oil pump disaster
Thread Starter
Intermediate
Joined: Nov 2012
Posts: 30
Likes: 0
oil pump disaster
Hey all I have been having some oil pressure problems under acceleration. I decided to go ahead and change out my oil pump. Everything was going great until I put in the new pump and started tightening down the bolt. With surprisingly little force I actually broke the threaded part of the equation. So now I have nothing to bolt the pump to. What will I need to replace now? I'm having a really hard time finding the words to even google this. I am attempting to get pics but not much room to work with. A nudge in the right direction would be a huge help. Thanks in advance.
Race Director
Joined: Apr 2003
Posts: 17,700
Likes: 1,667
From: moraga ca
If you have a stump to hang on to, use vicegrips. If not, you can try a small screwdriver and mallet to possibly unscrew the broken bolt. If that doesn't work, drill a hole down the middle and use an easy out screw extractor.
Thread Starter
Intermediate
Joined: Nov 2012
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Well the bolt is actually intact and good. Its really just what I actually tunnel that you bolt into. It just shattered. There was a little tunnel that I could run that bolt into and its just gone now??
Thread Starter
Intermediate
Joined: Nov 2012
Posts: 30
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I will attempt to get a pic to explain better. It happened late last night and I just did not think to take 1 (A little demoralized). In Tom400CFI you can see the bolt I am talking about thought. It is the threaded part that the bolt is being screwed into. Im at work right now and will post pics as soon as I can. Sorry for the bad description. Just really hard to explain.
The oil pump is not cracked its the part that is on the block. Or hopefully not on the block.
The oil pump is not cracked its the part that is on the block. Or hopefully not on the block.
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Thread Starter
Intermediate
Joined: Nov 2012
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I just did a fast search on that and I think you head the nail on the head. I will do some more research and post back what I find. Thanks for the nudge in the right direction. I wasn't even sure where to start after that. Ill post pics as soon as I can.
Melting Slicks
Joined: Nov 2010
Posts: 2,216
Likes: 113
From: Michigan
If you stripped/pulled the threads out you may still have enough good threads for stud use. Seen this happen not too long ago. You can use an ARP oil pump stud, just make sure it does not bottom out and contact the bearing and if you get the right one it shouldn't. I'll thread the stud in finger tight and back it out half a turn, use a wrench on the nut and an allen wrench on the stud too hold it and tighten the nut down, then do the final torque with the torque wrench and check for stud movement when I torqued it(look at the ARP letters on the tip).
If the cap cracked, sry you got a big problem.
If the cap cracked, sry you got a big problem.
Safety Car
Joined: Aug 2009
Posts: 3,752
Likes: 276
From: Melbourne, Victoria, Australia
The rear bearing cap is all you need, there should be plenty old 350 chevs in a wrecking yard.
I have even got one lying around from my old engine but i am many thousands of miles away, if your engine is standard another standard old engine brearing cap will do and re use your bearing. The 89 had the one piece rear main seal so make sure you bring your cap with you to compare.
I am surprised the threads or cap broke so easilly?
You have to make sure the oil pump drive rod is fully slotted in the distributor shaft and make sure the oil pump sits level on the bearing cap. Check the old oil pump and make sure the surface and bolt hole is even, would be very unlikly to have a different casting but you know if its from China weird things happen.
Good luck it should be a simple fix
I have even got one lying around from my old engine but i am many thousands of miles away, if your engine is standard another standard old engine brearing cap will do and re use your bearing. The 89 had the one piece rear main seal so make sure you bring your cap with you to compare.
I am surprised the threads or cap broke so easilly?
You have to make sure the oil pump drive rod is fully slotted in the distributor shaft and make sure the oil pump sits level on the bearing cap. Check the old oil pump and make sure the surface and bolt hole is even, would be very unlikly to have a different casting but you know if its from China weird things happen.
Good luck it should be a simple fix
Melting Slicks
Joined: May 2010
Posts: 2,082
Likes: 3
From: Conowingo Maryland
The problem being it is not as simple as bolting on a new cap. For the fix to be a proper fix you need to have the new cap line bored on the engine. This means that you have to remove the engine tear it down take it to a machine shop to have it line bored. Will just bolting on a new cap work it is a row of the dice would I count on it no.
Melting Slicks
Joined: May 2010
Posts: 2,082
Likes: 3
From: Conowingo Maryland
I think you would have better luch taking the cap to a weling shop and see if they can come up with a repair. I think they may be able to. Now what caused this I would take a dial caliper and measure the thinkness on the base of the new pump compaired to the old pump. It has been a long time but Iv seen differences in the bases of pumps doubtfull if that is it but does not hurt looking into. Most likely you have more *** in your arms then you though
Melting Slicks
Joined: Nov 2010
Posts: 2,216
Likes: 113
From: Michigan
The problem being it is not as simple as bolting on a new cap. For the fix to be a proper fix you need to have the new cap line bored on the engine. This means that you have to remove the engine tear it down take it to a machine shop to have it line bored. Will just bolting on a new cap work it is a row of the dice would I count on it no.
