Recommended water temp. for Perkins T6.354

[Kit_L]

On taking Sea Biscuit for a sea trial, we notices that the water exiting the wet exhaust contained steam, and the discharging water was hot (not too hot to hold one's hand in, but hot).

My mechanic want to rebuild the heat exchanger (the engine has only done 100 hours work in ten years; the oil on the stick is clean) as we assume it will be pretty grungy, as well as replacing the impeller. He wants to check the thermostats, too, so we will be grateful for any information.

A quick scan on the net suggests that the thermostat's opening temp. for this engine series is around 75°C, and that the fresh water side of the system will run at 80–85.

All opinions welcome; we head up to Qld next week to begin servicing her.

 

[DavidM]

Sea water exit temp should be no more than 20 deg F above inlet. Your temp sounds too high and is probably due to a fouled ht ex.


Your mechanics advise to rebuild is sound.

Does that engine have an after cooler? That should be rebuilt as well.

David

 

[Kit_L]

Thank you djmarchand.

Sea water exit temp should be no more than 20 deg F above inlet. Your temp sounds too high and is probably due to a fouled ht ex.

Your diagnosis is in line with ours, and we will be checking/servicing/rebuilding if necessary all the parts in the cooling process. Not sure about the after-cooler; I can't recall. We will be checking everything!

 

[Ski in NC]

Anything in the sea water flow path can cause low flow. Clogged through-hull fitting, clogged strainer, bad impeller, clogged aftercooler (if it has one), clogged gear cooler, clogged engine oil cooler, clogged coolant HX, clogged exhaust mixer, etc. All of these are in series so any one or a combination can slow the flow.

Start with easiest first and work your way through. Sometimes it is best to simply clean all of them and be done with the issue in one go.

 

[jleonard]

I ran one of those engines for about 10 years.
Biggest culprits for raw water blockage are the intercooler and the raw water exhaust manifold.
When I bought my boat the intercooler was 90 % blocked with mud. I had to press out the core and clean between the tubes.

A few years later I flushed and rodded out the exhaust manifold. Then I painted it with regular engine paint, not high temp paint. That way when it started to clog again I would see the discoloration.

Also had a blockage one time when the zinc in the heat exchanger broke free and clogged the inlet on the exhaust manifold.

Thermostat is 172 F as I recall.

Hope this helps.

 

[sunchaser]

Seabiscuit
Is this engine equipped with the dreaded manicooler design? If so, be sure to have correct seals and O rings for reassembly. Pressure test as well.

 

[Kit_L]

All excellent comments/questions. I will take pics of the engine as soon as I get to Qld, and please help me identify it. I have the serial number from the original survey, but it makes no sense to me. Sea Biscuit's Perkins is a T6.354, NA, and its serial number according to the survey is:

5711 496 A-2 24 E5

And thanks to Ski and jleaonard: excellent, practical suggestions.

sunchaser: as soon as I have pics, I will post, unless someone can decipher the S/N in the meantime!