Yanmar GM series F (closed cooling system) running temperatures!

[vas]

having sorted (I hope) my air in fuel problems, I was noticing that engine temp was low. Even running the generator for 1h at 3000rpm, it wouldn't pass over 60C. Temp measured via arduinos and digital thermistors, so it is correct, cross checked with an IR meter on the thermostat housing.
So, I assumed PO had removed the thermostat and bought a brand new one.
Today I opened up the housing to fit mine in, only to find a nice bronze original looking one inside. bummer!
Took it home, did the pot/hotwater/big alcohol thermometer test, bloody thing opens up normally at 71C so it's fine... Fourty euro for my spares bin.
Haven't examined v.closely the closed water circuit, but I fail to see how with the thermostat closed, temps wont rise swiftly to over 80, without any cooling!

Asked a friend and he said I may be letting too much seawater in so I need to strangle it, which I find absurd as sea goes in around and out not cooling the block.
Having said that, at some point before buying the thermostat, I did strangle the inlet seacock and temp did rise more swiftly, but seawater pressure had dropped significantly to 1/4 and I didn't like that-worried about flexhose/silencer longevity

So to end with a question, has anyone with a GM F engine got a proper temp gauge, and if so what is it showing at 2-3k rpm please? Mine originally had a temp switch which had never ever triggered.

cheers

V.

 

[AntarcticPilot]

There may well be a cooling effect even when the thermostat is closed; there certainly is on my Volvo 2003 where the cooling circuit is such that there is always water passing over the exhaust manifold (not merely the exhaust elbow). However, obviously that depends on the exact mechanism of your cooling circuit - the Volvo 2003's is particularly strange, and it took several iterations of discussion on the forum before even gurus like vyv-cox could work it out!

 

[lw395]

The temperature rise will vary with the load, not just the RPM.
A lightly loaded diesel can often fail to warm up. The excess heat goes out of the exhaust more than into the cylinder head.

that's why disease-alls tend to have auxillary heating more than petrols.

Your engine probably has some bypass coolant flow which does not depend on the stat opening. That seems to be enough to keep the temp down.
Mess with that at your peril though...

Put some load on it.

 

[vas]

thanks for the replies,
engine is mated to a 8KW generator, typical load is 2-2.5KW - watermaker + charger. Not that easy to get up to 4-5KW as that would mean I have to run the aircon (v.rarely use it!) or heat water (could do, slightly pointless many times)

V.

 

[lw395]

thanks for the replies,
engine is mated to a 8KW generator, typical load is 2-2.5KW - watermaker + charger. Not that easy to get up to 4-5KW as that would mean I have to run the aircon (v.rarely use it!) or heat water (could do, slightly pointless many times)

V.

I'd expect the 2kW of the water maker to be enough load to open the thermostat at least partially.
Maybe if you boil a kettle or two on start up, it will then maintain a reasonable temperature.
But maybe gensets often run quite cool?
They're intended to run for long hours, so maybe 60degC is enough to keep the oil dry?

 

[vas]

well, it's only the last couple of months that I installed all these sensors, only run the watermaker for half an hour as tanks were almost full, still testing governor settings and playing about with the dash start/stop panel I've programmed. Didn't go over 61-62C on that session, nor in charging or running it for an hour with various tools (well not much more than 500w...)
I'll try a combo of devices and see if it will reach and keep 70+
Not sure it's a good idea to run an engine at 60-65C, I'd much prefer it to run at 75 tbh.
Coming to think of it, this MASE generator had a v.tight grp box with sound insulation surrounding it which was falling apart and which meant I couldn't easily see what was going on, nor identify leaks or whatnot, so scrapped it (and improved the insulation of the e/r). Maybe with the box around it, it would run a bit hotter, maybe not, we'll never know...

cheers

V.

 

[vas]

...an update on this thread as well.
after a few weeks onboard with regular use of the generator for watermaker and a bit of battery charging I notice that with 27-29C seawater temp (yes I know it's bloody hot!) and 35+ e/r temps the circa 3kW load on the generator gets coolant system up to 65C - once saw 66, never anything more. For the record, during winter with seawater in the 20s coolant wouldn't go over 59-60C with the same load.
EGT (probe 50mm from the exhaust flange on the cylhead) temps on same load were up to 240-245C.
For the record, just running the generator for half an hour with no/minimal load coolant stays at 60C and EGT at circa 140C
All above are at 3000rpm. At 800rpm EGT quickly drops to under 110C

V.