Running temperature for Volvo Penta 2040

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XTE

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I worry about running the engine too fast and overheating, so I keep the revs down to below 2500. Not that I have experienced an overheat on this engine, but it was always a problem on my last boat, so it makes me cautions.

I have a temperature gun and when running I have measured 110 degrees C at the hottest part of the block. What would a safe temperature be for this engine?
 
XTE said:
I worry about running the engine too fast and overheating, so I keep the revs down to below 2500. Not that I have experienced an overheat on this engine, but it was always a problem on my last boat, so it makes me cautions.

I have a temperature gun and when running I have measured 110 degrees C at the hottest part of the block. What would a safe temperature be for this engine?
Click to expand...

It's difficult to judge exactly which temp you are measuring as there will be localised different temperatures, particularly near the exhaust manifold. However, I would guess that you are measuring the temp of the block somewhere near the coolant flow area as 110C is around the maximum temperature for the pressurised coolant. However, it does not mean a great deal as the coolant is thermostatically controlled so may well have plenty of cooling capacity in reserve should it be needed.

If you can measure that temp at 2500 revs and then speed up to max revs, or whatever, and still measure 110 then that is fine and shows that the cooling system/ thermostat are doing their jobs.

Richard
 
RichardS said:
It's difficult to judge exactly which temp you are measuring as there will be localised different temperatures, particularly near the exhaust manifold. However, I would guess that you are measuring the temp of the block somewhere near the coolant flow area as 110C is around the maximum temperature for the pressurised coolant. However, it does not mean a great deal as the coolant is thermostatically controlled so may well have plenty of cooling capacity in reserve should it be needed.

If you can measure that temp at 2500 revs and then speed up to max revs, or whatever, and still measure 110 then that is fine and shows that the cooling system/ thermostat are doing their jobs.

Richard
Click to expand...

Richard, thanks, that makes sense so I shall do that and measure temp at different revs to see if it make any difference. If it doesn't, then no need for me to worry about opening her up! I also guess that i should measure the temp at the thermostat housing so I have the water temp. I think that the thermostat is set to open at 75 degree C and the water should probably not exceed 100.
 
First, over running the engine. All diesel engines, cars, tractors, bulldozers, sports cars, boats have a governor in them so you cannot over rev them. If you're underway, then the effort needed to turn the propellor will absorb any tendancy for the engine to over rev as well.
Secondly, the cooling system is pressurised once it gets up to temperature and this is why you should never open a radiator cap when the engine is hot. Because it's pressurised one of the laws of gasses applies - Boyles Law or Charles Law, I forget which. This means that as the pressure increases so does the boiling point of the coolant water. The radiator caps have a pressure valve in them that releases at about 10psi so therefore your coolant water will be circulating at whatever temperature the thermostat opens at. Modern engines run more efficiently at high temperatures so the thermostat openning temperature is, now a days, very high and will be around 100 deg C if not a bit higher. So your temperature reading of 110 is nothing to be alarmed about, and you can happily run your engine at full throttle if you wish. Current thinking seems to be that you should vary your throttle speeds and every now and then give it a burst at full throttle if on a long run. Personally I don't.
As an aside the older volvo MD series engines had raw seawater cooling and so that the salt water didn't evaporate and leave the salt behind inside the engine waterways, their thermostats used to open at about 60C.
Hope this calms your fears. There are a lot more better things to worry you when sailing. Personally I still worry that the sky is going to fall on me (Asterix the Gaul) especially when everything seems to be working smoothly!
Mike
 
To be boringly technical, the reason you should not open the rad cap is not strictly speaking because of the pressure. It is not the pressure that makes the water shoot out when you take the cap off, not as such.

As we all know, water boils at 100C, but that's at 1 atmosphere (sea level). Due to the pressure in the cooling system the water can be at or even slightly exceed 100C in the system without the coolant boiling. When you remove the cap the system pressure drops and if the water is fully up to temp it instantly boils, hence you get a hot shower. :disgust:
 
XTE said:
I worry about running the engine too fast and overheating, so I keep the revs down to below 2500. Not that I have experienced an overheat on this engine, but it was always a problem on my last boat, so it makes me cautions.

