Water pump is killing me

[Parzival]

waterpump is killing me!
I decided to replace my water pump. I have now taken it off 3 times, and gone through 2 new gaskets, and two different types of gasket sealer.
I cleaned the mating surfaces really good and finished up with alcohol. Once dry I apply the gasket sealer and gasket, and bolt it toghether and let set over night, in this last case it sat for a 3 days. When I install it in the car I use the pressure checker and pump it up. It holds pressure for a few minutes, but after that I can see its dropping 1 or 2 PSI every few minutes. Spraying soapy water around I find bubbles around the water pump seal. What am I missing. After this last time I just can't imagine what else I could do to stop it.
It is supposed to be able to hold this pressure for longer then a few minutes right? I haven't put any coolant in yet, is it just supposed to be water tight? and not air tight? Should I test with coolant in there? I just dont know

[dmcnc]

What kind of RTV are you using on the gasket? Both sides?

[Parzival]

What kind of RTV are you using on the gasket? Both sides?

yes both sides. The first was grey silicone gasket sealer, and the second time I tried the Indian head gasket shellac.

[Delorean Industries]

Rtv is not right for this. You need to use hylomar to dress the gasket.

[81dmc]

I used rtv when I did mine, and AFAIK, I didn't have any issues with it.

Parzival, if you want my Volvo spec, complete Gates pump with deloreanclubuk bolt on aluminum pulley, let me know. I'd gladly sell it to ya:)

[David T]

When you pressure test you are supposed to fill the system with liquid (water and anti-freeze) and then pressurize the liquid. The liquid can seal tiny holes that air can leak out of and the pump seal needs the liquid to help it seal, it wont' seal tightly dry.

[Ron]

??? Sounds like he was saying the gasket is ok now, ie, it only leaks air at the seal...

If so, I'd suggest you fill it with water/coolant and check it.
Did you let it run a bit before testing it (the last time)?


Other thoughts:
+1 J- A lot of gasket companies say not to use any sealant. You would be better off using nothing than using RTV (but I wouldn't do it over if it doesn't leak).

You may have a leak somewhere else.

Did you pressure check the cap?

[Parzival]

??? Sounds like he was saying the gasket is ok now, ie, it only leaks air at the seal...

If so, I'd suggest you fill it with water/coolant and check it.
Did you let it run a bit before testing it (the last time)?


Other thoughts:
+1 J- A lot of gasket companies say not to use any sealant. You would be better off using nothing than using RTV (but I wouldn't do it over if it doesn't leak).

You may have a leak somewhere else.

Did you pressure check the cap?

I've never put the mixture unit back it, or put coolant in because both times it's not held air pressure at 15psi. I've only tried it with air only no coolant, This morning I pumped it up (with just air) and after a few minutes it was at 14PSI not 15, and then eventually like 10psi after like 5 minutes. Soapy water revealed air bubbles forming around the gasket. I can go add coolant and see if it holds, but then if it dosent I'm gonna have a mess on my hands.

[AugustneverEnds]

Years ago I had trouble getting a leak free seal on my water pump. Upon close inspection I found a tiny chip on the mating surface of the original water pump back plate. I replaced it with a new one from DMC Europe. Also I had a tough time with the gaskets from the vendors, they're thin. I traced one onto a sheet of cork gasket material I picked up at Advance Auto and have had no issues for three years now.

[Parzival]

When you pressure test you are supposed to fill the system with liquid (water and anti-freeze) and then pressurize the liquid. The liquid can seal tiny holes that air can leak out of and the pump seal needs the liquid to help it seal, it wont' seal tightly dry.

You think I should put some coolant in there and try it?

[eight8toy]

I just went through the same thing last week. Pressure tested and saw the tiniest wet spot, even had a good size leak at the radiator. I said the hell with it and filled it with coolant and under normal engine running pressure I haven't seen any leaks.

New DPI rad with fans is sitting in my garage but I dont have time to work on it now since I'm moving.

[Ron]

I've never put the mixture unit back it, or put coolant in because both times it's not held air pressure at 15psi. I've only tried it with air only no coolant, This morning I pumped it up (with just air) and after a few minutes it was at 14PSI not 15, and then eventually like 10psi after like 5 minutes. Soapy water revealed air bubbles forming around the gasket. I can go add coolant and see if it holds, but then if it dosent I'm gonna have a mess on my hands.
Ah, OK. When you said "seal" I thought you meant the shaft seal...why David an I said to fill it with water...

