Two engines temperature totally different!

[Boater On Thames]

My two Volvo Penta TAMD61A engines. The port side engine is way hotter than the starboard side engine. It's 20 C different! The below data measured after the engines run idle for one hour, checked by an infrared thermometer:

Port oil cooler: 75 c
Starboard oil cooler: 55 c

Port engine body: 75 c
Starboard engine body: 55 c

Port coolant tank: 70 c
Starboard coolant tank: 50 c

Any idea why? Thanks.

 

[kashurst]

lots of variables there. Is the hot water tank connected to the starboard engine?
how long and how hard were the engines running?
If you are running on a river/lake you ideally need to run one engine at a time so it is working hard(ish) and see what it is doing.

 

[Boater On Thames]

Only the port engine has a hose connected to the hot water tank. But the water tank is empty as I haven't used it for quite a long time.

I just testing the engines today after I fixed the airlock problem last night. They are running unload while the boat is mooring not moving. Sounds running smoothly. Only when I use hands to touch them found out the difference.

 

[kashurst]

better to check when they have had a proper run. Sitting on the dock can be very deceiving. Probably both are basically fine but give it a good run and then check. Good call using an IR thermometer - really useful bit of kit. Stick some black insulation tape onto the bits you want to measure, gives a better reading and you are pointing at the same spot each time you check.

 

[Freebee]

one has a thermostat one doesnt or its failed open

 

[waynes world]

one has a thermostat one doesnt or its failed open

that is the first thing i would of been looking at and fitting new in each engine.

 

[kashurst]

a long time ago I did exactly that in possibly similar circumstances. Completely wrong! the impeller was shredded in the other engine. See what a good run reveals.

 

[Boater On Thames]

Never know there is a thermostat to control the engine temperature. I thought there is only a temperature sensor to send a temperature signal to the gauge only.

I thought about the impeller. Then I think it may be ok as I replaced them just last year October and only had around 20 hours of engine running time since that. So I guess they should not break that quick. Will need to check it tomorrow anyway.

 

[Keith-i]

Check:
thermostat
impellor
heat exchanger
coolant level

 

[julians]

Before changing anything, I'd go for a proper run, say 30 mins at normal cruising speed, and actually verify that the temperatures are different.

 

[gordmac]

Another vote for making them work for a while and seeing what happens. Without doing that you don't really know if one is too hot or one is too cold. Those temperatures are not enough to open the thermostats.

 

[Boater On Thames]

Thanks. Will do tomorrow.

 

[AndieMac]

They are running unload while the boat is mooring not moving.

Are you berthed somewhere stable enough to run the boat in gear alongside the pontoon?
Make sure all your lines are suitably secured, if the boat idles normally at say 650 - 700 rpm, put it into gear and raise the rpm’s by another at least 100 to load the drivetrain, if you are single handed and can’t take the boat out on your own easily. This will bring the temp up fairly quickly and easily without committing to leaving the berth and limping home with overheat alarms ringing in your ears.
When doing my own pre departure engine check’s after being away from the boat for a few weeks, I always run alongside in gear right up to operating temp. If I’m going to have a problem, I would prefer to have it alongside.

As already mentioned, post coolant change airlock’s, failed raw water pump impeller‘s and thermostats, blocked exhaust elbows and heat exchangers are the usual culprits.

 

[Boater On Thames]

Okay. Finally got time to drive out today. The temperature is still difficult but less than no load.

Driving around 30 minutes at engine 600-750 rpm at a speed of between 5-6 knots. Can't drive any faster as this making waves on the river and complained by the rolling boat club coach on the way.

The starboard engine body is 75 C
The port engine body is 60 C

Seawater pump checked, no problems found. Maybe the next step I will have to remove and clean the heat exchanger to try.

Any suggestions are welcome. Thank you!

 

[julians]

I wouldn't worry about that difference, I'd just use the boat as is.

 

[Mr Googler]

Could well be a thermostat that has failed open. 60 sounds too low…75 about right. Could do with a proper blast though to find out what’s what

 

[gordmac]

I would say even 75c is a bit low, would be surprised if the thermostats are less than 80c

 

[Mr Googler]

I would say even 75c is a bit low, would be surprised if the thermostats are less than 80c

Agreed…but he’s only doing 750 rpm

 

[gordmac]

That is a point, not really working at all.

 

[markc]

It seems more like the thermostat on the cooler engine is stuck open - it may even have been removed??