Engineering Help needed : How to remove seized alternator mounting bolts ?

[martin99]

Folks, I have twin VP KAMD300 and because the alternators sit under the raw water pump they have occasionally been wet when impellers changed. This has caused corrosion on the bolt heads. I wanted to loosen all the mounting bolts to aid adjustment of the alternator belts but found them stuck. The long mounting bolt ( circa 120cm) is stuck with corrosion on both sides. I took the nut off OK but the 16mm head bolt wont move and am afraid I will shear it if I go up in spanner size with a tube to increase the leverage. I have soaked it overnight with penetrating spray- no change.

Will heating or freezing help?

If I do shear the head the bolt is facing a bulkhead so will be impossible to drill out and use a bolt extractor in a battery hand drill. Any other useful help if this happens appreciated.

 

[rotrax]

In my experience the long mounting bolts holding alternators to power units often pass through a long steel sleeve, often acting as a spacing piece.. This sleeve is often the cause of siezure, the bolt siezes inside it.

If there is such a sleeve on your installation, heating that should help.

Good luck.

 

[anoccasionalyachtsman]

Yes, heat will help. The very best way to do that is with the induction heater that some mechanics have, flame works just as well but does more collateral damage. Freezing can help shock it. Talking of shock, then a hammer or rod and hammer will also help break it free. Try tightening too, that avoids winding it into shear territory.

 

[pandos]

Patience and plenty of penetrating fluid applied liberally over a long time...I'd also try some kettles of boiling water as a starting point and cleaning it with a wire brush just to get away anything on the surface and to allow fluid to penetrate....

Whilst the bracket is well fixed to the alternator. Have you looked to see if the mounting bracket can be separated from the engine block?
(Mine has 3 bolts holding it on)

 

[anoccasionalyachtsman]

Whilst the bracket is well fixed to the alternator. Have you looked to see if the mounting bracket can be separated from the engine block?
(Mine has 3 bolts holding it on)

That's a good call.

 

[Alfie168]

Heat, penetrating oil and tap tap tap with a hammer rather than bash bash. Leave overnight, repeat and then try and ease it back and forth with ring spanner if possible. It will shift eventually but overstrain it and as you say, you are in the poo. If it doesn't go be prepared to leave it and come back to it and do it all over again. Losing your cool and forcing it won't work. Old saying "Little knocks can move great rocks where bigger knocks will break them "

I've had situations where a bolt has been stuck all day. Next morning it comes off first go. I can't really explain it, but it happens.

 

[Neil_Y]

Folks, I have twin VP KAMD300 and because the alternators sit under the raw water pump they have occasionally been wet when impellers changed. This has caused corrosion on the bolt heads. I wanted to loosen all the mounting bolts to aid adjustment of the alternator belts but found them stuck. The long mounting bolt ( circa 120cm) is stuck with corrosion on both sides. I took the nut off OK but the 16mm head bolt wont move and am afraid I will shear it if I go up in spanner size with a tube to increase the leverage. I have soaked it overnight with penetrating spray- no change.

Will heating or freezing help?

If I do shear the head the bolt is facing a bulkhead so will be impossible to drill out and use a bolt extractor in a battery hand drill. Any other useful help if this happens appreciated.

ACF-50 has worked well for me several times.

 

[waynes world]

If its a sleeved type then i would save the messing around and snap the head off, remove alternator and then get/make new sleeve and bolt. Or remove remaining bolt from sleeve and fit new bolt,

 

[martin99]

Thanks for all suggestions I am going to try this Wurth freezer too : Rost-Off Blue Ice Rust Remover | WÜRTH

 

[alan_d]

I've had situations where a bolt has been stuck all day. Next morning it comes off first go. I can't really explain it, but it happens.

I have had the same experience with crosswords, but I suspect the underlying mechanism may be different.

 

[PabloPicasso]

One of my crew is into old cars and has good 'spanner' skills. He has an impact gun. Looks a bit like a battery screwdriver but rattles Like hell when spinning which seems to make light work of apparently seized bolts.

I'd try boiling water first. It dissolves the encrusted salt, keep reapplying, and then your preferred easing oil/concoction.

Good luck with it and do. Please let us know what works in the end

 

[TiggerToo]

When that happened to me, the only thing that worked was cutting the bolt off with a hacksaw. Hard work, given the poor access

 

[Topcat47]

It depends on whether you're afloat near a power outlet or equally ashore near a power outlet but an electric heat gun (paint stripper) is the only safe way to apply heat to an alternator and you won't be able to adequately shield it when using a blowtorch or similar. I've never seen an induction heater used in a confined space. Cutting off the bolt head will only work if the spindle can be drifted out afterwards, in which case you'd be able to remove the bolt from the nut end anyway.

To get it moving, I would use couple of nuts locked at the end of the spindle. That way will protect the threads. Plenty of release oil overnight. Ten tap the bolt in both directions to get it moving, applying more release oil yo the exposed shaft. Smallie smallie catchie monkey as they used to say when I was an apprentice. Mole grips on the bolt head, if you can fit them are better than a spanner unless it's a proper hex. Total Brute force is never a good answer to this problem.

 

[martin99]

One of my crew is into old cars and has good 'spanner' skills. He has an impact gun. Looks a bit like a battery screwdriver but rattles Like hell when spinning which seems to make light work of apparently seized bolts.

I'd try boiling water first. It dissolves the encrusted salt, keep reapplying, and then your preferred easing oil/concoction.

Good luck with it and do. Please let us know what works in the end

No luck with freezer spray from Wurth tools. Am going to try and take it off the engine complete with bracket and adjustment bar. Although the middle section of the long bolt also passes through a part of the engine casing before emerging to the 'nut' end . I am hoping I can drift this as a complete unit, then when on a bench work on getting the bolt out of the alternator. Issue now is this alternator has stopped producing charging volts...will remake the sense wire and see if I have caused this ( old ) connection to be intermittent with all the body movement I have done down there.

 

[PabloPicasso]

If you can get it off you could take it into a tyre place. They'll have a pneumatic impact gun which may get the nuts off.

 

[Wing Mark]

One of my crew is into old cars and has good 'spanner' skills. He has an impact gun. Looks a bit like a battery screwdriver but rattles Like hell when spinning which seems to make light work of apparently seized bolts.

I'd try boiling water first. It dissolves the encrusted salt, keep reapplying, and then your preferred easing oil/concoction.

Good luck with it and do. Please let us know what works in the end

Amazing bits of kit.
I haven't quite justified buying my own yet, I got close to it last month, but a little heat from a hot air gun did the job, along with some '3 in 1' type oil.

 

[anoccasionalyachtsman]

Amazing bits of kit.
I haven't quite justified buying my own yet, I got close to it last month, but a little heat from a hot air gun did the job, along with some '3 in 1' type oil.

I succumbed about six years ago. Great toy!

 

[PabloPicasso]

And you'll also need to buy new more robust sockets and driver bits that are strong enough to withstand the hammering they'll get when you use an impact driver

 

[PCUK]

The other good use of an impact gun is that you can tighten nuts and bolts when you can't reach the nut to hold it!

 

[martin99]

Thanks all . There is no room to get an impact tool in. I took the advice of taking the bracket off the engine and was surprised that those bracket bolts came out easily, as they are threaded only low down the threads so not exposed to moisture as much. I was able to rotate the whole assembly whilst pushing the assembly off he engine mount hole. The long bolt as still firmly stuck in place.It looks like a UNC thread not metric so this is very slightly bigger than an M10 - that may have caused it to get seized in the hole .
Two new alternators on back order 70amp Prestolite £100+vat each from Superior quality vehicle components in Rochester.