Volvo Penta D3-160 running cold

[Boat-Man]

I have a Volvo Penta D3-160 diesel in my boat.
It has been running perfect for 10 years now, but always had an issue running cold at low RPM's. I'm second owner, but former owner had same "problem".
When running below 1800 rpm the water temperature does not get higher than 55-60 degree. At above 3000 rpm it reaches 80 degree, and stays there.
The temperature gauge has been checked, and it shows correct readings.
Thermostat has been change twice - but with no effect.
I have a hotwater tank heated by the cooling water - this takes energi, but I have tryid to close circulation to the tank, and it does not have any effect to the cooling temperature reading.
How does this work for other D3 owners??
Same story running at low RPM's??

Rgs,
Lars

 

[jamie langstone]

My Nanni 200hp does the same and so did my volvo TAMD i can only assume this is normal at low revs .

 

[A_8]

Coolant water is passing through even though the thermostats are supposedly shut, very common actually. Check that everything is mounted correctly and that the thermostats really close, use a bright light or something to check. There could be deposits that get stuck on the closing surfaces of the thermostats or they just don't close as they should in which case you need new ones.
If there are deposits make sure you flush the system thoroughly and change coolant or it will come back.
The engine should stay at operating temp at low revs.

 

[Boat-Man]

I checked everything - including closely look to the thermostat, but no failures found. Hoses correctly fitted. Service guy from marine shop had a look to the engine - and he replaced thermostat but nothing changed. He had no idea what else could be the cause. Mayby it's just how a modern commenrail acts.

 

[A_8]

Don't think its how its supposed to be. Happened to mine as well and it took a few thermostat changes for it to go away. Maybe its your hot water tank that not connected correctly i.e making the coolant bypass the thermostats?

 

[Boat-Man]

Newer really found any solution to the problem. Thermostat has been replaced three times, but no changes. Hoses are correctly connected, hotwater tank is correctly connected according to Volvo Penta specifications. No deposits on the seating, or in the cooling water. To make sure no influence came from the hotwater tank, I try to disconnect it completly. But nothing changed. The D3 just keeps running cold. Really strange behavoir.

 

[A_8]

Somehow coolant is bypassing the internal flow control or you have a faulty gauge. Have you tried to measure the engine temp with something else like an IR temp unit?

On my car I have electronically controlled cooling valves, are there any on this engine?

 

[Boat-Man]

Gauge has been chekked - no errors found. IR- temperature measure instrument has been used on the engine block, and temperature matches the gauge. No electical controlled by-pass valve on the engine. I'm close to give up, and Volvo Penta service has no ideas. They just say it's not normal.

 

[JorgenS]

HI.
Did you find out what whas wrong?
I have the exact same thing on my 2008 D6.
temperatur running at about 68degrees celsius when at 800-1000rpm. At 1600+rpm everything is normal. (85degrees)
I have checked the thermostat twice, I have measured the engine with IR thermometer ( the readings are correct).
I have changed the thermostat with the other engine. The problem is still on same engine.
I cant understand what else then the thermostat that can cause this problem

 

[A_8]

Don't know the details of the D6 but unless the coolant is long life it will develop "crystals" or hard particles if not changed per plan/spec and these will eventually get stuck on the coolant valve surface. Changing the valve will help for a bit but once you have the "crystals" in the system it needs one or more badass flushes so to speak and once clean a new valve.

 

[steadyeddy]

Try a thermostat with a higher opening temperature .

 

[A_8]

Try a thermostat with a higher opening temperature .

It won't help if the problem is what I described.

 

[BruceK]

On my Kads if I start off in idle and stay below 1000 rpm the motor never goes above 60C. Once I have given some load and brought the engine up to temp and then back off to idle speeds she will remain at 83C constant.

Is that what you are experiencing, or if you drop off rpm after reaching temp do the temps still fall?

 

[DavidJ]

As Bruce has described on my KAD43’s when I try to get the temp up to do an easier oil change the needle hardly moves no matter how much I rev at no load.

 

[JorgenS]

Some more info:
-I have 2 volvo penta D6 370hp
-Booth engines have always gone up to 85C in about 10-15minutes the last 5 years and stayed there no mather what.

last fall starboard engine dropped on the temperatur when running below 1000rpm.
When i startet the engine and try to get it up on temperatur with lets say 800rpm..It would never get up to more then max 70C

-I took the thermostat out and checked it with boiling water..It seems to work fine.
-I figured it was just temperary stuck or something and put it back in this spring. (winter storage)

I have the same problem this year
When I start it up and run for 1 hour below 1000rpm..Temperatur gets up to max 70..at 600rpm maybe 60+.
If I run at 3000rpm..Temperatur goes up to 85 and stays there.
When i take it down to 600rpm again..Temperatur will dropp..

Port engine is at 85 no mather what

I have changed thermostat with port engine..The problem didn`t move to the other engine..Still same..

I took it out and testet it with boiling water once more..seems ok.

Now Ì`m starting to question myself if I managed to somehow put the same thermostat back in..Beacause I can`t understand what else it could be.

The last time i boiled it . The temperatur went up to 85 the next time I ran the boat for 1 hour at low rpm..So i figured I had fix the problem somehow..But they day after..The problem was back..

 

[A_8]

The last time i boiled it . The temperatur went up to 85 the next time I ran the boat for 1 hour at low rpm..So i figured I had fix the problem somehow..But they day after..The problem was back..

This is typical for the issue I described earlier. You need to flush the system to make sure there are no particles left and once done I would get a new thermostat. It does not take much to let a bit of water through the thermostat and at idle that's enough to keep the engine from reaching operating temp.

 

[JorgenS]

Thank you I will try this