Help Needed - Overheating Mk2, Thermo Replaced

[Galaxy_Quest]

Hi folks,

 

Hope you can help - need some technical minds on this.

 

Background

A couple of weeks ago our Mk2 Galaxy 2.3 petrol (W reg, 154k), overheated for the first time reaching the maximum and the warning STOP! light coming on. 

 

I stopped, rested, then pootled to a local garage 3 mins away. A pipe had more or less exploded, emptying out coolant everywhere. I figured out that was the "in-line" thermostat housed in the coolant pipework T-junction at the rear of the engine bay (under the wipers / cowling).

 

Problem

I have now replaced it (3 awkward spring clips). The plastic was quite degraded and brittle in the pipes. I have topped up the coolant a couple of times. The car is still overheating, not on idle, but during driving after about 30 minutes. There is no coolant smell in the exhaust and no cloudy oil to suggest any head failures. 

 

I took it for a spin yesterday let it cool overnight. The coolant needs topping up (reservoir at minimum), but that could well be from replacing the part yesterday.

 

Car heats up to normal, as per usual, then after about 20 mins of driving slowly creeps up to max temperature. Pipes get warm / hot. Fans kick in at the right time. If I switch the car off and let it rest for 5 mins, temp gauge returns to normal.

 

History

Aircon has been down for years, we had condenser / compressors / regas, spent virt.

[seatkid]

I'm not familiar with the ford petrol engines, but I would suggest the two possibilities in order of likiehood are water pump failure, or a blocked radiator.

[xavier]

The Mk1's had a thermostat cover on the block, not sure if the mk2 has the same. I'd check there's not  a thermostat in there if you have it.

[sparky Paul]

As xavier says, the 2.3 should have the 3-way thermostat in the pipework, and nothing in the thermostat housing on the end of the cylinder head. A thermostat is sometimes mistakenly fitted here, and this can cause all sorts of problems, however I'm guessing that this is not a new car to you and that the problem occurred suddenly.

 

This leaves a couple of scenarios - either the system pressurised suddenly and found a weak point, i.e. the thermostat housing, or a defect in the housing caused it to burst, and subsequently caused some other damage due to sudden loss of coolant. It doesn't take long to do damage after a sudden loss of coolant, the loss of pressure causes the coolant to boil and much coolant can be ejected from the system, leaving the engine completely unprotected.

 

The 2.3 is an extremely robust engine, but you do hear of the occasional head gasket failure. I don't think they tend to leak coolant into the oil, so I would still be looking for signs of HGF, and/or cracked head. Any smell of combustion gases in the coolant? Is the system over-pressurising?

[Galaxy_Quest]

Thanks for the replies folks.

 

Went to my friend's garage today and he recommended changing the temperature sensor - which we did. Its an external piece mounted in the pipework to to the right of the head. Could have been a quick cheap fix but alas, 30 mins later it overheated on the way home.

 

There is no sign of coolant in the oil or exhaust, the coolant doesn't seem to be pressurising. The pipes are getting hot and water appears to be circulating well (if I disconnect a hose it pumps coolant out). We have a new ford main dealer ordered in-line thermostat and temp. sensor.

 

Still no ideas what's causing the over heating. We will be risking a 40 minute drive. Windows open, heaters on full blast this weekend!

[chromedome]

I'm thinking radiator blockage. I know it's sounds stupid but have you checked that something is not covering the radiator, plastic bag, etc.

[sparky Paul]

Another silly question, are you sure that the 3-way thermostat was fitted the right way round?

 

I would also add that the lack of coolant in the exhaust or oil does not necessarily rule out HGF. The first signs of HGF is almost always combustion gases in the coolant - you could get a combustion leak test done to rule it out.

 

Are you still losing coolant? IF you are, it's going somewhere.

Edited June 14, 2014 by sparky Paul

[Galaxy_Quest]

Thanks Sparky Paul and the others - silly questions welcome, sometimes its how we get stuff done.

 

Mrs drove the car, heaters on full blast windows open. Kept the temp at 90.

 

Will check in the morning on the coolant levels. I have to the best of my knowledge put the thermostat in the right way up based on the way the old one was put in. Will try and post pics.

[Galaxy_Quest]

Hi guys, sorry for the delay in responding.

 

The coolant levels are pretty static after all the air has worked itself out of the system. The only way we can keep the Gal from overheating when we drive more than about 40 mins is to have the blowers on full blast, drawing very hot air into the car and then windows open.

 

Not great in the summer.

 

When the fans come on, it sounds like the hovercraft in Southsea in Portsmouth has come in to land.

 

Any ideas anyone? 

[insanitybeard]

Is the water pump working? Quite often the impeller breaks and detaches from the shaft, therefore although the shaft may still be rotating ok, the pump isn't actually doing anything.

[sparky Paul]

Impeller not usually a problem on the Ford engine, but it's worth checking the simple things first.

 

Make sure that the coolant is flowing around the system properly. Start from cold, check the top rad hose to make sure hot coolant flows when the thermostat opens. Flow through the bottom hose should be noticeably cooler.

[xavier]

Hmm. Are the fans on all the time or when it gets hot? If they're like the 1.9, there's a sensor that operates the fans that's in the radiator, so I'd imagine they're getting hot and you're getting coolant flowing through them. Furthermore I'd expect there to be a decent flow of hot coolant as the fans would switch off once they had cooled the coolant in the rad (so it must be getting replaced). Where was the temp sensor you replaced located? Could there be an air lock at that position? For you to overheat a car with a working coolant system it must be getting pushed hard. Is the auto diff changing up / down correctly?

[Galaxy_Quest]

Is the water pump working? Quite often the impeller breaks and detaches from the shaft, therefore although the shaft may still be rotating ok, the pump isn't actually doing anything.

 

The pipes are getting hot, so I assume the pump is working. When I changed the in-line thermostat, I disconnected the pipes going to the reservoir tank to check there were no blocks in those pipes and the water seemed to be pumping out in a rhythm.

 

I don't know if that is evidence the pump is ok or not. 

 

Had to drive down the motorway yesterday, windows open, blowers going. It goes over 90 degrees when I go above 70mph (not that I ever do, of course!!).

[Galaxy_Quest]

Hmm. Are the fans on all the time or when it gets hot? If they're like the 1.9, there's a sensor that operates the fans that's in the radiator, so I'd imagine they're getting hot and you're getting coolant flowing through them. Furthermore I'd expect there to be a decent flow of hot coolant as the fans would switch off once they had cooled the coolant in the rad (so it must be getting replaced). Where was the temp sensor you replaced located? Could there be an air lock at that position? For you to overheat a car with a working coolant system it must be getting pushed hard. Is the auto diff changing up / down correctly?

The engine fans come on when it gets hot. We had them replaced a year ago when they were making a rattling noise.

 

It now sounds like a hovercraft coming down the road after about 20 mins on the road.

 

The temp sensor was located externally to the right of the head, it has a clip and push fits into the pipework.

 

Don't know about the auto diff - the car is very very sluggish between 0 - 40mph. I read somewhere that the octane rating (or something like that) can be set at the wrong level for the 2.3 Gals especially from a service. It used to be nippy, now sluggish and we have the overheating thing.

[chromedome]

Is it in third gear, limp home mode, all the time?

[xavier]

Do the autos have a rev counter? Can you see / hear it switching up and down ratios?

[Galaxy_Quest]

It doesn't seem to be in "limp home mode" just a little sluggish at low speeds - but it has been for a couple of years since a particular "service".

 

Gears and revs all seem normal.