Weird temperture behaviour 2.5 v6

[Pruts3r]

Hello,

I recently got a 99 2.5 connie. I had a whole lot of work done incl cambelts, radiator, thermohousing and a whole lot more.

Since then the car did 2 long journeys (1 hour and return) a few 30 min drives and a few 5 minute drives. No problem and a driving dream!

Only had to top up coolant twice (2 times a quater of a liter)

Yesterday evening i got a scary thing with it. Got stuck in trafic for 15 minutes and then got on the wrong lane infront of trafic light so had to drive of fast (had to push it hard cause this .... in a skoda wouldt let me pass). Then in 200 meters i stopped for the next lights having made it.

Now the temperature meter started to rise to 3/4 and instandley steadily dropped back to normal (fans were on).

Got at my destination and left again in half an hour. Now more traffic and after some driving and half an hour of creeping in traffic suddenly the engine overheating warning came on!!! Gauge shot to max, red light came on so i switched her off.

Was in ds middle of traffic so had to move so started again in 10 secondes after shutting her off. Started without fuss and temperature was perfect in de middle right away and stayed there for the whole journey.

Taking the car home again later that night i had to put in half a liter of water and noticed some mayo under oil cap... the whole one hour drive home she behaved perfectly. In slow city driving and on highway doing 70 miles an hour and even when i tried what happend if i used 'kickdown' and then slowed down...she did nothing wrong and temperature kept perfect...

Should i worry a lot? Or was there some air left in the system?

[T-Cut]

Hello Merijn, welcome to the Owners Club.
If you have to keep topping up the coolant then there's a leak. A good system doesn't need topping up. Low coolant combined with the sort of driving you describe will cause the overheating. The cooling system should trip on the radiator fan at low speed around 100°C. This is vital, so you should check it operates correctly. Low speed fan failure is a common problem and there are easy fixes. Search for the 'Demist Test'. That tells you how to check the slow speed fan. You may have some trapped air in the cooling system, which requires bleeding. Again the V6 bleed method is easily found using the search system. It's also described in the Haynes manual (No 4292), which is a good buy for any new 75/ZT owner.

Use this Forum specific search system for best results:

Click: https://cse.google.co.uk/cse?hl=en&c...iwAw#gsc.tab=0

Simply enter your key words.

Also remember that the 'temperature gauge' is next to useless. If the needle moves upwards from the 'normal' mark, the engine's already above 115°C. Check out 'Diagnostic Mode' for more on checking the actual temperature. The normal running tmperature for the V6 is in the 90°C area.

TC

[SD1too]

Originally Posted by T-Cut

You may have some trapped air in the cooling system, which requires bleeding.

Here's how to refill and bleed the V6 engine. Your garage probably didn't know this, unless they were an MGR main dealer.

Check out 'Diagnostic Mode' for more on checking the actual temperature.

Here's how to see a digital display of the actual coolant temperature.

Search for the 'Demist Test'. That tells you how to check the slow speed fan.

The 'demist test' is as follows:

1. Start the engine from cold.
2. On the heater/AC control panel press the windscreen demist button.
3. Get out of the car and walk to the radiator grille.
4. Can you hear the radiator fan running continuously?
5. If not, your slow speed has failed and this will cause dangerously high coolant temperatures.

Please let us know how you get on.

Simon

[Pruts3r]

Thnx for the help! My mechanic is an ex mg rover employe and he knows rover insideout.

The Low speed fan is motionless. Hear no difference when i switch on demist and i can see it standing stil through the grill. I put my ear to the grill. Should it be an oubvious difference?
... oh darn ... is this the easy fix? http://www.the75andztclub.co.uk/foru...ad.php?t=68336
High speed fan operation is working cause i can hear that kicking in every now and then when driving.

I ve covered about a 1000 km with it since i got it and the LS fan probable didnt work all that time. With an other time with serious traffic jams besides yesterday... but only yesterday i had the first trouble with the temperature gauge and the "overheating message".

Is it likely now that the engine is shot? (Like 4 cilinder K series when they 'overheat'?

[SD1too]

Thanks for your quick reply Merijn.

Originally Posted by Pruts3r

Is it likely now that the engine is shot?

No; not if it only overheated once, briefly, as you have described.

The Low speed fan is motionless.

That's the first job on the list then. If you still have the original fan system on your 1999 car it will be a three speed motor like mine. One or two of the brushes will have worn to their minimum length over the seventeen years. The motor casing can be opened and the commutator inspected for damage. If the fault has only just occurred the commutator will be fine and new brushes can be fitted at minimal cost, provided that you can find someone with the electrical repair skills to do it. The other choices are a new (very expensive) or used MGR 2 speed system. In both cases the resistor will need to be upgraded. This club can help guide you towards good suppliers of the parts you'll need whichever option you choose.

My mechanic is an ex mg rover employe and he knows rover insideout.

It's a pity that he didn't check the fan when your car was in for the cooling system work isn't it.

Finally Merijn, don't drive the car until you've fixed the fan. The coolant temperature will be reaching 112° and above and it's designed to run below 100°C. Sustained overheating may put the normally very robust V6 head gaskets at risk.

Simon

[Pruts3r]

I've got the newer type allready cause i can see the grey 'weak' resistor thingy true the grill behind the fan blades. My mechanic said he had seen that a newer type of fan had allready been placed so not his fault. It probably worked when het checked cause he knows about this fault. Hope my car will be allright cause i have to drive it to my mechanic (40km drive...)

[SD1too]

Originally Posted by Pruts3r

Hope my car will be allright cause i have to drive it to my mechanic (40km drive...)

Looking at the weather in Rotterdam at the moment you should be all right so long as you're not stationary in traffic jams for too long.

You'll need to buy a 'gold' resistor. Club trader Jules can supply one.

Simon

[Pruts3r]

Thnx i allready contacted him and i am going to buy that. I will stay clear of bussy trafic and drive there late in the evening or in the weekend.

Would it help to put the aircon on to keep the engine cool? Or just the heater and eco mode ?

I just have bad luck with fans. Earlier de viscosious coupling on my 85 vitesse didnt work and that made me lose the engine in there. Spend over 6500 euro on that car in about a year and a half.
Hope Sir Drinxcelot (my pet name for the 75) wont be another moneypit...

[SD1too]

Originally Posted by Pruts3r

Would it help to put the aircon on to keep the engine cool? Or just the heater and eco mode ?

Activate the digital coolant temperature display (instructions in post no. 3) at the beginning of your journey with the heating/AC in 'Econ' mode.
If you notice the temperature exceeding 100° you could select windscreen demist mode but it's doubtful in winter temperatures that the refrigerant pressure would rise high enough to trigger your fan's fast speed.
Keeping the car moving and driving gently is probably the best strategy.

Simon

[murphyv310]

Put the heater to Hi on both sides and use the heater blower on maximum, this will aid cooling (although you might overheat) and hopefully reduce the risk of the engine getting too hot in traffic. Best keep it on Econ as the aircon will be off and reduce the load on the engine, the cooling fan isn't working on low speed anyway.