PDA

View Full Version : Badly stuck spark plug



jclays
03-23-2017, 10:52 AM
#4 spark plug on my boats 350 Crusader engine is badly stuck. Have been soaking it with PB Power Blaster all week. Still tight last night. Will continue until Saturday. Thinking of using a small 3/8 drive Milwaukee impact wrench feathering the trigger to rock it. any ideas.
Thanks in advance
Jim

Gib Etheridge
03-23-2017, 11:16 AM
Have you tried running the engine until it's good and hot before using a breaker bar and socket?

It's not likely that you are using a 12 sided socket, but just in case, you should be using a 6 sided socket to avoid spinning it on the plug, especially if you use the impact wrench.

Bob (oh, THAT Bob)
03-23-2017, 11:26 AM
First, next time use a little anti-seize on the threads, especially if an aluminum head. And install with a torque wrench, you'll need one of the smaller "micro-torque" wrenches for accuracy as the torque is too low for standard ones (even if within the range, it's so low on the scale that the accuracy would be poor). $10 on sale at harbor freight (every other month it seems) for a click-stop one, they work great.

Second, Ford had a problem with parts of the plug being left in the head, the threaded part was clamshell construction instead of whole. If this happens, look up the procedure and tools for removing the stuck half from a Ford 4.6L V8.

Third, don't tap on the very end, that will just fracture the insulator, but I am thinking if you can slide a pipe over the insulator to tap (with a hammer on the end of the pipe) directly on the shoulder of the hex head, that may loosen things up.

Taper or flat seat?

Dumah
03-23-2017, 11:45 AM
What has worked for me in the past heat the plug red hot and quench with water, the shock usually disturbs the corrosion enough to free it. Hope this helps.

Dumah

Jim Bow
03-23-2017, 11:55 AM
I second the heat treatment. Bake it in a propane flame for a bit, then a cup of water.
Careful with the flame.

Rum_Pirate
03-23-2017, 12:05 PM
Form a dam around it with tap or 'play-do' etc.

Fill with a mixture of 50% automatic transmission fluid and 50% acetone. Keep it topped up (acetone evaporates quickly) for several hours overnight is good.

Give it a very light tap and then try and undo it. Repeat if necessary.

Gerarddm
03-23-2017, 12:08 PM
I was once told to slightly tighten a stuck bolt or screw first, then untighten. The few times I have tried this it seemed to work.

David G
03-23-2017, 12:08 PM
I imagine you already know that giving it a nudge first in the 'tighten' direction will sometimes break it loose quicker than a direct 'loosen' attack will.

Rum_Pirate
03-23-2017, 12:16 PM
I imagine you already know that giving it a nudge first in the 'tighten' direction will sometimes break it loose quicker than a direct 'loosen' attack will.

I think he does if he read Post # 7 by Gerarddm (http://forum.woodenboat.com/member.php?27221-Gerarddm) :D |;)

Garret
03-23-2017, 12:56 PM
I think he does if he read Post # 7 by Gerarddm (http://forum.woodenboat.com/member.php?27221-Gerarddm) :D |;)


They were both sent @ 1:08 - so he most likely hadn't seen it...

To the OP: I agree with the heat & also with a bit of tightening first.

Bob (oh, THAT Bob)
03-23-2017, 01:29 PM
Be careful with the heat if that is an aluminum head, you would be surprised at how low a temperature you can affect that, strength long before melting. Although AL conducts heat away awful fast, so maybe not a problem, but I would still keep flame away if AL. Cast iron, less worries, as long as you are not talking about an oxy-acetylene torch.

Bob (oh, THAT Bob)
03-23-2017, 01:33 PM
I was once told to slightly tighten a stuck bolt or screw first, then untighten. The few times I have tried this it seemed to work.

If you can tap inward on the bolt, it will be even better, unloading the threads a bit.

Ian Marchuk
03-23-2017, 02:08 PM
I was in the trade for quite some time before I ran into this problem. It was on a small block chev truck passenger side.
Often the problem is access for impact tools. After taking off the lhs tire and wheel I could get a reasonably straight line to the plug with about a one foot extension. I used an air powered impact and six point socket, after warning the customer that this was a hail mary attempt. The impact rattled fairly hard before it came free. This was a cast iron head thankfully.
If the head is aluminium it could be dicey, but impact tools should be safer than brute torque.
I have used a friend's Milwaukee 18 V impact on some pretty big and tight nuts and was really impressed with the tool.
Good luck , let us know how this turns out.
I use a dab of nickel never seize on plugs and torque very carefully, especially with alloy heads.

