Overheating after HGF Fix

Hi. Immeidiatly prior to my TF having a head gasket failure I tried solving the symptoms by adding Steel Seal to the coolant tank. Unfortunately it didn't work and the coolant turned into a wallpaper paste type gloop. Anyway, HGF fixed now and engine sounds good, but the garage can't seem to stop air blockages in the coolant which cause overheating. They reckon the steel seal has chrystalised in the heater matrix rads and is causing blockages leading to air blocks. Any ideas what to do next? I'm haemorrhaging cash on this car.....

Hi Martin.

Did the garage flush the coolant system out???.
If not try adding some washing powder to the expansion tank and running the engine for a while. Hopefully this will help to loosen the steel seal (only one fix for these engines and steel seal is not it). Drain the coolant system and refill, it could take a few time's. Keep refilling with fresh water adding the washing powder each time. Only refill with coolant once you're sure all of the sealant has been flushed out. Sorry I forgot to say between each refill use a hose pipe placed in the expansion tank and just flush away.

One more thing did the garage replace the expansion tank cap ???.

Hope the helps and don't forget to bleed from all 3 points.


:beer: :beer: Steve.

Mg rover solutions did the hgf repair on the wifes 'F a couple of years ago and struggled to stop it overheating due to the previous owner trying all the hgf "remedies" on the market before selling it on to us.

I took the heater matrix out and connected the pipes together then flushed the system out.

Got loads of gunk out of the system and quite a lot out of the matrix.

I have pictures somewhere of what came out.

I replaced the matrix with another one and bled the system thoroughly and haven't had a problem since.

Changing the matrix is a dash out job though so labour heavy if a garage is tasked with the job but not all that hard if your good on the spanners to some degree.

I've been working away from home for the past few weeks whilst the car went back to garage after being told that the radiator was blocked causing overheating and needed changing. my wifes had the car out a few times since but it still overheats after 5 miles or so. I'm home this weekend so apart:-? from checking and bleeding the 2 x bleed valves and radiator valve what else should I do?
I really need to drive the car back to Cornwall soon, 400+ miles, but it's just not capable unless I can stop it from overheating. The rubber hoses near the coolant bottle expand and bloat when it overheats, could they or the plastic coneectors be partially blocked?

It isn't clear in your post, but did you replace the radiator as advised?

Does turning on the heater to max help keep the engine cool

Try removing the pipes from the radiator and back flushing the pipes under the car and ensure you have flow to the expansion tank

the re-fill and bleed thouroughly.

What car is it? PRT or normal thermostat?

Could be blocked thermostat, among many other things

Are the fans working?

Hi. Yes, the fans are working fine, although they come on much quicker than they used to.

Go at it logically.
Establish that the head gasket fix was done properly by having a sniff test done. This will establish that the problem isn't combustion gases escaping into the coolant.

If that is fine then it must be blockages. As suggested bypass the heater matrix. Does it still overheat?

You changed the main rad so the only thing left is to flush the system with a crushed dishwasher tablet in the expansion tank. Give the car a run, flush that out and refill. Does it still overheat? Clean again...etc.

Aaargh.... Spent most of Saturday trying to get the coolant to circulate around the car following the thermostat change by my local garage who after fixing the HGF, have now given up on the car, leaving me less than pleased. After some greatfully received advice I called the AA. Peter, the AA man, worked really hard to help. Chemical & pressure test OK. All valves flowing freely under pressure. Still no circulation. Hot pipes to the radiator but cool pipes returning from it. Lots of gurgling when switching off. Water temp just increases way past half way after 20 mins or so. Duty calls and I've had to travel back to work in my daughters rather girly looking, baby blue, :woowoo: VW beetle convertible. I think it's time to call in the experts now before I lose my mind.

Does it have a PRT Thermostat fiitted? ie a plastic thermostat unit between the engine and the firewall?
And if so have they fitted a standard thermostat in addition?

Have you renewed the coolant pressure cap with a good oem new one?

I recently replaced the pressure cap, as a service item, with a new oem one. Next day I experienced bubbling up in the expansion tank and over heating. The expansion tank was almost full to the top when I looked after a run! Changed the cap back to the old one and problem has gone away! All back to normal :omg:

So even a new OEM cap can be faulty...:slapme:

Hello, I'll take a look when I next get home to see if has a PRT fitted. I'm guessing it's a standard one fitted. It's a new coolant cap but it may not be an OEM, MG Rover part. I'll order another one now, just to be on the safe side. I'll try anything to be honest. Chicken bones, sacrificial offerings the the MG gods....

Martin , don't loose faith . As many on here will tell you this sort of thing happens when the gasket is changed and the cooling system hasn't been bled correctly . Also as David has said , if your garage has seen the thermostat aperture hasn't got one fitted during the strip down they will fit one thinking that it has been removed to stop the overheating . The engine will not cool due to them fitting the earlier type stat if the later type is also fitted . Just by the by , when I replaced the H/G on my MG ZR , I had a real struggle to get the cooling system to bleed without it boiling up . This was due to the 'SAAB' heater valve and the jiggle valve being faulty and had trapped air in the system .

John