Since it is leaking at the gasket, something is probably wrong with the mating surfaces: using RTV, warped pump housing, heavy sanding/scraper marks, or chips, as Nick suggested.

[Parzival]

Ah, OK. When you said "seal" I thought you meant the shaft seal...why David an I said to fill it with water...

Since it is leaking at the gasket, something is probably wrong with the mating surfaces: using RTV, warped pump housing, heavy sanding/scraper marks, or chips, as Nick suggested.


ok, taking it back off, (Dana AKA DMC-81) are gonna both revisit it Tuesday as he has graciously invited me to bring it by his place.

[David T]

You really do have to pressure test the cooling system with liquid inside. If you don't want a mess just use water, you can dump it out and refill with anti-freeze after you find and fix any leaks. You can even drive the car a little with just water in it but don't do it for too long. Automotive cooling systems are not made to be tested using just air. Air will leak out of tiny holes that liquid won't.

[Ron]

ok, taking it back off, (Dana AKA DMC-81) are gonna both revisit it Tuesday as he has graciously invited me to bring it by his place.Cool!...I think he will spot the problem.

[Parzival]

You really do have to pressure test the cooling system with liquid inside. If you don't want a mess just use water, you can dump it out and refill with anti-freeze after you find and fix any leaks. You can even drive the car a little with just water in it but don't do it for too long. Automotive cooling systems are not made to be tested using just air. Air will leak out of tiny holes that liquid won't.

I think you're right, but how huccch leaking is likely to be stopped by liquid? Its losing 1 psi every minute or 2. That doesn't sound like too much?

[Ron]

I think you're right, but how huccch leaking is likely to be stopped by liquid? Its losing 1 psi every minute or 2. That doesn't sound like too much?I'm thinking we're not all on the same page...what we are saying is:
1. Paper gaskets (used between pump and engine) should never leak, ever!
2. The pump seal (used between the pump housing and pump shaft) may leak air but shouldn't leak coolant. (Especially true if you have let it run a few minutes to seat in, which is not normally required.)
3. If the coolant, engine, and ambient air temps are the same when you fill the system then pressure it at or below the caps rate, it may drop a few psi the first few seconds (hose stretch etc), then hold solid for at least 2 minutes.

Detailed instructions attached below. (Note it even says to wet the cap when you test it.)

[Parzival]

I'm thinking we're not all on the same page...what we are saying is:
1. Paper gaskets (used between pump and engine) should never leak, ever!
2. The pump seal (used between the pump housing and pump shaft) may leak air but shouldn't leak coolant. (Especially true if you have let it run a few minutes to seat in, which is not normally required.)
3. If the coolant, engine, and ambient air temps are the same when you fill the system then pressure it at or below the caps rate, it may drop a few psi the first few seconds (hose stretch etc), then hold solid for at least 2 minutes.

Detailed instructions attached below. (Note it even says to wet the cap when you test it.)

its the gasket. Its just leaking air (thats all thats in there) at 15 psi the hand of the gage is not visibly moving, but after two minutes or so it will be down to 14 PSI. Spraying soapy water around the seem between the water pump front and back (where the paper gasket is) is produces foam, indicating that air is getting out.

[David T]

its the gasket. Its just leaking air (thats all thats in there) at 15 psi the hand of the gage is not visibly moving, but after two minutes or so it will be down to 14 PSI. Spraying soapy water around the seem between the water pump front and back (where the paper gasket is) is produces foam, indicating that air is getting out.

It should not leak once you fill the system with water. Water will cause the gasket to swell and stop leaking. The air is leaking through the paper. Try using water and tell us what happens.

[Parzival]

It should not leak once you fill the system with water. Water will cause the gasket to swell and stop leaking. The air is leaking through the paper. Try using water and tell us what happens.

