Thread: 80series heater issues

Originally Posted by SiB

Apparently they have an arsehole too but can never see it when I drive it

I think it's behind the steering wheel

Seems to have improved since I took @ROKTOY advice and gave it another flush. With the work it's doing at the moment (low range 40km/h ish depending on chains 700m climb) should be running hot even though it's driving through the snow!

Did you flush water both ways trough the heater core? It is surprising how much 'crap' you can dislodge/unsettle by putting a reasonable flow of water through the core the opposite way to normal

Best way to flush a core is to blow compressed air into the water hose while flushing, and do what @ROKTOY said.

Tried both ways, don't think I used enough pressure on the hose the first time round

It will be a blocked core. Flushing will help but Ive found a strong solution of citric acid filling the heater core and pipes, sitting over a week end followed by a double flush will probably sort it.

if heater hose is about 1" size rubber....you could do what we did years back with lada and find one of the stainless steel pipe squeezy thingymebobbies that were used to squeeze shut vacumn hose on cups in dairy sheds....sort of a camber lock thing....open is open and shut is shut all go or whoa but simple. it will shut off your straight pipe for summer.....wonder if water pump it self is getting dodgy so less water flow all around????

I made up a piece of copper tube with a tyre valve welded onto it, connect it up to the hoses and while flushing with water you can blow some air through, the bubbles will eventually dislodge the blockages. If you have access to an air compressor I can send it up to you to give it a go. I have cleared some very blocked radiators in my time. If you are keen to give it a go P.M. me. James.

Cheers for the ideas guys, the valve got flogged out the plastic bit so new one coming, currently got a straight pipe through so running full hot the whole time. Seems to have improved but will try the citrus acid idea

I have just replaced the heater tap in my 40 series.
Never used to shut off properly.
But now the heater works a bit better too.
Mind you replaced a few hoses too.

Feeling the temp difference between the in and out hoses on the core will tell you if it's blocked or not.
If it's blocked take it to a specialist so they can wip the top off it and clean it out (if it is a serviceable one) - for the amount it would cost you would save with all the time your spending mucking around with it
Be careful about acid etc that you put it, had a guy in the other day that put something in his cooling system and failed to flush it all out now it's eaten the rubber seals in his head gasket lol


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my 2.8 Pajero heater never worked that well. Flaps in the cab worked, hoses felt warm but never pushed out the heat.
I had over heating issues/niggles and did the citric acid thing a couple of times to see if the radiator or cooling circuit would come good. Never did and eventually did the head gasket.
Had the head planed and pressure checked and it seems ok even though I was told they can still sometimes still be faulty.
There where two blocked small coolant holes on the face of the head. Don't know what they were but they were were crudded up. I picked them out before it was skimmed.
It was the end of summer when I did the head so don't know if the heater got better from the citric acid flush or from the head work but I do know that the heater works very well now.
That citric acid flush is well worth a try