The Mitsubishi Pajero Owners Club®

[Big S]

Where in the cooling system is the water temp sensor for dash temp guage on a 2004 3.2? I don't mean where is it on the engine, more like where in relation to the radiator does it read the temp? Does it read the temp as water leaves the radiator or just before it enters the rad?

I'm trying to get my head around a water loss problem when the truck works moderately hard (e.g. towing a 800kg caravan). The guage reads just under half for about 50 motorway miles and then starts to rise and then fall back to norm depending on if going up or down hill. This is the first warning that anything is wrong and at this point it will take approx 4 litres to top up the radiator. Allowing it to cool and then topping up will gain another 50 / 60 miles. This has been going on for about 3 years and it has not got any worse as I might expect if the was a head gasket problem. The truck can run solo for months without any water loss, although the expansion bottle is often empty.

So, considering my original question: why could the truck use water when working hard but not show any temp rise until the water level falls below water pump level?

On one occasion when it was doing this I managed to drive approx 100 miles without any water loss after the first top up by driving with windows and sunroof open and heating on full. So, I guessed at insufficient cooling and fitted a new viscous fan coupling but it made no difference.

Cheers!

[Google]

[SteveW-DID]

The sensor is on the head so it measures the water temp just before it enters the radiator. The spike in temp are probably due to super-heated steam coming into contact with the sensor when the water level falls low enough.

Is the car ever hard to start? ie occasionally reluctant to turn over?
If your front to rear heater pipes are OK I recon you have a cracked head.

[trekker]

Have you searched for a leak around the engine and associated coolant pipes. I once had loss of water, but also only on occasions, and eventually found a minute pin hole in a hose to the heater,  at the bulk head end.

You'll only see a trace of this type of leak when the engine is running, so that's when to search. Once the engine begins to cool off, and the water pressure drops, air will draw in through the leak, so you'll not see coolant leaking out then.

[Big S]

Thanks for the replies!
There has never been any problem with sluggish cranking.
The problem has been going on for about 3 years and it seems the same now as it did then (as in it's not got any worse as you might expect if something was failing or deteriorating)
On one of the hottest days in July I did a 500 mile round trip high speed solo motorway journey without incident. Last Sunday I did 60 motorway miles in the rain with a 800kg caravan on the back at 50 / 60 mph and it lost water...

Cheers!

[SteveW-DID]

The water is going somewhere. This is a leak or a cracked head. Normally with a cracked head you get occasional missfire on starting due to water in a cylinder. This only happens sometimes because the valves to that cylinder have to be open. The crack occurs on the exhaust port side. You do not get system pressurization like you do on a 2.8.

Sounds to me like you have a leak. Get it sorted ASAP or you WILL get a cracked head. Find a good garage and get the cooling system pressure tested.

[jimmybond]

Im thinking more along the lines of the egr valve cooler is leaking.
id be starting there 1st.
if not then the rear heater pipes.
the towing makes extra heat so more pressure on system.
if egr cooler is faulty it would leak down exhaust and get burnt.

[assassin]

Go to Toolstation or plumbers merchant and get some drain stain, costs about £6 per tub, drain and flush your cooling system and fill nearly full with pure water, drop half a tub of drain stain in and top up.

Run the vehicle and it will leave a stain where the leak is; and you can get come lovely colours, lime green, pink, red, blue, orange, etc.

[Saar]

If it is not the EGR, try to remove the air inlet and upper half of the shroud, so you will be able to see the water pump.
Turn the engine on and look at it - be careful, do not insert your hands while the engine works!
Maybe it is leaking.

Saar.
(I have an article in my blog about overheating, I wrote it after I had some issues with the cooling system)

[Big S]

I finally got a bit of time off work. Today I have blanked off the EGR valve and bypassed the EGR cooler. I have also replaced the expansion bottle as I suspect the original one may have a hairline crack. I have a trip with the caravan planned for next week so I will see what happens...

[Big S]

Well that didn't make any difference...

[David Cawdell]

I am so grateful for the help received on here that I thought I will provide the lessons that I have learnt.
Having lent my pajero to my son with a warning that there was an undetected slow water leak he returned it having 'cooked ' the head and blown the gasket.
After replacing the head the leak was still there and after frustrating experiments and hours of reading this forum....
I used the overflow tube to the plastic bottle to attach to my air compressor and put in 2bar pressure..Hay presto the leak was obvious and coming from the water pump shaft seal
The overheating had caused another problem in that the temperature gauge didnt work. the temp sensor had been dmaged but I couldnt find which one it ws..and as a result of this post I was able to solve this problem  as well...THANKS

Whilst doing all this a starting problem was cured by getting someone from near bournmouth to come all the way to loughborough and change the front seal on the injector pump for £150..what a star...details will be provided to anyone interested.