V6 dumps coolant at MOT

[Astraeus]

The test is easy to do. Works from cold or hot.
1 Switch on ignition and start engine.
2 Switch air con off. Either a button in non climate control models or press the economy button. This switches air con off.
3 listen to engine at front. No fan should be running
4 switch on demist/aircon
5 listen at front. Slow speed fan should be running. It should continue to run and not cycle between fan and off.


Symptoms of resistor failure
Fan cycles between off and fast ( this is the usual symptom)
Or
No fan at all which could be motor too.

In the case of resistor failure over heating more likely as the high speed fan does not kick in until about 115 degrees if I recall correctly. Certainly way past when the slow speed would.

Chris

[kaiser]

1/2 cup of coolant is next to nothing, less than 100ml.
After filling, where was the level in the expansion box.?

The MAX level surprises a lot of people, it is very low. When the level is correct, you hardly have water at the bottom of the tank.

Very easy to overfill.

But the fan operation should be checked in any case.
Maybe you need a new cap as well, they do get tired!

[SD1too]

Originally Posted by Salad-Dodger

... I read on here the other day about a guy who has wreaked his V6 when a pipe failed on the motorway.

Just to put things into perspective, that car had just returned from having its cambelts renewed. The oil pipes to the cooler have never been known to spontaneously break.

Simon

[Salad-Dodger]

Done the de-mist test and the fan runs at max all the time.
Went to work this morning with the on-board temp displaying. This is a ten mile motorway journey with little or no stops as its 6.30 am. temp didn't go higher than 84 and was dropping to 75 and rising again to 84.
On the way home I did the same but took the route through town at midday.
Temp got to 94 while in stationary traffic and backed off when on the move again. Pulled up on the drive at 84 and it went to 94. Pushed the de-mist button and it started to drop again. No loss of coolant.

Simon. As I said earlier, I did the cambelt change myself about a month ago and the system bled out with no problems first time. It was so easy that I can't see the problem really. I can remove the res and go through the motions but I'm not convinced it would work any better than just bleeding it on the hose.
The oil pipe subject. We were refering to the cooler itself. I was just mentioning that one other member had a pipe burst and wreaked his V6. I don't think pipe failure is a common occurence.
We send out dozens of those coolers where I work. The sooner I get rid of mine the better for a proper cooler, cooled buy air!

Kaiser. you are correct. Even a cup full would be no big deal but it did blow, so maybe a new cap or at least the O rings on the cap.
The res always has just a shallow puddle in the bottom, just so I can see the fins in the bottom. It really looks empty most of the time but it doesn't loose coolant.

Frankly, I've never seen or heard the fan work on any speed other than fast. It must be the fast speed as it practically causes the car to shake. Just need to know where I can get one of these resistors. I've had a good look at my rad from all views and I cant spot it anywhere. Can someone let me know where its located please? Steve

[SD1too]

Originally Posted by Salad-Dodger

Done the de-mist test and the fan runs at max all the time.

If the fan started running as soon as the 'demist' button was pressed, and remained running constantly at that speed, then it will be slow speed if you have an unmodified MGR fan system fitted. Others have been fooled by this. The slow speed on some 2 speed systems is very noisy.

Just need to know where I can get one of these resistors. I've had a good look at my rad from all views and I cant spot it anywhere. Can someone let me know where its located please?

Organiser has already told you Steve, in post number 6 here:

Originally Posted by Organiser

... have a look thru the front grille in the two o'clock position you should see the silver resistor by the blades.

So we're waiting for your answer, but it's not just a question of buying a new resistor! We need to find out first whether you have a 2 or 3 speed system, because 3 speeders don't have the resistor and 2 speeders do. So please tell us whether or not the resistor is visible.

Thanks for the coolant temperatures. They're all over the place which suggests to me that the system isn't pressurising. If so, this would explain why it ejected coolant during the MOT test. The reason for this could be because the expansion tank cap is faulty or because you have a leak.

As you haven't yet followed the MGR refilling and bleeding procedure, you run the risk of still having air in the system. When the engine is started from cold, unscrew the expansion tank cap and you should see a continuous small stream of coolant entering the tank neck from the narrow bleed hose, if you have successfully purged the system of air.

