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Thu Dec 13, 2007 12:25 pm

I am swapping in a new HD oil pump today. I have an extra set of pump gaskets (thick for the pump / thin for the cover) from Bus Depot. The pump also came with it's own set of gaskets. The thick ones are the same but the thin ones are different and I can't remember which gasket came with the pump and which one was the extra.

As you can see from the pictures, they are quite different. Any ideas as to which one is correct?

THANKS!!!

Thu Dec 13, 2007 1:56 pm

Gasket A goes between the pump body and the crankcase. It encircles the body.

B is for between the body and cover.

The groove is for oil that reaches it under pressure to loop back and be pulled in on the suction side, to keep it from forcing its way out under pressure and causing a leak. Gasket B covers the groove. If you use B, the old-timers install it dry. The idea is that it will absorb oil and swell a bit once in use.

I used to do it that way, but I don't use either anymore. I run a thin bead of the Dirko or Reinzosil sealant included in the Elring or Reinz engine gasket sets, respectively, around the back of the pump body flange. It flows between the body and case and forms a flexible, long-life seal that won't crack like the paper gasket can.

I also use no gasket under the cover, but only after I mike the gear endplay in the pump body. Install the gears in the body, lay a straightedge over the body face, and use feeler gauges to measure the free play available for the gears once the flat cover were to go on (this is shown in Bentley p.17.9, fig. 2). It should be 0.004". If it is, that is the right tolerance and adding a gasket, however thin, would increase the endplay once installed. That will cause the pump to raise less pressure when the oil is hot. The gears are steel while the body is aluminum. Aluminum has a far higher rate of thermal expansion than steel, so when the motor is hot, that endplay will only increase.

If the endplay dry is less than 0.003" , you should use the thin gasket. Otherwise, apply a thin continuous bead of sealant, 2mm wide, around the face of the body outside the groove and inside the stud holes.

Before installing the cover, make sure it is dead flat. Use a good straightedge and lay it across the sealing face of the cover at various angles. Look for any light coming under the straightedge, either in the middle or toward the edges. If it isn't dead flat, polish it on a piece of lubricated 100-grit on a piece of plate glass until the surface is evenly abraded. Clean it carefully with solvent before installing.

Always use new sealing insert nuts for the cover, or else remove the studs from the case and reinstall them with some Loctite Loc'n'Seal or Thread Sealant. The insert nuts just seal in oil that may seep up the stud threads. If you seal the stud threads in the case, and seal the rest of the pump well, the special nuts aren't needed.

Be careful to check the fit of the water crossover pipe before final installing it when using a 30mm hi-volume pump. The longer pump studs or bolts will probably need to have clearance added by dimpling the pipe with a ball-peen hammer at the appropriate places. Make small mods and test-fit carefully to be sure there is a tiny gap before final installing the pipe.

You motorhed, you.

Thu Dec 13, 2007 7:32 pm

Forgive me, Tencent, for I have sinned.

Before Tencent posted his reply (and I should have waited, dammit) I called Bus Depot and they said the beige gasket (A) was for the cover. I didn't have my computer today - I just saw this post - so guess which one I installed. Guess. Go ahead.

F*ck.

I used the beige (A) gasket. It's a thin gasket - as thin as the other gasket (B) and I didn''t use any sealer. Do I have to pull everything off the engine and replace the gasket?

Listen to Tencent. Oy.

Thu Dec 13, 2007 8:36 pm

Well I don't know how many motors they build over there at BD. In this case, they're wrong, I'm afraid.

What did you use behind the pump body then?

Do you have to pull the pump? No. The cover? I guess. With that gasket under the cover, there is now a thin gap under the cover between the gear pockets and the return groove. The gap is made by there being no gasket paper where there was supposed to be some. More oil than was intended is going to cycle thru there.

Will it affect OP? Can't say; I never did one that way, but I suppose it would.

Would I get the cover back off and correct my mistake? You're damn right I would.

Have a beer, Andrew, and try not to feel bad.

Thu Dec 13, 2007 8:46 pm

tencentlife wrote: Would I get the cover back off and correct my mistake? You're damn right I would.
Yep. I've got the jack back under the engine all ready to pull the carrier first thing in the AM. All I need at this point is the self-sealing nuts and I'm back in business.

Thanks for your help, as always.

