Stripped Block Thread...thought's On The Best Fix.

[opticaltrigger 52]

Hi gent's,

We were working on the build up of the project car engine today and during the final stage of the angle tightening sequence for the head bolts a thread in the block let go.... AGGHHHHH !!!

 

Anyway,I'm sure I'm not the first to go down this road and was hoping you guy's would have some thought's on the best fix.

For example is there a recoil kit for this, do they hold up the torque successfully, or is it best handled differently.

And also should they all be done to be safe.

 

All the very best

O.T.

 

This is the top section of the tread which came out still on the bolt.

 

 

[SweetBadger 94]

See here: http://www.205gtidrivers.com/articles.html/_/articles-guides/engine-related/guide-to-repairing-xu-alloy-block-head-bolt-thr-r101

 

Had the head off and on since doing them - the bolts took the oe torque settings and the engine was fine for a season of racing. If I was to do it again I'd use 2.5d helicoils.

Edited February 7, 2016 by SweetBadger

[opticaltrigger 52]

See here: http://www.205gtidrivers.com/articles.html/_/articles-guides/engine-related/guide-to-repairing-xu-alloy-block-head-bolt-thr-r101

 

Had the head off and on since doing them - the bolts took the oe torque settings and the engine was fine for a season of racing. If I was to do it again I'd use 2.5d helicoils.

 

Hi Alex and thanks for the reply and the great link.

Forgive my ignorance but what did you mean by the 2.5d heli's ?

 

All the best and thanks again

O.T.

[SweetBadger 94]

Hi, it's a measure for the length of the coil given as a multiple of the diameter, so a 2d m11 coil will be approx 22mm long.

[opticaltrigger 52]

Sorry Alex,

I was having a brain fade on the 2.5D's.

 

Your article on the subject is fantastic and thanks very much for it.

Stuff like that is pure forum gold.

 

All the very best

O.T.

[wicked 103 3 Cars]

It looks like you pulled out a helicoil already? That could mean that you cannot insert a new one??

I had the issue with a xu9j4 and inserted 2 coils in row, in order to have similar number of turns compared with original thread and spread the load on the coils. This seems a single coil, so you could try to insert 2?

Edited February 8, 2016 by wicked

[Tom Fenton 1,542]

I don't think thats a Helicoil. It looks like ally to me, its just the thread matl pulled out. I've seen this a few times TBH.

 

Helicoil wise, you can buy longer inserts so you just put 1 long one in, no need to put 2 in.

[wicked 103 3 Cars]

Agree with the last remark, but I couldn't find any with enough length by then. The thread in the block is very long...

[opticaltrigger 52]

Hi Wicked / Tom,

It's definitely not a helicoil, it's made of ally but I did worry because it looked like one at first.

I still think it's odd that it only pulled the thread from the top of the hole and not the whole thing though.

 

All the best guy's

O.T.

[hoodygoodwood 71 3 Cars]

When a head bolt thread stripped in my XU block I bought a V-coil set off Ebay in M11 x 1.5 size , the inserts that came with it were not long enough so I ordered a pack of 10 2.5 D coils and they did the job perfectly .

[TAG 25 1 Cars]

I had to helicoil one of the threads in the block on my 8 valve. It held up fine. It appears one of the other threads let go when the head went back on.

If I were to rebuild that engine, I would be inclined to helicoil all threads in the block.

[SweetBadger 94]

Yup, agreed.

 

I paid to have a threaded insert put in when the 1st thread went in my block as the engine was not in the car at the time, then another thread went the next time I pulled the head off (engine now installed) so after the second went I did all of them. If you're going to the hassle of getting one done then I'd do them all at the same time.

 

O.T. - If the engine is out of the car then I'd think about getting the block to a machine shop to have holes drilled out square to the block rather than messing around with drill guides.

[toolie72 67 1 Cars]

If engines on bench buy the kit and do all of them at once-the coils are the cheapest bit anyway. In a former life when building automated machines (ones that would fit in a room like-I'm not an ex-bottle factory genius) we used helicoils in all aluminium components and we were using high grade alloy-before any problems occurred as downtime was money

Also-one gone could be your fault but lets blame previous owner-rest might be once torque up away from going-you'll kick yourself

Yours

Mr Sods Murphyslaw

[petert 588]

I've got an alloy Mi16 block with 5 helicoils in it. Three head bolts and two mains. Better than original.

[opticaltrigger 52]

Thanks very much for all the advise and input on it gent's

Ordered up the required Vcoil kit and a pack of 10 27.5 mm 2.5D inserts to go with it.

http://www.ebay.co.uk/itm/V-Coil-Thread-Insert-Repair-Kit-M11-x-1-5-Compatible-With-Helicoil-/231838702804?hash=item35faa9dcd4:g:vFAAAOxyc2pTXo~b

http://www.ebay.co.uk/itm/V-Coil-Thread-Repair-Inserts-M11-x-1-5-2-5D-10-Compatible-Helicoil-/231814989107?hash=item35f9400533

 

Definitely going to replace all of the threads in the block with the inserts and to be very honest I'm quite annoyed with myself for not having just done them in the first place.

Anyway as Alex said above getting them straight will be the main task.

I really don't want to tear the whole engine down and take the block to the machine shop. So I thought that if I gaffer tape over the water box and liners then put a flat bit of metal bolted down across the liners, and then use a mag drill. If I can hire one with a Jacobs chuck and enough travel.

 

Be glad to hear any of your thought's on that one gents ?

 

All the very best

O.T.

[Tom Fenton 1,542]

Easiest way is on a drill press or mill. Take sump off and oil pump and the block will then sit flat on the bed.