Persistent Thermostat Problems... I Think...

[mc9320]

Last month I had a coolant leak in my Ford Focus Zetec 1.6, caused by a faulty thermostat which a Ford garage replaced. A couple of weeks later I checked the car and the coolant was at the minimum level! I took it to a local garage and they said this new leak was caused by a faulty head gasket, due to the initial problem from the first leak. They replaced the head gasket and water pump.

However, as soon as I picked up the car from the garage, the temperature gauge went into the red after driving for a few minutes. I know the engine wasn't overheating and there was no coolant leak, so I took it back to the garage and they said the most likely reason was a faulty thermostat.

They didn't have one in stock so they removed the thermostat and said they would order one for me.

I drove for a week without a thermostat and had no problems. However, when they put in a new thermostat, the same problem happened again i.e temperature gauge in red, but engine not overheating and no coolant leak. The garage cannot understand what the problem is so they removed the thermostat again and the car seems to be running fine at the moment.

Have I been just unlucky with thermostats? Or could it be another issue?? The car seems to be running fine without one. I'm taking it back to the garage in a week or so...

Any help would be appreciated.

[taffg]

Last month I had a coolant leak in my Ford Focus Zetec 1.6, caused by a faulty thermostat which a Ford garage replaced. A couple of weeks later I checked the car and the coolant was at the minimum level! I took it to a local garage and they said this new leak was caused by a faulty head gasket, due to the initial problem from the first leak. They replaced the head gasket and water pump.

However, as soon as I picked up the car from the garage, the temperature gauge went into the red after driving for a few minutes. I know the engine wasn't overheating and there was no coolant leak, so I took it back to the garage and they said the most likely reason was a faulty thermostat.

They didn't have one in stock so they removed the thermostat and said they would order one for me.

I drove for a week without a thermostat and had no problems. However, when they put in a new thermostat, the same problem happened again i.e temperature gauge in red, but engine not overheating and no coolant leak. The garage cannot understand what the problem is so they removed the thermostat again and the car seems to be running fine at the moment.

Have I been just unlucky with thermostats? Or could it be another issue?? The car seems to be running fine without one. I'm taking it back to the garage in a week or so...

Any help would be appreciated.

hi mc9320 ive read your problem and i have a few queries over your problem.

you initially had a leak due to a faulty thermostat, however the thermostat is housed in its own housing which has its own sealing ring and is prone to leaking, did your car overheat before the thermostat was changed at the ford garage? also did the car overheat after the thermostat was changed. you could expect the coolant level to settle over a few days as it self bleeds and may just have needed topping up. also i find it highly unusual that a ford workshop would miss a leaking head gasket. also with a leaking head gasket you usually get a few more symptoms,ie loss of power, creamy oil, white vapour out of exhaust.

so the local garage reckoned the heaad gasket had gone, was the car overheating then? and why did they change the water pump your only symptom at the moment was a collant level on the min mark, and for the life of me i cannot see a thermostat leak causing a head gasket failure unless the engine boiled ovet to an extreme degree. the focus has in built fail safe cooling protection.

stage 1: the cylinder head temperature sensor senses the temp and sends a single to the engine ecu which moves the gauge into the red zone. if the engine is not switched off and the temp continues to rise the multi function light will illuminate. does yours?

stage 2: the ecu will control the engine by cutting out 2 cylinders and restricting the engine to below 3000 rpm. when this occurs the engine warning light will also illuminate.

stage 3: if the engine temperature continues to rise then the engine will be totally disabled to prevent serious engine damage, also the engine warning light will flash showing the the driver the engine will stop in 30 seconds.

so i dont think yor engine has overheated at any point and i may be somewhat disingenuous to your local garage but i am scheptical the head gasket or the coolant pump needed work.

you should have gone back to the ford garage after they replaced the thermostat and got them to check theyre work.

however an easy way to check the thermostat is to boil some water, using a piece of wire dunk the themostat in the hot water give it a few mins and then remove, you will easily see if the thermostat is opening, as it cools it will close. the thermostat needs to be fitted correctly, in the correct orientation with the small air bleed hole in the thermostat uppermost when fitted. ensure all hoses are fully bled you may have an air lock somewhere causing the high temp indication, however have them check the cylinder head temp sensor as this may be faulty or have a poor connection, as this controls the temp gauge and the cooling fans. also the head gasket was replaced and unless fitted correctly they may well have blocked some of the cooling water ports on the cylinder head or engine block

hope this info helps and maybe you could ask a few more pointed questions of your garage.!

