Cooling system over pressureing 4.4 V8 L322

Hi,
I was wondering if you could help me, I'm having probs with my cooling system and was wondering if you could check somthing on your L322 4.4 V8 . My cooling system seems excessivily pressured, so much so that the hoses seam to be bulging !! Please could you open your bonnet after a run and feel your top rad hose and tell me what it feels like, mine is so hot you can hardly touch it and is really pressured up that I struggle to squeeze it at all. Also could you feel the bottom rad hose (front left, switch off engine otherwise will catch hand on viscous fan) And feel this hose for temperature mine feels cool to the touch and suspect the thermastat not opening.

I have had it on the diagnostics and it is reading 108 degrees which I believe to be too hot, any thoughts or ideas would be appreciated.

Thanks..............Adam

PS In the last couple of weeks I have had a new water pump, new radiator, new thermastat, new ECT (engine cooling teemperature sensor)

hi adam,sounds like an air lock ,or the stats in wrong,search through the posts on here im sure there was one on about the stat in wrong.if not either of those then could be gasket gone,you dont say why youve had those parts changed.just make sure the systems bled off correctly.hope this helps.

freelander22 said:

hi adam,sounds like an air lock ,or the stats in wrong,search through the posts on here im sure there was one on about the stat in wrong.if not either of those then could be gasket gone,you dont say why youve had those parts changed.just make sure the systems bled off correctly.hope this helps.

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Had cooling leak on pump and rad, changed both then found wiring melted to thermastat heater (due to previously been disturbed when pump was done) Replaced wiring and stat. The last time I had the stat out it was stamped with 105 degrees, in the workshop manual says the thermastat opens at 103 degrees and it controls the cooling system between 80-103 degrees. When on the diagnostics it is showing 108 degrees in engine and transmission box. Rad outlet sensor kicked up slightly from 69 to 72 degrees, but don't know if this is enough. When I had the stat out completly there is no pressure problems, but this is because the temperature is lower and therefore the pressure is lower. It is going in for it's second sniff test on thursday, but am not convinced with the thermastat but it was a genuine new landrover part, do these go wrong is it opening far enough, it is not as though I can stick it in a pan and watch it open.

I've done a search for stat and read some stuff but I think I have all the air out as the hose have been pulled off when I was filling the system and I waited till they all overflowed before connecting back up, did read that maybe my vapourizor on my gas system is as high as my overflow tank and could possibly have air there but I just can't see it (someone even fitted a bleed tap here). The fact that I'm getting this 108 degrees is bugging me and my rad outlet bottom pipe is still cold.

Thoughts ? a penny for them ? cars, aren't they great !

I have had the car tested today by my garrage, putting a large tube with 2 lots of coloured solution, on my water expansion tank. The theory is that if there are any exhaust gases getting into my cooling system then they will bubble through and change colour. Mine changed colour ! But not for ages until the car was well hot about 105-107 degrees on the diagnostics. Indicating that there is a start of a problem with the head gasket but it appears to only happen when the car gets to a critical temp, ie really hot and things expand enough to seap exhaust gases into the cooling system which then causes pressure problems.

What I have done to hopefully help/ iliminate / prolong failure, is to wire my electronic thermastat to ground, so that when ever the car is started the heated thermastat starts to warm up. How it normally works is that an ignition live is fed to one side of the thermastat heater and the other side goes to your ECU. When the ECU wants the thermastat to open fully because of it detecting big loads (towering or driving fast) it puts it down to ground to pre empt the impending extra heat generated from these activity's.

My mod means the result is that when the car is upto full heat it is running at 90 degrees instead of 105 degrees and isn't over pressured. (the design is to control between 80-103) with the electronic thermastat over riding and coming on at 113 degrees if the ECU hasn't already asked it to open.

I could have just removed the thermastat but this would have made the car take longer to heat up in the morning and as the electronic thermastat is only assisting the mechanical thermastat this wouldn't open until the cooling water is hot.

The temperature guage doesn't change as it isn't that sensitive. It will show exactly half way when it is between 80-103 degrees.

I would say that maybe the LPG conversion may not of helped as it does run a little hotter but could never know for sure. The 75000 miles and a possible over heat problem that happened prior to my ownership seams more plausable.

I would recommend anyone doing an LPG conversion on a L322 4.4 V8to also carry out this modification as preventitive maintenance to stop the car running any hotter than it needs to. The job takes 15 mins, you need to remove the top engine cover (4 allen keys bolts) take the plastic cover off the left hand wiring box, (this is about 1 foot long and is located over the left bank). Remove the plug/connector from the heated thermastat, confirm it has 2 wires going to it, one is red/blue 12V+ (ign live) the other is brown/white and goes to the ecu. Trace back these wires into the wiring box, scrape back the insulation on the brown/white wire (think there could be more than 1) and test with a multi meter that you have the correct one. Happy cut it, then check again with the multimeter that between the plug and the snipped wire you have continuety. Now connect this brown/white wire from the plug to a ground, I used a bolt in the engine bay top left where the brake resevour is. Get your multimeter check you now have 12 volts at your plug (when the ignition is on.) Put it all back together, the only way you can now check how hot your engine is running, is by sticking it on the diagnostic machine.

Think about the theory, does it make sense ? I believe this is the way forward to prevent an expensive job. I love my car, and really don't want to get rid of it or pay the thousands of pounds for head gasket repairs so maybe just maybe this will help ? I will now monitor. What I do know is that previously my car was running about 108 degrees and very pressured up on all hoses. Now running at 90 degrees and pressure is dramatically reduced, if the pressure is reduced this will help radiator, pump and hooses going as there is less strain on them.

I hope people read this and it helps...............................Adam

let me get this straight, You have had a sniffer test which confirms a head gasket fault, but instead of getting it repaired you are just going to make it run cooler by means of an electrical fiddle. Surely with a HG already leaking, the problem will just get worse regadless of engine temp. Seems to me you're just delaying the inevitable and run the risk af causing further problems.

save a penny and spend a few grand! Wouldnt advise anyone to do this, unless you fancy new heads and probably a new short motor!