Originally Posted by GILow
PM me your details and I will post it to you. If it works, I will send the other one. I was only keeping them on the boat for emergencies, better they do someone some good. If they work, you could send me your old higher temperature gauge as a trade
then I'll have useful backup.
Hmm… I don't actually have any gauge to send in return - none are fitted to the standard 2GM20
; hence the difficulty and this thread.
At this stage I going off the idea of fitting a NTC style temp. sensor because as others have said, it is quite a task to fit one. This is no spare bung just to stick it into. There is space to drill and tap into the head
casting part of the water
jacket but unless I had the perfect gauge and sender, it is too much work for a mediocre return.
Unless I find something better, I am leaning to Snowpetrel's suggestion back in post 3 and fit an Engine
Watchdog TM2 or TM4. These are thermocouple devices and the sensor is bolted on externally. There is even a suitable tapped hole in the head
directly above existing thermostat and sensor. See photo
Originally Posted by GrahamHO
I also looked for a suitable gauge and gave up on the idea as not worth pursuing, but if you find one I suggest you still do the checks I've suggested.
Yep, those checks are good practice, I currently (occasionally) shoot the IR thermometer over the head and exhaust
Check the TM2 mentioned above, you might find it suitable.
Originally Posted by GrahamHO
seawater thermostats are a consumable just like the engine oil
Change the thermostat every couple of years and check a few times between and you won't need a temperature gauge.
Maybe you could have 2 gauges in case one is faulty. But then you wouldn't know which one is faulty so you should really have 3 temperature gauges and if 2 read the same those will most likely be correct.
The temperature reading gun someone suggested sounds a good idea. You could direct it at different parts
of the engine occasionally.
This whole thread has allowed me to really think though all the issues so a big thanks to each and every contributor
Fitting a gauge allows for for monitoring:
1 Too low a temperature as when the thermostat sticks fully open.
2 A partially stuck open thermostat which was the genesis of the thread
3 Too high a temperature and a failed temperature switch. The temperature switch is never checked during normal operation and unless one removes it and tests externally, one is unaware of a failure until way too late
. FWIW, my temp switch operates at 62 C (145 F).
If the temp switch has failed, there is no indication at all
(without a gauge) until the water
starts boiling in the head - not good.
Engine temp monitoring is a critical engine parameter. I erroneously thought that water flow out the exhaust
was suitable fallback indicator for a failed temp switch but of course, this is wrong (at least in a 2GM20). So there is no fallback for a failed temp switch unless a gauge is fitted (or two temp switches
Note the nice tapped hole (actually two holes) just above and behind the thermostat and temp switch. Perfect place to bolt on a thermocouple
There is a big pile of water directly underneath these blind holes and it is the probably the hottest part of the water circuit.