Engine running at 40degC

[Palmtree]

Hi,

 

The boat's engines run at 40degC this seems low as the thermostat should be 82degC. The engines are marinised 2.5 di transit diesels. Is there a reason why boat engines will have a lower thermostat setting before I pull the thermostat out to check it's working.

 

Ian

[C.Ricko]

No, check the thermostat., it's probably the easiest start point and most likely to be the problem...

[Happy Jax 3]

Hi Ian

your engine will not run efficiently at 40degC, as Clive has stated it is most likely your thermostat, you may find some debris has caused it to stick open.

[Palmtree]

I did think there was a problem with the thermostat, but somewhere I read that marine diesels were set to run cooler than the automotive version. The thermostat housing looks corroded so might be a job to open up and check. I did not want to go through the hassle of getting it open only to find out later there was not a problem and was intended to run cool after all.

 

Thanks for the feeedback

 

Ian

[Happy Jax 3]

I did think there was a problem with the thermostat, but somewhere I read that marine diesels were set to run cooler than the automotive version. The thermostat housing looks corroded so might be a job to open up and check. I did not want to go through the hassle of getting it open only to find out later there was not a problem and was intended to run cool after all.

 

Thanks for the feeedback

 

Ian

I would expect these engines to run at a temperature of between 80-85degC, 40degc is far to low. I think you will have to bite the bullet and get the thermostat housing off.

[littlesprite]

sounds like good advice you've been given already, the one thing I would check first (being a simple soul) is that the gauge is working ok, we do tend to believe what they say without ever checking.

[Hockham Admiral]

Well said, Martin... we had just that last year and I simply replaced the "sender" plug.

[C.Ricko]

Sorry,  I had not read the initial post properly, I thought it was one engine with the issue.

I cant imagine both senders or both gauges would be at fault, I also doubt both thermostats have stuck open although one could have been faulty before the other...

Have you ever had overheating issues on a long or fast run? as the thermostat on an engine could have been removed to hide a head gasket or head problem, then the other removed to keep things the same??

I suspect there is no problem and the 'stats are just not in place.

It would be best to check it out if you took the boat off shore though just for piece of mind.

[BuffaloBill]

I would like to add that diesel engine's need to run fairly hot to run

efficiently and they need to be 'worked' too.

A diesel not 'worked' soot's up to the point where the injectors can

stop spraying fuel and lets the fuel in, in droplets besides the soot

clogging up around the valves and exhaust chamber. 

I think Clive may have put the finger on it but it will be good to know

the result!

[Palmtree]

Hi,

 

Just pulled the covers off to reveal the thermostats have been removed so will now source some replacements and see if there was a reason why they were missing.......

 

Thanks

 

Ian

[jillR]

the last time I came across removed thermostats it was due to the thermostate

 

having furred up and jammed shut.

 

ive also seen thermostats that have had a hole botched through them rather than try to

 

replace them.

[Gordon]

I believe it is possibly an accepted technique in some cases to drill small holes in thermostats to allow air to bleed through. I am however willing to believe there are those that would do so rather than replace

[Stranger]

sounds like theres been an overheating problem for some reason or another for them both to be removed i would be tempted to use a good cooling system flush and then refill with a good corrosion inhibitor antifreeze but check the engines dont overheat on just water to save on wasting the coolant first 

[C.Ricko]

I believe it is possibly an accepted technique in some cases to drill small holes in thermostats to allow air to bleed through. I am however willing to believe there are those that would do so rather than replace

there is normally a small hole in the thermostat which should be at the highest point (front of engine normally) just to let any air into the header tank..

[diesel falcon]

Used to run one of these engine,s in an open backed 23ft fishing boat out of Wells s , if you over filled the header tank it would fizz water out of the preassure cap until it reached it,s running level, it had a Bowman heat exchanger fitted with a silencer/swanneck straight to outside, worried the heck out of me until someone told me to leave it alone ,!!after this it gave no trouble.

hope you get sorted

[Palmtree]

Hi,

 

Thermostats (88deg) now fitted and the engine heated up to 95C on the gauge and kept there with no problems so far. As Diesel Falcon said there was a bit of water fizzing out of the filler cap overflow but nothing to worry about. I might now consider re-connecting the calorifier to the engine to make the most of the heat.

 

Thanks for all the info,

 

Ian

[Oddfellow]

Hi,

 

Thermostats (88deg) now fitted and the engine heated up to 95C on the gauge and kept there with no problems so far. As Diesel Falcon said there was a bit of water fizzing out of the filler cap overflow but nothing to worry about. I might now consider re-connecting the calorifier to the engine to make the most of the heat.

 

Thanks for all the info,

 

Ian

 

Depending on the installation, you may find that you need to bleed the clarorifier circuit to get any hot water, particularly if the pipework is lengthy.