Removing flex plate spacer bolts - Rover V8

[mickeyw]

Evening all. Over the weekend I thought I'd try removing the spacer from the rear of the crank, in prep for fitting of a flywheel and clutch.

It's held on by 6 cap head screws that are secured with Loctite.

Using two of the large bolts that secure the flex plate and starter ring etc, I positioned a long bar to hold the crank still. Then with a decent Unbrako Allen key, and length of tube I tried to undo the screws. I know from experience these can be FT, and they didn't disappoint.

Four screws came loose with the characteristic crack that makes you wish you'd worn some decent gloves. One the key slipped out and trashed the hex socket.

The last one refused to budge at all, and even with careful application of force has turned my best Allen key into spaghetti

I tried shaking some sense into it with a v powerful rattle gun mit hex tool, but that made no difference.

Any ideas what to try next? I don't really want to drill the heads off as I'll still need to beat the Loctite once the spacer is off.

The only upside so far is all my knuckles are still intact.

[Bowie69]

I think they will come out pretty easily once you get them cracked, or drilled off, IIRC the 'stickyness' is down to the heads binding on the flywheel, rather than the thread lock. Besides, you could always weld a nut on the end once you have the flywheel off.

Tight aren't they

[davie]

warm up with even something cheap like gas torch from b and q and then shock with a good squirt of freeze and release spray perhaps?

just enough to break that initial hold

[Boydie]

I don't know of your exact problem not having a V8 but when I had an auto on my 300Tdi I found the easy way was with a mini blow torch, I got my toy from a major electrical wholesaler, it's tiny little hand held re-fillable thing with pyzo-electric ignition, the beauty of it was I could easily heat the ends of the bolts holding the flex-plate through the starter motor entry and heat will break the grip of any grade of Loctite, given enough heat they came out easily, and the blow torch is great for soldering large electrical fittings such as battery lugs.

Cost was less than AUD$10.00

[mickeyw]

OK, for those unfamiliar with the back of a V8, this is what I'm dealing with.

And there are six of these little blighters holding it on.

Casualty - one decent quality Unbrako Allen Key that has lasted sixteen years of toolmaking, has not withstood undoing these screws. OK I was using a 2 ft tube over it, but that was what was necessary to loosen 4 of these screws. 2 remain stuck fast.

[zim]

Bigger impact gun. Or a nice long breaker bar and decent socket.

G

[Team Idris]

'Twas them on the end with a drift and lump hammer to crack them. It's my favourite fix at work with rusty old heat exchangers. Don't kill the thrust bearing though !

Heat sounds fair and safe.

For future folk reading this, if you mig weld a nut on, have the earth on the bit you are welding so you don't spark across you're bearings

[mickeyw]

The big tw4tting hammer may be the next move.

Last night - 2 ft breaker bar, and the 8mm key (from my old skool hit-it-with-a-hammer impact set) resulted in another chewed up screw head

Another Unbrako key just rounded itself to death. (Incidentally I realised my original key that twisted and bent was a Teng item.)

Measuring showed the Unbrako and Teng keys were bang on 8.00mm A/F, while the unknown but very tough item from the impact set was only 7.90, which I guess is why it chewed its way out of the screw head.

Scores so far

Unbrako -2 for it's cheese like strength

Teng +1 for standing up very well considering the abuse it took

Cheapo impact set - 0 points despite being tough, its accuracy was a total let down

Engine is still laughing a these poor attempts to remove its component parts.

Poor picture showing Unbrako (left) vs Teng (right)

Cheapo impact socket

[robertspark]

I'd wait for comments to this one but could you not weld one of the now knackered Allen keys to the cap screw after applying a swift clout with a hammer and something like a centre punch to break the clamping force then apply some steady (non jerked) force to the welded Allen key on a length of tube?

You have my sympathy given I can't see a way you can get that capscew loose without a) trying to get maybe an imperial one to fit (oversized) with a clout to maybe fit b) weld something on to it (Allen key or maybe a bolt head (hence you can use the threaded part for the welding earth)) c) drill it out (maybe a cobalt bit for 12.9 bolts never got a has drill to work on a tough bolt before (it may be me though)

[Escape]

I had the same problem a while ago and drilled out he stubborn bolts. With the spacer of, I could get a Stillson on them and they came out without much trouble. I don't even recall having a hard time drilling the heads of.

[Boydie]

This reminds me of the Mitsubishi factory works rally team LA Lancers back in the 1970's - every engine bolt on them was a socket head I guess the reasoning behind this was a reduced mechanics tool box at the service points. Great idea until you are digging dirt and crud out of the socket before you can undo it

Heat the bolt, use a good quality impact driver and give it / them an almighty hit with a big lump hammer, it may take a few hits but the combination of impact and the a small turn generated by the impact driver will eventually cause them to loosen. I wouldn't try welding as you can get arcing in the bearings and that's bad news.

[teslo]

When i was dismantling my engine i used impact gun and good quality socket. It took no-time.

[smallfry]

Had the same problem a while ago. I used a brazing torch.......

Used a cheap/old allen key in the head of the bolt, and heated the key until red hot, and the heat transfer does the trick. They come out easily while a decent key while still warm.

No damage the the adaptor or the rear seal.

Not sure if you could get it hot enough with a ordinary blowtorch if you had one. Worth a try ?

Or maybe a gas powered soldering iron, or a high powered electric one ?

[bobtailrangie]

Where in uk are you?

[mickeyw]

Right, tonight there was success out in the garage

It took a couple of hours, but all bolts are now out, not without a fair bit of effort though.

The method that worked was as follows:

Drill off the remaining screw cap heads. Yes they may be 12.9 grade screws, but that does not mean they cannot be drilled. A decent quality, correctly sharpened bit, plenty of cutting compound, and gentle with the spindle speed is the way to go. Power was provided by my trusty 700W Bosch mains powered drill.

This was done in stages, as it takes a Ø12mm drill to sever the heads. I started with a Ø8 drill, as this would centralise itself in the 8mm hex socket. Then a Ø9.5, and finishing with a Ø12. The screws are 7/16" UNF.

So here is the remains of the head, and the short length of threaded section protruding. Alas not enough to get hold of with Stillsons, or Irwin nut removing tools.

I have a decent SKF set of screw extractors. The success ratio of these tools IMO is pretty low, but as this screw is quite big I felt it was worth a go.

I drilled down the centre of the screw, picking up on the existing drill point from the previous operation. Ø5.5 is the size for a #4 extractor. Again, a sharp bit, plenty of lube, and keep the revs down. Once I had a hole about 10mm deep I tried the extractor using a proper tap wrench (an adjustable spanner would fit, but greatly reduce the odds of the desired result), and to my relief the screw moved.

I had to repeat this process for three more screws, but the job's a good'un now.

[Hybrid_From_Hell]

....and you can now breathe in again lol....

[Boydie]

Well done you shout yourself a beer or two.

My gut feeling is that the amount of localised heat that you generated on the bolts, even with the cutting fluid, had the desired effect.