hammmy

Hi all,

I spent today removing my water pump from my '81+ 12A, in order to sort out a leak coming from the bottom of the pump. Using the Chilton's procedure--by far more helpful than the factory manual, in this case--I've gotten to the point where the pump should slide right off the studs. Unfortunately, this doesn't happen. Instead, the entire "water housing" (Chilton description) tries to move forward, along with the air pump (which is connected to the housing at its pivot bolt). I figured a balky gasket was causing the pump to adhere to the housing, but I couldn't pop the pump off with a screwdriver and hammer, so I'm kind've stuck. I considered pulling the entire housing off, but that would require removing the OMP lines, which I consider a big no-no. Any help?

7aull

iTrader: (2)

Hi Dave- I just pulled and installed my water pump this week on my 80. If your pump BODY is trying to slide off with the pump itself, you have loosened too many nuts! Can you get your head in around the front of the assembly and see which ones really need to come off?
Only some of the nuts need to come off to free the pump from the body...the pump itself (I am talking the impeller part, not the body) doesn't really "slide on the studs" per se. The pump body does that. The impeller fits over the ends of the studs sticking past the pump body...and maybe a couple of the fasteners are BOLTS, too.
As to loosening the impeller pump assy itself from the pump body, try using a piece of 2x4 and hitting it with a hammer, or if you have a rubber mallet, hit the pump directly. usually one sharp blow will dislodge stuff. Or a flat blade screwdriver between the joints and tap at that with a hammer. Careful there because you don't want to score the face of the mating surfaces between the 2 pump parts! I am a bit puzzled since mine separated easily - but the engine only had 70K on her.
Don't sweat pulling the oil meter lines from the OMP - brainless. If you take the lines out of the clamp that attaches them to the water pump, they might not even need to be pulled from the OMP. They are quite flexible (unless yours are old and getting brittle, in which case get a new pair, they are cheap!)
A hint on re-assembly: a thin coat of plain old axle grease on ALL mating surfaces (with the gaskets "floating" between) will make future work a no brainer! No fossilized gasket remenants to be scrapping away! Likewise, same grease around neck of all the pump pipes: makes installing and removing hoses a dream!! Don't need much - I used a Q-tip to coat the surfaces-
hope this all helps... Oh! torque!! only about 15 ft-lbs to tighten the pump nuts!!! about the same as the spark plugs! So don't ream them on!!
Your going to have to re-gasket your pump body now that you've pulled it from the block, BTW. Don't forget there are one or 2 metal round SHIMS that the pump BODY has between it and the BLOCK on a couple of the studs. You will see these as you remove the pump body!
'Luck
Stu Aull
80GS in Alaska

MarkPerez

water pump, i just replaced mine. remove the fan , the belts oh and drain the coolent. every nut on the studs comes off and the bolt for the alt. bracket and the air pump comes off. no hammering, no prying the water pump comes right off. and theres no seperating the impeller from the housing. remove all the old gasket material on the engine and use a wire wheel to smooth out the gasket surface. i used that blue GE hi-temp silicon, using my finger spread a thin layer on the engines front cover where the water pump mounts, let it set a few minutes.place the new gasket that came with the new water pump on the engine, the studs will hold it on. on the new water pump i used the same silicon and spread a thin layer make sure to go around the bolt holes, let site for a minute. make sure all gasket material is out of the water passage. when the new pump goes on all the nuts and bolts go on at the same time and tighten evenly, don't over tighten ! now i had to remove two bolts and loosen the rest on the bottom pulley to remove the water pump pulley. so the water pump pulley goes on then the bottom pulley gets tighted up. install all the belts, fan , fill with coolent, when finished start the engine and let it reach operating temp while watching for leaks. i also removed my water neck or thermostat housing, cleaned all the crap out of it, prephared the gasket surface the same way and i have no runs, leaks, or errors. there were no shimms on my engine. ???

Jeff20B

iTrader: (13)

I replaced a waterpump last saturday on an '83. We had to replace the small gasket between the front iron and the waterpump housing because the housing always comes off the engine easier than the impeller part from the waterpump housing itself. It's pretty normal to have to do this, incase you were wondering. Don't forget the little shims/washers on the two studs without a gasket nearby (they're the same thickness as a gasket when it's crushed).

hammmy

Yeah, I didn't see the shims either. All four of the studs coming out of the block passed through the waterpump gasket. Unless. . . Are there supposed to be shims on the studs that aren't passing through the water-housing-to-block gasket? That would make more sense, now that I think about it. I used high-temp silicone RTV to replace that gasket, as no parts chain had a listing for it. Hopefully, that won't be a problem. I cleaned and sanded all mating surfaces really well, so that might do the trick.

However, I broke two 10mm bolts trying to put the waterpump pulley back on (after I installed the pump, because I forgot it). From looking at the bolts, it looked like the replacement waterpump had a slightly different thread pitch on its pulley flange than the OEM waterpump. I bought a BMG(?) waterpump from Schucks, as it was supposed to be new instead of rebuilt. Guess "new" doesn't mean "OEM specs". It was odd, as I finger threaded all four with no problem. I picked up some 7mm-1.0-16mm bolts from Home Depot tonight, along with an extractor set.

Oh, and the original leak I noticed coming from the waterpump area was draining out of the weep hole behind the pulley. I learned this was the common pump failure indication from Chilton's (failure of the "water gland"); unfortunately I didn't read it until I was into disassembly =p. Had to wait a day for the pump to come in.

hammmy

Oh, and btw--if anyone knows where to get those shims, let me know. Is blank gasket material available at auto parts stores?

Jeff20B

iTrader: (13)

You don't have to use the shims. Make some and a gasktet out of thin blank gasket material. Or maybe someone here could send you some?

hammmy

Or just put some silicone RTV around the studs. I think I may just do that. Thanks for the input, all.

hammmy

I drilled the broken bolts in the waterpump pulley flange, and extracted them. Had to take the pump off again to do so, but thankfully the water housing stayed in place. Thanks Stu, for the suggestion to use a little grease to keep the gasket from fusing to the mating surfaces. Drove it for a hour last night, will no ill effects.

Just as a side note, but the bolts for the BMG waterpump flange are 6mm-1.0x16mm. I said 7mm earlier. Thanks for the help, all.

Jeff20B

iTrader: (13)

6mm x 1.0 is the correct thread pitch. The length has changed a few times over the years due to different fan mounting flanges, etc. You can use FB electric window regualtor bolts or even oil pan bolts if you decide to remove the fan and flange.