Overheating Perkins - any ideas ?

[seadog30]

Has anyone any ideas where to look next please.

Perkins 4107, totally re engineered 4 or 5 years ago and runs well.

A few minutes after starting the over tempature alarm goes off, at this point the temperature gauge is still down arround 50 deg C. The area arround the Temperature sender is very hot however the rest of the engine is only just warm to the touch !!

Sometimes if we stop the engine and restart after 2 or 3 mins the Temperature gauge immediately starts running at circa 80 deg C eventually going up to about 90 deg and the over Temperature alarm does not go off !!

I have put a new temperature alarm switch in (95 deg C rated)

The raw water circuit is fine and plenty of water is circulating thro to the exhaust and the impellor has been renewed just in case.

In the fresh water circuit the heat exchanger has been checked as clean & ok.

We had suspected that the Thermostat was sticking but that has been romoved today and it opens on a bench check.

Any ideas where to check next ?


Seadog

 

[BGW]

Has anyone any ideas where to look next please.

Perkins 4107, totally re engineered 4 or 5 years ago and runs well.

A few minutes after starting the over tempature alarm goes off, at this point the temperature gauge is still down arround 50 deg C. The area arround the Temperature sender is very hot however the rest of the engine is only just warm to the touch !!

Sometimes if we stop the engine and restart after 2 or 3 mins the Temperature gauge immediately starts running at circa 80 deg C eventually going up to about 90 deg and the over Temperature alarm does not go off !!

I have put a new temperature alarm switch in (95 deg C rated)

The raw water circuit is fine and plenty of water is circulating thro to the exhaust and the impellor has been renewed just in case.

In the fresh water circuit the heat exchanger has been checked as clean & ok.

We had suspected that the Thermostat was sticking but that has been romoved today and it opens on a bench check.

Any ideas where to check next ?


Seadog

I would still suspect he thermostat - try running the engine without it to see if the issue goes away.

 

[Seanick]

Check your battery volts. Too high a voltage may 'excite' your sender.
or
as suggested, run it without a thermostat, just to test.

A guide for the correct temp is 'hand hot'. You should be able to touch the heat exchanger for about one second before it hurts. If it burns you straight away its running too hot.
-and that is from a Kelvin manual!

 

[seadog30]

Reply

Thanks Brian

I can't think of that it would be anything other than the Thermostat but before I put it back together with a new thermostat I would like to make sure that I had not missed anything.

Regards - Seadog

 

[Bobobolinsky]

Freshwater pump corroded?

 

[cimo]

don't know your perkins at all but...........

if thermostat area is getting too hot, sounds like you have a blockage somewhere in your raw water circuit. (the raw water you're seeing at the exhaust is coming via the raw water bypass at the thermostat?).

if the perkins thermostat is located in the frshwater circuit - then the blockage is there, or fresh water pump not doing its job as Bobobolinsky says.

I'd start by chasing the cooling circuits, looking for crud.

 

[seadog30]

Reply

Thanks all

The Thermostat is in the fresh water circuit.

Unfortunately Bobolinski may have a point it is worth checking the freshwater pump, it was taken off when the engine was reconditioned 4 or 5 years ago but that does not mean it is ok now.

Regards - Seadog

 

[pcatterall]

My 4108 suddenly started to overheat but the problem was graduall build up in the raw water system. Cleaned out the exchanger and had to get two elbows made up as the effective cross section(due to very hard solid deposits) was around 25%. I guess it was 'sudden' simply because the system had reached a critical stage. Worth going over the raw system anyway.

 

[vyv_cox]

Thanks all

The Thermostat is in the fresh water circuit.

Unfortunately Bobolinski may have a point it is worth checking the freshwater pump, it was taken off when the engine was reconditioned 4 or 5 years ago but that does not mean it is ok now.

Regards - Seadog

If you have antifreeze or summer equivalent in your engine it is most unlikely that there is anything wrong with the pump, which is a simple centrifugal one just like the one in your car. You may be able to check that it is working OK by squeezing the hose on the discharge side. I think I would start with the simpler/more likely areas first, which seems to me to be the raw water side, starting with the heat exchanger, pump and associated hoses. If everything in the raw water circuit checks out that may be the time to start with the fresh water.

 

[ianj99]

The area arround the Temperature sender is very hot however the rest of the engine is only just warm to the touch !!

Seadog

This might indicate that, as has been suggested, the engine water pump isn't working too well, causing a hot spot.

 

[Kevj]

I had a 4108 on my old boat.

Is the raw water exiting the boat, at the exhaust, luke warm, hot or very hot? I had a temp problem come up one time and I remove the stack from the heat exchanger (Bowman) it was severely clogged, years of build up, of antifreeze - a good clean , being careful not to damage any of the tubes, along with a running a radiator flush, through the system, sorted it.

I used to run my engine without the thermostat, maybe worth a go?