Danny_Troy

I was steered to this site from someone from the Club Sea Ray forum, in hopes that someone can give me the info I need on this conversion. It definitely looks like if any site has the answers I need, it's this one. That said, after going through several threads, I still haven't found all the answers I need.

Has anyone actually done this conversion on a 8.1L 496 Mag engine?

A few of the questions I have:

1. What model pump will work? I am leaning toward the Jabsco 50410-1501, but I don't know if it will mount correctly on the 3-bolt crank. I'll be at the boat tomorrow, studying and photographing the front of the engine, and taking some measurements.

2. What is the best way of dealing with the pressure sensor, presently mounted on the water pump?

3. What is the best way to route the hoses? Add two elbows, or just bend the hose? Any exact hose recommended for this application? I know it is 1 1/4" and has to be wire reinforced on the intake side.

4. Which bracket will work on the 496? Worst case scenario, I'll have to weld one up myself.

Thanks for any help....

BUP

iTrader: (9)

If you install a different design for a water pump application you will need to test the output water flow volume from the pump outlet side. If the water flow volume is not met compared to factory spec you will overheat the engine everytime out, the other side of the coin in which I DOUBT WILL HAPPEN is too much water volume flowed in which could cause too high of water pressure specs thru the cooling system.

BUP

iTrader: (9)

forgot the water pressure sensor moved in later years / engine serial # runs from the water pump housing area to the power steering cooler.

Danny_Troy

Sounds like a lot of testing is needed. I'm hoping to get someone that did the same exact conversion, and use the same pump as they did. Looks like it's not a common conversion on the 8.1L. I have a 2003, so I guess the sensor was still mounted on the water pump. I supposed I could put the sensor anywhere after the output and get a good reading. I was by a pump vendor another way to go might be to use a Volvo style pump with serpentine belt.

Keith Atlanta

Whats wrong with the stock pump?
There are stainless re-pro pumps sold with an exact match fit and there are also rebuild kits.

Danny_Troy

Nothing at all wrong with the stock pump, other than where it's located. In my boat it's a very tight fit, with little clearance against the hull. Most people that have my boat and the 8.1L engine hate doing the impeller change with a passion. You wind up putting off the job, when at the very least, you can check the existing impeller for wear, if it were front mounted.

BUP

iTrader: (9)

Well there can be a lot wrong with the GEN VII water pumps housing front & back side internal scaring. Very common issue. plus the expense of how much these pumps are to repurchase. Also front bearing / seal failures pretty common to.

Merc also has repair kit - the wear plates and .030 shorter impeller to install when the housing becomes scared internally.

Danny_Troy

Took a good look at the crank pulley today. The Jabsco installation instructions say that besides the three mounting holes, there are two larger holes, that fit on guides on the pulley. Unfortunately, I don't have those raised guides on my pulley. I thinking I'm out of luck with the Jabsco. I guess just bolting the water pump using the three bolts doesn't assure you that the pump is exactly dead center. It's starting to look like I may have to stick with the stock pump.

Danny_Troy

Well, I gave up on the idea of switching to the crank mounted pump, and just replaced the impeller on the old pump. Maybe when it's time to do it again, I'll either have another boat (which I doubt) or they will have come up with a solution (which I also doubt!). I'll probably put a stainless Hardin pump in, the next time this gets removed. I'm thinking in freshwater I'm good for about 3 years on the new impeller.