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overheating


rangie boy
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Hi All, i have as suggested looked back over numerous blogs about this subject including various links has been helpful but not entirely convinced. I have a 4.6 Range Rover 1996 with LPG conversion 128K miles. The car will run fine for 2 or 3 days then the temp guage goes up then drops back to normal one a while then returns steady, this can happen at speed on motorway and also in traffic. There is no emulsified water/oil present and no white smoke. sometimes the expansion tank is at normal level and other times it bubbles out the top when unscrewing the cap but never seems to lose coolant. It has had a new radiator, all new hoses fitted, i have contacted numerous 'speacilist' range rover garages and most seem to condemn the car without even lifting the bonnet, i have had everything from, cracked block, slipped liners, duff thermostat, duff viscous coupling, no thermostat, "you need a new engine mate £4-5K!!!" "they always go these 4.6 mate dont even need to look at engine". I am at a loss who to believe, anyone got any ideas, if the block is cracked then maybe then I can make a judgement and scrap seems a shame as it is in excellent condition autograpgh model special vehicle circa £72K new. Ahh the joys of RR ownership!!! many thanks Ken

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Well there's a lot it could be.

Why a new rad? was it doing this before or was the rad leaking? where is the rad from and is it new?

Have you got a new viscous coupling? I had to swap mine and can't believe the difference to be honest, the old one wasn't doing enough when the rad got too hot. Mine would buld up heat on a long drag then overheat when the car (and the air throught the rad) slowed down.

Is the water pump good, have you swapped or binned the thermostat? have you checked for a blocked block.

If it's not drinking water then don't panic yet, there's loads of other stuff it can be but for heavens sake be careful of overheating that block.

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Start with the basics (cheap and simple bits) - is the thermostat a genuine one & does it work? Is it mounted with the vent hole upwards to prevent air locks? (I had two non-gen stats in a row which did this, sent the needle off into the red and then pinged open and dropped back, just every-so-often <_< ). A quick cheat is to cut the centre out of the stat and refit (you need some restriction there for correct coolant flow), if it works then great, if not then you've not lost anything.

The 4.6 suffers heavily from idiots who believe every problem with it is a cracked block/slipped liner, chances are if it had a flat tyre they'd tell you the liners had slipped :rolleyes:

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Start with the basics (cheap and simple bits) - is the thermostat a genuine one & does it work? Is it mounted with the vent hole upwards to prevent air locks? (I had two non-gen stats in a row which did this, sent the needle off into the red and then pinged open and dropped back, just every-so-often <_< ). A quick cheat is to cut the centre out of the stat and refit (you need some restriction there for correct coolant flow), if it works then great, if not then you've not lost anything.

The 4.6 suffers heavily from idiots who believe every problem with it is a cracked block/slipped liner, chances are if it had a flat tyre they'd tell you the liners had slipped :rolleyes:

The p38's have a different style thermostat to the earlier. Quite a clever system.

It's a little plastic "bowl" that sits in the lower hose as it exits the radiator. It has a few pipes coming into it (i.e. return from heater matrix, top hose bypass etc.

This might be faulty ?????

range_rover_p38_thermostat.jpg

There are 2 slightly different plumbing combinations, depending on year :

post-9903-0-98629000-1299673935_thumb.jpg post-9903-0-70074600-1299673946_thumb.jpg post-9903-0-46449300-1299673954_thumb.jpg

Hope this helps

Gordon

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Well there's a lot it could be.

Why a new rad? was it doing this before or was the rad leaking? where is the rad from and is it new?

Have you got a new viscous coupling? I had to swap mine and can't believe the difference to be honest, the old one wasn't doing enough when the rad got too hot. Mine would buld up heat on a long drag then overheat when the car (and the air throught the rad) slowed down.

Is the water pump good, have you swapped or binned the thermostat? have you checked for a blocked block.

If it's not drinking water then don't panic yet, there's loads of other stuff it can be but for heavens sake be careful of overheating that block.

Hi

thanks for response, the radiator was new when I bought the car, is genuine and new not recon, have not changed the viscous coupling yet, will check stat and water pump the weekend, one of the 'speacilist' said there was no stat' but he did not even know where the stat was so he knew that I will never know!!

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Start with the basics (cheap and simple bits) - is the thermostat a genuine one & does it work? Is it mounted with the vent hole upwards to prevent air locks? (I had two non-gen stats in a row which did this, sent the needle off into the red and then pinged open and dropped back, just every-so-often <_< ). A quick cheat is to cut the centre out of the stat and refit (you need some restriction there for correct coolant flow), if it works then great, if not then you've not lost anything.

The 4.6 suffers heavily from idiots who believe every problem with it is a cracked block/slipped liner, chances are if it had a flat tyre they'd tell you the liners had slipped :rolleyes:

Hi thanks for reply, will order new stat and try the weekend, love the gag about flat tyre, sooooooooo true!!!

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The p38's have a different style thermostat to the earlier. Quite a clever system.

It's a little plastic "bowl" that sits in the lower hose as it exits the radiator. It has a few pipes coming into it (i.e. return from heater matrix, top hose bypass etc.

This might be faulty ?????

range_rover_p38_thermostat.jpg

There are 2 slightly different plumbing combinations, depending on year :

post-9903-0-98629000-1299673935_thumb.jpg post-9903-0-70074600-1299673946_thumb.jpg post-9903-0-46449300-1299673954_thumb.jpg

Hope this helps

Gordon

Hi Gordon

sorry for delay, have been working overtime in anticipation of big bills for the car!!!! will order stat and try the weekend

kind regards

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