Bob Adams
03-23-2017, 05:04 PM
He should have cast iron heads. I see no bad advice given. I also heartily agree with the anti seize.

BrianW
03-23-2017, 05:13 PM
Instead of flame, a air heat gun can work.

john welsford
03-23-2017, 05:15 PM
Be careful with the heat if that is an aluminum head, you would be surprised at how low a temperature you can affect that, strength long before melting. Although AL conducts heat away awful fast, so maybe not a problem, but I would still keep flame away if AL. Cast iron, less worries, as long as you are not talking about an oxy-acetylene torch.

I do service work on site, where I have to use heat I use a paint stripper gun. Very effective.
Also, to unstick threads I use INOX or CRC 66 Marine, not the standard stuff or WD40.

For a stuck spark plug, I'd soak it in the above for a couple of days, get a very fine cold chisel, cut into one "corner" and tap with a hammer, do up or undo doesn't matter, just get some movement then gradually tap to undo.
If its seriously stuck, smash the insulator,tap the middle out, the threaded part is like a tube with threads on the outside. Then use a fine hacksaw blade from a coping saw or similar to cut from the middle out toward the thread in two or three places, the use a fine pin punch or a cold chisel to peel the remaining part of the plug out.
You'd need to pull the head of the engine after that though as there will be some debris inside.
John Welsford

pipefitter
03-24-2017, 03:14 AM
The post above that recommended running the engine until hot was good advice. The head will go through various degrees of expansion and contraction. Perhaps even trying to free it at different intervals as the engine cools. Also, hitting the wrench with a whapper as pressure is applied also works when direct pressure won't. As is the case with plumbing fittings, if pressure cannot escape, penetrating oil will likely not penetrate and may only help as the plug starts to move.

Bob (oh, THAT Bob)
03-24-2017, 11:58 AM
I do service work on site, where I have to use heat I use a paint stripper gun. Very effective.
Also, to unstick threads I use INOX or CRC 66 Marine, not the standard stuff or WD40.

For a stuck spark plug, I'd soak it in the above for a couple of days, get a very fine cold chisel, cut into one "corner" and tap with a hammer, do up or undo doesn't matter, just get some movement then gradually tap to undo.
If its seriously stuck, smash the insulator,tap the middle out, the threaded part is like a tube with threads on the outside. Then use a fine hacksaw blade from a coping saw or similar to cut from the middle out toward the thread in two or three places, the use a fine pin punch or a cold chisel to peel the remaining part of the plug out.
You'd need to pull the head of the engine after that though as there will be some debris inside.
John Welsford

I always wondered if you did this, or drilled and tapped for a helicoil to repair a stripped hole, if you could just put a tube in there and vacuum things out, rotating the tube to all angles and corners?

Garret
03-24-2017, 12:03 PM
I always wondered if you did this, or drilled and tapped for a helicoil to repair a stripped hole, if you could just put a tube in there and vacuum things out, rotating the tube to all angles and corners?

How lucky are you feeling? ;)

If your own motor, it's one thing. A customer's? Different story I think.

Bob (oh, THAT Bob)
03-24-2017, 12:05 PM
How lucky are you feeling? ;)

If your own motor, it's one thing. A customer's? Different story I think.

Well, first, if you are gonna pull the head off, do that first and then mess with the plug with it off.

Second, on a recip engine, the dangerous stuff is the micron dust that gets trapped between the piston and cylinder. Stuff big enough to not fit there, but small enough to not cause an impact damage in there, will eventually get blown out the exhaust valve.

Garret
03-24-2017, 12:06 PM
Well, first, if you are gonna pull the head off, do that first and then mess with the plug with it off....

I agree 100%!

Bob (oh, THAT Bob)
03-24-2017, 12:09 PM
IIRC, Audi or someone else did a warranty rework to remove intake valve deposits, by blasting them with everything in place, I think with walnut-shell media, and then vacuuming it all out, but don't quote me.

john welsford
03-24-2017, 02:50 PM
I always wondered if you did this, or drilled and tapped for a helicoil to repair a stripped hole, if you could just put a tube in there and vacuum things out, rotating the tube to all angles and corners?

Yes as pointed out, its best to pull the cylinder head off first and work on it on the bench.

John Welsford

Bob (oh, THAT Bob)
03-24-2017, 03:00 PM
Yes as pointed out, its best to pull the cylinder head off first and work on it on the bench.

John Welsford

But that's more work.

