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Melbatoast 07-01-2019 09:18 PM

Oil pump failure
Put a mild built 454 in my boat for the summer while I rebuild my 496 blower motor. After the first hour on the water I lost oil pressure. It has a melling m77hv after I got it home I pulled the dist. And with my priming tool and drill can build almost 50lbs of pressure. Put the dist. Back in and cranked it and it wonít pump any. There is also a lot of play in the pump shaft now. I measured the dist. Shaft length and distance from the pump shaft to the intake mating surface and thatís correct. Wondering if anybody has any insight on what could have gone wrong before I pull the motor. Unfortunately I think the boat is done for the summer after only one trip out.

Rookie 07-01-2019 09:43 PM

I once had a roll pin holding the cam gear break. It appeared to be fine because I could see the roll pin, but it was in 3 pieces.
And I have used many M77HV pumps, my favorite pump.

Melbatoast 07-01-2019 09:52 PM

I looked it all over pretty well and couldnít seem to spin the cam gear. Iíll look it over tonight tho. Also it still turns the distributor because it still fires and will run. Thanks for the quick reply

Texascuda 07-01-2019 09:55 PM

Was the oil pick secured to pump my builder tack welded mine.

Melbatoast 07-01-2019 09:57 PM

It bolts to the pump with one of the housing screws. Itís definitely a real head scratcher

Crude Intentions 07-01-2019 11:42 PM

If the oil primer builds 50 psi I would say pump is fine. I would think it would be cam/dist gear related

Full Force 07-02-2019 06:07 AM

Originally Posted by Crude Intentions (Post 4694706)
If the oil primer builds 50 psi I would say pump is fine. I would think it would be cam/dist gear related

Agree, remember the cams can break also, had that happen once..

Melbatoast 07-02-2019 06:12 AM

Engine will still run and the distributor rotor turns so the cam is still together. I might throw a stock distributor in it and see if it will build pressure. At this point Iím just trying to figure out whatís happening because Iím gunna have to pull the motor out and apart to see what all damage came from the loss of oil

F-2 Speedy 07-02-2019 07:42 AM

are the lifters rattling when started ?

SB 07-02-2019 09:14 AM

If the engine runs/rotor spins the gear is fine.

If the priming tool builds pressure, the oil pump and it's drive rod is fine.

Must be the male 'key' in the distributor gear that's gone. Never head of it breaking but every few months it seems I run into something that I'm working on that I've never seen the distributor and turn it upside down and look at it.

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