Oil Pump Locked Up

Orange67

New Member
Joined
Jul 7, 2020
I’m trying to wrap my brain around my failure here. I have a new engine that was ran for less than 5 miles then cut off for the night. I tried to restart it and the xfi showed no oil pressure or ignition signal. I pulled the cam sensor and the gear was destroyed. I had the oil pump and cover blueprinted by a reputable GN shop. When I removed the timing cover, the oil pump shaft would not turn (even with a screw driver) and the tang that goes in the cam sensor was blue. I barely cracked the bolts loose on the oil pump and it spun freely by hand. There was no metal in the pump, no metal in the oil pump pickup screen and nothing on the #2 main bearings. Is there a smoking gun as to why this could have happened? Cam thrust was set correctly. After comparing to an OE timing cover, I realized that mine was apparently a Chinese cover. Could a misaligned cover cause a tightly set up oil pump to bind and lock up once I tightened the cam sensor down? The only other thing I’m thinking could have been cam interference but I don’t see anything glaring yet without tearing completely down. This was a ductile roller cam. Does this sound like a timing cover issue?
 

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How much oil pressure did you have? If I had to speculate, it looks like the pump was too tight as there is galling on the top and bottom surfaces where the oil pump gears are, caused excessive load on the cam and sensor gears and got extremely hot.
 
This happened last year and I am just now able to tear down. I was waiting for cam availability before I took everything apart and time got away from me. From what I recall, hot idle was 20-25. I was running Driven 10w-30 break in oil. This did have the longer high volume gear set up in it
 
High volume gearset should show about 40-50 psi depending what pressure spring was used.
Pump end clearance was too tight and self clearanced on startup. Pump housing metal is in the pressure bypass and filter. Clean it all when you replace the timing cover. Don't forget to port the suction and pressure sides before installation. Clean the crap out of the cover before installation too. Old cover quality is suspect, as the rotor side loaded and wore the housing unevenly.Toss the filter, and engine oil as there is prolly some aluminum from the pump in the oil pan that the filter missed. I would dump a pint of kerosene in the engine after the oil is drained, then with the plug still out, dump a quart of fresh oil in there to dilute the kerosene and wash more crap from the pan. Let it drain overnite, replace the plug and fill with fresh oil. Run it lightly for a half an hour and replace the oil and filter again. Cheap insurance. Buy a better cover and new pump too. I have seen the housing extensions not machined correctly and that can force the rotor off to one side too, as can improper fitting of the rotor extension plate.
TIMINATOR
 
Bison, either on his business' facebook page or the tech page he and Steve K. run, posted a video not that long ago that seems to cover what you experienced. Some of these China-sourced timing covers have the bore for the cam sensor not cast / machined correctly. it's eccentric or off-axis to where the cam sensor ends up at an off angle. While it will mate up with the oil pump driven gear shaft, the cam sensor gear at this off alignment will get destroyed by the camshaft gear.

The conclusion is the timing cover is scrap with that malforming / machining for the cam sensor hole.

Perhaps someone can find Bison's post from either of those f*book groups and link it here. I'll try to find it as well.
 
Very helpful info. I’m going to try to find the video and study up. I have an OE cover so I’m going to have it checked out and try again. Luckily, the debris fell in the pan and never made it thorough the system. Is the general consensus to forget about high volume pumps and stick with factory gears?
 
Unless the engine has a LOT of miles on it, in which case you shouldn't be trying to make a lot of HP with it anyway, or it was built "loose" clearance wise, by someone that doesn't understand Buicks, a stock pump is adequate, especially if the cover, oil filter adaptor, and the rest of the engine pressure and suction galleys are "ported."
Not necessarily bigger in size, (this is better left to experts) but rounded off in every intersection where the oil must change directions. Every engine that I build has this done in the oil pump and all galleys, but the drain back channels too. Every sharp edge where the oil changes direction, everywhere in the entire lubrication circuit causes a drop in pressure and volume. The Buicks have one of the worst oiling systems ever devised in a "modern" engine.
I also "stone" the gears with a piece of 600 grit on a machined flat surface or piece of glass on both ends, then lightly deburr the top and bottom edges when finished with a 3/8" diameter fine cratex point, and a light end sanding with the 600 again. This helps prevent scoring the cover and pump housing.
How to tell if your new pump cover is machined correctly? Remove the gear carefully from the cam sensor (mark it so you know which way it was installed), then install it and the pump, tighten the clamp and verify it all turns freely. If not, the cover is junk, or rarely, there isn't enough end clearance between the shafts, a bit of Dremel tool work will solve that issue.
It's small details like this that take time, and is why experts charge more to build a Buick, or any engine for that matter.
We all sell time, whether its on a machine or details like this. The Buicks and LS (not my favorite) engines are the only American engines that employ aluminum oil pumps. Aluminum expands with heat much more than cast iron too, and that changes the pump clearances (wider) as the oil heats up.
Just a few tips....
TIMINATOR
 
found what I mentioned in post #5 regarding aftermarket timing covers having wrong casting/machining for cam sensor geometry causing the cam sensor gear to be destroyed quickly.