Simon

[ProfDave]

Originally Posted by Salad-Dodger

Even a cup full would be no big deal but it did blow, so maybe a new cap or at least the O rings on the cap.

I was losing coolant from the bottom rail changed it and it was still losing a bit; bought new O rings and its fine! Well worth the £3!

In terms of fan resistors Jules does a kit but if your fan is on continuous when the AC is on and then goes of when you turn it to Eco or off the resistor is probably working

I think I would try the rings as a first step now!

[Salad-Dodger]

Originally Posted by Astraeus

The test is easy to do. Works from cold or hot.
1 Switch on ignition and start engine.
2 Switch air con off. Either a button in non climate control models or press the economy button. This switches air con off.
3 listen to engine at front. No fan should be running
4 switch on demist/aircon
5 listen at front. Slow speed fan should be running. It should continue to run and not cycle between fan and off.


Symptoms of resistor failure
Fan cycles between off and fast ( this is the usual symptom)
Or
No fan at all which could be motor too.

In the case of resistor failure over heating more likely as the high speed fan does not kick in until about 115 degrees if I recall correctly. Certainly way past when the slow speed would.

Chris

Just been out to the shops and climbed a very long, steep hill behind a farm vehicle. Temp went to 115 and the fan came on. The loud one that shakes the car! I don't think it came on at all before that. temp was constant 80 before that and climbed to 115 very fast.

I cant see any resistor at 2 o'clock on the fan area. been out there twice to check but there's nothing there. No coolant loss though.
Its obviously running a bit hot so I'll find some O rings and see what happens from there but it would be nice to know what system I have in respect of a 2 or 3 speed fan. I'll have another go at the bleeding thing in the morning when its cold.
What temperature do these engines run at normally? Its great having all these numbers in front of me but it would be good to know what it should be. Steve

[SD1too]

Originally Posted by Salad-Dodger

... climbed a very long, steep hill ... Temp went to 115 and the fan came on. The loud one that shakes the car! I don't think it came on at all before that. temp was constant 80 before that and climbed to 115 very fast ...
I cant see any resistor at 2 o'clock on the fan area.

OK Steve; it very much looks as if you have a 3 speed fan with the usual worn brush syndrome. This means that you have lost slow and medium speed. When this happens, if the fan motor continues to run, one of the worn brushes and its spring eventually releases itself from its holder and destroys the commutator. This might be the reason for the vibration. You should stop driving the car immediately, take off the front bumper and repair or replace the fan system. If you don't, I fear that you will break down.

Don't bother about 'O' rings or bleeding for now. You need to get the fan working properly first.

What temperature do these engines run at normally?

Mid nineties with excursions to 100° when stationary after a run.

Simon

[Salad-Dodger]

Hi Simon. Thanks for the info on this. Is there any way of testing the other two speeds before I strip the front of the car off?
I need to use it on Sunday afternoon to collect my Sister from Gatwick, a 25 mile journey there and back. would have to happen this weekend!
If I find a fan motor to buy, How do I know its not as bad as mine. Bet we cant get new ones either. There is this guy Jules on here I think who sorts things like this I think? Steve

[SD1too]

Originally Posted by Salad-Dodger

Is there any way of testing the other two speeds before I strip the front of the car off?

Yes. To test the slow speed, carry out the demist test as described earlier in the thread (which you don't seem to have done yet). If the slow speed doesn't work, it's enough justification to take off the bumper.

I need to use it on Sunday afternoon to collect my Sister from Gatwick, a 25 mile journey there and back.

As I said in my last post, that would be folly. You could break down (leaving your sister stranded) and/or put your head gaskets at risk. The sensible decision in the circumstances is for your sister to use public transport* or a taxi.

* Gatwick Express to Victoria, then tube to connect with service to Chatham.

If I find a fan motor to buy, How do I know its not as bad as mine.

You deal only with Arctic or Jules. But you're jumping the gun again Steve. First we need an accurate diagnosis which means carrying out the demist test and taking off the front bumper to see what you've got.

Simon