help needed with cross thread spark plugs
Discussion
christ ! can you believe it, was working on the 400SE getting ready for the MOT and rusty nail run last night and the simplest job i had to do was change the spark plugs and i have cross threaded two of them.
I am having difficulty in getting the spark plug now level and to meet the proper threads.
I was going to smash the car up and catch the train but instead my thoughts were to jack the engine up after loosing the engine mounts, which hopefully will give me some more room to see the hole and get it lined up correctly ?
i was hoping that somebody had been in and got out of the same sh3t hole mess i am in
help need
stephen
I am having difficulty in getting the spark plug now level and to meet the proper threads.
I was going to smash the car up and catch the train but instead my thoughts were to jack the engine up after loosing the engine mounts, which hopefully will give me some more room to see the hole and get it lined up correctly ?
i was hoping that somebody had been in and got out of the same sh3t hole mess i am in
help need
stephen
wild rover said:
Good idea lifting the engine,been there before. Try turning the plug ante clockwise until you feel the click,check the angle if happy go for it should help with a little copaslip on the end of the thread,best of luck fingers crossed.
going to give it another go tonight, have some copperease which sounds the same as copaslip, thanks for the tip regarding backwards turns.stephen
with my fingers crossed and my toes
The following technique MAY work and stop you having to remake the thread - which is a head-off procedure unless you have all the right tools.
By cross-threading it you may have formed two starts to the thread.
Expanding on what Wild Rover said.
The best way round this is to use an old plug, mark it up with tipp-ex or something so that you know where the main thread starts.
Carefully by hand put the plug into the hole and turn it backwards with a little bit of downward pressure on it, you should feel the slight dip where the front end of the plug thread drops off the front end of the thread on the head. Imagine that the thread in the head is a slope and you are dropping off the front of it.
There should be two of these, one is the original and the other is the new one formed by the crossed thread. Remember where these occur by checking the mark on the plug.
Try both of these by turning the plug clockwise by hand only (more feel) and see which of the two threads feels the best. The copa-slip should help.
See how far you can screw it in by hand only, if it starts to bind then back it off a bit and approach again.
Once you have gone a couple of turns then this should confirm that you have found the original thread, it should get easier not harder.
If you manage to get it right then mark the head to match the start of the thread marked on a new plug - so you won't forget to do it the next time you change the plugs.
To get the feel of finding the start of the thread try practicing on a big nut and bolt held in your hand.
In future always start threads in alloy heads by hand to start with - but it's a bit late to tell you this now.
Russ
By cross-threading it you may have formed two starts to the thread.
Expanding on what Wild Rover said.
The best way round this is to use an old plug, mark it up with tipp-ex or something so that you know where the main thread starts.
Carefully by hand put the plug into the hole and turn it backwards with a little bit of downward pressure on it, you should feel the slight dip where the front end of the plug thread drops off the front end of the thread on the head. Imagine that the thread in the head is a slope and you are dropping off the front of it.
There should be two of these, one is the original and the other is the new one formed by the crossed thread. Remember where these occur by checking the mark on the plug.
Try both of these by turning the plug clockwise by hand only (more feel) and see which of the two threads feels the best. The copa-slip should help.
See how far you can screw it in by hand only, if it starts to bind then back it off a bit and approach again.
Once you have gone a couple of turns then this should confirm that you have found the original thread, it should get easier not harder.
If you manage to get it right then mark the head to match the start of the thread marked on a new plug - so you won't forget to do it the next time you change the plugs.
To get the feel of finding the start of the thread try practicing on a big nut and bolt held in your hand.
In future always start threads in alloy heads by hand to start with - but it's a bit late to tell you this now.
Russ
Edited by E Ponym on Tuesday 14th September 12:44
If you are going to try re-cutting the thread you do NOT want any swarf dropping into the top of chamber,a bit dodgy i reckon.If a piece of rag is pushed into the hole so any swarf lands on top i reckon a strong vacuum suction would pull the swarf out followed by a tiny hook to extract the rag, but all a bit dodgy.
thanks all dix, wild rover, johnny, eponym, tempus and wooley
all added something
Shaun aka onefinger bandit been round and we have sorted one plug so far, does not sound much but believe me it is !
the rain stop play, so tomorrow, god willing the next plug
then MOT and the madness of the rusty nail
all added something
Shaun aka onefinger bandit been round and we have sorted one plug so far, does not sound much but believe me it is !
the rain stop play, so tomorrow, god willing the next plug
then MOT and the madness of the rusty nail
The thread chaser is a good idea - I have one and have never had to use it.
Always clean any oil from an old plug if you plan on re-use then use a plug brush to remove any carbon, then use a clean rag to remove any oil / dirt from the plug recess in the head.
Always turn the plug anti clockwise 1/2 a turn until you feel the click of the thread enguaging then turn clockwise. It should turn in easy.
If the plug chaser does not work - then it is probably a head off job to have a helicoil insert - I say probably as I've never dont it but any swarf would not be a good thing.
Always clean any oil from an old plug if you plan on re-use then use a plug brush to remove any carbon, then use a clean rag to remove any oil / dirt from the plug recess in the head.
Always turn the plug anti clockwise 1/2 a turn until you feel the click of the thread enguaging then turn clockwise. It should turn in easy.
If the plug chaser does not work - then it is probably a head off job to have a helicoil insert - I say probably as I've never dont it but any swarf would not be a good thing.
Alan
I had never heard of a thread chaser before, thats what is so good about this forum as it shows different approachs to your problem.
Found that the second plug put in tonight took 10 mins and was more a build up of crap.
Next time my plugs get treated proper, not like my first sexual exprience, rushed and end up in disappointment LOL
HOTTY
I had never heard of a thread chaser before, thats what is so good about this forum as it shows different approachs to your problem.
Found that the second plug put in tonight took 10 mins and was more a build up of crap.
Next time my plugs get treated proper, not like my first sexual exprience, rushed and end up in disappointment LOL
HOTTY
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