Spark plugs are bloody tight!

[LegoHead]

I think my plugs are a little tight, using a t handled spark plug remover they wont budge. Is this normal? I wasnt giving it everything as I dont want to strip a thread.

Anyone know if I should just give it more welly?

 

[MikeB]

yeah should be ok. if not use a ratchet

 

[Russ_16v]

you don't get any real leverage with a T handled one mate, use a ratchet, and turn gentle im sure they will come out

 

[LegoHead]

hmmm, well wish me luck. Was trying to do my compression test argghhh. Why do things take so long with clios?

 

[LegoHead]

I cracked one off.lol. 150psi on no. 3

 

[Russ_16v]

is yours low comp mate? as thats a little low i would imagine for normal comp ratio, though if all 4 are around that then its not a bad thing

 

[bearne1]

Always a bit sketchy when they don't come out nice and free, you feel that something is gonna go.

 

[LegoHead]

is yours low comp mate? as thats a little low i would imagine for normal comp ratio, though if all 4 are around that then its not a bad thing

done a bit of research and a good value is 17 x the compression ration.

Mine are 8.5:1 and getting 150psi on all 4 cyclinders. which gives me 17.7 x 8.5 , so pretty much spot on. Plus they are all reading identical.

I did manage to strip a thread, but it was only on the lower inlet manifold. The plenum has been on and off so many times i am not surprised tbh.

 

[Tigger]

What size does the removal tool need to be for taking the plugs out?

 

[stu-172]

What size does the removal tool need to be for taking the plugs out?

16mm buddy!

 

[Tom|Nbk]

16mm buddy!

No, it's 10mm?

Anyway yea use a socket wrench to remove plugs and then to fit new ones I always use the T bar and just nip them up past finger tight. Always the way I've done it never had a problem. Just have to be extra careful with stuff like this. Glad they dont need doing often tbh.

 

[pablo_ni]

cordless impact gun gets them in nice and tight

j/k, ratchet for me too and when tightening I tighten by hand then put the ratchet on and give a little nip.

 

[Tom|Nbk]

cordless impact gun gets them in nice and tight

Lolol, don't say that I've known of it being done.

 

[Fred@BTM]

25nm for spark plugs on them, its shocking how many people don't torque them

 

[pablo_ni]

never torqued a spark plug in my life to be fair. hand tighten plus a nip has always worked well enough.

 

[Tom|Nbk]

25nm for spark plugs on them, its shocking how many people don't torque them

Why, finger tight and then 1/16th of a turn is normally enough.

Just go by finger tight and then nip it up, always the way I've done it for years.

So long as the person doing it isn't a numpty and keeps tightening and tightening most get by without a torque wrench.

 

[Fred@BTM]

my own cars, whatever, customers get the torque treatment, preferably with them stood next to me while i do it, RS clios have a habit of blowing plugs out the head, you can see why!

the torque settings are there, so i use them!

 

[Dan R]

I think my plugs are a little tight, using a t handled spark plug remover they wont budge. Is this normal? I wasnt giving it everything as I dont want to strip a thread.

Anyone know if I should just give it more welly?

get the car red hot then try undoing them

 

[Tom|Nbk]

my own cars, whatever, customers get the torque treatment, preferably with them stood next to me while i do it, RS clios have a habit of blowing plugs out the head, you can see why!

the torque settings are there, so i use them!

What's the reason for them being blown out of the head?

Too loose?

 

[barnesautos]

It eventually arrived but spot on Dan R

 

[Dan R]

It eventually arrived but spot on Dan R

 

[Fred@BTM]

What's the reason for them being blown out of the head?

Too loose?

that and too tight (usually the cause) rips the thread out the head

 

[Tom|Nbk]

Surely you'd have to be a complete numpty to gorilla plugs in and the same goes for leaving them too loose, I think that if you've done a fair few plug changes in your time you know the acceptable amount of torque to use without over doing it?

I can see where you're coming from though Fred it is good practice to torque them in

 

[Fred@BTM]

some of the s**t i've had to do to get them out is unbelievable, breaker bar for example! (not a clio)

as you say, an experienced mechanic/spanner twiddler will be fine, its the "my mate dave" type jobs that do it!

