P38A Another P38 Overheating Problem

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DanClarke said:
Hi Renniks,
I for one am dying to know if you got to the bottom of this and have an answer. Any update?
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Hi Dan, in honesty I haven't done anything with it yet. I've been busy on (and recovering from) my stag do. I've earmarked this weekend to remove the condenser and give it another try though.

Don't worry, I will update as soon as I give it another try. Once fixed I'm determined to do a collated write up as a 'how not to diagnose a 2.5 overheating issue'.
 
So I'm going to remove the condenser today. Looking at it there are just 4 bolts and the 2 hoses (in addition to the slam panel and grill.

RAVE says that I must discharge the coolant and then gives a very long detailed explanation of, essentially, having to take it to a specialist coolant recovery station. Has anybody discharged the system without having it professionally done and are there any precautions anybody would recommend?
 
OOOpps I undid a pipe and heard this hissing noise haven't a clue what it was never mind carry on:rolleyes:
That's how it goes isn't it:D

just loosen the pipe and make a brew come back with said brew and carry on regardless.
 
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brianp38dse said:
OOOpps I undid a pipe and heard this hissing noise haven't a clue what it was never mint carry on:rolleyes:
That's how it goes isn't it:D

just loosen the pipe and make a brew come back with said brew and carry on regardless.
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Got Ya. I will just 'inspect' the fastenings. I'm pretty sure it is empty anyway.
 
Ok, so I removed the condenser and, guess what... Still the same.

It is a bit better in that it only needs a small increase in engine revs to bring the temperature back down, but I haven't put the slam panel or grill back on yet so I would imagine that it has made no difference at all.

So, to recap, temperature is fine when tootling around and stationary. When you push it or go on a motorway run and come to a stop, it starts overheating. If you give it some revs, it brings the temperature back down but will then overheat again until you put more revs on.

Taking the slam panel and grill off seems to have improved the issue in that you only need to increase revs to 1000 (as appose to 2500) to bring the temp down again.

I've changed the waterpump (which already looked new) the thermostat, the viscous fan and radiator. I've also removed the condenser. I've also drained the system twice and 'burped' it. Heaters work great and there is no water in the footwell, although the book symbol is present unless the aircon is off.

I'm stumped!!
 
Grrrrrr said:
Sure the viscous is locking when hot?
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Well, it's a completely new unit. It is also shredding a newspaper when I put it in (as did the previous unit). I don't feel that it changes speed though as it sounds the same all of the time. I might make a vid to seeing anybody thinks it should be louder/more powerful.
 
Renniks said:
Well, it's a completely new unit. It is also shredding a newspaper when I put it in (as did the previous unit). I don't feel that it changes speed though as it sounds the same all of the time. I might make a vid to seeing anybody thinks it should be louder/more powerful.
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Just because it's new doesn't mean it's working,
 
As said before when they are working and you increase rpm they roar like a tank no mistaking when its locked up, I can hear mine from inside the house when the wife drives of down the road.
 
Renniks said:
Would it still shred a rolled up newspaper if it wasn't locking? Are there different degrees of lock?
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I would think if it is shredding newspaper then it is probably working. When the car first starts it will roar as Brian says. Give it a few minutes and it should quieten down. At this stage you should be able to stop it with your newspaper. Then as the temperature climbs it will lock up again and start to shred your newspaper.
 
Grrrrrr said:
I would think if it is shredding newspaper then it is probably working. When the car first starts it will roar as Brian says. Give it a few minutes and it should quieten down. At this stage you should be able to stop it with your newspaper. Then as the temperature climbs it will lock up again and start to shred your newspaper.
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Thanks Grrrrr, I don't think it actually changes in terms of it shredding a newspaper or noise. You can hear it, but it isn't what I would call really loud (which is obviously subjective). I'll do the newspaper test again tomorrow and see if I can stop it at any point in the warm up process.

For the sake of £40, I may just order another new unit. I definitely think it is airflow now so if that doesn't work, I think I'm going to try the aux fan mod which a member in here has kindly sent me.

I'm getting slightly concerned now that I have changed everything, save for the head gasket. However, although it has got into the red on a number of occasions, I'm still not seeing any signs I would typically associate with a head gasket (famous last words)!

On a side note, I'm also going to learn about the braking system next week; rear pads have reached metal so I've ordered some new ones. It looks like the handbrake is seperate which means it should be pretty simple, thankfully.

Just waiting for the next failure so I can get to know that part of the car (hopefully not blend motors)!!!
 
Well, it did say disco 2 on the box. That's a good point, I will check.

In a wine endured moment of inspiration, I have had a thought....

The line from the top of the rad to the expansion bottle goes to a pipe that seems to be situated below the coolant line in the expansion tank (when coolant filled to cold line). As such, I don't see the constant flow of coolant that some describe; I presumed it fills below the water line.

The other line coming from the expansion tank seems to be a breather with a little hole at the top of the neck that vents to the inner wing. I have noticed that coolant does seem to come out of that pipe onto the inner wing which I always thought strange. Could somebody have connected these up the wrong way around?
 
image.jpeg
Just to make sure it isn't something as stupid as the rad pipe being connected to the wrong line on the expansion tank, is it supposed to connect to the left or right side on the below pic?
 
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Renniks said:
View attachment 135657 Just to make sure it isn't something as stupid as the rad pipe being connected to the wrong line on the expansion tank, is it supposed to connect to the left or right side on the below pic?
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Connection is fine, L/H from rad top, R/H vent to atmosphere. The coolant is overfilled, when cold should be to level mark halfway down tank. Looks like it has been venting and it looks far to strongly mixed, should be 50% water 50% antifreeze.
 
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Item description for the rad said in big bold letters, it has a baffle. I didn't check before I put it on but I've checked the old one and it does (and the fault existed with the old radiator in place).

I'm going to have to start eliminating items. One thing I thought about was 'locking' the viscous fan so it was at full capacity all the time. If the fault is still there, then I know it isn't the coupling. If the problem goes away, I know that there is an issue with it.

Does anybody know if it is possible to lock the coupling so it has drive all the time?
 
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