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Lost oil pressure - 30 Pontiac


SDLARS
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Have a little over 100 miles on my car and have had no serious issues. Took it out this morning for a short drive. Got about a half mile from home when it lost all oil pressure. Got it home to the shop, removed the oil line to the gauge and cranked it over without ignition. Did notice a little bubbling from the connection but not the volume I would expect. Went to the service manual. Was about to pull the distributor to see if the drive pin is sheared when I began to wonder if that's my problem, will the drive gear come out with the distributor or will it stay with the pump. Will I have to remove the pan?  Any and all guidance is appreciated. 

 

Edited by SDLARS
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If the pin is sheared off it will probably stay in the block on the end of the intermediate shaft. The gear can be lifted out with one of those long magnets.

It is also possible the intermediate shaft could be broken. This happened to another split head Pontiac last year.

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Paul - I have also found that one of those ‘grabber’ tools works well in that area.  I have used to pull the intermediate shaft out.  Your symptoms really sound that that your problem is either the pin sheared or shaft broke.  Did the engine make noise when pressure went to 0?  How did you notice the low pressure sound or sight?

Keep us updated.  

 

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On 9/8/2019 at 7:26 PM, Tinindian said:

If the pin is sheared off it will probably stay in the block on the end of the intermediate shaft. The gear can be lifted out with one of those long magnets.

It is also possible the intermediate shaft could be broken. This happened to another split head Pontiac last year.

intermediate shaft ?, i have never seen a intermediate shaft in a pontiac straight eight or straight six.

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2 hours ago, pontiac1953 said:

intermediate shaft ?, i have never seen a intermediate shaft in a pontiac straight eight or straight six

ALL split-head (6 cylinder with 2 three cylinder heads) Pontiac engines had a short shaft that ran between the distributor and the oil pump.  1926-1932 INCLUSIVE.

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On 9/9/2019 at 9:26 AM, 32Pontiac6 said:

Paul - I have also found that one of those ‘grabber’ tools works well in that area.  I have used to pull the intermediate shaft out.  Your symptoms really sound that that your problem is either the pin sheared or shaft broke.  Did the engine make noise when pressure went to 0?  How did you notice the low pressure sound or sight?

Keep us updated.  

 

 

On 9/9/2019 at 9:26 AM, 32Pontiac6 said:

Paul - I have also found that one of those ‘grabber’ tools works well in that area.  I have used to pull the intermediate shaft out.  Your symptoms really sound that that your problem is either the pin sheared or shaft broke.  Did the engine make noise when pressure went to 0?  How did you notice the low pressure sound or sight?

Keep us updated.  

 

Checking gauges when I start an engine is something I always do. Had 30-35 lbs as I left the garage. On these old engines I find myself checking often. I had gone less than a half mile when I noticed the gauge read 0. No particularly nasty noises (yet). 

Tried to remove the distributor. It is loose and has a small amount of up and down play but won't lift out. Something is obstructing it. I plan to drop the pan anyway and look for issues. 

Any advice at this point?

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Hard to say exactly where the problem is.  I have attached a couple of photos.  The first one is looking down into the block with a snake camera.  You can see the intermediate shaft and the slot that the distributor fits into.  Actually looking at this shows wear on it and I should eventually have a new one machined.  The second photo is what the shaft looks like provided to me a while back by Tinindian.  You can see this is one that should probably be replaced because it has twisted.  The slots are not parallel.  But it does give you an idea of what is in there.

 

Probably need to get the shaft out and shine a strong flashlight into the hole and see what the receiving end looks like on the pump.  

 

Also be careful to mark location of the shaft slot so that you don't have to play around with position when you put the distributor back in the block and it rotates as it meshes with the camshaft gear.  While it does not have to be perfectly aligned with the male portion in the distributor end it has to be close so that it slips in.  I  use a long screwdriver to rotate the shaft into the right position to meet the bottom of the distributor when I put it back in.

 

Also, photos of the end of the distributor where it mates into the intermediate shaft, the shaft, and if you can take a photo down the hole to the pump.  Those might be helpful.

 

You are not the first person to forget the set screw....

 

Distributor hole-4.jpg

0021.jpg

Edited by 32Pontiac6 (see edit history)
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I had a spare old shaft and when others had their shaft break I had a new one made.  My machinist/metallurgist said the slots were offset from new.  He said there was no indication that the shaft had twisted,  He charged me $60.00 to make a new one and case harden it. It was obvious that the old one was cracking.  Maybe everyone with a split head six should get a spare?

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Well now you know that part is okay.  Did you open the pump?  At least dropping the pan is not a big job, not like on a straight 8 Buick of the early fifties.

Good luck.

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Not yet. Had a few other tasks get in the way. I did put an electric drill on the pump and ran it in some oil. Seems to pump quite well. Have to check the lines. Don't know why, at this point, I didn't get more volume out of the gauge fitting in the block when I cranked it.

An early 50s Buick must be like an early 50s Pontiac. I've done it a couple of times on my 52 and have decided things will have to get serious before I do it again. 

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A post about a different make of car had a poorly installed cotter pin that wore through the distribution line in the crankcase.  Make sure you don't have a leak somewhere inside.

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Back to strong oil pressure. Gotta believe there was some little piece of crap that got lodged in the little line that leads to the gauge from the block.  

Oh well, learned a few new things about the car. We'll see what the next issue will be.

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