my first tech question- oil pump return spring

65swb45

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Yeah, it happens to the best of us. I doubt anyone out there has experienced this scenario [except maybe and hopefully Mark W] but I figured I would throw this one out there as the problem and the solution will probably be worth remembering.

Backround: I pulled a TBI350 out of a customer's cruiser and put in an F engine from tlcfj40 [Phil] that he had pulled for a vortec conversion in his own 40. Never saw the engine run, but Phil swore it ran good. Had a Roch carb and Delco dizzy, both of which were ditched for Non-US Toyota stuff. I posted a pic of the F over on Pirate on Phil's build up thread [fj40 buildup gaining steam]

Well, we started it up earlier this week, but couldn't keep it running for more than a minute or so. rogers69fj40 reminded me not to trust the valve adjustment, and sure enough, two of the intakes were overly tight. Readjusted to standard settings, the truck still would not idle.

I tweaked a couple of problems with the carb earlier today, and it started running better until BAM! THE DISTRIBUTOR SUDDENLY AND VIOLENTLY ROTATED 90 DEGREES COUNTERCLOCKWISE.! Well I immediately shut it down. I've been wrenching on Cruisers for 20 years and have NEVER seen ANYTHING like that happen before.

After thinking about it for a few minutes, I pulled the rebuilt dizzy out and checked it. It turned, but seemed a little more stiff than usual. I decided not to take any chances and went into the shop and grabed another dizzy to test with [to rule out whether the first dizzy was the problem]

Second dizzy did not line up with the oil pump the same position, so I put a screwdriver down the hole to line it up. When I let go of the screwdriver, IT ROTATED BACKWARDS BY ITSELF! :eek: I tried this several times while the customer watched. If I turned the screwdriver like 3 turns, it would rotate backwards almost half a turn! WTF? It almost feels like winding up a rubber band.

We took a used oil pump off the shelf and opened it up to see what the inside of one looks like [something I'd never done before]. There is nothing inside the pump but the two steel gears, one of which has the shaft that meets the distributor. NO BUSHINGS, no o-rings, and most importantly, NO EXTRA space where something could have fallen in while the longblock was sitting.

Needless to say, we will be pulling the pan on Monday to yank the oil pump and have a look-see. Just figured I'd throw this out there in case anyone else had ever seen a POSSESSED oil pump before. Yeah right. :rolleyes:
 

Pighead

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How long had the block been sitting?
I've got an old F on my engine stand, upside down, with the pan off. I noticed a big glop of sludge (very thick, almost rubberized sludge) covering the oil pick-up screen...
Did you have measureable oil pressure when it was running?
I could see that if the intake was clogged, you would create a vacuum inside the pump. Even if it was just turning it with a screwdriver. That might want to make the oil pump gears turn backwards.
 
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I think pighead is on to it. I saw this same thing on a Ford 351 before. Pickup screen was completly blocked with sludge.
 

Pin_Head

 
 
 
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That is a mighty peculiar problem all right.
1) It doesn't seem possible for the distributor to turn backwards w/o the engine turning backwards too.
2) My best guess is that the oil pump is either cavitating or the pickup tube is cracked and it is pumping air.
 

Pighead

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Mighty peculiar all right...
But, could a balky oil pump maybe cause the distributer to back out past the cam gear just enough to lose traction there while still being engaged with the oil pump gear? And if the oil pump gear wants to turn backwards, that may account for the backward running distributer?
 

Pighead

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So dude, what was it?
I been thinkin' all day about what could make a distributor go backwards and what "cavitation" means....so what was it?
 

Pin_Head

 
 
 
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Pighead said:
So dude, what was it?
I been thinkin' all day about what could make a distributor go backwards and what "cavitation" means....so what was it?
If you were from South Sac, you would know what "cavitation" is 'cause you would have a jet boat on your front lawn. :flipoff2:
 

FJ40Jim

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65swb45 said:
Well, we started it up earlier this week, but couldn't keep it running for more than a minute or so. rogers69fj40 reminded me not to trust the valve adjustment, and sure enough, two of the intakes were overly tight. Readjusted to standard settings, the truck still would not idle.
I tweaked a couple of problems with the carb earlier today, and it started running better until BAM! THE DISTRIBUTOR SUDDENLY AND VIOLENTLY ROTATED 90 DEGREES COUNTERCLOCKWISE. Well I immediately shut it down. I've been wrenching on Cruisers for 20 years and have NEVER seen ANYTHING like that happen before.
After thinking about it for a few minutes, I pulled the rebuilt dizzy out and checked it. It turned, but seemed a little more stiff than usual. I decided not to take any chances and went into the shop and grabed another dizzy to test with [to rule out whether the first dizzy was the problem]
That's weird. The distributor shaft turns CW. If the distributor bushing seized, then the dist body should also turn CW. Even if something bad happened inside the engine (like a spark crossarc firing a loaded cylinder 60deg early, causing the idling crank to stop and back up) then the distributor rotor should turn backwards. There is no reason for the distributor body to decide to come loose and turn backwards.
Second dizzy did not line up with the oil pump the same position, so I put a screwdriver down the hole to line it up. When I let go of the screwdriver, IT ROTATED BACKWARDS BY ITSELF :eek: I tried this several times while the customer watched. If I turned the screwdriver like 3 turns, it would rotate backwards almost half a turn! It almost feels like winding up a rubber band.
That is normal on a running engine. The air that is compressed in the crevasses of the oil system will push backwards on the gear type pump. The good news is this indicates a tight oil system.

When priming the oil system, doesn't the drill turn backwards a revolution when you let off the trigger?
It does on my side of the planet. :)
 
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