Instructor
Joined: Jun 2014
Posts: 178
Likes: 3
From: Pensacola FL
There might be enough meat left to install a Heli-coil and a stud. A longer bolt will crush the bearing around the crankshaft. You could possibly have a stud welded in place with a nickel rod.
You CANNOT just replace the main cap unless you get really lucky. The block will need to be align honed to get it to fit and be round... unless you are really lucky for bearing clearance as main caps are fitted to the block.
You can try another main cap using existing bearings and check clearance with "Plasti-Gauge" . If you can get .002 to .003 thousands at bearing crush it will be good but not necessarily round. It will run awhile.
Good luck!
You CANNOT just replace the main cap unless you get really lucky. The block will need to be align honed to get it to fit and be round... unless you are really lucky for bearing clearance as main caps are fitted to the block.
You can try another main cap using existing bearings and check clearance with "Plasti-Gauge" . If you can get .002 to .003 thousands at bearing crush it will be good but not necessarily round. It will run awhile.
Good luck!
Safety Car
Joined: Aug 2009
Posts: 3,752
Likes: 276
From: Melbourne, Victoria, Australia
You could drill and tap the bearing cap and oil pump where the bolt goes thru to accept the next size bolt, however you do not have much room to play with without weakening it. Also as others have said welding a stud on the bearing cap may work.
Bring it to a machine shop am sure some highly experienced engineers will be able to fix it in a flash.
I would not be worried with getting another bearing cap ''If your engine is standard'' and had never been rebuilt. Getting the bearing cap of a same year standard engine will do the trick. For sure use plastigauge and bolt the bearing cap on, then remove and see what the clearance is.
GM got all these parts made to specification for production line assembly, they could not afford to spend the time machining everything to fit for each individual engine.
My GM shop manual also notes a new bearing cap can be used but to check the bearing clearances, you can get undersized bearings and bearing cap shims.
The oil pump bolt torque is 88Nm or 65lb in my shop manual, however i would not go over 50lb. So you can see that is the same as cylinder head bolts or harmonic balancer bolt, quite a lot of force the bearing cap thread may have been damaged for it to fail with little effort.
Good luck
Bring it to a machine shop am sure some highly experienced engineers will be able to fix it in a flash.
I would not be worried with getting another bearing cap ''If your engine is standard'' and had never been rebuilt. Getting the bearing cap of a same year standard engine will do the trick. For sure use plastigauge and bolt the bearing cap on, then remove and see what the clearance is.
GM got all these parts made to specification for production line assembly, they could not afford to spend the time machining everything to fit for each individual engine.
My GM shop manual also notes a new bearing cap can be used but to check the bearing clearances, you can get undersized bearings and bearing cap shims.
The oil pump bolt torque is 88Nm or 65lb in my shop manual, however i would not go over 50lb. So you can see that is the same as cylinder head bolts or harmonic balancer bolt, quite a lot of force the bearing cap thread may have been damaged for it to fail with little effort.
Good luck
Melting Slicks
Joined: May 2010
Posts: 2,082
Likes: 3
From: Conowingo Maryland
You could drill and tap the bearing cap and oil pump where the bolt goes thru to accept the next size bolt, however you do not have much room to play with without weakening it. Also as others have said welding a stud on the bearing cap may work.
Bring it to a machine shop am sure some highly experienced engineers will be able to fix it in a flash.
I would not be worried with getting another bearing cap ''If your engine is standard'' and had never been rebuilt. Getting the bearing cap of a same year standard engine will do the trick. For sure use plastigauge and bolt the bearing cap on, then remove and see what the clearance is.
GM got all these parts made to specification for production line assembly, they could not afford to spend the time machining everything to fit for each individual engine.
My GM shop manual also notes a new bearing cap can be used but to check the bearing clearances, you can get undersized bearings and bearing cap shims.
The oil pump bolt torque is 88Nm or 65lb in my shop manual, however i would not go over 50lb. So you can see that is the same as cylinder head bolts or harmonic balancer bolt, quite a lot of force the bearing cap thread may have been damaged for it to fail with little effort.
Good luck
Bring it to a machine shop am sure some highly experienced engineers will be able to fix it in a flash.
I would not be worried with getting another bearing cap ''If your engine is standard'' and had never been rebuilt. Getting the bearing cap of a same year standard engine will do the trick. For sure use plastigauge and bolt the bearing cap on, then remove and see what the clearance is.
GM got all these parts made to specification for production line assembly, they could not afford to spend the time machining everything to fit for each individual engine.
My GM shop manual also notes a new bearing cap can be used but to check the bearing clearances, you can get undersized bearings and bearing cap shims.
The oil pump bolt torque is 88Nm or 65lb in my shop manual, however i would not go over 50lb. So you can see that is the same as cylinder head bolts or harmonic balancer bolt, quite a lot of force the bearing cap thread may have been damaged for it to fail with little effort.
Good luck