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 Engine & gearbox stuck together! 
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Firing on two.

Joined: April 9th, 2010, 12:21 am
Posts: 452
Location: West Sussex
Post Engine & gearbox stuck together!
Any suggestions on how to separate an engine & gearbox that's probably not been apart for 53 years and is rather reluctant to budge? It's a 1969 AK350 (M28) that's been laid up for at least 20 years. Body is off (waiting for new chassis to arrive). I'm ready to lift the engine & box out. I was going to separate them to make it easier, (I'm working by myself), & to check the clutch.
It only moves about 3mm apart, at all 4 points, but can be tipped diagonally to increase/reduce that gap by a couple of millimetres, (so it feels like it's stuck in the middle, on the shaft).
I can get a lever between the bell-housing and the flywheel at the top and similar at the lower sides using a flat screwdriver into a groove in the flywheel, & pressing against the bell-housing. This is how I got it to move the 3mm but it's not moving any further and obviously I can't risk using a lot of pressure. Similarly I can wedge a thin tool in between each of the mounting lugs but again, don't want to risk too much pressure on the castings.
I've removed the M6 screws to release the pressure & centre plates from the flywheel (in case the centre plate was stuck on the input shaft), so that the clutch can stay with the gearbox when the engine is pulled forward but that's made no difference.
In case the centre plate is stuck on the flywheel, I've removed the gearbox lid and engaged 2 gears, to lock the gearbox. When turning the crankshaft, the pressure plate is stationary with the gearbox (presumably stuck to the centre plate, which I can't see, as that's on the splines).
The engine still will not move any further from the gearbox.
So the only thing I can think of is the spigot, (which being a 1969 is probably a roller bearing, rather than the bush used on later cars): the crank is turning while the input shaft isn't (having locked the gearbox), so could it be that the spigot bearing rollers themselves are stationary and rusted onto the shaft while the outer race of the bearing is turning with the flywheel (?!?), so the rollers (on the shaft) can't get past the lip of the outer race ???? (It seems unlikely but theoretically possible...?).
If so, the only way I can think of to deal with this, is to tip the engine on its nose, with the gearbox upwards, so that when I spray loads of penetrating fluid in, it will run and sit in the bearing.
Any other thoughts/suggestions?
Thanks.


March 21st, 2022, 6:25 pm
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Firing on two.

Joined: December 21st, 2014, 7:33 pm
Posts: 848
Location: Rhayader Mid Wales
Post Re: Engine & gearbox stuck together!
Yeah give it a soak if you've got time and then I'd get some heat into the shaft, either a hot air gun or a blow torch and quench with penetrant and also keep pushing and pulling the gearbox to encourage more movement.
Once you can see that it is moving apart, you can repeat until the flamer gives up.

Good luck!

It's not tight on the dowels ? corrosion gets in them.


March 21st, 2022, 9:22 pm
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Firing on two.

Joined: April 9th, 2010, 12:21 am
Posts: 452
Location: West Sussex
Post Re: Engine & gearbox stuck together!
rob massey55 wrote:
Yeah give it a soak if you've got time and then I'd get some heat into the shaft, either a hot air gun or a blow torch and quench with penetrant and also keep pushing and pulling the gearbox to encourage more movement...
...It's not tight on the dowels? corrosion gets in them.


No, it's not tight on the dowels. The trouble with heat, is that you can't get near it, through the V-shaped hole underneath, with everything inside in the way: clutch fork, release bearing, pressure plate (the type with the big central circular rider block attached), centre plate and then it's the other side of the flywheel (thick heavy type with sunken area for the centre plate), ......but I'll give it a try after standing it on it's nose and soaking it for a couple of days.


March 21st, 2022, 11:10 pm
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Firing on two.

Joined: December 21st, 2014, 7:33 pm
Posts: 848
Location: Rhayader Mid Wales
Post Re: Engine & gearbox stuck together!
Ok, another option is to fasten the engine very securely to something that won't move (get creative here) and put chains around the stubs of the driveshafts connected to a winch and draw the box off the engine.

Or if not chains, then a big ratchet strap combo.


March 21st, 2022, 11:34 pm
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Joined: April 24th, 2010, 10:01 am
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Post Re: Engine & gearbox stuck together!
Hi Daras.

Have you succeeded? I would try leaving it under pressure for a few days. It may creep apart in time if left with a couple of metal wedges knocked in.

Or upend it and put a bit of pressure on gearbox by trying to lift it. Think this sounds like a leave under tension and walk away scenario?

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April 16th, 2022, 4:04 pm
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Firing on two.

Joined: April 9th, 2010, 12:21 am
Posts: 452
Location: West Sussex
Post Re: Engine & gearbox stuck together!
Yes. That's what I did. Came apart a couple of days later, thanks.


April 17th, 2022, 11:47 pm
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Joined: April 24th, 2010, 10:01 am
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Post Re: Engine & gearbox stuck together!
Nice one.

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1988 2cv 652cc
1993 Toyota Hilux Surf 3000cc runs on Bio Diesel
2004 Toyota Landcruiser Amazon 4200cc runs on Bio Diesel
1998 Daihatsu Hijet 1300cc
2005 Susuki Bandit 650cc


April 19th, 2022, 10:47 pm
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