Perkins 4108 Heat Exchanger

[SailnParadise]

Looking to run the plumbing for a Force 10 heat exchanger hot water heater. Trying to figure out where to run the coolant feed and return from the heater into the engine. Doesn’t seem it was ever installed or maybe was taken out? Runs fine on shore power. I’ll include a photo of my heat exchanger on the engine and the tank and fittings. It’s a 1986ish Perkins 4108

[rbk]

Depends if it’s a 4108 or 4108M. Is it a bowman heat exchanger (right side integrated into the exhaust) or rear mounted Hx with expansion tank at the front?

[SailnParadise]

Its not the Bowman. Rear mounted.

[rbk]

From memory it’s off the top the engine right behind the header tank there should be a plug see picture (not my engine). Return line is off the oil/tranny cooler at the back and requires a fitting. I can post detailed pics later when I get back to the boat sometime in the new year.

[SailnParadise]

Originally Posted by rbk

From memory it’s off the top the engine right behind the header tank there should be a plug see picture (not my engine). Return line is off the oil/tranny cooler at the back and requires a fitting. I can post detailed pics later when I get back to the boat sometime in the new year.

I think there is a thermometer there right now for water temp. I can take that off, fit a T and run a line from there to the heater. Then one from the heater to the cooler? Look for a similar plug? Or can I just T into a return line already there? Using standard 5/8th high temp hose?

[rbk]

You can relocate the temp sensor to the back right corner of the head or run the coolant out of that plug either way. You’ll need a length of pipe with a 90 and barbed fitting to run from the block to a hose. Cant remember if the return is a T in the line off the oil cooler or just a barbed fitting, leaning towards a T but can’t member off the top of my head.

[SailnParadise]

Originally Posted by rbk

You can relocate the temp sensor to the back right corner of the head or run the coolant out of that plug either way. You’ll need a length of pipe with a 90 and barbed fitting to run from the block to a hose. Cant remember if the return is a T in the line off the oil cooler or just a barbed fitting, leaning towards a T but can’t member off the top of my head.

Thanks. Will head to the hardware store in the AM and pick everything up. Seems easy enough

[DougR]

When I had a 4-108 the hot water was taken off from the fitting shown by RBK. There was a short nipple going straight up to get enough height to clear the expansion tank, then a “t” with the temp sender in one side of the “t” and a hose barb on the other side. There was a slight restriction built into the hose barb to restrict flow a little....

The return from the water tank went to a hose nipple which was integral with the water inlet pipe to the engine/transmission oil cooler. If your oil cooler doesn’t have the hose barb, just “t” into the coolant hose between the heat exchanger and the oil cooler.