Thread: Engine temp

Where's the temp sensor on the 4bd1 relative to the thermostat and coolant flow path? Does seem like a thermostat that is not closing completely.

Thermostat should be closed on a cold engine, would explain why the temp reads low then takes a long time to heat up.

If you get a new one, test it in a pan of boiling water first to check that it's operating at the right temp. Best practice IMO. They aren't expensive and usually a fairly basic job to change out- probably your first port of call.

Both of mine take about 5 minutes of steady morning suburban driving to get the gauge to budge and a few more minutes to get to the green zone.

Originally Posted by Toxic_Avenger

Where's the temp sensor on the 4bd1 relative to the thermostat and coolant flow path? Does seem like a thermostat that is not closing completely.

Thermostat should be closed on a cold engine, would explain why the temp reads low then takes a long time to heat up.

If you get a new one, test it in a pan of boiling water first to check that it's operating at the right temp. Best practice IMO. They aren't expensive and usually a fairly basic job to change out- probably your first port of call.

Just looked through the books. The cooling system does have a small bypass hose over the thermostat so coolant is always circulating (I guess so it doesn't dump cold water through an 82c (Where the thermostat opens) degree engine. That might explain it a bit.

If its cold enough and you have the heater on flat out and youre not working the engine hard sometimes they dont warm up at all

Point I was getting at is sometimes the temp sensor is not 100% indicative of what the actual coolant temps are in the areas that need to be monitored - liek the coolant galleries in the head, around valve seats etc. So aside from the thermal mass of the coolant (diffusion of heat, coolant circulation etc) local hot spots can and do appear in the head that are well above what the temp gauge reads. Then again, the temp probe may be picking up it's signal from pre or post radiator, in a bung of the head, before / after the thermostat etc... there would be markedly different readings at each point.

As for the TS opening and dumping 'cold' water thru the block/heads... probably not a huge issue. Every engine cycles like this. The Bypass tube will probably alleviate this temp difference to some degree. Also the engine coolant is about half of the engine's cooling capacity- the oil is also a key factor in engine cooling. So make sure your oil weight is correct for the operating temps you are likely to see.

Originally Posted by Blknight.aus

If its cold enough and you have the heater on flat out and youre not working the engine hard sometimes they dont warm up at all

That can't be good for the engine can it?
Mine gets there eventually. I don't think it would if the air temp was below about 10c though.

so long as its got oil pressure, fuel and coolant flow once you get it to start its an old school diesel so it doesnt care.

hell, it'd probably run all the way down to absolute zero at which point scienentitst will be giving it "Huh, uess we were wrong its wasnt brownian motion we discovered all those years ago, its just the rest of the universe reacting to the vibrations from all those old school idling landies... Wonder what happens if we get them all to idle in phase with each other."

Perentie used a fixed radiator fan obviously to reduce cost and maintanence. In the early 80's in GM car dealer visco hub was supplied with a/c unit for small Isuzu engines. The power boost hid the loss from the compressor.


Isuzu trucks and earlier mid 1980's 110 use a visco hub that will free wheel after a few minutes idling. common to most mid sized Isuzu sold in oz. If you have 110 3,9 idle with demister on you can wait a long time. in cooler areas they use radiator MUFFS or blind.


EXT244-1 - Exmoor Trim Defender Radiator Muff Black 90/110


I been driving the ser3 2 1/4 petrol to work 20 km. for 6.30 start. the local part seller only had low temp thermostat. the temp didn't make it to the top of the cold. obtained a hotter 88 thermostat and it made it to the bottom of the normal after 8 km.


I been using sand bag hessian material this winter to rap the grill. I found if it came up about an inch it negated the restriction. and when wet it helped. it also deadend some vibrations.


when I search for radiator muff I found 800 watt and 1200 watt 240 electric heater in UK,one had an electric circulation pump. rated at heating up to 60+ c in 40 minutes. American core plug heater a common but need 110 volt.