Rethreading spark plugs RS megane 265
Discussion
My megane RS 265 has blown the spark plug out and destroyed all the threads so there's no way of getting it back in.
Has anyone tried to rethread the hole before? Or how much would it cost for Renault to do it? Think they'd want to strip all the head off to get at it
Any help would be great, not had the car for very long
Has anyone tried to rethread the hole before? Or how much would it cost for Renault to do it? Think they'd want to strip all the head off to get at it
Any help would be great, not had the car for very long
You'll be wanting to make a reducer to fit to a strong vacuum afterwards to make sure you can get all the swarf out.
Cheap borescope will help you see if there's any remaining.
It does beg the question of how it happened, something you could do with finding out as you don't want it happening again. Plug over tightened? Under tightened? Cross threaded?
I'm not an engineer, but if the helicoil in the above post worked, I don't know why it wouldn't work for you, you definitely want to be removing all the swarf though
Cheap borescope will help you see if there's any remaining.
It does beg the question of how it happened, something you could do with finding out as you don't want it happening again. Plug over tightened? Under tightened? Cross threaded?
I'm not an engineer, but if the helicoil in the above post worked, I don't know why it wouldn't work for you, you definitely want to be removing all the swarf though
Kirkhouse said:
how much would it cost for Renault to do it? Think they'd want to strip all the head off to get at it
Renault would take the head off and farm the job out to a light engineering company. Your best bet is to find a local engineering works (word of mouth is best but Google and yell.com are good too) and ask them if they can do it in situ. If not, then it's a head off job. Helicoils, if you haven't encountered them, are fitted by drilling out the hole, tapping a thread that is bigger than the one you want, then screwing in a special insert with the thread you do want. As mentioned by someone above, swarf is an issue but a skilled experienced person will have a good chance of success getting all the swarf and drive tang out.
I would 100% remove the cylinder head.
The risk of contamination internally is significant and you don’t want to make this worse than it is.
Pull the head, deliver it to your chosen man with machines. I think you’ll also get a better job of the engineering because he can work with the piece on the bench properly rather than in situ.
At the same time you can take the opportunity to clean everything up, inspect valves, replace any consumables and generally make sure things are perfect.
The risk of contamination internally is significant and you don’t want to make this worse than it is.
Pull the head, deliver it to your chosen man with machines. I think you’ll also get a better job of the engineering because he can work with the piece on the bench properly rather than in situ.
At the same time you can take the opportunity to clean everything up, inspect valves, replace any consumables and generally make sure things are perfect.
I wouldn't know where to start to try remove the head, how big a job is it? Think it might be beyond me
The other concern would be is the helicoil strong enough to withstand the force?
Someone had bodged it up before by closing the gap on the spark plug, the coil was only held in by the screw at the top
The other concern would be is the helicoil strong enough to withstand the force?
Someone had bodged it up before by closing the gap on the spark plug, the coil was only held in by the screw at the top
My advice as both an engineer and a car mechanic is:
1) don’t get ahead of yourself with the engineering side of it until the piece is on the bench. Then, the engineer can decide the best course of action. A well installed helicoil or time-sert are both options but first you need to be able to properly inspect the what how and why.
2) split this into three jobs: car mechanic strip down, engineering solution, car mechanic rebuild and service.
3) the strip down is pretty straightforward if you have any skills and enthusiasm. Because of the head to block interface and method of attachment as well as the engine timing there are a number of things that you could very easily do wrong on rebuild. If you are feeling it, and you really want to do it, there is a lot of help on this site and also on the web in general from people with the experience who always admire others with a can-do attitude prepared to roll up sleeves and give it a go.
4) presuming you have home garage storage would it be possible to find a mobile mechanic who can come out and remove and refit the repaired head for you? It might prove more cost effective this way because garages hate dead cars with heads off at the engineering shop for a week!
Hope that helps. My accountant has a brilliant saying:
Q: “How do you eat an elephant?”
A: “In small pieces!”
1) don’t get ahead of yourself with the engineering side of it until the piece is on the bench. Then, the engineer can decide the best course of action. A well installed helicoil or time-sert are both options but first you need to be able to properly inspect the what how and why.
2) split this into three jobs: car mechanic strip down, engineering solution, car mechanic rebuild and service.
3) the strip down is pretty straightforward if you have any skills and enthusiasm. Because of the head to block interface and method of attachment as well as the engine timing there are a number of things that you could very easily do wrong on rebuild. If you are feeling it, and you really want to do it, there is a lot of help on this site and also on the web in general from people with the experience who always admire others with a can-do attitude prepared to roll up sleeves and give it a go.
4) presuming you have home garage storage would it be possible to find a mobile mechanic who can come out and remove and refit the repaired head for you? It might prove more cost effective this way because garages hate dead cars with heads off at the engineering shop for a week!
Hope that helps. My accountant has a brilliant saying:
Q: “How do you eat an elephant?”
A: “In small pieces!”
Of course I'd agree with all the above, but...
I once secured a blown out spark plug back into a Mk1 Cavalier using tinfoil and some sort of epoxy resin intended for repairing refrigeration evaporators.
It was only ever intended as an emergency repair to hopefully get the car to a garage, but unknown to me at the time lasted 3 months of daily use before going again which resulted in the car being scrapped as it was a wreck anyway...the owner replaced it with a Renault 18 which I flatly refused to work on!