Buick Grand National Tech f*book group - Sean C. posted on January 3, 2023 and January 11, 2023. Scroll for those post to read Bison's, Earl's, BobbyBuick's comments regarding geometry off due to aftermarket timing cover and probable zero backlash on gears.

Then, reference Bison's December 17, 2022 post to the group (screenshot posted below) reviewing cam sensor gear and camshaft driven gear.

I believe there is more discussion on the problems of aftermarket timing cover cam sensor geometry and backlash problems with cam gears in other posts. just have to find them.
Cam Sensor gear - zero backlash_Bison_17Dec2022.jpg
 
...general consensus to forget about high volume pumps and stick with factory gears?

high volume oil pumps put a lot of stress (and wear) on the cam sensor gear. been covered many times. no need to repeat.

do as Chuck noted to improve an OEM timing cover.
 
One of the "oldtimers" once on the site, made a fabricated cover using a late model cover and a 86 cover, cut and welded together.
His name is Kendall Fredrick. He was in Florida.
Haven't seen any more of him being on the site.
NE1 ever follow up on that idea?
 
I have a broken stock cover that I plan to assemble and mark the gears, and a new aftermarket cover to assemble and repeat to see if the pattern is the same or different.
 
found what I mentioned in post #5 regarding aftermarket timing covers having wrong casting/machining for cam sensor geometry causing the cam sensor gear to be destroyed quickly.

Buick Grand National Tech f*book group - Sean C. posted on January 3, 2023 and January 11, 2023. Scroll for those post to read Bison's, Earl's, BobbyBuick's comments regarding geometry off due to aftermarket timing cover and probable zero backlash on gears.

Then, reference Bison's December 17, 2022 post to the group (screenshot posted below) reviewing cam sensor gear and camshaft driven gear.

I believe there is more discussion on the problems of aftermarket timing cover cam sensor geometry and backlash problems with cam gears in other posts. just have to find them.
View attachment 396161
Excellent info. Thanks for digging this up
 
I’m not sure of the clearance. I did not set the oil pump up myself since I was not too familiar with all the Buick quirks. I did watch it get set in a fixture and located before the plate was drilled and pinned to accommodate the hv gears. It was not just tossed together. I sent it to one of the well known Buick builders to set up. I’d rather not name names because the internet can twist words and create drama. I’m figuring that all my trouble came from the Chinese cover and misalignment. I am going to verify everything now that I know the cover was not OEM before I move forward
 
One of the "oldtimers" once on the site, made a fabricated cover using a late model cover and a 86 cover, cut and welded together.
His name is Kendall Fredrick. He was in Florida.
Haven't seen any more of him being on the site.
NE1 ever follow up on that idea?
I think Turbo1DR did as well. Upper was 86/87 and lower was a later model gerotor setup. Pretty cool stuff!
 
I think Turbo1DR did as well. Upper was 86/87 and lower was a later model gerotor setup. Pretty cool stuff!
Yes I did. I took his idea and made a hybrid cover back in 2005. It had some initial problems that I had to overcome to get it set up right. One problem I had was not with the cover but with how I fit the hub of the balancer into the gerotor gear. I tried to just shorten the balancer and use a spacer in the pump gear but I wasn't fond of that idea due to it being too short and cracking at the keyway....and that's what it did. I pulled the cover just to check it after running it for about 500 miles or so. The second time around, I machined the hub of the balancer smaller to make it fit inside of the pump gear. I didn't like that idea either and after checking a few hundred miles later...it too cracked at the keyway. My final attempt was to machine *flats* on the hub and have the pump gear bore enlarged to slide over the hub. This time it worked without any problems. I'm still running the same balancer and gerotor cover to this day without any more problems. It's got about 40,000 miles on it. Doing this type of oil pump takes the stress off of the timing chain due to it being crank driven and not chain driven.
 

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