MD7A water pump not priming

[Shawn67]

"Also, I have searched Home Depot/Lowes and found some sink o-rings that work pretty well for the copper pipe. "

You can get the correct washers at West Marine. WM part 10511004 about $10 for the kit. That includes 4 of the square washers and the O ring and gasket for the thermostat.

Shawn

[twinboat]

I tried all sorts or O rings on my TAMD40B sea water pump, pipes. Nothing sealed right, except the Volvo Penta square O rings.

All of their stuff is metric.

Sent from my VS840 4G using Cruisers Sailing Forum mobile app

[hpeer]

Originally Posted by Shawn67

"Also, I have searched Home Depot/Lowes and found some sink o-rings that work pretty well for the copper pipe. "

You can get the correct washers at West Marine. WM part 10511004 about $10 for the kit. That includes 4 of the square washers and the O ring and gasket for the thermostat.

Shawn

I'll have to check that out. Thanks.

Twin,

I have a little kero two burner cook stove. The built in pump requires a metric o ring. No SAE size will work. So I'm now the proud owner of 375 spare metric o-rings in the kit I bought to get the one I needed.

[hpeer]

Originally Posted by Shawn67

"Also, I have searched Home Depot/Lowes and found some sink o-rings that work pretty well for the copper pipe. "

You can get the correct washers at West Marine. WM part 10511004 about $10 for the kit. That includes 4 of the square washers and the O ring and gasket for the thermostat.

Shawn

Shawn.....how did you determine the correct part number? I don't have the stern drive and I can't tell what the o-rings are for.

[Shawn67]

The manufacturer is Sierra part# 18-0376.

Sierra 18-0376 Cooling Pipe Gasket Set

It has the 4 square O rings that are in the cooling system of the MD-7a. One is in the exhaust manifold, one in the thermostat housing, one on the outlet of the water pump and the other on the inlet to the water pump. It also has the O ring between the thermostat housing and the exhaust manifold, the gasket for the thermostat and the gasket for the outlet of the transmission to the water pump inlet.

If you have a local West Marine and order online they will ship to the store for free.

I'm in the process of cleaning out my MD7A. Cleaning out the exhaust manifold and housing, flushing the head and block and then will be converting it to fresh water cooling.

Shawn

[hpeer]

I've got a "spare" engine half apart in the basement. This could come in handy.

First I need to see if I can get compression! Or just keep it as a spares source.

[terah]

I managed to borrow another o-ring (square) and with two in place the push fit seems a lot tighter. A liberal application of PU40 and I'm convinced the input side of the pump is airtight. Still no water coming through.

In desperation (lift in was this morning) I took the cover off again, cleaned up and sanded the outside of the it, and put it on backwards. Didn't get a chance to test again before going in, so delightedly surprised to get a good flow within a minute of starting it up.

So looks like it was a combination of air leaks in both the push fitting and the pump cover.

Incredibly chuffed to have it working and thanks again for all the help. Will look at moving the siphon loop later and probably also get a speedseal.