Stumped on oil leak

[Ricko1966]

Although not ideal but 125 isn't low enough to cause a miss and if you are not fouling the plug on number 3 you might get along for years going with valve cover breathers with a catch can,to relieve the crankcase pressure. I'll see if I can find you a pic

 

[squaredeal91]

Mark #3 position on the distributor body pull the cap,disconnect power to the HEI and rotate the motor until the rotor is pointing at your #3 mark. Screw an air fittings into #3 plug hole take of the oil cap and put a rag over the hole,then hit it with some air. If air hisses out of the carbureator you have an intake valve problem if it hisses out the exhaust you have an exhaust valve problem if it blows the rag off the valve cover, you have a bad oil cap. JK if it blows the rag off you're probably looking at rings,maybe a piston. The thing about the bad oil cap I was doing this exact thing at work,rag in the tail pipe,rag over the throttle body,rag over the oil fill. Service writer comes over and asks what I'm doing. And the way I explained it to you,with the bad oil cap,that's how Dave explained it to the service writer. Lol,and he believed it

How much shop air is acceptable?

 

[Ricko1966]

I use what ever the shop compressor has,never checked,probably at least 130lbs but you wouldn't have to have that much. You may have to improvise a wedge for the balancer to keep the engine from turning but so far I haven't had to. I know a couple of ways to wedge the balancer if you need to. If you get to that point post,I'll try to wedge a couple and take pics.

 

[Bronze Knight]

Mark #3 position on the distributor body pull the cap,disconnect power to the HEI and rotate the motor until the rotor is pointing at your #3 mark. Screw an air fittings into #3 plug hole take of the oil cap and put a rag over the hole,then hit it with some air. If air hisses out of the carbureator you have an intake valve problem if it hisses out the exhaust you have an exhaust valve problem if it blows the rag off the valve cover, you have a bad oil cap. JK if it blows the rag off you're probably looking at rings,maybe a piston. The thing about the bad oil cap I was doing this exact thing at work,rag in the tail pipe,rag over the throttle body,rag over the oil fill. Service writer comes over and asks what I'm doing. And the way I explained it to you,with the bad oil cap,that's how Dave explained it to the service writer. Lol,and he believed it

Assuming I did this correctly. I got a good bit of air out of the Carb.

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[Ricko1966]

If your rotor is pointed at the number 3 spark plug wire,and you blew shop air into #3 cylinder,and got significant air out of the carbureator. You have a leaking intake valve. Try adjusting the valves first. Hopefully that one's a little too tight. Just thought pull the pcv valve and try again,just making sure crankcase pressure isn't blowing through the pcv valve into the intake. Are you using the hose from your air compressor to pressurize the cylinder.

 

[Bronze Knight]

If your rotor is pointed at the number 3 spark plug wire,and you blew shop air into #3 cylinder,and got significant air out of the carbureator. You have a leaking intake valve. Try adjusting the valves first. Hopefully that one's a little too tight. Just thought pull the pcv valve and try again,just making sure crankcase pressure isn't blowing through the pcv valve into the intake. Are you using the hose from your air compressor to pressurize the cylinder.

Yep, that's what I did. The roter cap was pointing at the vacuum advance which is where #3 is at I rigged up an air hose with some rubber line and the blow gun on the air compressor with some hose clamps and after I got it jammed into the spark plug just right I was getting air out the carb.

I'll try again tomorrow and pull the PCV valve. I did this test a few times and sometimes it seemed to just pressurize the cylinder and it would pop the air hose out. But other times it would push air out the carb.

 

[Ricko1966]

Sounds like an intake valve,but just to be sure try without the pcv valve plugged in. If it's the valve try adjusting the valve. I have 2 more tricks up my sleeve for trying to get the valve to seal before you pull the head. Check it tomorrow post back. As for that oil catch can/breather not the one I'd use but wanted you to have a visual. I'd make one,but we'll cross that bridge if or when we have to.

 

[YakkoWarner]

....

Spoke too soon. I was feeling good about the truck so I drove it to work on a Friday a week or two ago. Everything was good on the way into work. But on the way home at every stoplight I was getting a small oil smoke cloud. Made it home thankfully but when I looked in the hood the oil dipstick was out of the tube a little bit and I had oil on the inner fender and all down the underside of the passenger side of the truck. This was somewhat disappointing but life goes on. Anyway, I got back to it last night and ran a compression test and it looks like cylinder 3 has found something better to do.