 

[Tom|Nbk]

Yup I had a b**ch of a plug in mine on Cyl 4, surprising considering the previous owner had it done at an Indy they had obviously got some sort of bodybuilder to thug them in.

 

[stu-172]

No, it's 10mm?

Anyway yea use a socket wrench to remove plugs and then to fit new ones I always use the T bar and just nip them up past finger tight. Always the way I've done it never had a problem. Just have to be extra careful with stuff like this. Glad they dont need doing often tbh.

Plugs are def 16mm! The manifold bolts are 10mm!

 

[pablo_ni]

spark plug sockets are numbered differently for some reason. so a 16mm regular socket might work but if you go buy a spark plug socket (well worth it as they hold the plug in place while lowering it in) it will be a 10mm one.

 

[Tom|Nbk]

spark plug sockets are numbered differently for some reason. so a 16mm regular socket might work but if you go buy a spark plug socket (well worth it as they hold the plug in place while lowering it in) it will be a 10mm one.

Yep!

You need a 10mm Spark plug Wrench or Socket.

 

[sideways danny]

spark plug sockets are numbered differently for some reason. so a 16mm regular socket might work but if you go buy a spark plug socket (well worth it as they hold the plug in place while lowering it in) it will be a 10mm one.

sparkplug sockets are sized strange. They're 5/8 technically too, not 16mm

 

[dajones]

bit off topic but are sockets numbered wierdly aswell? i found a 12mm and 13mm earlier and the 12mm was larger :S

 

[Alastair.]

Renault have actualy sent us a spark plug socket which has the correct preloaded torque setting, i still havent used it.

 

[Mark One]

done a bit of research and a good value is 17 x the compression ration.

Mine are 8.5:1 and getting 150psi on all 4 cyclinders. which gives me 17.7 x 8.5 , so pretty much spot on. Plus they are all reading identical.

I did manage to strip a thread, but it was only on the lower inlet manifold. The plenum has been on and off so many times i am not surprised tbh.

HOLD UP

14.695949 x 8.5
off the top of my head

fankyou and goodnight.

 

[LegoHead]

HOLD UP

14.695949 x 8.5
off the top of my head

fankyou and goodnight.

what are you talking about? I am confused?:S

 

[Tom|Nbk]

Renault have actualy sent us a spark plug socket which has the correct preloaded torque setting, i still havent used it.

:lolup:

 

[Mark One]

what are you talking about? I am confused?:S

you are saying multiply the compression ratio by a conversion to get a figure in PSI

1 atmosphere is 14.695949 PSI
you have 8.5 compressed into 1. That makes 8.5 atmospheres (or 8.61 bar OR 124.92 PSI)

But then that's absolute pressure. So you want to minus 1 atmosphere to get a PSI gauge pressure reading

=110.22 Psi
meaning 150psi is very good

Unless I've missed something. I've had a couple of beers....

Edit: have I missed the point here ....lol
edit: think I have....why have you used 17.7

 

[LegoHead]

compression ratio is independent of units. 1 whatever is compressed into 8.5 whatevers.

I have been researching a little into what compression you should get based on theoretical data and my figures are in the right area. plus they are all identical.

 

[Mark One]

I don't get the 17.7 multiplier tho?? you said compression ratio multiplied by 17?

that's what threw me. thought it was a typo for 14.7. Should really keep my ideas to myself! lol

 

[LegoHead]

I don't get the 17.7 multiplier tho?? you said compression ratio multiplied by 17?

that's what threw me. thought it was a typo for 14.7. Should really keep my ideas to myself! lol

14.7 would be ok if the system was a perfect system with only pressure change , but there are loads of other factors that give you a higher pressure than you would expect.

 

[Mark One]

ah yeah. Temperature changes under pressure etc.
my bad.

 

[sideways danny]

ah yeah. Temperature changes under pressure etc.
my bad.

it was only a rough guide, dynamic CR will change loads with different cams, so you'll only ever get close (within 1 bar ish i'd say) with a rule of thumb

it's roughly right if you take stock static CR as 10.9:1. multiplied by 17 you get 185, and a good health 172 engine is normally around 190psi