Running temperature for Volvo Penta 2040

shortjohnsilver said:
Okay. I’ll get the boat out onto the river before I do anything and run her up and down under load and check the heat exchanger casing temp. If that’s hot then I’ve no need to worry and that the thermostat is working correctly. And more importantly the engine is NOT running cool.
I’ll then go to the calorifier and clear the restriction hopefully.
However if the HE is NOT as hot as should be then I should suspect the thermostat?
Again many thanks for your advice.
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The correct temperature is far to hot to touch . Ideally you need some means of measuring the temperature such as a contact temperature probe or an IR "gun". I have the later, I think I would aim to measure the temperature of the cylinder block close to the overheat warning light sensor or where the sensor for a temperature gauge can be fitted to the HE.

Removing the thermostat and flushing the a calorifier both require the coolant to be drained. I think I might do both while the system is drained.
 
In update, I had a proper blast up and down the river a week or so ago and all seems okay.
As per Tranona’s mention the HE was pretty hot, but not silly hot.
The engine ran well, with hot water (coolant) going to the calorifier and back. Hot water at taps, so hopefully no blockage or air lock there.
The exhaust raw water flow remained good, with no smoke at all to indicate unburnt fuel.
WOT for a good twenty minutes but generally revs retained at 2500, with tide and against.
All good, it appears?
However, I monitored the temp gauge closely as it had been suggested that the engine is running too cool.
The gauge responded as the engine heated, indicating around 60/70 C at normal revs an picking up to about 80/90 when WOT, then falling back to settle at around 65 C when revs bought back down.
We were out for about two hours, enough time, surely, to reach running temperature?
Back in the berth and after allowing time to cool, I checked the coolant level which was unchanged. Also checked the impeller and all intact.
As said no exhaust smoke white blue black or anything unexpected, even at WOT

So, the questions that remains niggling in the back of my mind are this; is the engine running too cool? Or do I just have a temp gauge that under reads?
If the thermostat was faulty/stuck open would this result in a low temp reading at the gauge?

This is relevant as if the thermostat is considered the problem then I’ll need to drain the coolant again so as to access the thermostat housing to get at the thermostat! Messy job.
If the general consensus is that all seems okay and I’m worrying needlessly, then I won’t do that and not worry about the low temp on the gauge. I’ll leave and change the thermostat at the end of the season when I need to change the coolant anyway.

Thanks all and this forum for all its advice.
 
At the temperatures you mention I would not rush to test the thermostat.

IIRC the sensor for the temperature gauge is located in the side of the heat exchanger below the tube nest If that is so it will be in a coolish part of the system so will tend to show a lower than expected temperature, especially at lower power levels ...... but check that is the gauge sensor and not the alarm sensor ( the wiring colour will tell you which is which)
 
VicS
Many thanks for your advice. Yes, I’ll check the sensor and gauge. I’ve never had an overheating problem with this engine and hence an overheat alarm, but it would be good anyway to know that it is functioning correctly.
Si
 
By way of comparison my MD2040 reaches an indicated 75 C when cruising and 80/90 when flat out. 60 C sounds a bit low but it could be the gauge (or potentially a stuck thermostat). The sender for the gauge is the one in the side of the heat exchanger. I'm not sure if yours is the same but on mine you need to remove the sender in order to pull the HE stack.
 
Ammonite, thanks that’s quite reassuring actually, thinking about it.
Certainly when WOT the temp looks comparable to what you’re getting, maybe a little lower though. However I would be happier to see 75 C when at cruising revs as that would marry with the opening temp of the thermostat. Maybe the gauge is under reading? Need to test that.
But I’m reasonably happy that the engines running well and certainly no evidence of unburnt fuel, so, this weekend I’ll have another look at the gauge temps.
Thanks
 
shortjohnsilver said:
Ammonite, thanks that’s quite reassuring actually, thinking about it.
Certainly when WOT the temp looks comparable to what you’re getting, maybe a little lower though. However I would be happier to see 75 C when at cruising revs as that would marry with the opening temp of the thermostat. Maybe the gauge is under reading? Need to test that.
But I’m reasonably happy that the engines running well and certainly no evidence of unburnt fuel, so, this weekend I’ll have another look at the gauge temps.
Thanks
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I feel your temperatures are on the low side especially under no load though this might be the result of a cold calorifier cooling the water which maybe bypasses the thermostat. Does this low temperature normalise as the calorifier comes to temperature? If the engine temperature is correct then you should be just able to keep your hand on the hottest parts of the block for 5/10 seconds . If you can hold your hand on the hottest parts the engine is not up to temperature.

Should you find the temperature changing significantly as power changes then maybe the heat exchanger needs attention and is struggling to keep the temperature at the thermostat setting which is possibly should be around 80/90 C .
 
The HE is definitely clear, having had it out, treated about twenty months ago, along with replacing the elbow, cap ends and flushing the whole system through. The engine didn’t miss a beat over our summer excursions, some of which required some extensive motoring.
On a recent check run, I did check temperatures and as you have indicated and yes I could hold my hand against the block for no more than ten seconds. The thermostat housing equally hot to touch, but not ridiculously hot and at the end of the check run where I ran the engine over the full spectrum of revs, the calorifier was full of hot water, with the coolant pipes in and out hot.
If I don’t find improvement then I’m beginning to think that the thermostat may not be operating properly - also renewed twenty months ago and I’ll drain down the coolant again and renew the thermostat again.
The engine does not overheat, it’s just that the gauge temp seems low.
Many thanks to all of you that continue to persist with me in trying to resolve this anomaly.
Si
 
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