Which Timesert Kit To Repair Xu9 Head Bolt Threads?

[SweetBadger 91]

Hi,

 

I pulled the head off my recently rebuilt mi16 engine yesterday to machine the head for larger cams, and also because after following the 95nm method of torquing up the head bolts the head gasket was showing evidence of a small coolant weep from the back of the block.

 

When removing one of the head bolts it brought most of the thread with it (that's the second one that has pulled out, and this was at only 95nm!)

 

So I need to repair the thread that's pulled out in situe (if I have to take the engine out of the bloody thing again it'll be petrol & matches time for it).

 

Looks like a timesert kit is the best option, and as I'm going to use the 300 degree method to torque the head bolts when I replace the head, it makes sense to get a kit due to the likelihood that another thread will go...

 

I've measured up the thread depth & length as follows:

 

Full depth of thread from top of block - 75mm

 

Length of threaded part in block 23-24mm

 

So I think I should be looking at a 22mm long m11x1.5 insert.

 

Wurth offer this kit: http://www.wurth.co.uk/hand-tools/thread-repair-and-reinforcement/thread-repair-system-time-sert/time-sert-assorment-m11x1-5

 

It looks like the drill/taps/fitting tool etc should be just about long enough.

 

Has anyone used a timesert kit before? If so which one, and where did you order it from?

 

Thanks.

[Tom Fenton 1,524]

I can't comment on timeserts but I've helicoiled many alloy XU head bolts with 100% success. 22mm depth sounds about right as I always use 2D length helicoils.

[petert 549]

Same here, I've only used 2D helicoils.

[SweetBadger 91]

Thanks for the info, it looks like the helicoil option is going to be the cheaper, and should be reliable if installed properly. Any tips on getting the installation spot on (e.g. Drill speed, tapping technique, etc)?

 

Still waiting on a quote from wurth for the timeserts, as they seem to be preferred for head bolts, but I can get a V-coil kit (looks exactly like a helicoil kit) plus 10x 2d inserts for £40.

 

I think the really tricky thing with installing either kit in situ is going to be keeping the drill straight - I was thinking of finding somewhere to turn up a collar that will fit in the top of the head bolt hole and keep the drill bit centered. Any thoughts on this and suggestions on where I could get something turned up?

 

Finally, if two threads have gone already I think it's probably worth doing them all, as if I get to 300 degrees on say 8 out of 10 bolts and thread number 9 goes I'll have wasted another set of head bolts and a gasket - agree/disagree?

 

Sorry for all the questions, but I want to get this right!

 

Thanks.

[welshpug 1,621]

bolt some steel plate/bar to the deck using the other head bolt threads and use a magnet base drill (cant remember its proper name, typically used for drilling girders)

[petert 549]

I'd use a drill press/column drill or mill, 600 rpm and plenty of coolant (kero or WD-40). Take the engine out. Do them all, set up time is minimal compared to the consequences, especially if you have a close relationship with the block.

Edited July 29, 2014 by petert

[Tom Fenton 1,524]

I have used a rotabroach before attached to a steel plate but to be honest as long as you are not a chimp its perfectly possible to do a good job using a pistol drill in situ, as I've also done that a few times. Once the bolt has ripped the threads out to the major diameter the drill is not removing much material anyway. Tapping it square is important as well but there is no magic solution to this other than as above not being a chimp about it.

[SweetBadger 91]

I've ordered the helicoil kit and have a chunky piece of steel plate that could be bolted to the block to serve as a drill guide, or to mount a rotabroach to - only issue with that is you can't get m11x1.5 bolts for love nor money so I'd have to use the old head bolts to clamp the plate down and I think they might get in the way.

 

For anyone interested, the Timesert kit was £200 + ... pricey! And I couldn't get confirmation on the length of the drills / tap with the kit so it may not even be suitable. I think the best deals on these kits are on ebay, buying from the states.

 

I'll give it a go with the engine in situ whilst trying to behave in a non-chimpish manor - will post back the results; if it all goes tits-up look out for a picture of me swinging from the garage rafters with banana in hand throwing faeces at the shagged engine!

 

If it does go wrong then the engine will have to come out anyway and I can look to getting some steel threaded inserts turned up and installed, or just get my spare block decked to match the liners in the existing block.