I am rigging my boat and need some input on where to bring in the water line that goes to the trans cooler. Do I just tee off the water inlet line before the water pump or run a line from the thermostate housing? I am running a Hardin marine stainless pump. Any input would help. Thanks in advance.

If the trans cooler has 1-1/4" fittings, you should be able to put it inline on the main cooling line, right after the pump, or after the power steering cooler, if you have one.

My logic is to put the trans cooler before the engine oil cooler, because you want the transmission to run cooler than the engine oil. The transmission likes it about as cool as you can keep it (~140) , whereas the engine oil must get up to 200 or more for the engine clearances to function properly. On my last boat, I had an eddie marine 3" cooler that had a large and a small section to it, so I saved some plumbing.

P.S., with a 2" power steering cooler in front of the 3" combined cooler, I didn't have any trouble keeping a steady 20-25 psi block water pressure at speed.

Drill and tap a hole in the seawater pump right before where the hose connects for the water going out. Put in a 90 degree fitting to attach a 3/8" hose to run to the cooler. That's the way the Merc pumps are. The hose exiting the cooler should go to a dump overboard above the water line.

picklenjim,
My water pump looks like it has a 3/8 tapped hole that came with a brass plug. I was thinking of running a 90 degree like you mentioned but didnt know if I could do that or if it would supple ample water to cool.

If it's in the pump body right above the neck that the OUT hose connects to than that's it. Something I should have asked you first is what trans you have. Merc Trans ll or Borg-Warner? This set up that I am saying is for the Merc Trans ll. That could be a drain for winterizing if not above the out neck. Hope I didn't get you confused. So what trans do you have?

What tranny are you running? If you are running Merc Trans then what Picklen said is correct. Otherwise the cooler goes in line with the water pump outlet hose.

I really dont know what trans it is. How can I ID it?

If it's a Merc Trans ll it should have a plate on top on the bell housing that says Merc Trans ll. Also the bellhousing and trans are all one piece made of aluminum. Also there will be 2 fittings next to each other to connect 3/8" hose to for the cooler down low almost even with the bottom of the trans on the starboard side.

If it's a Borg-Warner the trans and bellhousing will be seperate.
Here's a picture of a B-W with the cooler laying on top of it.
http://cgi.ebay.com/ebaymotors/Mercr...item2556812154

Here's a Merc Trans ll. http://www.kcmarinetr.com/Default.aspx

It looks as if I have the merc trans. Thanks for the help guys. Just got my boat back from the interior shop and it came out sweet.