V6 Head Gasket Failure

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Once agin "thanks" Retsgom. If it reduced my bill from £1500 to £500, then I think yo charges are a good deal!

Only thing is - I aint sent the letter yet, I woz waiting to see what happened with kicking up a fuss - it seemed to work. The letter was the next campaign in the war, but they capitulated :)

you and Mondeo had free drinks all last night at the Gaylander, but no-one turned up. lol
 
The Mad Hat Man said:
blurry 'ek
remote thermo
engine oil cooler
gearbox oil cooler
is there no end to the expense?

answer = no

dont worry about remote thermo mad hat, v6 already has remote thermo. one of the ingress is directly from the engine.
engine & gearbox oil cooler are around AU$350 aprox if you fit yourself. hmmm...yes it is still called exnpense :D
 
my V6 dont have remote Thermo. it is in centre of the V - see piccy.
 

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The Mad Hat Man said:
my V6 dont have remote Thermo. it is in centre of the V - see piccy.

Hi Mad hat,
As far as I know remote thermostat is for 1.8 (dont why they call it remote, maybe because the location is moved to just behid rad).
With remote thermostat, the thermostat read the coolant temp directly from cylinder block. With the old thermostat in 1.8, It read coolant temp from radiator.

This is from Rave CD for KV6 "Coolant returning to the thermostat housing, from the cylinder block, the coolers and the heater matrix, bypasses the
thermostat and flows back to the coolant pump inlet to begin the cycle again."
So it is working just like remote thermostat for 1.8.

Can you clarify this, since they are working on your. can you ask them to take off the housing and whether there is coolant flow from cylinder block to thermostat through the bottom of thermosrtat housing :D

If it so and I think KV6 might suffer from uneven engine temp between the two banks since coolant from one bank goes directly to housing and the other bank goes to rad. so the bank that goes to rad might be warmer than the other bank. what you guys think?

HGF is result because of either thermal shock, HG do not withstand high temp, or head bolt strecth because high temp. so the common word is TEMP.

Bottom line is, making the temp even and a little bit cooler by making mods (Even my mate 1.8 still get HGF after he has remote thermostat. Now he is bypassing some amount of coolant from rad over the thermostat just to make it cooler. It takes around 15 minute to get the temp gauge to mid mark) will help avoid HGF. *hopefully* worth a try :D




 
Thermo housing definnately fits into block, however I dont know if coolant is flowing from block into thermo, or from thermo into block, Mine are being replaced (I think) so I will endevour to get old one to "investigate". Will report back when I have more info.
Certainly an electric water pump and a thermo which fits into output from block rather than input would help. I refer to article already mentioned. I will copy section and post below.
 
Fixing the Problems
As a 1.8 litre there are, or were, two minor problems, design features of the basic engine which did give rise to problems when the engine was tuned. The first is the positioning of the thermostat in the cooling system, which was not designed for engines frequently put under heavy load. It was first designed as an efficient engine for lightweight front wheel drive cars, typically the Rover Metro and the current Rover 25, with good fuel consumption and requiring low emissions from start-up when the car was likely to see a large number of very short inner city journeys. It was thus designed to give very rapid warm up by placing the thermostat at the coolant inlet to the engine, where the thermostat measures essentially cooled water from the radiator with a very small quantity of heated water from the balancing circuit until the stat opens. This is a very unusual coolant path design, but is effective in its required purpose.

The system does not function well in cooling circuits with a radiator a long way from the engine in the cooling path, or for engines constantly seeing high engine speeds .The problem arises when the engine is put under heavy load, causing high engine temperatures that are not immediately read by the thermostat because cold water in the radiator and hoses has to pass the thermostat first. This can cause enormous thermal gradients across the engine, causing both distortion of the head and block and also gasket failure. The vehicle which suffered most from this was the Land Rover Freelander. Apparently, the typical owner for this vehicle is the middle class housewife and mother who use it for large numbers of short shopping trips to the supermarket!! Being heavy and 4x4, the 1.8 litre K’s tend to be pushed very hard from cold. This results in the engine getting very hot before the water can circulate and open the thermostat. Result – blown gasket. Early last year, Rover introduced a new thermostat, the PRT thermostat that will open with pressure as well as temperature, the result is that it opens much more quickly and prevents this thermal shock across the engine. There still appear to be problems with the Freelander, amid concerns that Ford have already executed a cost down on this new thermostat. However, it is quite apparent that as soon as the thermostat is moved to the output on the engine that temperature related gasket failure no longer becomes an issue. It is something of a surprise therefore that the Ford engineers concerned with the installation and performance of the K in the Freelander do not adopt this simple approach. The PRT thermostat is also a very expensive item that must be an issue with such pressure for cost downs. However effective the PRT thermostat is for a road car, a far more effective solution for any engine used on the track, and in fact any Elise with its problematic long coolant hose runs is to move the thermostat to the output side of the engine. Both Elise Parts.com and QED do inexpensive remote thermostat housings for this purpose. When one of these units is employed, the thermostat is measuring the engine temperature and is therefore able to control the coolant temperature quickly and sensitively.