Ok, I took it out, but have not separated it. I'm taking it over to dana's house tomorrow for further inspection. If we thinks it good, I'll do that and let you know. or if we pull it apart and try again with a new gasket.
His held 15 PSI over night with just air in the system. Like you said, that might not be necessary, but it's damn impressive. you know you did one hell of a detailed job on you cooling system if it does that with no liquid in it. My water pump was not even leaking before. It was just original and I didn't want to worry about it. So I decided to do this preventative approach. This is my second time into the valley, and I don't mind the practice, but I would like to go for a drive before too long, so I want to get all this back in. I'll keep you posted..

[Ron]

It should not leak once you fill the system with water. Water will cause the gasket to swell and stop leaking.I disagree. According to Permatex's 10 Most Common Gasketing Mistakes (https://www.permatex.com/ten-common-gasketing-mistakes/):
"10. Using a gasket maker as a dressing on a conventional gasket.
This might be the most common gasketing error of all. Many mechanics will use an RTV gasket maker to hold a conventional or cut gasket in place during assembly..."

The gasket manufacturer RAM says, "...paper is a cellulose fibre base impregnated with a plasticized chemical treatment: to resist oil, petrol air, water, alcohol, grease and most solvents."

=====
$.02

It's the mating surfaces, torque, use/usage of RTV.
I suspect you will be purchasing some Hylomar (HYLOTYTE RED 100) if Dana doesn't have some on hand.

:cheers:

[Parzival]

This last time a used Indian Head Gasket Shellac on the gasket. Its made by permatex

[Parzival]

I went to DMC-81 AKA Dana's house yesterday, we took the pump back apart, and cleaned it again. ran a tap through all the threads, and cleaned the bolts to insure they thread smoothly so that we could get accurate torque readings. We checked the mating surfaces were flat and smooth. Cleaned the surface, and applied gasket shellac to the surfaces with a small paint brush. We did this the same way he had when he did his and when he managed to get his system to hold pressure at 15PSI over night. We were probably way more thorough then anyone has ever been when installing a water pump.
I will pressure check it tomorrow, and post the results.
More importantly, after doing this for the third time trying to get it right, I was pretty frustrated, but doing it with a friend made it much more bearable and ended up being a really good time, one of the best times working on the car so far, and that stands wether it leaks again or not!
Thanks again Dana!

[Ron]

No luck??

[Parzival]

No luck??

it leaked again with coolant in it. We are baffled. getting another pump and backer from DMC, will take a week, but after 3 times, what else can we do?

[David T]

Make sure you are using the correct bolts in the correct spots. If you put too long a bolt in the wrong place it will feel like it is tightening up but it is really just bottoming out. Make sure the gaskets are not slipping out of position and the surfaces are clean, flat, and no scratches or burrs and you removed all traces of the old gaskets and sealer.

[DMC-81]

Make sure you are using the correct bolts in the correct spots. If you put too long a bolt in the wrong place it will feel like it is tightening up but it is really just bottoming out. Make sure the gaskets are not slipping out of position and the surfaces are clean, flat, and no scratches or burrs and you removed all traces of the old gaskets and sealer.

Yeah, we covered all that and more.

[Parzival]

Make sure you are using the correct bolts in the correct spots. If you put too long a bolt in the wrong place it will feel like it is tightening up but it is really just bottoming out. Make sure the gaskets are not slipping out of position and the surfaces are clean, flat, and no scratches or burrs and you removed all traces of the old gaskets and sealer.

trust me, we did it all, we cleaned it again. Perfect flat surface, we placed both halves together with no gasket to see how well the 2 halves met. Our last assembly was text book.
The pump was also leaking from the plug in the back. There is just no way I'm going to keep trying the same thing for a 4th time and expect a different result. Logically, If I try the same thing again, its gonna do the same thing again.
So i ordered a new pump and backing from DMCFL they are going to assemble it, and i'm just gonna go pick it up and put it in.
I'm not gonna lie, failing at a simple job like a water pump is not something that helps your confidence any. I just can't seem to see anything else I can do. I could have put the car back together and It would have been drivable because the leaks were so minimal, So minimal in fact that I doubt it would have really been much of an issue. The whole reason I was replacing it was because the original was... well... original, but it wasn't leaking. I'm not putting it back toghether anything less then 100%

[Ron]

:shocked:

[Parzival]

:shocked:

Tell me about it!
On a brighter note, Dana and I had a delightful time lol.