Supertramp96

I've got a 1983 Mustang GT 5.0 4spd. The original motor was rebuilt from late last summer to mid-late last fall. It was unusually warm in December. I ran the car on Christmas Eve and blew the pump gaskets, and the pump has been on and off about 7 times since. It would start leaking about a week after replacing gaskets (each time trying different kinds of rtv and silicone). Finally, I replaced the whole pump and the car was fine for about a month and a half until yesterday when it started leaking again. It always leaks from the same place (and yes, I did check to see if it was leaking from somewhere else, and am 99% sure it isn't), and that is between the plate and the pump. Where the bolts hold the plate to the pump. I think it is the worst design for a pump I have ever seen, and can't figure out why Ford chose to even make it a two piece pump (maybe I'm missing the reason why it's necessary???). Why not just make it a solid, single unit? You can't re-torque the plate bolts when the pump is on the car. Very frustrating. Regardless, it's leaking again and I am getting very discouraged. What am I doing wrong? Should I be tightening the plate bolts as hard as I can (which I wasn't doing before)? Maybe there is something I can do without taking the pump off? I'm really running out of ideas here. The cooling system is the only thing holding me back from really enjoying the car. Any help is greatly appreciated. Thanks

88 orangepeel notch

Any cracks in pump case itself or timing chain cover / housing ? If it always leaks at the same spot, that would tell me it's cracked or a surface is warped and not sealing completely. Common sense stuff I know, but you just really never know till you pull out a straight edge and magnifying glass.

Welcome to the forum by the way...

Urambo Tauro

Welcome!

I've heard differing opinions on the use of silicone on these gaskets. Personally, I've always had good luck with smearing a light but consistent layer on both sides of the paper gasket, then torquing the bolts down to 50-75% of spec, and tightening the rest of the way after the RTV has cured. Of course, cleaning the mating surfaces is extremely important.

But maybe your problem isn't the gaskets. "Tightening the bolts as hard as you can" isn't the answer. You really should be using a torque wrench. And keep in mind that torque ratings are worthless if there's anything causing extra resistance, so those threads (both male and female) need to be clean.

But orangepeel might be on to something there... If the bolts were overtorqued, there is a chance that you might have damaged something.

Supertramp96

Thanks for the welcomes.

The pump itself is brand new. I have a hard time believing it was damaged. I never did torque the bolts (which I will be doing this time). One stupid thing I did was lose two of the original pump bolts (which I should have replaced at the beginning) and replaced them with bolts of the same thread, however for some reason they would get hard to turn before they even made contact with the pump, if that makes sense. The original threads are not stripped. So I've purchased new bolts and am getting new gaskets. How should I be tightening the bolts that hold the plate to the pump? As I said, there is no way to re-torque them once the pump is on the car.

Urambo Tauro

I just re-read your top post and found some pictures to get a better sense of what you've got there. I'm afraid my 5.0 experience is limited to the variety with an exposed impeller, like my '95 has. But I wouldn't expect you to have to tighten that backing plate of your pump at all, especially on a new unit. Did you open it up for some reason?

If it was leaking from the backing plate without you disturbing those bolts, I would consider that a parts warranty issue. But perhaps it's easier and faster to seal it back up yourself. I take it that's what you're after here.

I see now what you mean about not being able to access those bolts with the pump on the timing cover, and that definitely hurts your ability to use a two-stage tightening process. What kind of gasket does that backing plate take? Is it rubber? Paper?

rmodel65

assuming like said above check the surface with a straight edge etc..but i also wonder if youre buying cheap pump?? if so id personally buy a OEM motorcraft unit rockauto.com has a motorcraft pump for 75$ MOTORCRAFT PW291 go to retailmenot.com and get a 5% discount code for rockauto and it will be a little cheaper..

88 orangepeel notch

And the use of the wrong bolts could be a big problem. Bottoming out threads in an aluminum housing is asking for trouble. When your tightening the bolts past the usable threads, your putting ALOT of pressure on the sides of a weak case or housing. Hopefully that didn't crack it.

And thanks for telling us that part, it might be a bit embarrassing, but we've all done it. Sometimes more than once lol.

JPJP

I recommend you chase all the threads with a tap. Also make sure you get ALL of the coolant out of the tapped holes. If something is causing your screw threads to bottom out you will not get the proper clamp load on the sealing surfaces thus you will not get a proper seal.

When running in the bolts make sure to use teflon pipe dope on the threads.