I changed the front drivers mount to a poly one as the standard rubber one was shot through. During the process of removing the mount, the bolt that goes into the engine block was extremely tight. With a long bar, we managed to get the bolt undone. However, the bottom of the bolt was really messed up and was just a solid clump of metal, almost like it had melted. When driving the bolt back in, it would only go in 3/4 and no more. I didnt want to overdo it in case the bolt head snapped. I think this is causing some new vibration issues, most noticable with the aircon on.

What are my options here? Is it possible to rethread the bolt hole inside the block? Also, will this cause my grief if i intend to get manual gearbox conversion? It is unlikely that this bolt will go in if it has to come out again.

Dave, a manual conversion wont require the mount to be disconnected from the block, the only reason you would do that is if the poly mount was to fail. It is possible to rethread the block but risky...

is it the middle 17mm bolt? The one next to the 2 x 17mm nuts?

is it the middle 17mm bolt? The one next to the 2 x 17mm nuts?

Yep, the middle one.... It was a prick to get out, once we did there was no thread left on the last half inch or so

If the thread was damaged why on earth would you try and drive it back in that just asking for trouble.Are you shaw the thread was damaged and not just clogged with metal.That mount bolts to an alloy mount on the engine there a good chance the thread on the bolt was just clogged up with alloy from that mount.I have seen it before when doing a mates mount.We thought the thread was screwed but on closer inspection it wasn't so we just carefully cleaned the thread out and was like new again.

If the thread was damaged why on earth would you try and drive it back in that just asking for trouble.Are you shaw the thread was damaged and not just clogged with metal.That mount bolts to an alloy mount on the engine there a good chance the thread on the bolt was just clogged up with alloy from that mount.I have seen it before when doing a mates mount.We thought the thread was screwed but on closer inspection it wasn't so we just carefully cleaned the thread out and was like new again.

Going by the amount of force it took to crack it (in comparison to my own and another members) we are fairly certain that the bolt had welded itself to the block...

heli-coil FTW.

seriously, why would you put a damaged bolt back in? :nuts:

if it were mine I'd drill it out, re-tap and heli-coil it. lot's of work, but at least it'll be strong enough to hold.

cheers,
.wook

When helping with a sprintex install this particular bolt was loaded with aluminium where there'd been a reaction I suppose between the bolt and the aluminium. Use a hack saw blade to carefully 'file' the alum off the thread if you *must* reuse the bolt. Otherwise a helicoil or similar is the go. You will need the drill bit to suit the helicoil and that may cost a lot more than you're prepared to pay. Have fun. Btw, we reused the bolt to get the car running and it stayed tight-as ever since. As mentioned - it depends how much material was actually removed with the bolt and what condition the remaining threads are in.

Yeah sorry to repeat but bad call putting that back in!! it is probably the thread from the alloy clogged up the bolt, and the force use to extract it bonded it nicely, try retapping the hole, just clean it out with an identical size tap and get another bolt from the wreckers, when threading it in add some copper lube compound to help it. i used that stuff before and it works well.

Seriously just throw the bolt over your sholder, the 2 17mm nuts would be strong enough to hold it.

If you are that worried about it just change the mounting bracket. It has 4 x 14mm bolts holding it in. You have to remove the alternator cause there is one hidden behind it too.

Are you able to get whats left of the current bolt out? if so rip and out and see if the vibration is still there, if it isnt then its the bolt, if it is, then its not the bolt and perhaps another mount is damaged or the poly one is giving you the vibration.

Doesnt this bolt use a super fine pitch for the size? 12x1.5 comes to mind....

wow lots of replies!

Why did the bolt go back in? Well it was 11PM at EGOS house, and there was poker to be played and brain had mostly stopped functioning after the complete ballache we had with the mount overall.

Upon Rhino's advice, if the mounting bracket is removable from the block then that may well be the easiest way to fix this! I will go to wreckers this weekend and source a new one. Before that, I will remove the bolt completely and see if the vibration is still there.

I think it would be a mistake to leave the bolt off and just have two, its there for a reason.

I think it would be a mistake to leave the bolt off and just have two, its there for a reason.

I think from memory that particular engine mount is only a torque stay mount anyways? its not a load bearing mount?

This is the thing I love about our tech forums, all the BS stupid ass guesses that in the end will get someone killed

Guys, if you do not know STFU please or wander elsewhere onto a holden forum and give them your crap ass guesses

For starters LIFE, it is not the block you need to drill, and if anyone lets you near their car with a drill then I really feel sorry for them

Secondly, THIS IS NOT A TORQUE STAY MOUNT FFS, it is one of the 2 main mounts that keep the freakin engine in the engine bay.

Thirdly, there are so many Magna's out there with this bolt missing, as Rhino stated, it can safely be left out if you CBF replacing the mount section that is bolted to the block. A lot the time it will not be that long until a belt or the alt has to come off anyway and the mount can be replaced then

The process to replace
Remove alt
Remove harmonic balancer
Remove PS pump tensiner
Remove lower timing cover (helps if the top ones are off too)
Remove the bolt facing the front of the engine in the aircon bracket
Remove the 4 bolts in the side of the bracket
Lift engeine up and work out the angle you need to lift this sucker out, be careful of the belt that you do not damage it

You can also do as Wook suggested, drill and helicoil but will not be a cheap option is is a big coil and the kits can be hard to find

Sorry about the dummy spit but I am sick and bloody tired of watching all these crap guesses. This is a tech section guys, not a best guess gets an icecream and not multiple choice

The matter has been answered so no need to keep this going