New water pump installed, leaking

[richg]

1973 Bronco with 302.

My old water pump was leaking so ordered a Dayco DP8101 from rockauto (their 'heavy duty' pump).

Swapped it on, and have a slow drip-drip leak. It appears to be coming from inbetween the backing plate at one of the backing plate bolts. I did not touch or check torque on these (nor the gasket inbetween pump and backing plate).

Is this a common thing to have to tighten up those bolts? The gaskets included were pretty high quality so I did not put any sealant on them either.

What else could this be?

Videos here:

Drivers side -

Passenger side -

 

[SevenT]

I have never run gaskets dry on a water pump. You may want to take that pump off and put gasket sealant on the backing plate.

 

[billh1289]

I replaced a water pump on a 92 years ago and neglected to check those bolts. Had a leak and it turned out they were loose. Something I always check now.

 

[ba123]

I use permatex grey on water pumps and never had one leak. Only the tiniest bit needed.

 

[richg]

So those two backing plate bolts were indeed not tight. Since the gaskets were now ruined, I got a replacement pump from rockauto. Those two bolts were barely snug on the replacement pump. I used some grey RTV and tightened those bolts down, put the pump on and all is well.

 

[nvrstuk]

I literally use about enough Gray permatex to show up on a wtrpump gasket

 

[Wild horse 75]

They don’t tighten those bolts because you’re suppose to put something on the gasket and then tighten the bolts. I’ve used aviation form a gasket on anything gasket water related for years and never had a leak. It can be messy but it works.

 

[ntsqd]

I use The Right Stuff silicone on everything. Diff covers, water pumps, timing covers, whatever needs to be sealed. Except for air cooled engine case halves and anything fuel related.

I slather the bolts with marine grade anti-seize. I particularly want the long bolts to be completely covered in anti-seize so that there is no opportunity for them to lock up in the timing cover due to corrosion.

 

[richg]

They don’t tighten those bolts because you’re suppose to put something on the gasket and then tighten the bolts. I’ve used aviation form a gasket on anything gasket water related for years and never had a leak. It can be messy but it works.

The instructions for this pump specifically say NO SEALANT. So I didn’t disassemble or put RTV originally. The gasket included was a quality gasket and I agree should not need RTV if you torque properly and you have decent mating surfaces.

 

[ntsqd]

Experience has taught me to use a sealant of some sort on nearly everything. Be it Right Stuff, Hylomar, or 545 almost everything gets a sealant.

 

[nvrstuk]

The instructions for this pump specifically say NO SEALANT. So I didn’t disassemble or put RTV originally. The gasket included was a quality gasket and I agree should not need RTV if you torque properly and you have decent mating surfaces.

You said it..."decent mating surfaces"... on new parts you might be ok but unless the gasket has a raised "bead" on it to take up surface imperfections no matter how small then like I mentioned b4, the absolute minimum like .020" or less will be your guarantee.

That's what I do on timing covers & wtrpump housings for sure...

 

[ntsqd]

I keep a long board with 80 grit on it just for "tuning up" gasket surfaces like those on the timing cover.

 

[Steve83]

The WP gasket to the backing plate doesn't seal near those 2 short bolts, anyway - it only keeps the plate flat, so it doesn't really matter how tight those bolts are. If they keep the plate & gasket in-place while you assemble the pump, they're tight enough.

All the sealing happens around the impeller & the 2 offshoots going to the 2 coolant journals, which is where the gasket between the plate & the timing cover seals. If water gets past the gasket at those locations, the rest of the gasket won't stop it. So those are the only areas that need some kind of waterproof sealant. I use shellac on the 3~6 engines a year that I change WPs & TC gaskets in, and have no leaks.

(click this text)