Water pump won't seal, need advise.

[quikveedb2]

^ lol, the gasket did seem to have all the structural integrity of tissue paper. I ordered a new gasket from WorldPac that's supposed to be here tomorrow. I also tore the motor back down and re-cleaned & sanded the mating surface on the block & pump. I'm going to go with the gasket with a light coating of Permatex to adhere it to the pump, & another thin coating on the block. I hope this is the last time I've gotta go through this, I want to get back to driving the car instead or working on it. It certainly has made me think a bit harder about a motor swap before the timing belt comes due again.

[wodcutr]

The gasket that comes with the graf pump is bogus. Order a new gasket from pelican and you won't have a problem. It is much thicker and works the first time. I had the same issue with this job once and have always since ordered a second gasket. The graf gasket is so thin it is easy to mangle and cause damage to it when installing the pump. Do not use RTV unless the block mounting surface is pitted and then use it sparingly to only fill in the pitted part. Good Luck!

[NickL]

Ive done it both ways. One with the paper gasket one with RTV. Just make sure both surfaces are clean and before you lay the pump back on take a straight edge to it and see if either of the mating surfaces are warped.

[quikveedb2]

Thanks for the suggestions, guys!

[TimKninja]

I love done quite a few m20 water pumps now .

I always clean the crap out of the block . Wire wheel it, sometimes left over hardendrd gasket is a bitch to remove. Then brake clean it so its perfect.

Then I use a thin layer of sealant on the the pump too glue the gasket into place. Sometimes it takes a few tries to get it lined up. I've never used JUST the paper gasket . I always use sealant to glue the gasket to the pump and then before it all dries I bolt it too the block . Never have had a leak .

[downforce22]

First off, thanks for the thoughtful & insightful replies.


@downforce22
I dunno how you did the pump without removing the belt as it's part of the tensioner assembly too? Do the 2 tensioner mounting bolts hold the belt in place firmly enough that no tension is lost without it?

At this point I'm thinking I'll redo the job with gasket maker & let it cure overnight since I had better results with it on the last attempt than the gasket. I'm on the fence as to whether new gasket is worth trying since it worked out so poorly before.



Thanks for that. :)

The water pump holds the mount for the one side of the tensioner spring. When you pull it off the tensioner stays in place because the other two bolts should be tightly in place holding the tensioner in place. When you reassemble with the belt on you have to put the tensioner spring and pin back in place, then rotate the water pump into place under tension of the spring. I believe that is why the first time I missed the bolt holes and gasket because I was holding the pump against the tension of the springs trying to line up the bolt holes. It was easier when the gasket was sealed to the water pump so I could just line up the bolts and tighten down.

[FLG]

Grab a can of the "right stuff" your never use another silicone again. It's amazing.

Sent from my SCH-I545 using Tapatalk 2

[quikveedb2]

I've never had luck with silicone based gasket sealants. I use this stuff:



Put a very thin coat on each side of the gasket, letting each "tack" before assembly. Most of the time, this stuff sticks so well the gasket tears in half on removal down the road.

That's exactly what I used on the 2nd attempt, and followed the directions. No gasket though, do you think both would net a better result?

@ Cletonious

Interesting, I'm not sure if the B27 water pump is different but I don't think so

[TobyB]

Have you checked the pump to make sure the sealing surface is flat?

I can't see the block warping enough to do this, but if something went wrong
in the pump casting, IT could be warped.

Quick and easy to check- once it's off- just put it on a very flat surface, and see
how it's sitting.

RTV CAN work for this- it's not the OEM way, but it's gotten 25 years better since the
OEM way was specified. I routinely use it for diff covers, trans housings, etc and it
does well enough...
...but unless I was in a pinch, I'd use a paper gasket, because as noted above, there's
no inbuilt provision for the RTV to make a long- lasting flexible seal.

hth

t

[Cletonius]

I dunno how you did the pump without removing the belt as it's part of the tensioner assembly too? Do the 2 tensioner mounting bolts hold the belt in place firmly enough that no tension is lost without it?

IIRC, when I did mine, the pump was totally separate from the belt/tensioner assembly. The tensioner lives under the cover with the belt and the pump is in the open. Maybe this is a B25/B27 difference? I remember feeling like my scenario was different than described in the diy articles.

[AndrewBird]

I've never had luck with silicone based gasket sealants. I use this stuff:



Put a very thin coat on each side of the gasket, letting each "tack" before assembly. Most of the time, this stuff sticks so well the gasket tears in half on removal down the road.

[quikveedb2]

First off, thanks for the thoughtful & insightful replies.

@Exodus_2pt0

Re-read my original post & you see that I did install the gasket dry and on a clean surface on the first attempt & it worked out worse than the 2nd when I used gasket maker.

There is a small chamfer around the outside diameter of the water pump mating surface, but I doubt if it's doing much good as it doesn't even appear continuous to the naked eye.

@SmokeE30

I've read in some write-ups to use some Permatex with the gasket, I'm wondering if having more stuff between the block & the water pump will create more avenues for leakage. I did notice that one bolt was missing it's washer when I removed them, and another cracked it's washer during the first install, which I found out wen I removed it the 2nd time. I find it hard to believe that that small amount of extra thread would cause the leak, but new washers will be going in this time anyway.

@Cletonius

Have not, will check when disassembled. I hope the water pump isn't the cause.

@downforce22

The gasket was slightly ovalized at one of the bolt hole locations, not torn at all, and I find it hard to believe that the coolant would leak at the rate that is did from something so small. I dunno how you did the pump without removing the belt as it's part of the tensioner assembly too? Do the 2 tensioner mounting bolts hold the belt in place firmly enough that no tension is lost without it?

At this point I'm thinking I'll redo the job with gasket maker & let it cure overnight since I had better results with it on the last attempt than the gasket. I'm on the fence as to whether new gasket is worth trying since it worked out so poorly before.

You'll get it together and won't have to worry about the pump for another 50k miles.

Thanks for that. :)

[downforce22]

Bummer Dude. This happened to me in February.

I did the water pump and everything only to find when I filled it I had a stream leaking out the pump. The gasket did not get put on right and was ripped a bit in a spot. I grabbed some rtv sealant and sparingly applied it around the edge of the gasket and applied it to the water pump. After it dried I cleaned the mounting surface and just bolted it in. I did not put rtv on the block itself. I put it back together and I have not had any problems for 6 months.

I have heard of people using old belts and not having a problem with them. Having said that I did the pump with the belt still on the car, I just took the radiator and hoses out.

You'll get it together and won't have to worry about the pump for another 50k miles.

[Cletonius]

Maybe you got a shit water pump. Something is causing the surfaces to not make proper contact with the gasket.

I could see this happening.

OP: have you checked the mating surfaces with a straightedge?

[SmokeE30]

I have had success with permetex water pump and thermostat sealant in the past just put a very thin layer on to stick the paper gasket to, let it tack up and then put the gasket on and then another very thin layer. You don't want much but I have had good luck with it on m20 water pumps so that itself probably isn't your issue.

One thing that I have seen that could be your problem is if one bolt or more that hold the water pump to the block has been replaced with a bolt that's just slightly too long the bolt will bottom out and become tight before the pump is properly sealed against the block, It took me a while to diagnos one bolt having a couple extra threads on one car that was leaking after 2 gaskets.