closed cooling, and reverse rotation questions???
 

Guys,

I am helping my new boss do a little work on his cruiser, 1986 Cruisers Inc., twin 350 closed cooling.

We have establisehed that the engines rotate opposite due to different firing order, but which one is standard?? Starboard I believe???

OK, now, since one is reverse........

are the circulating pumps the same, or different for each motor????

and, since it is closed cooling, and the circulating pump is only pushing antifreeze, is it OK to use autotive style pumps??? He doesnt want to spend the $$$ on marine ones, I need to give him a good reason not to use automotive, if there is one???

Thanks,

Rick

Re: closed cooling, and reverse rotation questions???
 

You can use a automotive one however I have been told that the marine ones use better bearings.....

I was in a pinch and no one had a marine unit so I put on a auto one. It lasted quite a while.....

Jon

Re: closed cooling, and reverse rotation questions???
 

Thanks Jon,

anyone know about rotation???

Rick

Re: closed cooling, and reverse rotation questions???
 

the water pump is different on the reverse engine it has straight blades and is usualy called bidirectional.....be careful setting the timing as it is on the other side of tdc an advancing light helps. stay with the marine pump its not worth skimping in the long run

Re: closed cooling, and reverse rotation questions???
 

You can rebuild the marine pump, or at least re-use the impeller (it will be stainless or bronze) in a cheapo automotive housing.

Cam drives backwards with a gear drive in most Merc reverse motors. This means distributor rotation is normal, as is the direction you turn for advancing/retarding. Marks are of course backwards on the timing plate (Crusaders have a timing window in the bellhousing - very cool).

Which motor is "normal"? Depends on whether it is a vee drive or straight. Obviously, they aren't sterndrives cause they'd both be running normal motor rotation.

Differences in marine pumps versus auto are: Corrosion proof shaft and impeller. I've seen some that are cast in bronze. Bearings aren't better than auto pump by nature, but ARE better than cheapo pep boys auto bearings. You can always get a lifetime warranteed pump though and as long as you don't mind replacing it every so often no biggie.

Re: closed cooling, and reverse rotation questions???
 

The wires are definitely reversed on the cap from port motor to starboard. It is a straight drive, not vee. The engines are closed cooling, so there is only anti freeze running thru them, which is why we believe the automotive ones would survive, BUT, the questionis, would it work correctly on the reverse motor????