GolfGTIforum.co.uk
General => The garage => Topic started by: GTI-BOY on 26 August 2004, 17:06
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I've seen the threads about blue smoke, rocker cover breather, valve stem oil seals etc, I got the cylinder head on my 8v digi reconditioned about a 3 months ago, but recently when I step off on the accelerator at high revs, leave it for a few seconds then re-accelerate I get a huge puff of blue smoke!! :o It doesn't do it on tick over or on normal acceleration and i can avoid it by dipping the clutch when I'm slowing down, it just happens when I back off on the throttle for a few seconds and re-accelerate! The engine was rebuilt, new piston rings, cylinders honed etc etc. I know it's not the breather pipe thats blocked . Would it be anyway possible that the valve stem oil seals could go so quickly??? ??? I don't want to strip it again!!!!!!!!! >:( >:( >:( :o :-X
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Certainly sounds like valve guide oil seals. Shouldn't go that quickly unless the guides themselves are worn. As you have had the head reconditioned, assuming that was done properly, they should all be ok. Maybe one of the seals were damaged when pulled over the valve stem :-\
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I'm just wondering now if I drove it too hard too soon? I took it very easy for the first 1000 miles to let the new rings bed in nicely and then got back into normal driving (not rallying! ;)).
Has anyone changed the seals with the head in situ? I really don't fancy taking those manifolds and stuff off. I know you can get an airline that you connect to the spark plug hole to pressurise the cylinder etc etc, but I can imagine (knowing my luck!! :D) putting a little pressure on the valve and it falling in!!! Anyone successfully done this?
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I've just bought the gear for doing it as I think I'll be doing Hazels Audi to get it through its next MOT.
I would have thought that if you bring the piston to the top, before you start, it won't fall down so far that you can't get at it :-\
Another idea I have heard is to insert non-fraying rope into the spark plug hole, with the piston down, when you have 'enough' in there, bring the piston up so compressing the rope onto the valve. Worth a thought if you don't have access to a compressor.
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Now that sounds like a plan!! :D
I'll try that when I get a free weekend , i'll try and get some pics as I go :)
Cheers ;)
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Good luck. Yeah, let us know how you get on..........I've never done the job without removing the head before, but deffo intend on trying on Hazels Audi.
Just out of curiosity, if using the compressed air technique, anyone know how you crack the collets loose? Usually with the spring compressor it takes a little initial effort to crack the collets and then its easy to wind the spring down.
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my 8v use to do that randomly. I'd just flew past Vix once and it puffed out a cloud ;D
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If you are using the compressed air method, put a socket on the top of the collet retainer and give it a sharp whack with a hammer. That usually breaks the collets free and you should have no problem compressing the spring and retrieving them. Don't do what I did once and switch off the compressor, came out of the house later to find the valve had dropped down into the cylinder >:.( Oh well, had a full head set anyhow :-\).
Steve.
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Cheers Steve. Out of curiosity, when that valve dropped, did you have your piston at TDC? Just wondering, had it been at TDC, whether you might have been able to pull it back up again without taking the head off :-\
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Tdc, as when you pressurise the cylinder it will go down to bottom dead centre ::). If you use the string method I would look into some way of locking the crank as it will want to roll over from tdc when you press down on the valve. Let me know how it goes with Hazels car.
Steve.
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I was actually planning on using my compressor and using the compressed air technique to do the Audi. I suggested the rope trick just as an alternative, for those that don't have a compressor.
So let me get this right as Steve, I do value your experience and opinion:-
I plan to tackle the job by moving the relevant piston to TDC, locking the flywheel, as it will obviously rotate to BDC with 100 psi bearing on it, as you have already stated (I guess I took that bit for granted :-\). Chucking 100psi through the spark plug hole and changing the valve guide oil seal. The piston won't move to BDC as I have locked the flywheel (already have a tool made for the job). What I don't know, as I have always assembled a head before fitting to the block, is, if I should lose compressed air with the piston at TDC will the valve drop down so far that I need to remove the head to retrieve it?
I'm thinking that if it is possible for a cambelt to snap and valves to meet piston crowns, that must mean that the valve will not drop down too far if the piston is at TDC for this job :-\
Or am I forgetting about such things as inertia and valve bounce?
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If you have the piston at TDC, I think the valve will touch the piston and not drop down to low. I have done a few and have let the piston go down to bdc, I dropped a valve on one because I switched the compressor off and the air pressure dropped down to nothing (about 1 hr) and there was nothing to hold the valve closed >:(.
Steve.
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That must have been annoying when you were obviously trying to avoid removing the head in the first place >:(
I think I will leave mine at TDC, just in case...........hopefully if the same thing happens, the piston will save it dropping.
Thanks for your advice :)