V6 Boiling/pressuring Up.

[eupho]

A couple of days ago, after a bitterly cold night, I had problems with 1997 V6 overheating(after about ten miles). The pressure in the header tank was high and a lot of water was lost as I released the cap a number of times. Assuming that perhaps there was some frozen blockage, I left it for a couple of hours then drove home, seemingly without a problem, although I did not actually check under the bonnet. But it has now done the same twice in last 24hours.

 

It tends to run cool normally, near the N on the gauge, so rightly or perhaps wrongly I think that the thermostat is not the reason, in that it perhaps never fully closes anyway. If this is logical then clearly I need to look elsewhere. I have read a number of threads concerning faulty header caps. But surely if the seal was not good then pressure would escape rather than build up?

 

I am assuming that if all else is well, maybe the head gasket is blowing, pressurising the cooling system.

 

What other checks could I make ? I have solved a number a problems thanks to other members, which I much appreciate, and am again optimistic.Thanks in anticipation.

Tom

[?Bleeno?]

Tom before you start thinking about the head gasket and with the icy weather we've been having have a look at all the cooling pipes very carefully, particularly the joints. Look for any signs of fluid leakage and check the tightness of the joints. The next thing to check is whether or not the water pump impellor is still attached (There are threads on here that include a check on how to find out). Although a blown head gasket would give you similar symptoms, a leaky pipe will do the same due to the system not pressurizing correctly and therefore the water starts to boil and produce steam. Thats one reason you shouldn't remove the water expansion tank cap on a hot engine.

[eupho]

Thanks for advice. I have tried to find advice in respect of checking water impellor but cannot find a thread for V6. Any help please.

 

Thanks for science lesson, I assume therefore that water under pressure boils at a higher temperature.

 

Tom

[sepulchrave]

eupho, is there any reason why you would suspect frozen coolant Like does it have tap water in it's veins?

 

If not, then I really do suggest that a dodgy thermostat is the most likely culprit.

[snapper]

Had the same problem, replaced the water pump yesterday put it all back together today and took it on a run... guess what still gets very hot after 5 to 7 miles.

Fitted new drive belt and will test again tommorow.

I can let it idle all day but as soon as i drive it temp just keeps rising.

Thermostat and housing for me then see what happens.

 

I am not loosing any fluid and the oil seems clear, no abnormal smoke as far as i can tell in this cold weather.

[eupho]

Drained the cooling system down, by removing bottom hose as recommended in Peter Russeks excellent manual. However as the cooling system is 9litres, am surprised that on refilling it only took about 5+litres. I am not quite sure on how the plumbing is arranged on these. I did all the right things, including making sure that the heater was set to hot. I am about to go and check thermostat. The link of FAQ is fine for the stripping of the housing but doesnt mention removing it in the first place. I hope that the assembly is only held in place with 5mm hex bolts?

 

Thanks for advice in anticipation.

Tom

[snapper]

Same problem as eupho, can't see enough of the thermostat housing or feel enough to get at the bolts that hold the housing to the block.