Still can't get it to bleed.....

[powelly]

I'm still have real problems with bleeding this f**king car, I just can't get all the air out.
I have done the head gasket and had the head skimmed (just a clean up) but it's still giveing me the same problem it was before I did the gasket, I have replaced the thermostat with a brand new genuine BMW item and that made sod all difference.
When I filled it from cold I had the bleed screw open, I started getting coolant out of it so I started the car, it warms up and sits right on the middle of the guage but with the expansion tank cap off it just spits the coolant back out especially if I rev it. Whats really weird is that the coolant in the header tank stays cold and the bottom hose takes forever to get warm, whats more it feels like there is no pressure in the hoses, even with the cap on. I must also add that I am getting hot air from the vents, perhaps not as hot as it could be but definatley hot, lastly, now this is strange, with the guage registering half and the cap on I can open the bleed screw and get nothing out of it, not even steam. I'm at my wits end with this, I just don't know what to do next!!!!!
Should I take the thermostat out altogether and see if that makes any difference.

PLEASE HELP ME!!!!!!!!

[march109]

None of that seems to make sence.

If you have a quick sniff from the coolant tank whats it smell like? I hate to say this but you could have a gasket problem, exhaust gases entering the cooling system. Get a quick sniff test done, you can buy home kists on ebay for around £20.

[powelly]

This is my worry, I can't understand it though, I have done the headgasket, and had it skimmed, I suppose the block could be the problem.

[march109]

Did you have the head pressure tested then? Get a sniff test its cheap and in my mind at least the most likely culprit.

[powelly]

Just looked, they are £25 on e-bay.

[march109]

A garage would charge you £15-£25 so thats a good price to be able to do it yourself again and again.

Was the head pressure tested when it was skimmed? Could be theblock too? Why did you change the HG in the first place?

I have to be honest I suffered the same symptoms and it was HG failure exhaust gases escaping into the coolant system so I'm leaning to that for sure. The increase in pressure will force (orspit) the coolant out and it will read warm whenit isn't and will build up air pockets in the system too.

[powelly]

I didn't get the head pressure tested, i'm thinking now that it might have been a good idea. I actually did the gasket because of the very symptoms i'm still getting.
The more I think about it the more I'm convincing myself that this is the problem, I only visully checked the head over, it looked in very good order, I guess we all know looks can be deceiving. I really hope it's not the block, thats going to be an engine replacment job

[march109]

To be honest I think an engine swap is easier than a HG change, but thats my personal preference. Probably costs about the same too once you salvage salable parts from the old block.

[powelly]

I think i'll do the block test first, if that confirms the worst i'll have to hunt down an engine. Fookin marvellous.

[march109]

Don't you mean sniff test? since that will confirm the presance of CO2 in the coolant, stripping the engine and having the block tested seems a bit extreme to me.

[powelly]

Sorry, yes sniff test is what I mean, the stuff on e-bay is actually called universal block tester.

http://cgi.ebay.co.uk/UNIVERSAL-CYLINDE ... dZViewItem

[march109]

Thats the bad boy.

[maxfield]

Have you tried drilling a little hole in the thermostat (About 2mm) I've read this can help with bleeding.

[hartgefan]

im assuming youve started wth the easy stuff like radiator,water pump and checked the small header tank pipe for blockages!

[mr_dink]

are you opening both bleed nipples?

there should be one on the thermostat housing as well.

when we did the radiator on my m40 we had the same symptoms you describe when we were trying to bleed it up, i.e. seems all good then spits it all back out again.

we replaced the thermostat and housing, opened both nipples to bleed it up and it was nice and easy to bleed.

What engine do you have, and did you replace the housing when you replaced the thermostat?

[powelly]

Sorry chaps it's an M20 B25, I wasn't aware that there was another bleed nipple????? I have also flushed the rad through, there doesn't seem to be any blockages, i'm getting a good flow of water through it.

I did think about drilling a hole in the thermostat, I figure though that if I just take it out altogether this will have the same effect and will obviously save me drilling a brand new rather expensive genuine BMW part.

[mr_dink]

Your m20 may be different from my m40 but mine has another bleed nipple on the thermostat housing.

First time we were trying to bleed it we didn't touch that nipple as it was very rusty and crusty and looked like it would break.

Have a look on the thermostat to see if there is another nipple as this helped us no end.

You do have a different engine though.

HTH

[powelly]

Well I've stumped up £28 for a coolant exhaust gas detector, will have to wait and see what the results of this are and then decide what to do, at the moment I just want to set fire to the f**king thing

[powelly]

Ok, I have now done a block, or sniffer test as they are more commonly known.
I don't really have any experience of using them so i'm hoping someone on here might have. I did as the instructions said and emptied out some coolant, I then let it idle and get up to running temperature, it reached it's usual half way on the guage and then proceeded to puke some coolant out, even though I had emptied the header tank, I then switched it off for a moment and restarted it after the bubbling had subsided (just a few seconds) and inserted the block tester. Here are the results....







So, i'm still unsure, the instructions say it should turn yellow, it says it may turn green on a diesel, as you can see that's what has happened here, I did give the rubber bulb a good few pumps, not quite for the minuite it suggests but the colour change was pretty obvious, the colour literally just changed in a second.

Does anyone need to borrow a block tester