Sat Oct 01, 2011 9:34 am

Just read this, after an annoying episode with the oil light flashing, and doom buzzer sounding today after a rebuild, basically, as well as other engine work, i fitted a new german made (kolbenschmitt) oil pump, but followed the workshop manual and fitted the 'B' gasket with the 4 small holes in, (the previous pump had no gasket under the plate, just blue hylomar type sealant, I'm now sure that this added clearance from fitting a gasket is what's causing the buzzer to go off at around 2000 rpm, like simulating a worn pump, in effect! i thought i was doing right changing the pump while the engine was out for other work, but i now have to try and get the mount cradle and pulley and water pipe back off, get the coverplate off the pump, and carefully follow the above advice. i really hope this cures the prob. thanks for posting this info!!

Sat Mar 30, 2013 7:53 pm

tencentlife wrote: Gasket A goes between the pump body and the crankcase. It encircles the body.

B is for between the body and cover.

The groove is for oil that reaches it under pressure to loop back and be pulled in on the suction side, to keep it from forcing its way out under pressure and causing a leak. Gasket B covers the groove. If you use B, the old-timers install it dry. The idea is that it will absorb oil and swell a bit once in use.

I used to do it that way, but I don't use either anymore. I run a thin bead of the Dirko or Reinzosil sealant included in the Elring or Reinz engine gasket sets, respectively, around the back of the pump body flange. It flows between the body and case and forms a flexible, long-life seal that won't crack like the paper gasket can.

I also use no gasket under the cover, but only after I mike the gear endplay in the pump body. Install the gears in the body, lay a straightedge over the body face, and use feeler gauges to measure the free play available for the gears once the flat cover were to go on (this is shown in Bentley p.17.9, fig. 2). It should be 0.004". If it is, that is the right tolerance and adding a gasket, however thin, would increase the endplay once installed. That will cause the pump to raise less pressure when the oil is hot. The gears are steel while the body is aluminum. Aluminum has a far higher rate of thermal expansion than steel, so when the motor is hot, that endplay will only increase.

If the endplay dry is less than 0.003" , you should use the thin gasket. Otherwise, apply a thin continuous bead of sealant, 2mm wide, around the face of the body outside the groove and inside the stud holes.

Before installing the cover, make sure it is dead flat. Use a good straightedge and lay it across the sealing face of the cover at various angles. Look for any light coming under the straightedge, either in the middle or toward the edges. If it isn't dead flat, polish it on a piece of lubricated 100-grit on a piece of plate glass until the surface is evenly abraded. Clean it carefully with solvent before installing.

Always use new sealing insert nuts for the cover, or else remove the studs from the case and reinstall them with some Loctite Loc'n'Seal or Thread Sealant. The insert nuts just seal in oil that may seep up the stud threads. If you seal the stud threads in the case, and seal the rest of the pump well, the special nuts aren't needed.

Be careful to check the fit of the water crossover pipe before final installing it when using a 30mm hi-volume pump. The longer pump studs or bolts will probably need to have clearance added by dimpling the pipe with a ball-peen hammer at the appropriate places. Make small mods and test-fit carefully to be sure there is a tiny gap before final installing the pipe.

You motorhed, you. is this do-able with engine in the van? this i think is why my oil psi is so low after my rebuild, now with 12k on it [-o< my engine is still ok. is there a show how pics/video tutorial link anywhere??

Sun Mar 31, 2013 11:38 am

devesvws wrote: is this do-able with engine in the van? this i think is why my oil psi is so low after my rebuild, now with 12k on it [-o< my engine is still ok. is there a show how pics/video tutorial link anywhere??

very do-able with engine in the van. I recently had to reseal the pump housing and cover plate on my 2.1 due to a bad oil leak and it wasn't too hard of a job overall. Had to remove the muffler, cat converter, rear engine carrier bar, motor mounts/bracket, water pump pulley and belt, and the coolant crossover pipe.
I read online how a lot of people also remove the crank pulley, but I saw no reason why this was necessary. The pump housing can be fully removed and installed with the crank pulley in place. Hardest part for me is the exhaust, I still cant get it to properly seal up after trying a couple different times. Exhaust leaks are annoying :x

Tue Apr 02, 2013 10:56 am

how much reinzosil do you use not using the seal?? and do you cover the same area as the seal??

Tue Apr 02, 2013 11:32 am

a common mistake causing low oil pressure is to use the thick gasket between the pump body and cover. I also run no gasket between these, just thin film of Curil OUTSIDE the oil return groove. If it's inside it can get sucked into the input side and wind up in your oil.