First some background: this is a 98 caravan with 150k miles and the 3.0 liter engine. The water pump was leaking, i believe, from around the gasket. I replaced the water pump, but I'm having trouble getting it to seal.

First off, RTV or no RTV? I've heard both. I've seen situations where you're supposed to install the water pump gasket without RTV. I've also seen instructions that tell you to apply a thin coat of RTV to glue the gasket in place. So which one is right for this car? Now that I think about it, when I scraped off the old gasket, it didn't have RTV. But maybe that's why it leaked in the first place?

What's the difference between blue and brown RTV?

When I put the water pump on the first time, I pressure tested the cooling system (without adding anymore coolant) and it leaked at around 5psi. I could hear it hissing around the water pump. This was with blue RTV if that matters, and I think the RTV set up before I could get the pump on the car. So I took it apart and reinstalled it with brown RTV and let the RTV set up for a couple hours. When I pumped it up this time, It went up to around 12psi, then started hissing. I tightened the water pump bolts and got the hissing to reduce a lot, but not totally go away. :-/

Am I wrong in thinking it should be able to hold at 16psi? That's what's on the radiator cap.

I have a couple options now. I could put it back together and hope for the best. I'm thinking that the RTV may set up more and seal the leak. I'm thinking also that the cooling system in normal use wouldn't get up to 16psi. I'm also thinking that I could put a can of stop leak in there and fill the gap. Or it could just leak after I get it back together.

Should I take it apart, put on new gaskets, and do something different this time? Like no RTV? Or a different RTV? Let it set up longer? Something I haven't though of?

So what do you think?

brian

 

Are you sure you didn't cut or roll the oring. And by all means use silicon on the gasket, both sides. Dealer silicon is black, it works great.

 

I used vaseline on the o-ring. When I took the the new water pump I h ad just installed back off the first time, the o-ring was in good shape. I replaced it again anyway, but I think the pump housing and pipe are in good shape. I doubt it's leaking from there.

One more thing. The chiltons (I think it's that one) says that the procedure is to put the two halves of the water pump together, then attach that ridiculous screw from the back, then put it on the car. When I do this, I can't get the water pump back on the car. I can't get the opening on the back of the pump to line up with the pipe.

My solution to this was to put the back of the water pump housing on first. This allows me to put the housing right on the pipe on the first try. Then I attach the other half of the water pump. The down side to this is that I can't put that screw on the back of the water pump. But I think the screw isn't doing much besides keeping the halves together while you put it on. I'm not sure if this matters here.

brian

 

the water pump we get from mopar is both pieces so I haven't had to deal with the assembly issue.