Removing the thermostat altogether, as currently practiced by some, is no solution, firstly because engine warm-up becomes protracted, with all the implications for premature engine wear and secondly, because the engine temperature is at the mercy of the pump speed, if engine speed falls, the coolant in the radiator will cool disproportionately, then as soon as engine speed builds and engine temperature with it, the pump speeds to sends a mass of very cold water from the radiator suddenly to the engine. There is no thermostat to even this process out so the engine is repeatedly subjected to thermal shock. Bad for the head, bad for the block, and sooner or later the gasket will go. Fit the thermostat to the coolant output and the extreme temperature gradients that beset the engine when used on the track are significantly mitigated.


Ignoring the bit about middle-aged housewives. In summary, The important bts are...
The Thermostat is on the RETURN path from the radiator, not the OUTPUT path.
The engine suffers from Thermal shock due to its design.
The V6 is, by nature a high reving engine, unlike a diesel, this leads to the critisism of the use of the Jatco box, which, by all accounts is not the best at coping with gearchanges at high revs. A necessity when linked to the V6 engine.

This where I suggest the use of an electric water pump to even out flow rates, and a remote Thermostat in the water OUTLET line, both would help aleviate the problem of thermal shock. We cannot do anything about disproportionate cooling across the "V" in a transverse mounted engine. - An in-line engine/box, such as in the Discos would be a better option, hence the discussions on V8's - unfortunately the Hippo is just not "Man enuf" to take it.
 
and breathe........


Also the rear bank of the V gets twice as hot as the front due the proximity of the bulkhead and the lack air flow compared to the front.

I had a V6 Calibra which suffered head geasket failure, the engine was located close to the bulkhead like the KV6 and the thermo-stat was located in the same place.

Must be common in alot of other manufacturers.
 
The Mad Hat Man said:
Thermo housing definnately fits into block, however I dont know if coolant is flowing from block into thermo, or from thermo into block, Mine are being replaced (I think) so I will endevour to get old one to "investigate". Will report back when I have more info.
Certainly an electric water pump and a thermo which fits into output from block rather than input would help. I refer to article already mentioned. I will copy section and post below.

The Mad Hat Man said:
Thermo housing definnately fits into block, however I dont know if coolant is flowing from block into thermo, or from thermo into block, Mine are being replaced (I think) so I will endevour to get old one to "investigate". Will report back when I have more info.
Certainly an electric water pump and a thermo which fits into output from block rather than input would help. I refer to article already mentioned. I will copy section and post below.

Yes you are right. a thermo which fits into output from block is a must. If you can find out about your old thermo would be very good. and what treev is also true, the other bank is twice as hot as the other bank.solution??
 
dearot said:
Yes you are right. a thermo which fits into output from block is a must. If you can find out about your old thermo would be very good. and what treev is also true, the other bank is twice as hot as the other bank.solution??

not sure there is an easy solution. The obvious answers are....
turn the V6 so its in-line not tranverse (cant do)
Fit the return coolant pipe into the rear bank of the "V" ,therby cooling that bank first with the cooler water. Without a thorough knowledge of thermal dynamics and the physical capacity to fit the pipe into the rear bank, this is also unlikely to be achievable.

I can only think that if the heat is removed from the gearbox so there is a lower amount of heat to transfer to the block, and the coolant is kept to a more uniform temperature, these would be the best that can be practicaly achieved. ie

lower the heat being produced.
remove the heat as quickly as possible.
 
When you park up the amount of latent heat must cook the rear V block. In Vauxhalls and Saab's they use a secondary electric water pump to get cool water to the rear block while the fan runs also.

I can't remember if the Freelander has one, i doubt it does.
 
Should be easy to find parts.

There are tons of V6 Calibra's to rob parts out of cos they suffer with pre-mature cam belt failure which ends up with 24 bent valves.

Suddenly head gasket failure doesn't look so bad.
 
Thoughts just occured to me......

where is the coolant temperature sensor situated - is it in the inlet or outlet side of the coolant system?

any ideas
 
The Mad Hat Man said:
Thoughts just occured to me......

where is the coolant temperature sensor situated - is it in the inlet or outlet side of the coolant system?

any ideas

its in the outlet of rad
 
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