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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 won’t 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 that’s 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. |
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. |
I looked it all over pretty well and couldn’t seem to spin the cam gear. I’ll look it over tonight tho. Also it still turns the distributor because it still fires and will run. Thanks for the quick reply |
Was the oil pick secured to pump my builder tack welded mine.
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It bolts to the pump with one of the housing screws. It’s definitely a real head scratcher |
If the oil primer builds 50 psi I would say pump is fine. I would think it would be cam/dist gear related |
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 |
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 I’m just trying to figure out what’s happening because I’m gunna have to pull the motor out and apart to see what all damage came from the loss of oil |
are the lifters rattling when started ?
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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 either.......so.....pull the distributor and turn it upside down and look at it. https://cimg5.ibsrv.net/gimg/www.off...9e728c8bb6.jpg |
Originally Posted by SB
(Post 4694740)
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 either.......so.....pull the distributor and turn it upside down and look at it. https://cimg5.ibsrv.net/gimg/www.off...9e728c8bb6.jpg |
I’ve checked the key or pump drive (what ever you want to call it) and it’s good. It’s in place and not chewed up and by the wear marks on it looks like it’s fitting all the way in the pump shaft slot. I’m wondering if the downward pressure I have to put on it with the drill to keep from slipping off is pushing the drive gear down enough to make pressure. The amount of play in the pump shaft seems excessive to me, enough that I’m thinking the pump may be suspect |
Originally Posted by F-2 Speedy
(Post 4694724)
are the lifters rattling when started ?
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Is there a certain depth the distributor needs to be set to? I believe you have to cover some hole in the block. If I don't have my priming tool collar set right I can't build pressure. Stock distributors?
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Something just does not make sense. If the engine runs then the distributor is turning and the cam is not broken etc. If you are getting oil pressure with the priming tool then the pump is ok. The play in the pump drive is normal if you used the shaft with the metal sleeve instead of the plastic one. I think that is what they recommend with the M77HV anyway. I never use the plastic sleeves on any type of performance build. Not sure what you are missing. Where are you checking the oil pressure ? Mechanical gauge or electric ?
I would pull the filter and cut it open and check for metal before you pull the engine. |
The engine was making lots of noise and a crazy amount of blow by when I shut it off. To be honest not real sure how long it ran with out oil pressure. I had opened it up for the first time after I broke it in for about a hour. And was messing with trim trying to see what the boat liked. After getting towed, because of a pretty horrible launch I had to fire it up to get it back on the trailer and it was running good and sounded alright. I’m reading pressure from the rear oil galley tap with a manual gauge. I plan on opening both my oil filters the next time I work on it. I might just pull it and look at the main bearings since that’s easy enough. |
A head scratcher for sure. Have you tried a different distributor? |
I have not tried a different distributor yet. I’m hoping to get some time tonight to check it out more |
try rotating the distributor shaft by hand with the cap off..........
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Originally Posted by F-2 Speedy
(Post 4694969)
try rotating the distributor shaft by hand with the cap off..........
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I realize that if all is normal, but your engine isn't normal at this time, it also has a sheer pin in it.
Edit: this really doesn't make any sense, dist is fine, cam is fine and wont pump oil but runs fine, but will pump oil with a drill and prime tool, something is missing |
[QUOTE=F-2 Speedy;4694974]I realize that if all is normal, but your engine isn't normal at this time, it also has a sheer pin in it. Edit: this really doesn't make any sense, dist is fine, cam is fine and wont pump oil but runs fine, but will pump oil with a drill and prime tool, something is missing[/QUOTE I know it didn’t have oil pressure on the water and doesn’t build any while cranking in my shop. My plan is to borrow a distributor from another motor and fire it up and see if that changes anything. Thank you everybody for your responses. I’m determined to figure this out. |
Originally Posted by SB
(Post 4694740)
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 either.......so.....pull the distributor and turn it upside down and look at it. https://cimg5.ibsrv.net/gimg/www.off...9e728c8bb6.jpg |
I had this happen on the dyno one time with a slip collar dist. The engine ran fine, but had no oil pressure. The cam gear was engaged, but the oil pump shaft was not. Dropped the distributor a little and all was good.
