Trojan Boat Forum

This may have been covered but I cannot find it.

As I intend to use hot water from engines as a heat source for my hotwater heater via heat exchanger in water heater; first are the rh and lh circulation pumps the same, second is the 318 automotive pump the same as marine other than below? I think so?

The reason to ask is the input ports on top of the pumps are very small pipe thread plugs, which is where I would return the water from the hot water heater. If marine and automotive are the same then would consider the automotive type as it has a larger return port, (from the car heater core)

Does anyone know for sure?

Larry, I have used a non marine circulation pump with no worries, albeit, they corrode faster.
Most circulation pumps are bidirectional for the marine application. Many newer Chrysler pumps, even for the 5.9 small block (360) run off serpentine belts, which may vary and some are opposite rotation. So if you want to use a late model pump for example, the listing should tell you if it's opposite rotation, if not bidirectional.

Thanks S man, I had the opinion that most impellers are straight vanes, different from your usual centrifugal type pump in non engine use which are curved. I agree with you that they will interchange but needed to hear other opinions.

I did some more research and some say there are special seals in marine water pumps to withstand the raw water that you do not have in a closed system? Wish I could figure out where to get the parts to rebuild a circulation pump so if the above is true could use that seal with an automotive pump, ergo would have larger return line for hot heater water. Anyone know who supplies the rebuilders?

Larry just a thought----have you thought to just drill out and tap the existing hole to the size you want ----easy enough,but sometimes a lower flow rate allows more time for heat transfer ----just some ideas ----Mike

Thanks mike, I had thought of it and may be the best option. I really am not convinced there are different seal in the marine pumps due to dirty raw water. I have seen plenty of nasty water in closed auto cooling systems with no issue. Wish I could definitely find out via a rebuilder or rebuilder parts supplier. Someone out there provides the parts to rebuilders, albeit they seem to be obscure and not easily found.

Just a warning about the front pump on the 318. I believe that a couple of the bolts that hold on the pump go into the cooling passage of the block. Make sure you note which ones and use sealant on them.

I believe the far fore and aft studs of the exhaust manifolds are the same.

http://www.justanswer.com/dodge/2lox2-n ... dodge.html

instructions for 318 water pump (non marine) does not mention sealing bolts,(above) will check on Chrysler manual. I found another site that basically says seal all but one. The four big ones go into water jacket, and bottom one goes into timing cover, possible oil there.

found the following:

"The two stud's on the end's of the head, are in the head with a stud w/a nut,
is because those are in the water passage's. The bolt size is 5/16x18 coarse thread, in all hole's. Just make sure you use some kind off good sealer, on the two end bolt's. Some on this site, say to use Permatex Copper RTV. As for trying to remove the stud, I would use some decent heat, but don't go overboard. I have also mig welded a nut on the stud to aid help in removing it. You may have to heat it more than once, just be careful to not destroy anything. Good luck."

I will pull the end studs and seal each as well as water pumps, Thanks for the tip. Just a thought if it did seep a little water probably would not hurt as would only be losing a few drops of raw water.

If your using a automotive pump in raw water engine don't expect a long life from them .

not gonna use the auto one, just gathering information, Thx

I have found a source for water pump rebuilding parts, so one can do it himself. It has been my experience pumps are pretty simple devices to rebuild once parts are located, here is the URL:

http://www.kelloggautomotive.com/index.html

http://www.kelloggautomotive.com/index.html

Well, here is my report back about pump parts and rebuilding, Kellogg is a supplier of all parts water pump, Onan, Chrysler and all others. According to them all 318 Chrysler pumps are bi directional, some have plastic impellers, they have the bronze replacement and marine seals. The 318 cast iron housings are the same as automotive.The difference in marine vs regular is ceramic/graphite lapped vs steel/graphite lapped however they only use the first for all apps which is better quality.

Here is a biggy; they will rebuild all pumps for Onan for 200 to 400 dollars depending on reusable parts verses what has to be made. That is a solution to the spendy pump problem for our Onan's

BTW many of the new generation type of pumps are throwaway and not rebuildable, no surprise.