Author Topic: Removing rusted spark plug & remove valve guides  (Read 627 times)

Online KeithA

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Any advise for removing this rusted spark plug. It has had a soak with some diesel for many months. I have tried the extractor but it wont budge.
I want to apply a little heat, but I;m concerned it might crack somewhere.
Would I need to pre heat the whole head first, or would a little local heat be OK.
Also I have to drive out the old guides. I assume I need to clean off any carbon scale from around the guides and drive them out from the inside using a brass mandrel/punch.
Is it best to do this also whilst the head is warm??
Thanks

adm: title edited to reflect topic subjects. Please make separate topics for different questions

Online orabanda

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Re: Removing rusted spark plug & remove valve guides
« Reply #1 on: 19.05. 2018 00:21 »
Plug: I would drill it out from the other (combustion chamber) side. You will be able to accurately reference the hole centre from this side.  Do not exceed the tapping drill size.
Then you can run a 14mm tap through, and relax and watch THE WEDDING!!

Online muskrat

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Re: Removing rusted spark plug & remove valve guides
« Reply #2 on: 19.05. 2018 00:28 »
G'day Keith.
Gee that is a mess. The trouble with easyouts is they tend to expand the plug making it even harder. You will need to heat the head to remove the guides (about 1/2 hour at 200-250 C (use the bbq or wait till the wife goes out and use the over)) so try the plug again at the same time.
If that don't work I'd drill 12mm to start and try to pick the rest out. Tapping drill size for that thread is 12.8mm which is the next option and run a tap down to clean it out. The last resort is drill out further and use an insert.
Cheers
ps. Just had another idea re plug. With the porcelain removed you can run a 3/8" cycle thread tap down and use a bicycle axle to screw in all the way and some then put a spacer and nut on the combustion chamber side. Put locknuts on the outside and try to screw it out.

PPS. Richard beat me.
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Online orabanda

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Re: Removing rusted spark plug & remove valve guides
« Reply #3 on: 19.05. 2018 00:40 »
Hey Musky,
Methinks I could never beat you on the road!

Online muskrat

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Re: Removing rusted spark plug & remove valve guides
« Reply #4 on: 19.05. 2018 01:13 »
Maybe not but I bow to your engineering skills. *respect*
Cheers
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Offline BSA_54A10

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Re: Removing rusted spark plug & remove valve guides
« Reply #5 on: 19.05. 2018 05:00 »
Get a can of liquid freeze.
It will be cheaper from an electronics shop than an engineering shop.
When you pull the head off the BBQ spray the inside of the plug with the liquid freeze.
Do it a couple of times then try the easy out while the head is still warm.

People worry about cast iron cracking because they do not understand metallurgy.
Cast iron fire grates can get to yellow hot at the middle and still be black at the ends.
This stems from the problems associated with electric welding cast iron where you have 3 phase changes happening within a 1/2 of each other.
The when it cools tensile stresses are created by the phase change and the iron cracks.
If you are not melting the iron it can take loads of heat.
Again, think pot belly stoves, particularly the coal or coke burning ones .
Bike Beesa
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Online KiwiGF

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Re: Removing rusted spark plug & remove valve guides
« Reply #6 on: 19.05. 2018 05:35 »
Any advise for removing this rusted spark plug. It has had a soak with some diesel for many months. I have tried the extractor but it wont budge.
I want to apply a little heat, but I;m concerned it might crack somewhere.
Would I need to pre heat the whole head first, or would a little local heat be OK.
Also I have to drive out the old guides. I assume I need to clean off any carbon scale from around the guides and drive them out from the inside using a brass mandrel/punch.
Is it best to do this also whilst the head is warm??
Thanks

Could you weld a rod what remains of the plug? Then get some real turning force on it?
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Online Black Sheep

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Re: Removing rusted spark plug & remove valve guides
« Reply #7 on: 19.05. 2018 06:33 »
Don't use the easy out. There are infinitely better extractors out there - the square section ones are best. I had the same problem with an iron head and soaked it for ages in penetrating oil then used heat and a square extractor - applying pressure both ways - and did this daily over the course of a week and then it finally shifted. 
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Online Triton Thrasher

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Re: Removing rusted spark plug & remove valve guides
« Reply #8 on: 19.05. 2018 08:24 »
If you know anyone with an acetylene gas torch, get the plug remains red hot and let cool again.  It will lose its grip on the head.

A drift for valve guides can be steel, though maybe brass has an extra safety factor for putting new ones in.

Online chaterlea25

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Re: Removing rusted spark plug & remove valve guides
« Reply #9 on: 19.05. 2018 15:10 »
Hi,
Going back to removing the valve guides
As the head is somewhat corroded, I would first get it blasted before trying to remove the guides
Or
Machine away the top portion of the guides, heat the head  as above and drive the guides down into the ports
That way there is a lot less likelihood of damaging the guide bores in the head

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Offline jachenbach

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Re: Removing rusted spark plug & remove valve guides
« Reply #10 on: 19.05. 2018 15:20 »
I had a broken, stuck plug in the Norton when I got it. Soaking, extractors, heat, didn't work. Drilled with progressively larger bits until I just started to see threads, then ran a spark plug tap down to clean out the rest. Worked out fine (so far).

Online Greybeard

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Re: Removing rusted spark plug & remove valve guides
« Reply #11 on: 19.05. 2018 15:48 »
...Machine away the top portion of the guides, heat the head  as above and drive the guides down into the ports
That way there is a lot less likelihood of damaging the guide bores in the head

As I have no way of machining the valve guides I snapped the tops off using a hammer and a drift before knocking them in to the combustion chambers.

Online KeithA

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Re: Removing rusted spark plug & remove valve guides
« Reply #12 on: 25.05. 2018 10:29 »
Just a quick thanks for the help and advise for getting the guides and spark plug out.
I had success with breaking away the top of the guides, and then heating the head in the oven at @220C for 30 minutes, and knocking the remains down into the ports with a brass drift.
No misses, so no issues. *smile*
I didn't have many specialist tools available to tackle the spark plug problem, so drilled out the body to 12mm, and managed to pick out the rest with a pointed screwdriver, without any damage to the threads. Now I have the basis for an original head with no broken fins.
Now just need to tackle the rust inside the ports, and I think the seats will come up OK with a suitable cutter.
Cheers Keith

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Re: Removing rusted spark plug & remove valve guides
« Reply #13 on: 25.05. 2018 11:47 »
Excellent!

Online duTch

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Re: Removing rusted spark plug & remove valve guides
« Reply #14 on: 25.05. 2018 13:17 »

 I needed to push my valves partially out for some reason,  and used a long-enough *fine-thread* 5/16" bolt through the guide and a variety of washers,  sleeves and other implements of destruction, and drew them out carefully and controlled.
 No banging, busting, or bashing involved and worked a treat (can't remember if I added some heat or not,  but probably did)
  Kinda did the opposite to put 'em back
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