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Originally Posted by snapmorgan
(Post 4695087)
I had this happen on the dyno one time with a slip collar dist. The engine ran fine, but had no oil pressure. The cam gear was engaged, but the oil pump shaft was not. Dropped the distributor a little and all was good.
thanks for the info! |
Look at the bottom of the distributed tang you can normally see if it was not engaged and slipping will leave shiny marked on the outside of the tang not in the center. Can you show pictures of the ware marks on distributer gear from camshaft is it close to center? |
Originally Posted by 14 apache
(Post 4695128)
Look at the bottom of the distributed tang you can normally see if it was not engaged and slipping will leave shiny marked on the outside of the tang not in the center. Can you show pictures of the ware marks on distributer gear from camshaft is it close to center? |
:party-smiley-004:You have lipstick and are willing to share that info with us means a lot to us. Thanks. :evilb: |
On top of what's been said about the seating depth of the dist drive into the pump...Does the engine maintain pressure when you run it on the priming tool or did you just run it up to Pressure - hit 50 and stop??IF it holds there...you know the distributor driving the pump is your issue
I know of 3 circumstances where the issue was in the pan - (1) had a cracked pickup tube, (2) not mounted to the block securely and (3) the other was wrong pan/dipstick combo... with the dipstick, the jobber/hack put his engine together knowing that the dipstick read deep (read full before safe) and never got around to changing. Sold the engine to new owner who did an oil change to the mark (backyard boater *not a mechanical person more than what you can see on youboob) and ran the engine ....I'm sure it primed up until it cavitated |
Originally Posted by speicher lane
(Post 4695224)
On top of what's been said about the seating depth of the dist drive into the pump...Does the engine maintain pressure when you run it on the priming tool or did you just run it up to Pressure - hit 50 and stop??IF it holds there...you know the distributor driving the pump is your issue
I know of 3 circumstances where the issue was in the pan - (1) had a cracked pickup tube, (2) not mounted to the block securely and (3) the other was wrong pan/dipstick combo... with the dipstick, the jobber/hack put his engine together knowing that the dipstick read deep (read full before safe) and never got around to changing. Sold the engine to new owner who did an oil change to the mark (backyard boater *not a mechanical person more than what you can see on youboob) and ran the engine ....I'm sure it primed up until it cavitated |
I just re-read my post - to be clear, I wasn't stating that your engine was cavitating. Specifically directed towards the hacked up cobbled together engine b4 it ate itself up.
Hope you get it squared away... |
Here’s pictures of the dist. The tang doesn’t look beat up at all. Do you think that the wear marks on the gear are to low? https://cimg1.ibsrv.net/gimg/www.off...e008ed429.jpeghttps://cimg2.ibsrv.net/gimg/www.off...76b368c12.jpeg |
I’ve also grabbed the tang with needle nose and tried to twist, pull, wiggle it but it doesn’t budge |
What distributor and intake are they, did you check the clearance on the oil pickup to pan ? pump might be cavitating if its to close to the pan, spinning it on a drill is much faster than at idle.
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Originally Posted by F-2 Speedy
(Post 4695239)
What distributor and intake are they, did you check the clearance on the oil pickup to pan ? pump might be cavitating if its to close to the pan, spinning it on a drill is much faster than at idle.
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The tang is beat up it is not engaged enough that's why there is no oil pressure. It needs a slip coller distributer. The tang is rounded over on the drive side |
Originally Posted by 14 apache
(Post 4695249)
The tang is beat up it is not engaged enough that's why there is no oil pressure. It needs a slip coller distributer. The tang is rounded over on the drive side Makes sense to me. |
Originally Posted by Baja Rooster
(Post 4695281)
Worked until the metal fatigued, rolled over, then poof - game over? Makes sense to me. |
Originally Posted by 14 apache
(Post 4695249)
The tang is beat up it is not engaged enough that's why there is no oil pressure. It needs a slip coller distributer. The tang is rounded over on the drive side |
Originally Posted by SABER28
(Post 4695291)
this is the only explanation that makes any sense. good news its easy to fix.
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