I once secured a blown out spark plug back into a Mk1 Cavalier using tinfoil and some sort of epoxy resin intended for repairing refrigeration evaporators.
It was only ever intended as an emergency repair to hopefully get the car to a garage, but unknown to me at the time lasted 3 months of daily use before going again which resulted in the car being scrapped as it was a wreck anyway...the owner replaced it with a Renault 18 which I flatly refused to work on!
Another thought if the engine has done galactic miles is to simply replace it! There is a complete new until as an exchange on eBay now for a couple of grand:
Here:
https://www.ebay.co.uk/p/1358838833?iid=3239888101...
How about that for an extreme solution? Whip the old one out, new one in, job done! I’m only half joking as well!
Best of luck whatever you decide.
Here:
https://www.ebay.co.uk/p/1358838833?iid=3239888101...
How about that for an extreme solution? Whip the old one out, new one in, job done! I’m only half joking as well!
Best of luck whatever you decide.
Taking the head off will multiply the cost of repairing this problem, probably by a factor of ten.
It is possible to repair without taking the head off.
A time-sert should be used not a helicoil
The thread cutting process is done with hand tools not high speed machinery. With precautions there is no need to risk leaving bits in the engine.
It is possible to repair without taking the head off.
A time-sert should be used not a helicoil
The thread cutting process is done with hand tools not high speed machinery. With precautions there is no need to risk leaving bits in the engine.
Julian Thompson said:
Another thought if the engine has done galactic miles is to simply replace it! There is a complete new until as an exchange on eBay now for a couple of grand:
Here:
https://www.ebay.co.uk/p/1358838833?iid=3239888101...
How about that for an extreme solution? Whip the old one out, new one in, job done! I’m only half joking as well!
Best of luck whatever you decide.
How to turn a £300 job into a £3,000 job...Here:
https://www.ebay.co.uk/p/1358838833?iid=3239888101...
How about that for an extreme solution? Whip the old one out, new one in, job done! I’m only half joking as well!
Best of luck whatever you decide.
HustleRussell said:
Taking the head off will multiply the cost of repairing this problem, probably by a factor of ten.
It is possible to repair without taking the head off.
A time-sert should be used not a helicoil
The thread cutting process is done with hand tools not high speed machinery. With precautions there is no need to risk leaving bits in the engine.
It is possible, yes.It is possible to repair without taking the head off.
A time-sert should be used not a helicoil
The thread cutting process is done with hand tools not high speed machinery. With precautions there is no need to risk leaving bits in the engine.
It is not simple, however, to find someone local who will take on a job where they are going to earn a couple of hundred quid at most if they get it right vs a couple of thousand pound claim if they fail to prevent contamination.
That’s why Renault will remove the head and that’s why I’d remove the head too. Finding a garage who will do an in situ insert just won’t be a simple thing because you’re blurring the lines between mechanics/engineering when most garages are more comfortable doing oil changes and fairly basic work.
PS The new engine isn’t as daft as it sounds IF the car has done big miles.
But obviously each to their own! The OP has a range of options here now :-)
Kirkhouse said:
Did it survive? Worried about getting a load of metal filings inside the engine
Yes, he poked an oily rag down the spark plug hole first which removed most of it then had a small vacuum that went in afterwards. The car was perfect for many years afterwards, the whole process took him no longer than about 10 minutes and it was clearly something they did often as he was completely unphased by the job. I too was worried and thought about new engines etc.Also it may have been a time sert, I just assumed it was a helicoil.
The firm was https://www.foxwooddiesel.com/ in Chesterfield.
From their website:
"Some services, such as re-threading sump plugs and spark plug bores, or dealing with broken studs and bolts, can also be offered on site at your premises. Simply call us, and we’ll quickly work out the best way to help you."
Edited by PaulGT3 on Monday 25th May 12:47
Kirkhouse said:
I wouldn't know where to start to try remove the head, how big a job is it? Think it might be beyond me
The other concern would be is the helicoil strong enough to withstand the force?
Someone had bodged it up before by closing the gap on the spark plug, the coil was only held in by the screw at the top
No need to remove the head. A mobile specialist would put a new insert in and charge around £40. We use a local guy to do any of this sort of work. He's also done injector threads and glow plug threads. The other concern would be is the helicoil strong enough to withstand the force?
Someone had bodged it up before by closing the gap on the spark plug, the coil was only held in by the screw at the top
Re vacuuming a small plastic tube can be taped around a crevice tool and will do the job just fine. Any small debris will exit the exhaust once started, no damage will be done.
A1VDY said:
Any small debris will exit the exhaust once started, no damage will be done.
Won’t do the turbo much good though.We drilled a plug out of my sisters old Ka after it snapped in situ. Duck taped a piece of old fuel pipe to a vacuum cleaner crevice tool and stuck it down the plug hole, moving it around for a few minutes to hopefully get rid of any swarf. Put a new plug in and it fired up and ran with no ill effects, but I’d have been much more hesitant if the engine had been turbocharged (or the car worth more than the £500 this one was.
I guess you might get away with it, but it’s a risk.
Speaking to Renault customer services tomorrow hopefully, but the Renault garage is shut till 1st June. Will get a price and see what they'll do with it.
Cars at 69000 miles and 2013 so is probably due the major service anyways (cambelt and water pump) would maybe get it done at the same time but depends on how much they want for it all
Cars at 69000 miles and 2013 so is probably due the major service anyways (cambelt and water pump) would maybe get it done at the same time but depends on how much they want for it all
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