Fiesta (Endura engine) with seized (but working) spark plugs

I've got a 10-year-old Fiesta with the 1.3 Endura engine. The spark plugs are probably rusted into the cylinder head, and may snap if I try to remove them, a known issue with this engine. They were probably replaced 3 years ago. The engine runs fine at present, so I haven't forced the issue by applying lots of torque to them.

I will probably get rid of the car within 2 years, so what's my best strategy? Should I just keep using the car, while watching out for misfires and lumpiness? Is a spark-plug likely to fail suddenly and leave me stranded? At present, I'm periodically putting a bit of engine oil in each well, in the hope that it might penetrate over time.

If I am forced to replace the plugs, my steps will probably be:

- Apply lots of Plus Gas, wait a day.

- Get the engine warm.

- Apply freezer spray to plugs.

- Try to get the plugs out.

- If they snap, learn about and buy stud removers, etc.

- Call scrap yard to arrange collection.

Any suggestions?

Reply to
Simon
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Like any tight, seized old bolts, a quick twist in the _tightening_ direction first helps to break the seal and reduce the risk of snapping as they're undone.

Other than that your general principles seem about right.

Reply to
asahartz

pour a bit of oil around each plug and use the car for a few days. Generally I would try to undo them with the engine hot. When you try to undo them use a proper spark plug socket and a breaker bar or preferably a T bar, avoid any sideways force on the plug. As these are taper seat plugs I would not try tightening first as there is no where further to tighten them, unlike a conventional plug with a compressible washer. If it does snap off then it is usually quite easy to insert a large torx bit into the hole in the middle of the thread and undo the remains.

Reply to
Mrcheerful

We bought a kit ages ago to fix this, it was not expensive so just ask your local garage .

Reply to
Fred

Yes, and if the insulating ceramics break up you could end up with more than just the plug top sort out...

At present, I'm periodically putting a bit of engine oil in each

Hmm, do you understand how an engine works?! Think about it, what is one of the most important mechanical properties that any sparkplug needs, then ask how any penetrating oil will get to the threads past the gas tight seal - Duh...

Get the job done properly, by people who understand the problem?...

Reply to
Jerry

Yes

No, worse case you limp home on 3.

Sounds OK

OK up till here, I think using an impact wrench on a low setting is less likely to shear the plug, steady tap tap and lack of side force being the theme. If you do shear the plug I'll bet it's the thread corroded to the head rather than the taper that's holding it. In which case it's likely to need drilling out and helicoiling, this may be possible in situ but have the piston approaching tdc and fill the combustion chamber with grease, to later eject the swarf.

AJH

Reply to
AJH

In message , Jerry writes

The oil will still be able to penetrate the taper seal given time. It won't be as "gas tight" as you think. During normal operation, the combustion gasses have to negotiate the long threaded portion of the plug before reaching the taper seal. This reduces the pressure that the taper seal has to deal with.

Reply to
Paul Giverin

Hmm, a taper is a very good seal, you might be correct about sparkplugs that use a washer - the problems with these engines started after Ford converted them to the smaller dia. thread standard and taper seals, I *suspect* that the problem is caused by the fact that hot gases can't escape after passing though the thread.

Reply to
Jerry

Just to add, the same (seized plugs) problems occoured on the Pinto engine, the saving grace with those plugs was the coarse thread and bulky nature of the body plug.

Reply to
Jerry

Corrosion itself can form a very good seal. After a few ezperiments of my own, I have yet to see any evidence that Plus-Gas, or any other 'penetrating oil' works on a well rusted or corroded thread.

It simply doesn't penetrate. I have left rusted nuts and bolts immersed in Plus-Gas for as long as 24 hrs. Then cut the nuts off. The threads were completely dry.

I recall 'Which' carrying out a similar, but more scientific experiment on proprietary penetrating oils many years ago with a same results.

Of course that doesn't mean it's pointless using it. If the thread is not too badly corroded you could get lucky. It might work as intended and free the bond enough for the plug, nut, screw, etc to be removed.

And, If the corrosion bond can be broken, jiggling the screw or nut will allow a thin oil or penetrating oil to work it's way into the thread.

If I were in the OP's position, I'd be inclined to use the car until a plug or plugs actually needed replacing. At worst the head will only need a Helicoil if the thread is to badly damaged to be reused.

As an aside you can make your own penetrating oil by a mix of oil and petrol, or parrafin, if you're wary of using petrol. Petrol and parrafin have excellent 'searching' properties. Mike.

Reply to
Mike G

Also quite explosive

Reply to
steve robinson

try tightening the plug slightly first , this often breaks any corrosive seal

Reply to
steve robinson

At worst it could mean a bent valve or locked up engine should the sparkplug break up in service, depending on how it breaks up, just the ceramic floating around can cause problems that mean the head needs to be lifted...

Reply to
Jerry

Siezed spark plugs do not break up leaving bits in the engine. Mike.

Reply to
Mike G

But (service) life expired plugs can, the point is, what I'm saying is, the problem needs to be sorted before the fault develops into a more serious issue. No one has ever suggested that a seized plug can break-up in service simply due to being seized - it's what might happen should the plug be left in service to long...

Reply to
Jerry

Dunno where you got that from, because I can assure you that it is not true. No way is a plug likely to break shedding parts into the engine. Doesn't matter how long it's left in service. Mike.

Reply to
Mike G

Well I can assure you that it *IS* true and has been for the last 30 odd years that I've been around the trade. Not common but it can and does happen.

Think what you like, it doesn't mean you are correct, in fact I've still got such a damaged plug sitting on the bench (removed a couple of weeks ago), with half the nose ceramic missing - the cause being a missed plug change, in fact the owner missed the service, and as the plugs had not been changed at the pervious service...

Reply to
Jerry

IME plugs do not break in that way simply because of old age. There's usually an outside cause, like faulty mixture, timing, or wrong plug. Also IME if it does happen, the broken pieces go out of the exhaust without causing any problems. They could cause damage, but the chances of that happenning is very low IMO, so I don't think the OP need be overly concerned about replacing them just because they might have exceeded their recommended life. As long as the car is running well, as it appears it is, I don't think there's any great urgency. If it were mine I'd change the plugs anyway, but I have a Helicoil plug kit, so even if the threads did strip when removing them, it wouldn't take that much longer to do the job if I had to Helicoil all of them. Mike.

Reply to
Mike G

Then you have f*ck all 'experience'....

Again, you then have f*ck all 'experience'. What happens should a piece of ceramic get caught in the valve seat, preventing the valve from fully closing - especially if there is little or no clearance between piston and valves at TDC...

They could cause damage,

Than, yet again, you have f*ck all 'experience'...

But what happens when the car isn't running OK anymore...

But you don't need a Helicoil kit, unless you're ham-fisted with little or no mechanical/engineering knowledge or 'experience'...

Reply to
Jerry

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