I have a temperature gun and when running I have measured 110 degrees C at the hottest part of the block. What would a safe temperature be for this engine?
Click to expand...

You dont say exactly where you measured a temperature of 110C. I'd not expect to see that temperature anywhere on the cylinder block. Maybe on the cylinder head in the vicinity of the exhaust ports.

RichardS mentions "exhaust manifold" but I dont know what part he is referring to as there is no separate exhaust manifold. It is an integral part of the heat exchanger and coolant head tank assembly

FWIW the thermostat should start to open at 82C and be fully open at 95C . ( The 75 C which you mention refers to the 2010 and 2020 engines). It might be worth checking this at some stage. At least it's reasonably accessible on a 2040 unlike others in the range which require removal of the whole heat exchanger / header tank assembly ( 2010 and 2020) or the coolant pump ( 2030)

You should check the exhaust for a good flow of water . If there are any doubts about this then the seawater pump impeller, the heat exchanger tubes and the exhaust injection point are all areas to look at..

I think the area to monitor with your temperature gun while you vary the engine revs under load is the body of the heat exchanger / head tank, the thermostat cover plate or adjacent to it perhaps. I'd not expect to see a temperature above the 95C specified fully open temperature for the thermostat. If the temperature stays below that all is well.
 
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Provided the cooling system is in good shape there should never be any overheating problems on a 2040. As previous posters say, the freshwater system is pressurised and well controlled, so provided the seawater is flowing well it should be fine. 2500 rpm is only drawing about 2/3 maximum output and the engine is rated at 3200 rpm. You have an overheat alarm to warn you. However in normal use you rarely need to go over 2500, but from time to time worth giving it a run at full revs to reduce the possibility of coking in the exhaust.

Can appreciate your concern based on previous experience as many older engines, particularly seawater cooled were susceptible to overheating at higher revs either through poor design or because waterways got clogged up over time.
 
VicS said:
RichardS mentions "exhaust manifold" but I dont know what part he is referring to as there is no separate exhaust manifold. It is an integral part of the heat exchanger and coolant head tank assembly
Click to expand...

It's irrelevant to the OP's question. I was just making the point that there will be variations in temperature in different parts of the engine and these will be highest close to the exhaust manifold/outlet/pipe/port/heat exchanger/elbow. (delete as applicable :rolleyes:)

Richard
 
Hi All,

I also have a Volvo 2040 (D).
I normally cruise along at 2500RPM. However, as of late I have noticed that the engine is running hotter than normal.
This is indicated by the water coming out of the sink tap is now almost too hot to hold your hand under. Plus, the engine “bay” fan
Is coming on more than usual.

Things I have done so far…

Replaced the raw water pump impellor (two blades were missing!!) – I only found one of them!
Rebuilt the raw water pump (it was slightly dripping water).
Removed and cleaned the heat exchanger (this is where I found one of the missing rubber impellor blades).
Replaced the thermostat
I also replaced the exhaust elbow (two seasons ago) as the old one had pitted and was leaking – admittedly, I have not checked the elbow so far this season.
Flushed out (about 5 times) the fresh water coolant and replaced it with Volvo coolant.
The Water coming out the back of the boat appears to be pumping nicely!

The plot thickens……. I have now removed the thermostat (for test purposes) – and it still runs just as hot!
I have removed the rad cap and can confirm NO pressure what so ever in the heat exchanger (I guess because there is now no thermostat) – but if
the head gasket had gone I would still expect it to be pressurising.

Fresh water pump perhaps? I don’t think so based on the fact that we have hot water coming out of the taps (indicating water is being pumped around the system).
Also, the heat exchanger heats up as quick as the engine does, again indicating water flow around the fresh water system.

So I’m still thinking that I have a partial blockage / restriction somewhere?
I’m going to the boat tonight – I’ll video the water coming out the back of the boat.

