1800 Overheating!

[sam75]

Our 1800 petrol, (non-air con) has been in the family from new, 93000 miles, and has never caused any problems, (until now). 5 years ago I had the head gasket changed as a preventative measure with an MLS gasket. In August of this year whilst towing our (relatively light) caravan the car suddenly overheated without warning. Called the RAC who diagnosed a blown head gasket and towed us home, (fortunately we were on the way home anyway). I put the car into the local garage, (who we have used for years). They removed the head and found no obvious gasket failure or problem. We had the head pressure tested and lightly skimmed, new elastomer gasket, (based on advice I found through the forum) new bolts, strengthened oil rail in the bottom and a new thermostat, cooling system vacuum filled,(cost just short of £1k). Within a week the car had overheated again, (switched off immediately). The only warning was an increasing water-flowing noise from behind the dash which got worse as the week went on). Water level in the expansion tank never changed as the week went on. Took the car back to the garage and had a new radiator, water pump (in case it the impellor was letting go when it got hot) and a replacement set of known good cooling fans, (another £400). The car has overheated again after another week, (again increasing water rushing noise behind the dash). I have run the car in diagnostic all week. Engine temp was holding at 88-90 at the start of the week, but has crept up to around 93 as the week has gone on. On Thursday it crept up further whilst the car was standing, fan cut in at 105, but temp just kept rising. We have spoken to the garage again, they are at a loss, the only option seems to be a recon engine at around £2000 fitted. We had a trip around the local car garages yesterday to look at buying a new car, but after spending what we have so far, don't have much money left to buy anything decent which isn't going to cause us trouble. The garages will only give us £100 for the Rover - really sad as it has been meticulously maintained throughout its' life and overheating aside, it is pretty much immaculate! Do we bite the bullet and fit a new engine? Any other ideas anyone? I have read a few threads on this from people with a similar problem but nobody seems the have come up with the solution. HELP!

[Bigal2218]

I would strongly recommend speaking to Jules of Colwyn Bay. My car would be on the scrap heap by now if he hadn't been servicing it. He is not to far from Louth and much closer than me in South East London. I'm on my third cooling fan, though mine is the diesel. First time I drove to Jules I had the fan in the boot in pieces, completely frustrated with having endured 9 months of problems that no-one seemed able to diagnose and fix!

[murphyv310]

Hi and welcome to the club.
It is unlikely to be the engine as a unit.
Do you have the full list of what was done on the both recent "repairs"? What year is the car? The reason I am asking is you say it has a new thermostat. Later cars have what is known as a PRT thermostat fitted, it has three pipes and lives along the lower edge of the radiator. Often a garage will fit a standard thermostat where they were originally fitted on the early production cars effectively having two thermostats in the cooling circuit. Some find it works OK but many have the overheating issues you have. Time to get it confirmed if you can.
The other issue is bleeding it should be done as MGR suggests, although vacuum filling should be fine.
Another simple thing is the condition of the coolant expansion cap, any doubt fit a new one not a cheap copy, the O rings in the grooves of the cap can get flattened and cause pressure drop and leak, sometimes new O rings are all that is needed.
The trader DMGRS here can supply a new cap and O rings.
Good luck and don't give up.

[sam75]

Thanks for the quick responses guys, I really do appreciate it! I spoke with Jules last week, he said we had done everything he would have done already and didn't have any other suggestions. He suspects a crack somewhere within the engine which is causing the water jacket in the block to pressurise and eventually air-lock the cooling system as the car is used, (although the head pressure-tested fine). The car is a fairly early one, (built Easter 2000 at Cowley) so no PRT stat! Coolant cap has been checked and is sealing fine.

[Plezier]

Suggest you go through the cooling system especially checking the heater unit and hoses. Not sure if the 75's use jiggle valves but the MGF's do and these if blocked cause over pressure and even air locks leading to overheating.

[T-Cut]

I thought DTJ (Double Thermostat Jeopardy) as well but, the year's wrong - unless someone did a PRT conversion before the HGF.

TC

[sam75]

Thanks everyone!

On the last trip to the garage they had the console out and checked the heater matrix, also did a pressure test on it and all fine. It hasn't had a PRT conversion, my dad bought the car new and I have had it for the last 8 years - we have every bit of paperwork for it and it has never had anything like this done! Also forgot to mention - no sign of any mayonnaise or water in oil at any point!

[Yorkshire GOC]

Sam - i see you are in Louth -are you aware that Trikey (a 75/ZT guru on this forum -see posts ) is based at South Reston on the Louth Mablethorpe Road -(Just 75's Northern- Spares and Servicing)) -so you are lucky to have him based 6/7 miles away- worth a visit for you i think and he has a full MG Rover diagnostic T4 set. And he is very good.

[sam75]

Thanks for the info about Trikey - I wasn't aware there was anyone with a T4 so close!

Update - I have spent the afternoon pulling the cooling system apart. All hoses are clean and clear. Thermostat very clean as is the housing. I put the stat in a pan with the original one, (the one the garage took out when they did the head gasket) - both open at the same time and to a decent amount, (start to open as the water just shows signs of boiling). I also blew through the heater, radiator and cylinder block - all clear! All joints and hoses are holding with no signs of any leaking at all at any point and are all dry along their full lengths, (I didn't check the connections on the heater matrix but was assured by the garage that these had been checked along with a pressure test and were fine - carpets are dry anyway so I don't really suspect these). I have bled the system again, but having found nothing wrong, am not hopeful!!

[SD1too]

Originally Posted by sam75

I put the stat in a pan .. start to open as the water just shows signs of boiling ..

That's too late. The stat should begin opening at 88°C. Renew it, and you'll need to repeatedly flush your cooling system to extract the K-seal which otherwise will ruin your replacement thermostat.

Simon