I'll tell ya what ya could do. Vacuum things out and then look inside with a lighted borescope, those have gotten cheap. In fact, I would tape a small vacuum tube to the scope extending just beyond the tip, so you can watch yourself vacuum. That should do a pretty good job. And it's less work.

If the vacuum tube won't fit beside the borescope tube through the plug hole, use a large tube that fits around the borescope tube, and then branches off outside the head.

I'm never smarter than when finding a lazier way to do something.

jclays
03-25-2017, 10:46 AM
Going to remove the manifold and elbow on the left side of my port engine. I ordered new units and this will also give me clear access to the spark plug. Have been spraying it down with PB Power blaster all week. Took a strain on the plug with a six point socket and ratchet and it didn't budge. Going to try the impact wrench.BTW cast iron head. No aluminum 350 Crusader (Chevy 350).

Bob (oh, THAT Bob)
03-26-2017, 12:26 AM
Going to remove the manifold and elbow on the left side of my port engine. I ordered new units and this will also give me clear access to the spark plug. Have been spraying it down with PB Power blaster all week. Took a strain on the plug with a six point socket and ratchet and it didn't budge. Going to try the impact wrench.BTW cast iron head. No aluminum 350 Crusader (Chevy 350).

The problem is the taper or flat seat is sealing too well from the outside to let any of the blaster seep into the threads. Pulling the head and inverting, and spraying on blaster from the underside, should get blaster onto the threads. Try that.

Gib Etheridge
03-26-2017, 01:34 AM
Or make a mix of 50/50 acetone/ATF and soak the entire head in it for a couple of days.

Canoeyawl
03-26-2017, 12:49 PM
If you going to go ahead and pull the head, just pull on that wrench hard enough to break the plug. I would use an air impact gun and a good (Snap-on) 6 point socket.

*I have seen internal damage that turned a spark plug into a perfect rivet...

hawkeye54
03-26-2017, 03:48 PM
Jclays, I do not think this has been brought up - is it possible that a previous servicer / owner has cross-threaded that spark plug and it
is more or less jammed into the cylinder head? (Just a random thought, as I am not familiar with that engine or installation)

Rick

David G
03-26-2017, 04:30 PM
Jeebus... is that plug STILL stuck? Time for the dino-myte...

Nicholas Scheuer
03-26-2017, 04:51 PM
I would'a thunk by now ya'would'a either been looking at the hole where it used to be, or snapped off the plug.

TMny
03-26-2017, 09:11 PM
A breaker bar offers more relevant torque than ratchet handle... impact wrenches are considered best.

The vibrations from tapping down on the hex , and expansion from heat ... help penetrant penetrate.
Some plugs just have thinwall tube connecting the insulator assy to the threaded sleave with gnd conductor.
If the tube breaks, a tapered thread remover can be inserted (may straighten the gnd electrode) , and may allow removal of the sleave.

Gib Etheridge
03-26-2017, 09:39 PM
I wonder if the head would warp if it were just thrown in a fire until it was nearly red hot, then use the breaker bar.

Bob (oh, THAT Bob)
03-26-2017, 09:58 PM
I wonder if the head would warp if it were just thrown in a fire until it was nearly red hot, then use the breaker bar.

Well, it'll be stress-relieved as all heck.

For Pete's sake, once the head is off, before going to extreme measures, invert the head and spray on thread-breaker from the thread side, where it can get to the threads, without being blocked by the taper or flat seat on top. Wait a day or two. Try to untorque.

Canoeyawl
03-26-2017, 09:59 PM
I wonder if the head would warp if it were just thrown in a fire until it was nearly red hot, then use the breaker bar.

Yes it will, every surface will have to be checked and likely machined again. Head deck surface redone, both intake and exhaust manifold surfaces, and depending on how much you have to cut, perhaps even the intake manifold. Valve seats may have be replaced and at least re-surfaced, spring seats machined, valve guides replaced, and say a little prayer that the Chevy press in rocker arm studs don't have to be replaced?
Far less expensive at this point to just buy a new head.

A professional with tools and experience shouldn't have much trouble with this. It is a common problem. I would do it in situ even if I had to use a heli coil or "threadsert", but I don't think I would (there are several other ways around this)
Do not use any lubricant to machine cast iron, drill, tap or whatever,

If you are going to pull the head, go ahead and pull them both then have a valve job done on both.
Take note of my earlier comment, that the inner surface of the plug may be hammered into a perfect tubular rivet.

TMny
03-26-2017, 09:59 PM
> I wonder if the head would warp if it were just thrown in a fire until it was nearly red hot,...