ANY thoughts or suggestions will much appreciated

Many thanks

Ian
 
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Ianqv said:
Hi All,

I also have a Volvo 2040 (D).
I normally cruise along at 2500RPM. However, as of late I have noticed that the engine is running hotter than normal.
This is indicated by the water coming out of the sink tap is now almost too hot to hold your hand under. Plus, the engine “bay” fan
Is coming on more than usual.

Things I have done so far…

Replaced the raw water pump impellor (two blades were missing!!) – I only found one of them!
Rebuilt the raw water pump (it was slightly dripping water).
Removed and cleaned the heat exchanger (this is where I found one of the missing rubber impellor blades).
Replaced the thermostat
I also replaced the exhaust elbow (two seasons ago) as the old one had pitted and was leaking – admittedly, I have not checked the elbow so far this season.
Flushed out (about 5 times) the fresh water coolant and replaced it with Volvo coolant.
The Water coming out the back of the boat appears to be pumping nicely!

The plot thickens……. I have now removed the thermostat (for test purposes) – and it still runs just as hot!
I have removed the rad cap and can confirm NO pressure what so ever in the heat exchanger (I guess because there is now no thermostat) – but if
the head gasket had gone I would still expect it to be pressurising.

Fresh water pump perhaps? I don’t think so based on the fact that we have hot water coming out of the taps (indicating water is being pumped around the system).
Also, the heat exchanger heats up as quick as the engine does, again indicating water flow around the fresh water system.

So I’m still thinking that I have a partial blockage / restriction somewhere?
I’m going to the boat tonight – I’ll video the water coming out the back of the boat.

ANY thoughts or suggestions will much appreciated

Many thanks

Ian
Click to expand...

My thoughts are that you simply do not have an adequate flow of seawater through the heat exchanger due to a restriction somewhere or a worn seawater pump.


BUT BUT BUT with most of this series of engine the orientation of the tube bundle in the heat exchanger is vitally important. There is a hole in the outer casing which must align with the incoming coolant connection and there is air vent which must be on the top to allow air to escape . The tube bundle is also marked "up" .

From the 'shop manual.
"4. Fit the insert in the heat exchanger. NOTE! Make
sure that the insert is positioned correctly. Make
sure that the hole in the insert casing comes opposite
the hole in the housing and that the vent hole
comes upwards. The insert is marked with "UP". "​

This may not apply to later versions but unless you are certain that the tube bundle has been fitted correctly or that this requirement is not applicable to your engine this is something you should check.
 
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Ianqv said:
Hi All,
I also have a Volvo 2040 (D).
I normally cruise along at 2500RPM. However, as of late I have noticed that the engine is running hotter than normal.
Things I have done so far…
Replaced the raw water pump impellor (two blades were missing!!) – I only found one of them!
I’m still thinking that I have a partial blockage / restriction somewhere?
ANY thoughts or suggestions will much appreciated
Ian
Click to expand...
I'd have a very good look for the 2nd. pump impeller blade.
 
I don't know the engine but have you checked that removing the thermostat actually guarantees maximum cooling?

I'm more familiar with auto engines where, generally speaking, the engine is overcooled if the thermostat is removed ...... but I believe that marine engines are not necessarily all like that.

Richard
 
Hi VicS

Many thanks for replying. I will investigate re the orientation of the exchanger tubes and let you know!!

I took some video of the raw water side being pumped.

Link to - water being pumped into an empty strainer: https://youtu.be/BLwkYih2pEE

Link to - raw water exiting the exhaust: https://youtu.be/jRIei00xzj4

Link to - raw water being pumped into a bucket on deck: https://youtu.be/GCsLlbXSSII

Re the last video, I disconnected the raw water pipe which goes into the heat exchanger and just added another length of pipe so I could get a really good idea just how much water is being pumped.

Other jobs done tonight... water intake (under the boat) checked and cleaned.
All rubber hoses on the fresh water side removed, checked for blockages - none found, both were totally clean.

Engine has done approx. 1300 hours. Just out of curiosity, I removed the oil filler cap whilst the engine was running. I'm pleased to say that there is no crank case compression.

