V8 3.9 overheating

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daven2695

New Member
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19
Hi, Just been away with the caravan over easter and the Disco overheated and lost most of the coolant whilst going up a steep long climb, let her cool down refilled

Apart from having to top up with about 2 litres of coolant she has since covered about 400 miles with no real problems including a trip round Knowlsey Safari Park ( about 2 hours of stop/start very slow moving on a very warm day) and another 90 odd miles with caravan on back and the only time the gauge moved off normal was again a long steep climb (with the van on) but this time although the needle was going up she did'nt overheat. I have had to put in another litre of coolant this morning.

There are no signs of a water leak, there is no oil in water or visa versa, the heater matix seems fine the front carpets are bone dry. Has anyone any ideas what the cause of the coolant loss could be? I have heard of a problem with the later 4 and 4.6 litre engines of "porous blocks" but don't really have any details and don't know if this problem affects the earlier motors.

The car has covered almost 220,000miles has been on LPG since 29,000, she starts and runs very well, very smooth and has plenty of power.

Any Ideas please. Dave
 
dave.i,ve got the same problem with mine,no leaks etc.have you had head gasket test?check inside the oil filler cap for white gunky stuff.mines got a build up off pressure in the sysstem i,m gonna change waterpump when i do the camshaft.best of luck cheers craig
 
My disco had a small hole in the heater hoses... In particular the last section as it enters into the block.. Not big enough to let water out, but enough to leave air in and cause a vapour lock :((

mjc
 
Hi, Just been away with the caravan over easter and the Disco overheated and lost most of the coolant whilst going up a steep long climb, let her cool down refilled

Apart from having to top up with about 2 litres of coolant she has since covered about 400 miles with no real problems including a trip round Knowlsey Safari Park ( about 2 hours of stop/start very slow moving on a very warm day) and another 90 odd miles with caravan on back and the only time the gauge moved off normal was again a long steep climb (with the van on) but this time although the needle was going up she did'nt overheat. I have had to put in another litre of coolant this morning.

There are no signs of a water leak, there is no oil in water or visa versa, the heater matix seems fine the front carpets are bone dry. Has anyone any ideas what the cause of the coolant loss could be? I have heard of a problem with the later 4 and 4.6 litre engines of "porous blocks" but don't really have any details and don't know if this problem affects the earlier motors.

The car has covered almost 220,000miles has been on LPG since 29,000, she starts and runs very well, very smooth and has plenty of power.

Any Ideas please. Dave

Sounds to me like the head gasket is leaking coolant into the bores and buring off. If it is then it will get worse.
 
Thanks for the replies, going to get it pressure tested and then will do the heads, I'll let you know the progress. Dave
 
I have an M reg 3.9 V8. Had the same problem as Dave so had the heads off, skimmed, new headgaskets, new water pump, new seals etc & a full service etc. No sign of water loss before, or after. Left to run for whole day and fine, took out a few times & fine. On one occasion I watched the needle go sky high from just under the half way mark and it spat the contents of the water resovoir out. Cooled down, topped it up and has been fine since. This happened before I got the heads done so am getting paranoid now. Any further advice available please as this is wierd !
 
Always change the thermostat, and if rebuilding after a skim, use composite head gaskets, not tin ones.

Bleeding of the cooling system and use of the correct coolant is critical on the V8, any air in the system will cause an air lock if it gets into the pump.

Peter
 
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