Well, I guess I got my comeuppance today. I've changed the waterpump twice on my 1987 740 turbo, using no gasket seal, with no problem. Today, I spent 5 hours trying to replace the waterpump on my wife's 1993 940 Volvo. I scraped clean the mating surface on the cylinder head and did not use any gasket seal. Installed a new OEM Volvo waterpump. Got a good tight fit on the hat seal on top. Then, when I put in new antifreeze, it was leaking like a sieve! Leaking from the bolt threads and the bottom, through the gasket. Though the Haynes manual does not mention gasket seal, I'm betting the professionals use a thin layer of it.
Question 1: What brand gasket seal do you folks recommend? Is it flexible? Can it be used on the bolt threads?
Question 2: The Haynes manual does not give a torque specification for the waterpump bolts and nuts. I've misplaced my Bentley manual, due so spring cleaning. Anybody have those specs? (I do not want to break a stud. I've done that in my youth, and I don't want to repeat that!)
Thanks, guys.

 

I always use a thin layer of sealant: first I glue the gasket to the pump, then put more sealant on the clean side, then mount the pump--never a problem; no sealant on the treads, but around the holes where the bolts will pass. Never put sealant on the upper O ring or the heater pipe o ring. Any reputable "gasket maker" type seal will do... I don't torque such small bolts/nuts like the ones on the water pump, I go by "feel". The OEM bolts are pretty good quality, I've only heard of the aftermarket ones snapping off.

 

Thanks, Lev. After a day like yesterday, I'm thinking of retiring from being an amateur mechanic. But, I'll probably change my mind when I get a quote from a professional mechanic. Still . . . I'm getting older.

 

I know the feeling! But these old Volvos need us; as many times as I promise to quit, I know I'd be missing them too much if I quit playing with them. Probably $200 labor at a shop...

The water pump can be frustrating, lifting it and trying to line up the holes while the gasket and sealant slide around-- I do remember my first time...

 

Lev,

You wouldn't know offhand what brand and type of gasket sealant you used? I see all kinds online, like Permatex, but none of them specifically says they are used for adhesion (except for rubber). And the waterpump gasket is not rubber. Thanks.

 

Right now I am using the Permatex Black Silicone Adhesive Sealant...I have used many things over the years--I like 3M products, used to use the yellow (elephant snot) for many years. Not that crucial of a choice really... more important how you apply it. Use a thin bead, not too much, just to get a good area spread over the surface--I don't like to see excess bulging out after the surfaces mate...

 

I replaced all the seals and gaskets on my pump recently and didn't quite run into a problem like you, but I do still have a small leak from the top seal. I will have to pull it apart again to figure it out. I didn't find the job too difficult.

However, one thing I recommend is to loosen all the bolts, not fully, but just loose. Then make sure you re-tighten each bolt in a star pattern progressively. Once one bolt is hand-tight, move to the next until they're all hand-tight. Tighten a quarter turn for each (or more, depending on the feel) Then finally torque them all down, again in a star pattern.

From your description, my guess is there is a point where your pump isn't sitting flush against the block. Improper tightening of the bolts would do that. Paper gaskets are relatively forgiving with small imperfections. Its either that or your gasket is torn somehow.

 

Thanks, Lev and modifierwong. I bought the Permatex 97 Super High Tack Gasket Sealant. I will first try modifier's idea; then if it's still leaking, I'll go with the gasket sealant. I do admit that I may not have done the tightening in the star pattern.

 

I don't know about this "star pattern"... The pump when first goes on hangs on the two studs sticking out, I hand tighten those nuts. The pump has oval holes when the studs go--that's because the pump is first secured with the nuts that go on the studs, then lifted up vertically to line up with the holes for the bolts to go through. You should be able to tell if the pump is fitting flush just by looking at the big O ring...

 

MW, I did as you suggested. It seems to have worked on a cold, non-started engine. Yesterday, when I poured in the coolant, it was running like a waterfall through the waterpump. So, I loosened all the nuts and bolts and handtightened in a star pattern. Then I gradually increased the torque on the nuts and bolts in a star pattern. I know enough to do that, but I was tired, frustrated, and flustered last night. Luckily, I had enough sense to step back, come to this forum, and tackle it on a new day. I did have an ever so small leak coming from the #1 nut (left top), with the oval. But, rather than risk breaking the stud by overtightening, I used some old Bondo #2 gasket sealant around the bottom of the nut. I'll put everything together tomorrow and see how it looks when the engine is running. Thanks, MW and Lev.