Many thanks

Ian
 
Sorry for resurrecting an old post but..
I too have a VP 2040 and have recently discovered that my hot water is not being heated via the engine coolant. I’m satisfied that there is water in the boiler as when the immersion is selected, the water heats as it should, it just doesn’t heat via the engine as it had before.
Admittedly, I have noticed this when running the engine berthed and not underway. Even when I put the boat under load, this has little affect to improving the temperature.
Today, I carried out a service, changing filters and oil and ran the engine accordingly once completed and followed the coolant pipes to and from the boiler - probably a couple of meters max. I could feel that the feed pipe was warm, not hot really, just warm, but the return, was cool.
I also found that the impeller had, this year, broken down considerably, losing three blades out of the five. I had failed to notice that the exhaust water discharge had reduced. Not massively but now with a fresh intact impeller fitted, the exhaust water discharge is very much improved.
I have recovered all the missing pieces from the heat exchanger entry. Thankfully. Whisk doing this I checked the heat exchanger and it was clear and clean as it had been when I extracted it and changed the exhaust elbow about eighteen months ago.
I have come some extensive motoring since then for some hours and have had no overheating issues whatsoever.
Then I started to question my engine running temperature as, as said, I’ve not had any overheating issues, but now worry that maybe I’m running too cool?
Now, I’m thinking that the thermostat has failed and maybe stuck open? Would that cause the engine to run cool and would that also impact the coolant temperature and therefore the coolant heating the hot water?
Sorry, lots of thoughts and just wanted to obtain a clearer understanding of what’s going on and whether my draining down the coolant again and changing the thermostat would help?
Thanks all.
 
I had same issue of poor hot water heating and feed pipe only mildly warm. Removed calorifier and connected water hose to input - no flow through the unit. Gave it a blast with a plumbers compressed air "blockage clearer" and a wad of crud/possible old impellor pieces shot out. Now hot water again!
 
shortjohnsilver said:
Then I started to question my engine running temperature as, as said, I’ve not had any overheating issues, but now worry that maybe I’m running too cool?
Now, I’m thinking that the thermostat has failed and maybe stuck open? Would that cause the engine to run cool and would that also impact the coolant temperature and therefore the coolant heating the hot water?
Sorry, lots of thoughts and just wanted to obtain a clearer understanding of what’s going on and whether my draining down the coolant again and changing the thermostat would help?
Thanks all.
Click to expand...
The thermostat should just start to open at 75C therefore you would expect the engine running temperature to be just a little higher than that.

If the thermostat has stuck open, or simply broken , it would result in a low engine temperature ( assuming the HE is clean and good flow of raw water)

Things you can do:
  • Make sure there is no air lock in the connections to the calorifier
  • Check the engine temperature
  • Test the thermostat if the engine temperature seems low ,
  • Flush the calorifier
 
Thanks Vic.
So, there could be two issues here; the thermostat is faulty - stuck open, meaning the engine running temperature is low and therefore the coolant temp is low too and as that heats the water in the calorifier this means low temp hot water to domestic side.

And/or there’s an air lock or blockage within the calorfier, within the coolant coil, as its warmish going in cool coming out. Immersion works fine.

I’m thinking that first I should get the boat out of the marina and give her a good run up and down the tidal river. That should give me a real working running temperature at the gauge, when under load, rather than alongside the berth on the ropes.

What should I see. Look for? Centigrade Farenheight wise as an acceptable running temperature?

If there’s no improvement, then, I’ll drain down the coolant and get the thermostat out and check it. I’ve a new one here ready if needed
Replace, refill and hopefully that will sort it.

To flush the calorifier, is this a case of removal of coolant line in and coolant line out and then pressure wash through the coolant coil, somehow?

Theres a small valve at the coolant exit and when I release this I do get coolant exiting here, with the resultant drop of coolant level at the heat exchanger header tank, but there’s no pressure really just a dribble, does this mean that the calorifier is partially blocked rather than air locked? Maybe Aquanaught’s method could work?
Anyway, thanks everyone for your advice and consideration.
 
Unlikely to be the engine running too cool. Before you check the thermostat run it under load for 10 minutes and feel the heat exchanger. If it is hot to touch then the engine is not overcooled. much more likely to be restriction in the heating coil in the calorifier.
 
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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