[RustyNail]

I have exactly the same problem with the temp gauge going into the red every so often.

If the engine is sitting idling (i.e sitting in queue of traffic for 10 mins) there is no problem. As soon as I am on a longish run at mway speeds it will suddenly go into the red. If I turn the heating up full blast 8/10 times it will make the gauge go to normal.

The (non Ford)garage have done the following so far.

Replaced the thermostat twice.

Replaced the radiator.

Removed the thermostat and this seems to cure the problem.

There are apparently no leaks in the system, however the water levels drop occasionally and need refilling up to the max mark but not always.

When opening the coolant bottle sometimes there is a rush of air and the coolant level goes up to the max line.

There are no signs that it is the head gasket. The water pump appears to be functioning.

I need to get this sorted as I am looking to sell the car as I want to buy a newer model.

Any ides would be appreciated.

[btmaldon]

Try changing the expansion tank cap. If its not holding the pressure the coolant will boil at a lower temperature and stopping the coolant from circulating properly.

My Father in Law had a similar problem. A garage looked at it and decided it was the head gasket. Cost him £700 and it still overheated. I changed the cap and no problem after that.

[artscot79]

Try changing the expansion tank cap. If its not holding the pressure the coolant will boil at a lower temperature and stopping the coolant from circulating properly.

My Father in Law had a similar problem. A garage looked at it and decided it was the head gasket. Cost him £700 and it still overheated. I changed the cap and no problem after that.

must admit this one is strange i cannot believe ford would miss a faulty or gone head gasket either i would try the expansion cap as well and in response to the other post when the systems working it pressurises this pressure increases the boiling point of the coolant it also creates a partial vacum so opening the cap will release air thats the pressure dropping as the airs released no vacum means the coolant level will rise when left the coolant cools and the vacum pulls it back into the sytem coolant level returns to normal make sure the upper hose hasnt collapsed due to the reverse vacum if you release it put the cap on theres no vacum to suck the hot coolant back so the hose collapses on itself take the car to ford independants dont have a clue theres a valve on the heater hose that could be the issue as well as a fauklty temp sensor saying the cars hotter than it actually is has ayone done the dash trick and watched the enine temp and seen ifg the fan cuts in

[IMW]

I had a similar problem on a Rover 400 - it turned out to be the thermostat housing that was the culprit. It had earlier passed an AA roadside pressure check for leaks but fortunately a garage found the solution.

[RustyNail]

must admit this one is strange i cannot believe ford would miss a faulty or gone head gasket either i would try the expansion cap as well and in response to the other post when the systems working it pressurises this pressure increases the boiling point of the coolant it also creates a partial vacum so opening the cap will release air thats the pressure dropping as the airs released no vacum means the coolant level will rise when left the coolant cools and the vacum pulls it back into the sytem coolant level returns to normal make sure the upper hose hasnt collapsed due to the reverse vacum if you release it put the cap on theres no vacum to suck the hot coolant back so the hose collapses on itself take the car to ford independants dont have a clue theres a valve on the heater hose that could be the issue as well as a fauklty temp sensor saying the cars hotter than it actually is has ayone done the dash trick and watched the enine temp and seen ifg the fan cuts in

Thanks for the suggestions btmaldon and artscot79, will look at these over the next few days.

Just as an aside, my wife drove to an relatives tonight 23 miles, and it went into the red 5 times putting the heater on full blast cured it!

However when I drove back the reverse journey same speeds, it did not happen once.