if you don't know how to do one.

Warm up your Engine, remove all the spark plugs.

Do a normal dry test.
Test each Cylinder and record.

Then retest and Record each Cylinder, first pulling a little bit of motor oil down in each Cylinder threw the sparkplug hole.

Things this can tell you:
On dry test if you have 2 cylinders right next to each other with low compression could mean a blown head gasket and 1 or 2 Cylinders with low compression not next to each other could be Bad valves.

On the wet test if compress increases a lot (25 Psi+) over the dry test it likely means your rings are bad or going bad. Normally when rings go bad most all the Cylinders are effected the same.

Goodluck...
Author:  Dodgeman50125 [ Thu Feb 12, 2004 9:38 pm ]
Post subject: 
My engine is doing the same thing that yours is doing. My oil is pumping up through the air breather from the crankcase hose. I was told that the check valve on the pipe that comes out of the back of the block that attaches to the underneath of the carb maybe clogged or not working properly. This pipe is to recirculate excess gas through the carb that was not burned off in the cylinders
Author:  Michael_Cuda [ Fri Feb 13, 2004 3:02 am ]
Post subject: 
That is the PCV(Positive Crankcase ventilation) system. Even the Best engine has a low amount of Blow-By. Blow-by is when gasses from the explosion in the cylinder gets around the rings. Sense this is a metal to metal contact with gaps in areas which are in motion, gasses seep by... This means the crankcase gets a positive pressure, so the PCV system removes the pressure. How it does this via a hose connected the carb with the vacuum source coming from the intake manifold. This hose then connects the PCV valve which regulates the flow threw the hose. So if the valve or the hose is pluged it can cause the pressure in the crankcase. I don't see how this alone could lead to Oil puking out of the engine. I suspect it has to be either to much oil in the crankcase, or a major blow-by problem. I had a PVC system and was causing an oily film on the valve cover. basically its was misting oil out of the breather cap onto the valve cover.
Author:  Daddiojoe [ Mon Feb 16, 2004 6:03 am ]
Post subject:  Pukin' Oil Update--Compression Test
Well, I was able to do a compression test over the weekend, along with a vacuum test. The vacuum, hooked up to the carb, showed things to be normal, although I didn't get a 100 rpm drop when disconnecting the PCV valve (actually, disabling it, because to disconnect it totally would cause the engine to die.

All cylinders were between 110-115 PSI except for #4, at 150 (!) and #6, which as at 60 :( .

The guy who's helping me out with this, and who has a lot more experience, thinks it might be a valve problem for #4. I re-adjusted the valves in November. Have always had some degree of misting (good term!) out of the breather, though.

Could this be valves? If only one cylinder is bad, what would people recommend?

Thanks as always,

Joe
Author:  Eric W [ Mon Feb 16, 2004 6:25 am ]
Post subject: 
Did you do a wet test (put a little oil into the cylinders) to see if the cranking compression went up? Looks like the rings in #6 are going. Don't know what to say about #4. As a reference, the readings on my engine are 142 to 150lbs. Yes, one cylinder with bad rings will cause excessive blow by. Don't ask me how I know.:wink:
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