Water pump flow and torque specs

[1970Thunderbird]

Hello,

Yesterday, I installed my new water pump in the lower unit of my 1978 Mercury 800. According to a rebuild manual, the four bolts that attach the water pump to the lower unit need to be torqued. According to my manual, two get torqued to 30lbs, one to 20, and one to 40. However, when I tighten the nuts and bolt, the plastic cover of the pump starts to "shoulder" under the nut. Basically, the plastic deforms and rounds out beneath the nut.

Is this normal? Are these torque specs crucial? I really don't want to break my new water pump housing, but I don't want it leaking, either.

Also, when I ran water directly to the water tube in the lower leg (not the one coming out of the pump), I had good water flow through the tattle-tale port. Before reattaching the lower unit, I want to make sure my water issue is resolved.

I'm assuming the power shaft in the lower unit turns whenever the engine is running, thereby powering the water pump, correct? If the shaft is not spinning, I won't have water coming out of the pump, correct? Yesterday, I attached ear muffs to the lower unit, but no water came out the tube if the shaft was stationary. A little came out when I turned the shaft by hand.

Thanks!

 

[shimano]

Re: Water pump flow and torque specs

The shaft is always spinning.So even idling on muffs you should have a good stream,It will increase with the rpm's.I wouldn't tighten the nuts that much,If you are warping the housing it must be too tight.I'd recheque the torque specs.

 

[1970Thunderbird]

Re: Water pump flow and torque specs

But what if the shaft isn't spinning? I have the lower unit off the engine and no water comes out the tube from the pump. When I turn the shaft by hand, a little comes out. The torque specs are listed in the Selco manual. I haven't even torqued to spec for fear of breaking the housing.

 

[shimano]

Re: Water pump flow and torque specs

if you have the lower unit off ,it's pretty hard to test the water pump by hand.you said with the lower unit off you hooked water up to the tube that was still attached to the engine and had good water flow,so you should not have any blockages.Reattach the lower unit hook it up to muffs and you should have a good stream if you replaced the pump correctly.Maybe the torque is in inch lbs?.Ive never torqued them ,Just to where they nwere good and snug and everything was seated.

 

[Gomer50]

Re: Water pump flow and torque specs

You wont get any water out of the pump until you reinstall your lower unit and crank her up.As for those torque spec's as mentioned in the above Post sound pretty high to me.I just get them nice and snug and away we go..

 

[1970Thunderbird]

Re: Water pump flow and torque specs

Thanks for the advice. I only hope the cover isn't damaged from the warping. There are no cracks. I guess I'll just run her and keep an eye out.

 

[saumon]

Re: Water pump flow and torque specs

Are you sure you aren't confusing between inch pounds and feet pounds? Made quite a difference!

Here's a generic torque chart for fasteners in inch pounds. Have a look in the aluminum column and refer to your bolt size. That's the MAXIMUN torque you can apply.

http://www.thelenchannel.com/1torque.php

 

[1970Thunderbird]

Re: Water pump flow and torque specs

Thanks for the torque site. A great reference. I'll bet the measurement is in inch pounds. I'll double check on it.

 

[emckelvy]

Re: Water pump flow and torque specs

Torques for the water pump are Most Definitely in Inch-Lbs!

As follows:

1/4-28 thread nuts: 30 in-lb

1/4-20 thread bolts: 20 in-lb

5/16-24 thread nuts: 40 in-lb.

Remember 1 ft-lb is 12 in-lb so if you were torquing to 30 ft-lb you're putting 360 in-lb of torque on that fastener instead of 30!!! Lucky more damage wasn't done.

I'd check the pump carefully for any resultant damage and replace as necessary.

HTH..........ed

 

[1970Thunderbird]

Re: Water pump flow and torque specs

Yea, I stopped tightening as soon as I noticed the plastic deforming. I think it's ok, but I may replace the housing, just to be sure.