Have ordered a NASA exhaust temp alarm. on a 2GM20 what should the alarm temp ?

[UK-WOOZY]

Have ordered a NASA EX-1 exhaust temp alarm. on a 2GM20 (raw water cooled) what should the alarm temp be set to please? I asked on the Yanmar facebook page but had nothing of use from there,

many thanks

 

[sailorman]

why not run the engine up & check with a laser thermometer
Personally i wouldnt rely on one

 

[skip50]

I fitted one of these several years ago. IIRC the instructions say run the engine at max revs, then set the alarm for that temperature plus 10 degrees. The instructions are available online on the NASA website if you want to check before your unit arrives. HTH

 

[Akestor]

Have ordered a NASA EX-1 exhaust temp alarm. on a 2GM20 (raw water cooled) what should the alarm temp be set to please? I asked on the Yanmar facebook page but had nothing of use from there,

many thanks

Hi
I am thinking of buying one of this one day for my VOLVO MD2B. I think it needs experimenting with this. Do you have a temp gauge? If the gauge shows 70C and thats the operating temperature of the engine, i would expect something less in the exhaust hose because the cold water should mix with the direct hot coming out. So i first would find what is the temperature in the hose when the engine is at operating temp. That might be much less than 70 beacuse of mixing for example 40 or 50.
When my md2b overheated, i could feel the water at the exhaust outlet very warm but it would not burn me(because of the mixing with cold). Hope i am understandable!

 

[Minchsailor]

I fitted one of these last spring - seems to be OK. At normal running (2200 revs, max is 3500) it shows a temperature of <30degC. As the engine is too big form my boat (folly of the previous owner) I havn't had a chance to run at full revs, so I set it to alarm at 60degC on the basis that a catastrophic failure of the pump will give a very rapid rise in temperature. A more gradual failure of the pimp, such as the loss of a vane, will give a higher than normal reading which I will notice and I can investigate.

A point worth noting is that when the engine is stopped the stationery water in the engine exhaust will get hotter, so until this is removed by new water when the engine is re-started there can be quite high readings - I've seen >45 degC for a short time

 

[GHA]

This is beta 35 with thermometer attached to the head block and one on the exhaust bend >

 

[reeac]

This is beta 35 with thermometer attached to the head block and one on the exhaust bend >

Is that with no load on the engine I.e. in neutral? That would explain the cooling affect of increasing the revs from 1600 to 1900 .....little extra power being generated but lots more coolant flow.

 

[GHA]

Is that with no load on the engine I.e. in neutral? That would explain the cooling affect of increasing the revs from 1600 to 1900 .....little extra power being generated but lots more coolant flow.

Mostly under load - rev increase to speed up a little here's another one with SOG, there's an anchored log entry at 13.37 so the engine was probably turned off just before then. These are just ds18B20 sensors cable tied or epoxied to the exhaust bend and engine lifting lug so prob reading a bit lower than the actually lumps of metal.

 

[alahol2]

On my Beta 13.5HP the exhaust alarm is set to 40C reading on the exhaust elbow. That's enough to stop it triggering on a long high speed run. It will trigger for a short while on a restart after a decent run and short rest.

 

[blan321]

I have temp sensor on exhaust elbow of my 2GM20 and runs approx 35 degrees C on long runs in summer e.g. across channel. High 20s in Chichester harbour.

 

[blan321]

Sorry, forgot to add that's a well loaded engine (southerly 100) at around 3200rpm