Positive crankcase pressure?

[1979 Quartermasters]

Well, I thought I had the " oily bilge" problem licked. Still has a leak at the distributor.

Our work mechanic said there shouldn't be oil that high unless there is positive pressure. The tubes coming from the valve covers going to the carb appear to be open.

I re-sealed the engine as described in thread " timing cover question". I'm afraid I will blow out all those seal again if this problem is not addressed.

Is this a common problem and how would I deal with it.

Thanks......

Ken

 

[alldodge]

Re: Positive crankcase pressure?

Agree with your mechanic. leaking oil from the distributor leads me to you have way to much blow by. Only way I know to fix blow-by is replacing the rings during overhaul

 

[1979 Quartermasters]

Re: Positive crankcase pressure?

I hear what you're saying, but compression is up ( 170-175 all around) and the engine only has 2-300 hours on it.....

Ken

 

[Bondo]

Re: Positive crankcase pressure?

Well, I thought I had the " oily bilge" problem licked. Still has a leak at the distributor.

Our work mechanic said there shouldn't be oil that high unless there is positive pressure. The tubes coming from the valve covers going to the carb appear to be open.

I re-sealed the engine as described in thread " timing cover question". I'm afraid I will blow out all those seal again if this problem is not addressed.

Is this a common problem and how would I deal with it.

Thanks......

Ken

Ayuh,.... Are ya Absolutely, Positively, without Any doubt, Sure it the distributor flange,..??

Did ya change it's gasket,..??

If the end pieces were used from the intake gasket set, it Could be leakin' there,...
There's also the pressure oil port, right next to the distributor,...

 

[NHGuy]

Re: Positive crankcase pressure?

I feel your pain. I just pulled my motor last winter and did every exterior gasket. Then I put it back in and when I ran, it I found a power steering leak.
There IS a gasket that belongs on top of the intake where the distributor passes through, does it look torn, cut, or crushed? If you are getting real blowby you will likely see blue smoke when the motor starts and runs. Plus it will foul your plugs.
What oil pressure is your gauge showing? I get 40 on startup, then 65 or 80 at running speeds til the oil gets warm. It goes down to 20 or so at idle when warm.
It's true that there should not be any oil that far up the distributor shaft as someone already said. But if the leak is big enough any pressure will seek an escape route.
You might be getting a leak around the oil pressure sender which is right back there too. Or possibly from the back of the intake manifold.
Clean it up really well, maybe get some of that bright colored oil dye and be positive of where it leaks. But if you know it's leaking right where the distributor clamps down, get the gasket, it should be #34486 3. It couldn't cost enough to matter.
You will want to put the motor to a good spot like top dead center, for removing and reinstalling the distributor. Mark where the rotor aims against the inside of the distributor. Makes it really easy to put everything back in the right place.

 

[NHGuy]

Re: Positive crankcase pressure?

Oops, Bondo always says it quicker and better!

 

[Bondo]

Re: Positive crankcase pressure?

Oops, Bondo always says it quicker and better!

Ayuh,.... Single digit efficiency,.... :laugh:

 

[1979 Quartermasters]

Re: Positive crankcase pressure?

No oil burning, pretty sure of that.

Payed special attention to intake sealing, ( used black RTV). No leaking, as far as I can tell, anywhere except a trail from behind the distributor into the first valley in the intake.

The gasket is new.

In the valve covers, there are some baffels under the PVC hole. Any chance they could be blocked?

Ken

 

[tfret]

Re: Positive crankcase pressure?

I had a similar problem when I replaced my heads over the winter on my 5.7L. The first time out I noticed oil leaking bad from the seal between the intake manifold and the block, not too far from the distributor. At first I thought it was the oil pressure switch just not screwed in tight enough, but upon closer inspection it was for sure the manifold seal. I didn't understand how oil could leak from there. I didn't think there would be any pressure under the manifold. A quick google search turned up this quite common problem. There is always some blow by pressure in this area. I had to pull the manifold and reseal it. The trick on the 5.7L is throw the end gaskets away and just use a good bead of RTV. Worked like a charm.

 

[1979 Quartermasters]

Re: Positive crankcase pressure?

I used RTV on the ends and sure it's not leaking from there. Those areas are dry.
Where the oil trail starts(shinny) is under the distributor gasket on the back side (opposite the clamp) and then runs onto the intake the down the back of the block.

In four or five hours of wake boarding I lost about a quarter cup. Not much, but none is best!!

Can I seal that gasket to the block and not stick it to the distributor so I can still adjust it?

Ken

 

[NHGuy]

Re: Positive crankcase pressure?

I'd think you could put down a bit of Perfect Seal under the gasket. Try to just put some between the gasket and the intake. It sets up like wax. I love that stuff.

BTW, have you looked over the flange on the distributor and the seat surface on the manifold? Do they look flat?

