Thread: 1985 County 110 Izuzu Overheating, Help?

Hi Nic, if it's a standard LR isuzu setup it won't have a viscous fan so not being able to turn the fan by hand will be normal. These motors don't have any history of overheating so there is obviously something causing it. The other thing in the cooling system you haven't mentioned is the water pump itself. If you are satisfied that the the radiator is ok (nothing like grass seeds or insects blocking the core in front or internal blockage in the tubes from corrosion) then the only other suspects are thermostat or water pump. You mention that it blew a hose earlier - was it overheating then? Blowing a bottom hose is usually caused by the thermostat not opening and allowing heat and pressure to build up in the motor. Did you replace it with the correct thermo - should have 82c on it. Are there any other symptoms that led up to it blowing the hose? Other thing I haven't mentioned is the rubber sealing ring that goes on the thermostat - did you replace it with a new one. This is important but won't cause overheating.

You will possibly find the initial overheating has disturbed scale which has finished up in the radiator cores

AM

Hi guys,

Firstly thanks for replies.

So the leadup to it blowing the hose that links pump to thermo housing. which was very badly perished. I was towing a heavy load and the motor gradually got hot, i was in woop woop so stopped to cool and went again.

It only gets hot under pressure i.e towing or now driving on highway, around town its fine unless you meet a large hill.!

There was a spare thermostat in the landy from pre owner so i boiled that to check it opened and put that in.

Im pretty convinced the rad is ok.... it gets hot on both sides and no core damage... i put the garden hose in top and it flushed through easy.

Another thing is the heater doesnt work!?

Shall i take out the thermostat and take for a drive to see if that changes anything?

Water pump- How to check? i presumed because the system was under pressure and when i ran the motor with the rad hose off it spurted water out that the pump was working.

??????????????

thanks

Have you checked to ensure that you don't have an airlock in the cooling system? It may be that your coolant level and flow is lacking as a result.

If you are sure that everything is fine and you don't have an airlock, you may have to remove the water pump to check for internal corrosion or failure. First check the small hole in the pump body behind the pulley to see if coolant is leaking from it.

I have had similar symptoms to yours in the past. Unfortunately it turned out to be the head gasket. Given the pain and expense in replacing the head gasket (and the likelihood that it is something simpler and cheaper), I'd suggest you check every other possibility first.

Thanks,#

Yep ive been hopeing its not the head gasket. I have been told that if it was youd see bubbles in expansion tank... which i dont.

Airlock- How else to check? i did think this, when i drained the coolant and refilled i left the nut on top of thermostat off and cap of tank and left it for ages.. however i think the heater matrix has a fault as only one pipe is hot going into it... could this be the fault? and so no hot air inside vehicle.

I guess i could go get a compression test done to see.... ugh.

ill check water pump hole later and if i need to i guess ill take it off and see if it ****ed.

Do these not have thermo fans??? i was reading up about the different fans etc.

Why is it that if i turn off highway and its nearing the red that within 30sec the temp drops right down,.,

thanks everyone for help/advice. please keep it coming.

any more advise???

Nic,

The standard 4BD1 does not have a viscous coupling on the fan but it is a common modification. Does yours have one? If it does it may not be working. They only work when the engine starts to heat up under load. You should be able to hear it come in.
Dont run it without the thermostat and check that it actually opening at the correct temperature (should be 82deg).
Have you checked that the motor is actually overheating? A test is run the engine hard up a steep hill under load. When you see the overheating starting pull over and switch off. Immediately check the actual temperature around the sender on the block with an infra red temperature reader (cheap at Jaycar or Dick Smith).
If the temp is under 100deg it is not overheating and then suspect the sender unit or temp guage.
If all of this fails take the rad into a specialist and have them rod the core.
Also take the pump off and check for a worn or blocked impellor.
Regards,

Originally Posted by nic_denmark

any more advise???

What have you checked Nic, Did you find anything?