Sea Water Pump Adjustment Range

[76SeaRay]

Now for issues with Sea Water Pump fit. I rebuilt the pump with new seals and impeller and bench tested. Works great so decided to go ahead and install it. When I did, I found that I only had 1/4 inch of adjustment range. Swinging it to the outside, the top of the bracket hits the timing cover and the end of the adjustment slot. I think that is normal however at that point I only have 1/4 inch clearance to the edge of the damper.

Investigation showed that the new damper is an 8 inch damper but that one is called out for the 7.4L engine. The damper should be 6 3/4 inches for the 5.7L. So, taking the damper back to the machine shop on Monday. Once I removed the damper, I can only get 1/2 inch adjustment due to the plug on the Sea Water pump hitting the side of the oil pan (won't know about damper clearance until I get the replacement). In this orientation, I can put in 4 pump to bracket bolts and the hoses line up great. I can rotate the pump about 180 degrees to put the plug on the outside but then I can install only 3 pump to bracket mounting bolts and the pump outlet port doesn't line up very well with the pump to oil cooler crossover hose. Either way the pump pulley to the crank pulley is also very close.

Anyone using this pump that can tell me more about the adjustment range and if the mounting looks correct? Note that the top bolt for the bracket to engine sits in an odd spot relative to the slotted hole. Thanks..

 

[76SeaRay]

All of my parts match the part numbers on the 1996 Mercruiser 5.7L parts diagram with the possible exception of the balancer/damper. So, don't know why there is so much of an issue with the bracket and adjustment range.

None of the Mercruiser information gives the diameter of the balancer/damper. I am assuming that Mercruiser used the 6 3/4 inch on the 5.7L since the 8 inch is giving me clearance issues. I wonder if I can just notch the side of the bracket and use the 8 inch damper since here is what I found in a Motor Trend article after searching the internet about balancers.

If the engine is used in any long-duration closed-course racing, is installed in a boat, or is driven on the street, you should always use the biggest, stoutest balancer available. Assuming use of a factory balancer, the proper 8-inch unit designed for your performance engine offers the widest operating range and the best cancellation of unwanted resonant frequencies. As noted crank grinder Hank Bechtloff (aka Hank the Crank) puts it, "Even though it's more weight, the larger damper helps keep the frequencies that shake the crank apart from happening."

 

[Bondo]

All of my parts match the part numbers on the 1996 Mercruiser 5.7L parts diagram with the possible exception of the balancer/damper. So, don't know why there is so much of an issue with the bracket and adjustment range.

None of the Mercruiser information gives the diameter of the balancer/damper. I am assuming that Mercruiser used the 6 3/4 inch on the 5.7L since the 8 inch is giving me clearance issues. I wonder if I can just notch the side of the bracket and use the 8 inch damper since here is what I found in a Motor Trend article after searching the internet about balancers.

Ayuh,..... That's the Fun parta "Seat of the pants Engineerin' ",.....

Try it, it works,.... or it don't,.....

A 350 I did a couple years ago, I went with a crank mounted pump, like an inboard, or some Volvos,....

 

[76SeaRay]

I thought about the crank mount but already had the Jabsco (actually DJ) pump and just needed to put in new seals and an impeller). The crank mount is only designed for the hoses to run down the Port side which doesn't have room with the oil cooler there and using the low alternator on the Port side.

The Mercruiser parts diagram is also confusing as it shows a brace on the back side of the pump and there is just no way that I can see to put that brace on it.