scoobystiv1

Hi people, my very first time on the forum posting something, usually read forums and not really post on them, my problem is this, i have just changed the water pump on my impreza, i've put the timing belt back on and torqued up the tensioner but the tensioner next to the water pump has worn the thread, i was tightening it up and then felt that horrible feeling where it just goes loose, I found i put the wrong torque measurement on it! my problem now is what to do about it, the car still starts and it doesn't seem like the bolt is moving but i have that little voice in my head that says it could unscrew if i go over a bump or down the motorway, what should i do?? am i going to have to take the belt off again and how would i resolve the worn thread because it seems like it is part of the engine block, i don't think i could get a replacement part!!! please help!!!!

chopperman

You maybe able to fit a hellicoil but it will need re tapping to fit it. Not sure if you will be able to do in situ. Other way if the engine has to come out is get the hole welded up the re-drill and tap.

Broxi

iTrader: (11)

Do not use it, the bolt will come loose and you will kill the engine.

get it down to a local engineering firm, as Chopperman has said, i am Sure they will be able to fit a Helicoil in their for you, with the rad out they should be able to do it in situ.

scoobystiv1

hi, thanks for the advice, the engine is not coming out, and what do you mean 'situ' and last question, how does helicoil work, thanks for your help!!!!

chopperman

In situ means still situated ie not taking the engine out.
A helicoil is a stainless steel thread, i looks a little bit like a spring. You use a special tap to re tap the hole. You then screw the coil in using a special tool until its at the correct depth then tweak it back in the opposite direction very slightly. This causes the coil to grip the threads that the coil is screwed into. You then knock the little tang out of the centre of the coil that the insertion tool fitted into. Job done.

When looking up torque figures, be aware of inch pounds and foot pounds.

This is just a random pic so you know what the kit looks like. You can buy these kits in several sizes.
http://www.ebay.co.uk/itm/Helicoil-t...item5d340aab5a

scoobystiv1

thanks soo much, i appreciate everyones help, looks like i'm going to invest in helicoil

chopperman

Your welcome mate ,Fitting the helicoil is an easy job. The hard bit is if you need to drill the hole before you re-tap with the engine in situ. Take your time and do it right first time as you will only get one go. After that if you 'F ' it up it will be ,weld up hole ,drill and tap. That will be a specialist job and may need engine removing. Good luck.

pflowers

Try and find someone with a Wurth 'Timesert' kit, these can be fitted by hand using a tap wrench. As there is no need to use an electric drill it should easily be fitted in situ, possibly without even removing the rad.

chopperman

I didn't mention timeserts because most peeps consider helicoils better. Timeserts have a habit of coming back out . If all the threads come out with the bolt the hole could be clean enough to tap without drilling.

What size bolt are we talking about here?

pflowers

I've used loads over the years and have never had one come out, if fitted correctly they should be fine.

chopperman

Do you use thread lock with these? I think the reason they are more likely to come out with the bolt when you unscrew is because timeserts are solid unlike helicoils. Because the helicoil is like a spring it tends to grip the outer thread when the bolt is unscrewed because it can expand slightly unlike a timesert.
But if the OP thinks timeserts will be easier to install in situ then it maybe worth a go. Personally ive always used helicoils and quite often you dont need to drill. You only drill if some of the damaged thread remain in the hole. I would have thought this would be the same for timeserts?

chopperman

The other point to be aware of if using a timesert is there flanged on the top. This could prevent a flush fitment unless you countersink the top of the hole being repaired.

scoobystiv1

its a size 14, and when would i drill? i don't quite understand that bit :/

chopperman

If your buying a helicoil kit there will be instructions with it. But basicly you need to tap a thread in the hole that will hold the helicoil in place. The hole needs to be a certain size for the tap and the hole needs to be clear of the old broken threads. This is where drilling maybe required. You should get the drill bit, tap ect in the kit.
Its not a big job but can be a bit daunting first time. If your not confident you could always call out a mobile engineer to do it.

pflowers

Timeserts are slightly tapered internaly before you fit them, when you use the correct tool to insert it forces the sides out to form the new threaded hole, the timesert is then forced outwards driving it into the wall of the item being repaired.

If you are bolting into the timesert so that the head of the bolt hits against the timesert it is possible that if you over tighten it can lock the timesert to the bolt therefore the timesert winds out with the bolt when removed. If you are bolting something to the timesert like a bracket etc it is not possible for it to come out.

The kit comes with a countersink tool so you can fit the timesert flush.

BTW I have no connection to Wurth I have just used them in loads of awkward places and find them brilliant. As long as you have enough clearance ( about 3-4 inches ) you can even get a ratchet spanner on the supplied drill.