Greetings to all gear heads/ engineers that can help,

I’m getting ready to drop a great condition perkins T6.354 200Hp diesel into my 30’ flybridge. The engine comes factory with a half system cooling wise. I’d really like to switch the cast iron exhaust manifold over to run on the closed cooling circuit.

for the sake of argument let’s say the heat exchanger cooling capacity is unlimited and the EGT doesn’t effect the heat load. (I have bigger heat exchangers if the factory one can’t cut it)

my plan is to put in bypass valves. so I can have the block, head, exhaust manifold, and heat exchanger on the same circuit during warm up to bypass the the thermostat. on another bypass valve there would be raw water from the pump dumped straight into the exhaust elbow. Once the engine is up to temp I can direct flow through the thermostat on the closed side and open up the raw cooling side to the heat exchanger.

any thoughts? If you aren’t familiar with this engine set up just think 454 half system conversion to a full system, same parts are involved.

Ayuh,..... If the exhaust manifold is brand new,..... it might work,......

If yer using the old manifold, that's been run in saltwater, the odds are the heat exchanger will clog up, on the side you can't clean out,.....

'n I donno why you'd want to clutter the system with the valves for warm up, as the t-stat will do the same thing,....

Dear Mr. Bondo your knowledge is stuff of legend,

the valves are needed to keep the exhaust manifold from running dry when the thermostat is closed. Also I acid clean out the cast manifold. It’s in pretty decent shape now. These manifolds on the perkins clear 1500 for 1 if you can find them. Hence why I want to preserve this one.

What about just not running a stat at all. Might be easier. Half the guys on here don't use them - would make life easier

The closed cooling system I run is full flow. So when the stat is closed, it just bypasses the heat exchanger, but still we still have full flow of coolant around the engine. This is built in to the design of the heat exchanger.

I'm not currently running the manifolds on the heat exchanger, but if I do, I'll just add the manifolds to the end of the circuit - so they also have full flow out of the engine, through the manifolds and then through the heat exchanger.
Can't think of any reason why you'd run no stat. Engines want to run at the right temperature.

I've been to the perkins engines factory and had a tour of it all (did some work for them a few years back). The factory is still their original one, I think it's a single building 1/4 mile long.

I am selling a pair of freshly rebuilt Merc 502 Heat Exchangers (less than 50 hours of run time) - cost me $1,000 to freshen em up last year. $1,000 plus ride if interested.

Even if there sold, would you have picture of the exchangers, ..trying to figure size constrains

Seaford,



The large one is what I was told to use in place of a thermostat.

Thanks. Brad.

Hi!!!