So now what? I have a few options that I can think of. The first is to redo the rings and main bearings. I have never had an engine that far apart before and I am willing to try. But I wonder is that my best option? It could be a bent or stuck valve, and then I'd have to look into redoing or replacing the heads and all those parts.

No matter what I think I'll have to pull the head(s) off and look at them but again I've never torn an engine apart that far and I'm worried I'll miss something.

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My friend Dave had this happen on his SBC truck - it was substantial blow-by pressurizing the lower crankcase - on his truck you'd rev it and the dipstick would pop about halfway out. It also contributed to a lot of other oil leaks because the front and rear main seals are not designed to retain significant pressure, so that much blow-by would force oil past the seals. Worn rings were the main culprit.

 

[Bronze Knight]

OK so I did the test again and I may have had the distributor clocked wrong yesterday. I also figured out a better setup for air fittings using the adaptor off the compression tester, a union, an air fitting, and hose clamps. Anyhow for today it would simply pop when I took the hose off but no air out the carb or exhaust as far as I can tell. I tried it with the PCV valve in and out didn't seem to make a difference.

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[Ricko1966]

Okay that tells me valves are okay no hissing out the valve cover?. I'd vent the valve covers better and call it a day. Rings and rod bearings would be another cheap option but a lot more work. Like I said 125 won't cause a miss and if it's not fouling plugs, I'd be real tempted to vent the valve covers better. I'm goingbto put up another pic, again not exactly what I'd do but to give you a visual of what you want to accomplish. The way I would do it and why, I'd use a piece of pcv pipe with a cap glued on one end and a motorcycle pod style air filter on the other. Mount the pcv on the firewall filter facing up. Drill and tap holes on the side of the pipe to route 1 hose from each valve cover to the pipe. Reason for this is I can use large hoses and plenty of filter area to let the crankcase breathe. Oil in the filter will run down in the pipe instead of running on the engine. The crankcase presdure is what's blowing out the dipstick and blowing on things,if we can relieve the pressure we can stop the oil problem. We still are treating the symptombnot the cause,but if its not a daily driver and seeing lots of miles,just making it usable might be all you need. Look at the thumbnail,see how much ventilation that provides. We are trying to do that without dripping oil on the engine. Dam it no way to attach a link for some reason, check back. I'll try again

 

[Bronze Knight]

Well, I made a minor change but it seems to have fixed the issue.

The valve covers I got have a 1-inch hole for a PCV vent. It would seem that 1'' filters are a bit less common, now you can get them on Amazon but I didn't do that. I went down to the auto parts store and got a 3/4'' filter which did not fit inside the grommet that came with the valve covers. So for testing, I joined the filter and grommet with a bit of fuel hose. With that setup, I had a little bit of oil coming out of the dipstick on acceleration from stop lights. I have since sourced another grommet that had a larger opening that I was able to fit the filter into with any of my homemade adaptors. I have since done two test drives about 8 miles and then today I did about 40 miles with no issues. I'm still concerned about the low compression in cylinder 3 but for now at least its on the road!

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The parts.

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The old setup

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The new setup

 

[Ricko1966]

Vent as much as you can,I'd run a remote vent with a BIG filter, think motorcycle air cleaner and 1 large vent hose per valve cover. 1 never got that pic up. Sorry,forgot I'll do it now. It may run the rest of your life low on #3 since it didn't leak out the valves,I suspect ring lands,so wait until you are ready to completely tear down the engine.. BIAB with that pic.

 

[Ricko1966]

Okay pics. Mount pvc on fire wall 1 port facing up with an air cleaner on top. 1 port facing down with a plug and a drain as an oil trap. 1 port facing left going to a valve cover 1 hose going right to a valve cover. .I'd actually make my x piece with a longer piece of pipe and tap fittings into the sides for my vent hoses,so I could have a deep oil catch. Kinda the like the last pic but 2 and larger vent hoses tapped into the pipe with fittings.

 

[Ricko1966]

Think this on the fire wall,with 1 large vent hose per valve cover. Use a piece of pipe,tap in 2 fittings. Motorcycle breather on top. You could ventilate a barn.