Coolant Bleeding problem on KV6

[paulh260260]

Originally Posted by SD1too

Hello Paul,

How did you get on with completely draining the system and refilling with the expansion tank supported so that your hands are free to refit the bleed screw? This should be done whilst coolant is flowing from the orifice.

Your air lock could be stuck in the heater matrix, for example, which would explain why you don't see air being expelled through the bleeding port.

When the engine is running with the expansion cap off, are you getting a steady uninterrupted flow into the filler neck from the small diameter cylinder head bleed hose?


Refer to the MGR procedure which I gave you Paul. Drain the system, remove bleed screw and expansion tank cap, add coolant until it emerges from the bleeding port without bubbles then insert the screw against the flow.

I think your confusion is arising because you haven't drained the system first.

Simon

Cheers Simon

Yep I haven't drained it yet as I want to do both the oil and coolant at the same time (but separately) whilst I'm under the car...I must do that next ( once the sump plug washer arrives)

With regard to the flow from the bleed tube and the pin hole below it I thought Id checked following Ducattis and TCs advice in the original overheating post, however I'm now starting to question if I did it or got distracted with the HGF nonsense instead.

I'll try that again in the morning and report back

Paul

[SD1too]

Originally Posted by paulh260260

So based on my opening description where do you think i'm going wrong to have to do this for a fourth time ...

You're not beginning with an empty cooling system Paul.

Simon

[paulh260260]

Originally Posted by paulh260260

Cheers Simon

Yep I haven't drained it yet as I want to do both the oil and coolant at the same time (but separately) whilst I'm under the car...I must do that next ( once the sump plug washer arrives)

With regard to the flow from the bleed tube and the pin hole below it I thought Id checked following Ducattis and TCs advice in the original overheating post, however I'm now starting to question if I did it or got distracted with the HGF nonsense instead.

I'll try that again in the morning and report back

Paul

Well I've braved the howling wind and rain here in Manchester to see if there is a flow from the bleed tube and pin hole and there isn't. I checked it from cold for about 1 minute on idle until the coolant had risen to the bottom of the filler neck.

I've also stuck a paper clip into the pin hole to make sure it is not blocked.

Firstly is 1 minute enough to test this properly?

Secondly shouldn't there be an associated sound somewhere to confirm this diagnosis?

Cheers

Paul

[SD1too]

Originally Posted by paulh260260

Well I've braved the howling wind and rain here in Manchester to see if there is a flow from the bleed tube and pin hole and there isn't.

I would say that's firm evidence that you have trapped air. Please proceed with the drainage and refilling following the MGR method exactly (when the weather allows).

Originally Posted by paulh260260

Firstly is 1 minute enough to test this properly?

Yes. It's not time related, the flow should be immediate.

Originally Posted by paulh260260

Secondly shouldn't there be an associated sound somewhere to confirm this diagnosis?

Didn't you say that you hear gurgling?

Simon

[paulh260260]

Originally Posted by SD1too

I would say that's firm evidence that you have trapped air. Please proceed with the drainage and refilling following the MGR method exactly (when the weather allows).

Yes. It's not time related, the flow should be immediate.

Didn't you say that you hear gurgling?

Simon

Yep Simon there is gurgling occasionally not every time though, I suppose it depends on how long it has run for. Once I've drained it I'll report back.

BTW cant remember if we concluded that just an airlock coupled with a small thermos leak could cause such high temperatures

Thank

Paul

[vitesse]

Originally Posted by paulh260260

Yep Simon there is gurgling occasionally not every time though, I suppose it depends on how long it has run for. Once I've drained it I'll report back.

BTW cant remember if we concluded that just an airlock coupled with a small thermos leak could cause such high temperatures

Thank

Paul

Think I posted my experiences with an airlock + working fan + minus 12c outside: the V6 overheated twice on the way home through town despite hardly more than tickover, got towed the last bit as I was freezing with a non-working heater and couldn't wait for the car to cool down.

If the refill doesn't help you might want to try a few unconventional methods I tried. Pressurised the system while running with compressed air (any type of radiator tester would do) - I got the idea having owned a Saab V4 and Rover 820, the clutches just won't bleed unless under pressure. I believe it led to the "burp" I've earlier described. And then the slow drives locally, upon return opening the bleed screw - every time I got a bit more air out, took about three trips before only coolant was expelled.

The car is now used daily with confidence (touch wood) but this blend of anti-freeze is staying in the car forever as I have no intention of going through this all again.

Good luck

[T-Cut]

If all else fails, use MGR's default Workshop method of pre-evacuation. This removes all air from the empty system then sucks in the fresh coolant so every nook and cranny is full. It's guaranteed to refill any cooling system airlock free, no matter how convoluted. No bleed screws, no tank lifting and no hassle. It can easily be done using the popular Pela type oil pump and a rubber bung. Heck, there's even a HowTo on it: https://www.the75andztclub.co.uk/for...ad.php?t=41864

I used this method for my very first coolant change and recommend it for anyone finding 'standard' proceedure a hit'n'miss affair. But the 1.8T is so easy I don't bother now, with the Pela, Haynes or MGR. Mine simply burps like a baby.

TC

[paulh260260]

***Update***

I've now drained and flushed the coolant but I now cannot remove the bleed screw.

No matter how many time I try its stuck fast , I can only think I tightened it too much the last time I bled it.

I've tried to get a mole grip around the serrated edge but I cannot get a good grip.

This must be a fairly common issue is there an easy way to resolve this other than removing the bottom hose completely and trying to remove the screw whist out of the car?

Cheres

Paul

[vitesse]

Originally Posted by paulh260260

***Update***

I've now drained and flushed the coolant but I now cannot remove the bleed screw.

No matter how many time I try its stuck fast , I can only think I tightened it too much the last time I bled it.

I've tried to get a mole grip around the serrated edge but I cannot get a good grip.

This must be a fairly common issue is there an easy way to resolve this other than removing the bottom hose completely and trying to remove the screw whist out of the car?

Cheres

Paul

On one car I worked on the slot for a screwdriver was rounded. I heated an old screwdriver to red-hot, plunged it into the plastic, cooled it and was then able to release the screw.
Would recommend buying a replacement first though, T-Cut provided this link in another thread:https://www.ebay.co.uk/sch/i.html?_f...screw&_sacat=0

Good luck

[paulh260260]

Originally Posted by vitesse

On one car I worked on the slot for a screwdriver was rounded. I heated an old screwdriver to red-hot, plunged it into the plastic, cooled it and was then able to release the screw.
Would recommend buying a replacement first though, T-Cut provided this link in another thread:https://www.ebay.co.uk/sch/i.html?_f...screw&_sacat=0

Good luck

Ha, that's brilliant Vitesse, although with my luck I'd set fire to the car

I've finally managed to free it using a box spanner, took 45m minutes using all sorts of different tools though!!!

Fortunately I have a project car I've nicked the bleed screw from and refilled, bled and tested.

Leaving it overnight then short drive to see if the overheating issue has resolved.

Cheers

Paul