The Great MD7 Cooling Fix

[Maine_Buzzard]

Wish I had a better "before" picture... Previous butchers had kludged the connections to the raw water pump by using 3/4" hose clamped to the outside of the pump bosses, plastic adapters, and 1/2" hose to the transmission outlet and to the badly bent copper pipe going to the exhaust log and thermostat housing.



You can see the blue striped hose above the water pump and the black adapter on it. The useless strainer was gone before I hit the water and a Groco now lives on the side wall.

I have seen that the copper pipe plugs up first, causing the dreaded Volvo redzone temp gauge, so I'll be addressing it this winter.

I'm making two bronze fittings to adapt the water pump to take 1/2" hose directly. I'll fab a saddle bracket to clamp the two adapters to the pump and seal properly. The first adapter is complete here, along with an older pipe used on another engine.



Following that, I have 1/2' O.D. tubing that will get a tee fitting to replace the worn/ crimped copper tubing. A few new rubber gaskets, and I should have a solid, non wallet flattening cooling solution.

What are others doing when the copper tube goes south?



This is also a spare. Mine's crimped worse.

[Michael Abramson]

I did this repair on my engine, but you may consider it a kluge. The boat is some distance away so I can't look at it easily to refresh myself, but I recall I did both inlet and outlet sides of the pump. I cut off the original metal pipe on both sides of the pump, saving the spuds with the flare that the rubber seal sits against so about 1" of straight pipe stuck out of both inlet and outlet outside of the flare. I used fresh Volvo seals on both before inserting into the pump.

I also found a barbed fitting that threaded into the tapped outlet of the transmission water jacket. I think I used 1/2" id reinforced heater hose from an auto parts store to make the interconnecting runs, but I found hoses that had an integral 90 degree end on each. They were of sufficient length so there was no sharp bend where it came out of the transmission barb, and at the water pump end, the right angle of the hose fitted nicely on to the upward inlet spud.

On the outlet side, I did the same thing, with the right angle hose end at the pump, and used a good length of hose so it made a nice approach to the engine metal water pipe, which I cut off at approximately the rear of the exhaust manifold.

To secure the hoses to the pump, I fitted good all stainless clamps to tighten the hoses to the projecting spuds of the original copper water pipe. Then I used stainless safety wire that was fed inside of each clamp, looping around them, to tie the inlet and outlet clamps to each other. Once the clamps were tightened, that pulled them towards the pump body and I think it is unlikely they could come off, barring some kind of external damage.

If I have a chance to go to the boat soon, I'll try to get a photo that shows the result. It is not pretty, but I think it is adequately reliable.

I added a Groco strainer after this project to prevent the occlusion of the trans water jacket from occuring again!

Nice job on the brass barb to fit inside the pump body. Wish I had two of these when I did that job. Might be something you could sell, if you come up with a good way to secure them in place in the pump.

On the original engine, there is a small metal wire clip that secures the 2 stock pump spuds to the pump body. You can probably see it in a parts diagram online at one of the Volvo parts $peciali$t$.

Michael

[Maine_Buzzard]

Yep, doing almost exactly as you have described. I like the wire under the hose clamp concept, and thought of doing a similar strap arrangement. I'll probably make a saddle bracket to go around the pump.

No brass in saltwater, it's 954 bronze and designed for marine use. Oh my, it turns like a dream. Very easy to machine. Made the second fitting tonight and started the tee section for the copper tubing. Have not silver soldered in years, will have to test.

Will fixphotos when possible.

[Maine_Buzzard]

Much progress made- The cooling tube is fabbed, need to get the silver solder and make things permanent. Time to order parts from Marine Parts Express.



I'll be pulling the old tube off over the weekend. Hate to pull the log, but might have to for clearance.