cross threaded spark plug B14

Post by **shimon340** » 06 Dec 2006 12:03 am

hello!

A friend of mine was over zealous putting a spark plug into his B14

Used the wrench pretty much right away

so the thread is damaged pretty bad - the spark plug was inserted at the wrong angle

I recovered most of the little aluminium ( well alloy ) shards but Im thinking ( and from looking here ) that the only real solution is to helicoil ( or something similar ) the thread.

Now, to avoid metal dropping into the cylinders I think the best thing is to remove the head then helicoil it or timesert ( www.timesert.com ).

Any way to avoid removing the head for this?

I'll got for that once I have a decent gasket set....

I new engine might be easier ( this was the same B14 I posted about which idles ok till its warm then it only barely idles on full throttle - my gut instinct tells me this is an air leak from the manifold. Never seen that on a B14 but the noise from the manifold area - like a blown exhaust sound - lends itself to this idea ) but that depends on finding one!

Post by **classicswede** » 06 Dec 2006 12:30 am

A helicoil is the answer to the thread.

Personaly I'd leave the head on and just blow it out with compressed air.

Post by **shimon340** » 06 Dec 2006 12:37 am

hello

What dya mean Dai?

insert compressed air line into spark hole?

I was thinking of getting a from somewhere a tiny vacuum cleaner head - also useful for getting the glass out the front of my other 340s heater vents by the screen from when it was replaced....

I think it'll be cool to have look inside the cylinder afterwards for debirs with one of those fibre optic camera. Another time I've wanted one was to peek inside my filler pipe and tank to source a leak!

Post by **shimon340** » 06 Dec 2006 12:38 am

When it rains it pours!

Personaly I'm not keen on taking off 1.4 heads as the liners have a bad habit of moving.

The best thing to do whould be to turn the engine over so the exhaust valve is open on that cylinder and blow compressed air through to clean any swarf out.

Cheers

Dai

Post by **Chris_C** » 06 Dec 2006 11:35 am

Eh, Dai posting with Shimons account... confused

When Kar's engine went, I didn't have much choice about taking the head off, but Andy come and gave me a hand (read Andy did the job and told me when I could be useful...) Green books are the way forward, and make sure you have Volvo tool number 574387 or whatever it was, which if you need I think I still have, basically a 2" washer on a bolt with the headbolts thread, which I made at my handy workshop facilities.

Didn't cure the problem, but wasn't too scary a job to do. But, if you reckon you can get the bits out the other way, might be easier.

Post by **Essex1** » 06 Dec 2006 02:47 pm

I guess you could do it in situ if you bought the piston to the top of the cylinder and took off both manifolds - that would safely allow you to blow out any swarf with an airline, assuming you left one valve open (or can or air cleaner from maplins if you haven't got a compressor). The added benefit to this is you could then replace the gasket manifolds which is likely to help your running problem, plus you have a good chance to conduct a through investigation of everything else that may cause a problem - not easy to see under carb in situ. Alternatively, you could duct tape (or connect via the hi-tec bag and elastic band combination) a small plastic tube to a vacuum cleaner and suck the debris out if you didn't want to touch the manifolds.....
You'll have to be verrrry careful not to damage the piston when cutting the new thread - alot of these thread repair kits get you to drill the hole oversized as a first step then you cut the thread into a clean hole.

Post by **classicswede** » 06 Dec 2006 10:21 pm

Chris_C wrote:Eh, Dai posting with Shimons account... confused

Shimon was just quoting what I sent in a PM - there is nothing untoward going on

Tbh it is only ally after all. The companys that recut the spark plug threads are quite happy doing it with the head on and never have a problem. Ally is quite sort and should not cause any damage but is still good practice to blow out as much as possible.

Post by **foggyjames** » 15 Dec 2006 09:47 pm

Agreed on repairing the thread, but I've never got on well with helicoils. I prefer a rigid insert (cue: Mick with smutty comment).

Here's what I did when I did my 240's plug thread...

Obtained re-threading kit consisting of a tap (thread cutter) and a load of threaded inserts (tube threaded inside and out). Greased the crap out of the tap, then wound it in 5mm at a time before backing it out and cleaning off the swarf, and regreasing. The grease is highly effective at catching the swarf. Repeat until tap is all the way through. Finally, crank the engine over for 5s or so without a plug in that pot (and with a LT wire pulled from the coil, so it doesn't run on 3 pots) to blow anything which did escape out of the plug hole.

Finally, put a dash of loctite on the outside thread of the insert, grease the inside one (and put a plug in it) and wind it in nice and tight. Leave it overnight, and you're done.

Dead easy, and took about 10 mins to fit. One thing to watch though - make sure you use the right insert. The 240's head had already been repaired using a shorter version of the 'correct' insert which had failed due to a lack of 'meat' to hold onto. Full instructions come with the kit, but attempt #1 had been done by a representative of the motor trade...

cheers

James