With the situation of a bolt or stud the 'red' heat softens the steel , because (standard alloy/carbon) steel is allotropic, ie., it changes its crystalline form to a softer configuration which is far more malleable .
The head casting is designed to operate from say, -20*F to 230*F. Red heat is on order of 1000*F <https://en.wikipedia.org/wiki/Red_heat> , which is well below its freezing point when cast, but beyond operating levels, so it probably would change shape a bit, and the process of cooling from such elevated temps could affect the mechanical properties, including hardness and brittleness.

The problem with heating a sparkplug is its' position in the 'well' , and the construction, limit the ability to effectively conduct adequate heat to the threads, where it would be useful.

Bob (oh, THAT Bob)
03-26-2017, 10:02 PM
^what he said^

(From body-centered-cubic to face-centered-cubic, like copper, if I recall correctly? It's been a long time.)

Canoeyawl
03-26-2017, 10:41 PM
Cylinder heads are (gray) cast iron, not steel. It can be done heated red, but it will have to be re-machined.

Most bets are off about exactly how exactly they will behave, think about it a minute and venture a guess what the combustion temperature of a flammable gas compressed with oxygen might be! Think about cast iron exhaust manifolds for example. I have watched these run red hot with no damage. They are tightly fastened to a fixture, the head itself. Many engines do not use a gasket in that application for this reason.

(I have done this, heated cast iron heads red hot, welded them, then allowed them to cool in an oven overnight. Down from 1200f, still too hot to touch in the morning. Every surface had to be remachined, and at about $1000 worth of work it was worth it. There are no other heads like this one left on the planet. and makng one from a billet was out of the question)

Bob (oh, THAT Bob)
03-26-2017, 11:47 PM
Cylinder heads are (gray) cast iron, not steel. It can be done heated red, but it will have to be re-machined.

Most bets are off about exactly how exactly they will behave, think about it a minute and venture a guess what the combustion temperature of a flammable gas compressed with oxygen might be! Think about cast iron exhaust manifolds for example. I have watched these run red hot with no damage. They are tightly fastened to a fixture, the head itself. Many engines do not use a gasket in that application for this reason.

(I have done this, heated cast iron heads red hot, welded them, then allowed them to cool in an oven overnight. Down from 1200f, still too hot to touch in the morning. Every surface had to be remachined, and at about $1000 worth of work it was worth it. There are no other heads like this one left on the planet. and makng one from a billet was out of the question)


You must be like that welder in No Country for Old Men.

Carson Wells (http://www.imdb.com/name/nm0000437/): [Wells sits back and studies Moss] What do you do?
Llewelyn Moss (http://www.imdb.com/name/nm0000982/): I'm retired.
Carson Wells (http://www.imdb.com/name/nm0000437/): What did you do?
Llewelyn Moss (http://www.imdb.com/name/nm0000982/): Welder.
Carson Wells (http://www.imdb.com/name/nm0000437/): Acetylene? Mig? Tig?
Llewelyn Moss (http://www.imdb.com/name/nm0000982/): Any of it. If it can be welded I can weld it.
Carson Wells (http://www.imdb.com/name/nm0000437/): Cast iron?
Llewelyn Moss (http://www.imdb.com/name/nm0000982/): Yeah.
Carson Wells (http://www.imdb.com/name/nm0000437/): I don't mean braze.
Llewelyn Moss (http://www.imdb.com/name/nm0000982/): I didn't say braze.
Carson Wells (http://www.imdb.com/name/nm0000437/): Pot metal?
Llewelyn Moss (http://www.imdb.com/name/nm0000982/): [annoyed] What did I say?

Canoeyawl
03-27-2017, 12:13 AM
On second thought, go ahead and toss it in fire.

Rum_Pirate
03-27-2017, 07:48 AM
So what is the latest status on the spark plug removal?

jclays
03-28-2017, 09:34 PM
Success.....had to reset and drive in the square drift/ez out until it held firm on the fourth attempt with a half inch drive large ratchet and fair amount of force it popped and started to move then unscrewed. Wow relief. Got my new manifold and elbow delivered yesterday. Time to put it all back together. The manifold looked good however the elbow was very restricted. Just going to change out both. Thanks for the ideas. OBTW the plug had disintgrated when I tried to remove it with a brand new spark plug socket and a very long handled ratchet. All the guts of the plug and the nut head came off leaving the threads inside the head. Thats when I did the above. Success. Now time to reinstall a new manifold/elbow and plugs all with anti seize.
Jim