Overheating?

[andrewwild]

Hi all, need help diagnosing what appears to be an overheating issue.

Car can run for a distance of 5 or so miles and the guage will begin to rise until it reaches 3/4, at this point you can see bubbles rising in the expansion tank.
I can release pressure, top up and continue the journey with no issues, however I can then complete the whole return journey of around 20+ miles with no issue atall.

However I have noticed that the temperature quage will go to 3/4 when warming up before then cooling, and when the car is not overheating the guage will sit between 1/4 and a half which seems abit cool to me.

There is no gunk in the water, New radiator was fitted earlier in the year, thermostat has been checked and replaced to eliminate that, and the water pump appears to be pumping the water.

Would it be the headgasket, as the water appears to be clear with no gunk, and the guage will not go above 3/4 even if I keep driving?

Many Thanks, Andy

[Karlos]

Hello,

First off which model of Dolomite do you have, I guess a Sprint? Secondly do you check the coolant level before setting off and on completion of the 20 mile journey?

[Karlos]

Also did you fit the dual valve type thermostat - the one with the foot on the bottom of it? Like this one:
http://www.ebay.co.uk/itm/like/19181644 ... 122&ff19=0

[andrewwild]

It's a 1980 1850Hl, It has the correct thermostat fitted, have checked and replaced to eliminate it from suspicion.

The level in the expansion never lowers, infact it rises, even if I ensure it has the perfect amount in, the bottle is always full to the brim after a drive and never drops back, yet i am able to fill through the thermostat housing with not far off two litres after the scenario has taken place.

[Flyfisherman]

Andrew

Sound like you have a air lock in the system - are you refilling the water system from cold with the heater control in the "HOT" position and there is a special proceedure for filling and bleeding the water system - All to reduce the possibility of air locks.

Paul

[Carledo]

Its normal for the expansion bottle level to not alter, or rise and also for the system to need filling from the stat housing.
My next step would be to check the pressure cap as the pressure on warm up with the stat closed may be enough to overcome the cap.
I am a little concerned about the bubbles rising in the header, but don't rush to blame the H/G till you've checked out all other possibilities.
A persistent airlock is also possible, as mentioned above but the problem is a bit too consistent for that. I'm also concerned that the temp goes up to 3/4 before the stat opens and it drops back, this suggests that either the new stat is opening late, or (if it was the same with the original fitted) that the guage is over reading (also a not uncommon problem)

Steve

[Karlos]

Sounds like the head gasket is possibly on its way out and so the coolant is being forced out of the engine and into the expansion bottle. If you have eliminated everything else then I would try re-torque-tightening the cylinder head nuts/bolts.

[Mahesh]

Only a suggestion, I would get another thermostat and a temp sensor from a different supplier and check/change the voltage regulator above the fuse box before getting into heavy handed work.

[andrewwild]

Definately not the thermostat, all thermostats have been checked and it bahaves the same way regardless of which thermostat is fitted.

The system has been fully bled several times, even going as far as using a special device to completely suck all air out of the system, this worked as all the hoses went completely flat, then refilled again using the system, still behaved the same way.

Voltage regulator is new, again behaves the same way, I'm running out of ideas, even fitted a new pressure cap, its a tight fit.

Only things left that I can think of are headgasket and water pump, though that appears to be pumping the water just fine, I'm even wondering if the new Radiator I got is a dud, sometimes the pipes dont feel hot enough, even one side of the radiator appears cooler than the other

[Mahesh]

Have you got the old radiator, or know someone who has a spare.

[GTS290N]

I had the same on my 1850, the hg had gone allowing a leak from one of the chambers into the coolant.

[Karlos]

I had the same on my 1850, the hg had gone allowing a leak from one of the chambers into the coolant.

Sounds right. Symptoms of over pressurised system/dumping the coolant along with bubbles in the expansion tank are indicating HG failure.

[sprint95m]

You need to now do a compression test, Andy.




Ian.

[soe8m]

These discussions do make me always wonder don't they have in the UK a chemical tester? 100% diagnose to leak or not to leak. No question.

Jeroen

[GTS290N]

These discussions do make me always wonder don't they have in the UK a chemical tester? 100% diagnose to leak or not to leak. No question.

Jeroen

Like this?
http://www.ebay.co.uk/itm/COMBUSTION-LE ... SwJQdXAq3f