Fatboy11

Fatboy11

New Member
My 2.5 na (12J) 90 has had some overheating problems lately so I have just fitted a TM-2 watchdog so I can monitor the engine temperature a bit better.

I know water boils at 100oC but at what engine temperature should I decide to be concerned ?

I'm not sure if the antifreeze in the coolant raises it's boiling point at all. Also I seem to remember reading somewhere that because the coolant system becomes pressurised that increase the boiling point too.
 
It ain't as simple as that. Thermodynamics of a vehicle engine takes into account the coolant pressure ( increase in pressure increases boiling temp), the coolant being used and localised hotspots.

As most thermostats are set 88deg to 90 deg, I would suggest about 92 - 95.
 
Cheers, so 92-95 would be maximum operating temp ?

I read your post about making a coolant sensor too, which I plan to do next. Went out to the plains last Sunday and when I got home the expansion tank was empty and needed about a litre to top up so want to monitor that too.
 
coolant does raise the point a little and so does the pressure ,depends on what thermostat is fitted but anything past mid 90s
 
Fatboy11 said:
Cheers, so 92-95 would be maximum operating temp ?

I read your post about making a coolant sensor too, which I plan to do next. Went out to the plains last Sunday and when I got home the expansion tank was empty and needed about a litre to top up so want to monitor that too.
Click to expand...

That also depend where you are measuring temp, too. Hottest temp is output from thermo housing to rad. Coolest temp is return to water pump. It is my belief ( others disagree) that it is best to read the highest temp ( ie at thermo housing or top pipe, as yu want to know if the engine overheats, not how efficient the radiator is. Personally I would monitor the temp over a few runs and see what the average temp is, and tgen set an alarm 3-5 degrees higher than that. Irrespective of what it is.
 
I connected it to the rear rocker cover bolt as this seemed the easiest place when I fitted it. I'll have a look to see if I can route it safely to one of the thermostat bolts.
 
My dad has a temp laser which we use on the thermostat housing and top hose, as far as I know my thermostat is an 82 degree one. If you haven't got one handy just feel the top hose, general rule of thumb (for my dad and me) if we can hold the top hose then it's generally running ok :rolleyes: Having felt a top hose on an overheating engine I know it can get quite toasty :D
 
Last edited:
jase you will find 99% of the time its still down to a blocked rad especially with the salisbury plain mud

you need to clean the rad front and back continuously mine took about 1hr untill water runs clear thru the rad fins

a rad flush may also help
also check the intercooler also isnt clogged up a blocked intercooler will also increase the running temp of the engine
 
But I thought Jase's engine was a N/A, so no inter-cooler...

Surely if you're loosing coolant, it's got to be going somewhere?
I was told that glycol-based coolants/ant-freezes have a "searching" property, so if there is a tiny leak somewhere it will find it.

Have you changed the coolant recently?
Is there the possibility of an air-lock somewhere?
 
It is the NA. Coolant was done last year.

It did run very hot coming back from the plains just edging into the bottom of the red ! I think I may have just lost some out of the overflow pipe. Spent about 15 mins cleaning rad and still had some colour to the water so maybe just need to do it for longer.
 
Fatboy11 said:
It is the NA. Coolant was done last year.

It did run very hot coming back from the plains just edging into the bottom of the red ! I think I may have just lost some out of the overflow pipe. Spent about 15 mins cleaning rad and still had some colour to the water so maybe just need to do it for longer.
Click to expand...
yep mine took over an hr:mad:
 
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