jgtr
Part of things
Posts: 270 
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Hi all, got an issue with a VW T25 that I could really do with some help on as it has us stumped.
I’m helping change a head gasket on a 1.9 water boxer engine. Head sits on studs. We can slide the head off approx 10mm then it gets stuck. It’s getting stuck on one stud - we believe the stud is corroded and stopping the head from coming off. The head can move back and forth but just won’t come off any further than 10mm. We’ve tried all we can think of, next step is to remove engine and look at some kind of penetrating oil or corrosion dissolver- wondered if there is anything out there that is recommended?
Failing that we’ll have to cut the stud then we're into a whole world of hate replacing the studs :-(
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Hi,
just a thought. If the stud had corroded as bad as you say, would it not be compromised anyway. Usually when the steel exfoliates the stem of the stud would be eaten away. So maybe a replacement is necessary.
Are you able to get anything down the side of the stud, i.e thin piece of metal. If so maybe try engine oil and poking the thin metal down the side of the stud to see if you can free of the rust.
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jgtr
Part of things
Posts: 270
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Yes I think that’s going to be the case and it’s likely a new stud will be needed. Ultimately it’s going to require a rebuild/reconditioned engine but we’re just trying to get the head off with minimal damage and if the stud isn’t too badly corroded put it back together temporarily until my mate can afford to have it rebuilt. We could cut the stud but then it doesn’t leave us much to get onto to remove it
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My only other thought would be to use a tapered wedge of hard wood and tap it into the 10mm gap while your friend wiggles the head around the stud, clean engine oil or penetrating oil down the side of the stud would help.
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Can you not remove the stud? I'm not sure the specifics of that engine but normally you can put 2 nuts onto the stud lock them together and unscrew the stud from the block.
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jgtr
Part of things
Posts: 270
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My only other thought would be to use a tapered wedge of hard wood and tap it into the 10mm gap while your friend wiggles the head around the stud, clean engine oil or penetrating oil down the side of the stud would help. Tried that! Next step is to remove engine so we can rotate it to allow us to bathe the stud in penetrating oil or similar. Not sure if there was a product specifically designed to break down corrosion? |
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jgtr
Part of things
Posts: 270
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Can you not remove the stud? I'm not sure the specifics of that engine but normally you can put 2 nuts onto the stud lock them together and unscrew the stud from the block. That may be an option, but not really enough thread to get 2 bolts on and likely will snap stud, so want to exhaust all other options first |
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You'd definitely want to have a look at the state of it before deciding you have to cut it, I agree. It may just be a little bit of non-disasterous surface corrosion and some crud. is it this engine?  |
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jgtr
Part of things
Posts: 270
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Jun 11, 2019 21:21:35 GMT
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Hi, yes that looks like the engine.
Recon is coming in around £2.5k which is likely worth more than the van!
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Jun 12, 2019 10:35:38 GMT
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So my thoughts, which could be utter nonsense, are that you are trying to remove a head from horizontal studs and they will be quite long. I presume you're doing this in the engine bay so access and room to manoeuvre are tight. If the engine has been dismantled previously it may well be that some of the studs are not quite true anymore if the head was moved without full care in the past. The head may have been rested at the end of the studs, bending them slightly off-true. They'd only have to have been bent a very small amount to make removal next time more difficult.
The weight of that, once it gets moving, is going to start resting on the stud's threads. The further out it goes, the more dificult it's going to be to slide it straight off with perfect horizontal motion.
So just as a thought alongside everything else you're trying... have you tried putting straps underneath it so the weight can be lifted as you pull to try and stop it resting and catching on it's way off the studs? Maybe even an engine hoist holding straps, just to stop it wanting to pull downwards, might help to work it off the studs.
Edit: Hmmm, just watched this video of somebody removing the head and they look to be as light as a feather, so maybe this ^ isn't going to be a factor at all...
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Last Edit: Jun 12, 2019 11:41:47 GMT by Deleted
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Jun 13, 2019 11:10:54 GMT
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If I’ve read this right your engine is still fitted? At this point I should also add that I don’t know anything about the waterboxers... so anything I say is just made up anyway  and not sure how they differ, but it’s not catching on anything else? I’ve taken beetle heads off that have become attached to the barrels and had to take the barrel off with the head, but couldn’t because of the bellows thermostat for the flaps. The other thought was a water pipe is still attached and stopping it coming free... we all know that choke cables are strong enough to lift the car with the engine when you forget to remove them  Good luck! |
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chamba
Part of things
Posts: 199
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Jun 13, 2019 11:39:42 GMT
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Could you not use careful use of heat (using a hot air gun or torch to expand the cylinder head, which I'm guessing is ally on these? That and penetrating oil may be enough for it to loosen its grip on the stud.
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Jun 13, 2019 19:27:01 GMT
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'80 s1 924 turbo..hibernating
'80 golf gli cabriolet...doing impression of a skip
'97 pug 106 commuter...continuing cheapness making me smile!
firm believer in the k.i.s.s and f.i.s.h principles.
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jgtr
Part of things
Posts: 270
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Jun 14, 2019 23:16:18 GMT
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Cheers for all the help and advice - the studs are quite long and flexible and not rigid like normal studs so I don’t think and misalignment would stop the head coming off.
We originally thought it was stuck on the liners but these appear to be free, it definitely seems to be this one stud as all the others can be “wiggled” in their hole apart from this particular one. Also have found someone who had the same thing happen and it didn’t end well :-(
Engine coming out on Monday, hopefully we'll be able to soak the stud for a few days and see if it will loosen off, will try that Rost Off, good shout.
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jgtr
Part of things
Posts: 270
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Jun 17, 2019 21:48:16 GMT
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Managed to get the head off, removed engine, bit of heat and a few decent hits with a hammer on a substantial casting on the head. Corrosion clearly visible around the stud when removing the head. Studs look ok, slight pitting but not enough to change them and risk one snapping. Hopefully just a good clean up and build it back up.
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Last Edit: Jun 17, 2019 21:48:48 GMT by jgtr
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and not sure how they differ, but it’s not catching on anything else? I’ve taken beetle heads off that have become attached to the barrels and had to take the barrel off with the head, but couldn’t because of the bellows thermostat for the flaps.