 

[1979 Quartermasters]

Re: Positive crankcase pressure?

That's what I thought I would try. Before I went to work today I painted the manifold side of that gasket with Perfect Seal and stuck it to the manifold. Tomorrow I'll put it together and on the weekend we'll give her a try.

Thanks everyone for help....

Ken

I didn't think that would be an issue. I'll check that in the morning.

 

[1979 Quartermasters]

Re: Positive crankcase pressure?

Well guys, it's leaking as bad as it ever did. I don't know what to do next.
Need help to diagnose problem.
Why doesn't this engine have the same where the PCV attaches to the back of the carb and sucks the pressure out like my gmc does.

 

[Bondo]

Re: Positive crankcase pressure?

Well guys, it's leaking as bad as it ever did. I don't know what to do next.
Need help to diagnose problem.
Why doesn't this engine have the same where the PCV attaches to the back of the carb and sucks the pressure out like my gmc does.

Ayuh,.... Are the vents, 'n baffles in the valve covers clear,..??

Is there actually Positive crankcase pressure,..??

Was the distributor's bottom flange perfectly flat, 'n smooth,..??
Is the distributor's body Cracked,..??

 

[1979 Quartermasters]

Re: Positive crankcase pressure?

Thanks Bond for your help.

Yes the vents are clear.

I don't know of there is positive pressure. How would I diagnose this. We suspect it because oil is once again coming out in a couple of places. I'm thinking its not possible as the PVC vents are open.

Distributor and oil pressure sender are sealed( not leaking)

I re-sealed the engine a payed special attention to the week areas.

There is oil sitting on the intake (starboard rear corner), sitting on the corners of the timing cover/oil pan , and dripping off the bottom of the timing cover. All of those joints are new.

When I first started the engine, all was good. It progressively got worse.

This has surpassed my knowledge level and I hope you guys can help.

Thanks.....

Ken

 

[1979 Quartermasters]

Re: Positive crankcase pressure?

Somebody must know how to deal with this. I think I will pull the engine again, but I think changing the gaskets again would be a waste of time if the "WHY" is not addressed.
Should I invest in a leak down test?

??????

Ken

Any chance this could have something to do with block being a 1999 and the accessories not?

 

[alldodge]

Re: Positive crankcase pressure?

Thanks Bond for your help.

Yes the vents are clear.

I don't know of there is positive pressure. How would I diagnose this. We suspect it because oil is once again coming out in a couple of places. I'm thinking its not possible as the PVC vents are open.

Distributor and oil pressure sender are sealed( not leaking)

I re-sealed the engine a payed special attention to the week areas.

There is oil sitting on the intake (starboard rear corner), sitting on the corners of the timing cover/oil pan , and dripping off the bottom of the timing cover. All of those joints are new.

When I first started the engine, all was good. It progressively got worse.

This has surpassed my knowledge level and I hope you guys can help.

Thanks.....

Ken

Pull the oil filler cap and start the engine, if oil spits out that might be ok, but if you see a bunch of oil being blown out it is positive over pressure. If over pressure I'll go bak to there must be some bad rings

 

[1979 Quartermasters]

Re: Positive crankcase pressure?

Well, I broke down and bought the fluorescent additive and the light and glasses. I'll dump that stuff in and then we'll know exactly where those leaks are.
I'll probably do it at the lake instead of on the muffs cause at the lake I can make her work and we'll see where it leaks.

More comments are welcome......

Ken

 

[achris]

Re: Positive crankcase pressure?

I don't know who told you there was no oil in that area, but I'm sorry, there is. That is right by the end of the camshaft, with the lifters going up and down and the camshaft spinning (with the distributor drive gear on it), there's going to be oil flying around all over the place there.

You do need to confirm EXACTLY where the oil's getting out. Hopefully your fluorescent dye will give you that information.

Couple of things. There is no PCV valves in these engines. The hose between the valve covers and the carb air intake is just that, a hose. The metal thing on the end is just Merc's way for connecting the hose to the valve cover, it's completely hollow. So any pressure being built up in the crankcase would go straight out those hoses. I would be looking at the vent holes in the base of the distributor. If you have somehow got oil communication between the lower part of the shaft and the sensor plate, the oil could be coming out there... Dye should be able to tell you.

Chris.....

 

[1979 Quartermasters]

Re: Positive crankcase pressure?

Thanks Chris for your response. Everybody seems to think its pressure in the crank case. I can't see how as the PCV hoses are wide open.

Is this likely the mechanic (me, not really a mechanic) didn't seal the engine properly. I believe the PO had problems with this as well. The ski locker had quite a bit of oil residue in the carpet. He said he "kicked a jug of oil over". Oh well, what can ya do!

I sure hope the motor is not pooched....

Ken