 

Well, I checked this morning and there is still a leak from the upper left stud of the waterpump. Lev, you said to put sealant around the hole where the stud or bolts pass through. My question: Do you put the sealant in the hole of the waterpump or do you put more sealant on the mating surface next to the mounting hole? Or both? Thanks.

 

No, not in the hole, just around the hole on both side of the gasket--he coolant is not leaking out of the stud, it's leaking from somewhere in the vicinity where the gasket/sealant is absent and coming out of the stud hole...

 

Thanks, Lev. I should have left this project alone. The previous waterpump only had a minuscule lead, and we could have lived with it. Instead, in seeking perfection, I have opened up a can of worms. Tried the Permatex 97 Super High Tack Gasket Sealant. Jeez, the stuff was tacky right out of the tube. It's worthless! (More than the money, I wasted a lot of time dealing with a failed product!) I had difficulty even spreading it on the gasket. I tried putting the waterpump on and couldn't get a bite on the middle bottom bolt. So, I pulled it and cleaned all the surfaces again and tried with a new gasket kit, with no sealant. Only thing, I must have damaged the hat gasket on installation, so now I've got a leak on the rear passenger side of the hat gasket.
Question: On your Permatex Black Silicone Adhesive Sealant, is it pretty easy to spread?
Thanks. (I just may end up taking the car to a pro.)

 

I used Permatex black RTV, not on the waterpump, but for many other things. It spreads well, but the only downside is the difficulty in keeping the rest of the tube drying out when you're done. I have to repeatedly free the RTV from the tube everytime I take it out.

When trying to locate the hole, try using a thin screwdriver and poke it around. That way, you can feel where the hole is, in relation to the slot on the pump.

Now that you have the same problem as me, I'm curious how your fix works out. When I get around to fixing my leak on the upper O-ring, I'm going to use progressively finer sandpaper on the block to make sure that surface is smooth, followed by a thin layer of RTV. Still going to put on the gasket dry. Don't forget to let the RTV dry before refilling your system. I waited overnight, but I've read others wait just a couple minutes.

 

Do not seek perfection, you'll only find frustration.
Still, I am all for fixing leaks... I don't know, when I get stuck, I walk away for a while, but I don't give up; "pros", never!
The black silicone is fine... Put he gasket on the pump, put the rubber rings on with vaseline, slap the pump on, hand tighten the NUTS on the studs, lift the pump up to get the bolts in using a pry bar of some sort, then tighten them all. I don't usually wait to put the coolant in.

The pump I did a year ago I didn't even have a gasket, so I just used the sealant, and all is well...

 

Thanks, guys. I was trying to get the car ready to go to the airport to pick up our new puppy. Now, we have to rent a car. We'll have to drive the leaky car to Hertz, or take a bus, so as to get the rental. You're right, Lev. Maybe, I'll take a long break.

 

Okay, here's a conundrum. I've bought two sets of IPD waterpump gasket kit, $2.43 each. The paper gaskets look fine. The hat gaskets, though, have a slight burr on the rubber at the top, where the wider part (or hat) joins the main cylinder. Seems like a separate piece of rubber was vulcanized at the top to make the lip. I removed my original replacement hat gasket (OEM) as a matter of course, but that hat gasket did not leak. It has the vulcanized layer at the bottom, with a slight burr. This hat gasket was under compression for 24-36 hours, but otherwise looks fine. Which hat gasket would you guys use? The new IPD ones or the slightly used OEM one? Thanks.

 

One other question. What does "RTV" stand for on the black silicone adhesive sealant?

 

RTV - Room Temperature Vulcanization... traditional rubbers had to be heated quite hot to turn solid (aka vulcanize), while these silicone RTV rubbers are triggered by moisture in the air to solidify without heat....

re: that IPD gasket kit... I would only use Volvo brand gaskets on a water pump, just about anything else is junk, especially that tophat little seal.

 

Thanks, Pierce. Looks like I'll be going with the OEM tophat.