Help - 05 focus 1.6 coolant plugs leaking causing misfire

[tinhead]

After some advice to repair my shed, got an 05 focus 1.6 petrol which has been virtually faultless for 2 years but today developed a misfire p0304 cylinder number 4.
Managed to crawl home, luckily it would still run ok under light load, although the hilly motorway sections were a bit touch and go.
Found a lot of rusty water around the spark plugs when I removed the caps, removed the cam cover and it was obvious that there's been water leaking for a good while.

Now the bad bit, both coolant core plugs (Welsh plugs?) Have obviously been bodged before I bought the car to try and seal them, one is covered in an epoxy putty and the other one has red silicone sealant over it.
I've cleaned it out as best I could and run it again but still misfiring on cylinder number 4, I'm hoping that will clear when it dries fully or is it possible it could have damaged the coil pack?

Can anybody point me to the correct size Welsh plugs for my car, I can't measure the existing ones without removing this sealant which I didn't want to do before I made the repair.

Also is it simply a case of prizing out the old one and knocking in the new plug, just watched a video on YouTube and it looked fairly easy, famous last words.

Just hoping a previous owner or mechanic was just very lazy and decided to try and seal them unless there's a reason why they couldn't fit new plugs.

[E-bmw]

You should be able to go to main dealer & tell them what they are for & get the right ones.

I have only ever fitted one before & found that it resealed just fine, yes they are as simple as you think to fit/remove.

[GreenV8S]

They should be as simple to remove and refit as you'd expect. Use a block of wood as a drift when refitting to keep it square. Don't go mad with the hammer - remember the block is just a thin casting at the end of the day.

[p4cks]

Can't help with the welch plugs but the water ingress I can, having had identical happen to me and here's how I rectified it... https://www.pistonheads.com/gassing/topic.asp?h=0&...

[LarJammer]

Coreplugs.co.uk

[tinhead]

p4cks said:

Can't help with the welch plugs but the water ingress I can, having had identical happen to me and here's how I rectified it... https://www.pistonheads.com/gassing/topic.asp?h=0&...

Thanks for all the replies, I didn't realise the core plug issue was so common and they were easily available on eBay, I've ordered 5 in case I mess up.
There's no doubt the core plugs need replacing but after drying out the car this morning it's still has a misfire on number 4, now I'm not sure if the water has caused a fault possibly with the coil pack or the water was a red herring. The bodged repair and probably the water leak has been there for 2 years so maybe the car has just developed a separate fault yesterday with a HT lead or coil pack.
I've tested the number 4 lead with a multimeter but obviously that doesn't guarantee it's not breaking down under load, it's a shame I can't swap them around because of the length or think of a way of testing the coil pack, will probably have to bite the bullet and buy new ones as well as repairing the core plugs.

[Zener]

Move the leads from No1 coil tower to No4 coil tower and see if you can move the misfire try swapping out the plugs too or better still just renew them, then get back

[tinhead]

Zener said:

Move the leads from No1 coil tower to No4 coil tower and see if you can move the misfire try swapping out the plugs too or better still just renew them, then get back

You must have read my mind or vice versa
I managed to swap Leads 3 and 4, had to extend the short lead with a piece of wire but the misfire is still showing as cylinder number 4 so I think the lead isn't the problem.
I swapped the plugs over and the misfire is still there as you would expect but I can't get it to throw a warning anymore, so not sure which cylinder
I've ordered a new coil for now to see if that fixes it, I've got the new core plugs coming as well as that need sorting whether it's the water that's caused the problem or not, it's definitely dry enough that it shouldn't be causing the issue at the moment.

[Krikkit]

tinhead said:

I swapped the plugs over and the misfire is still there as you would expect but I can't get it to throw a warning anymore, so not sure which cylinder

Easiest way to tell is either with your hand next to or an IR thermometer reading each exhaust manifold branch, 3 will be hot, 1 cold.

[GreenV8S]

tinhead said:

misfire is still there as you would expect

Is the plug on the misfiring cylinder basically clean and serviceable? Is it coming out wet or dry?

[tinhead]

Sorry for the late update
the fault code did return after I swapped the plugs and it was still showing misfire number 4, so not the plugs or leads.

The new coolant core plugs arrived but it was a right mess in there, one was covered in chemical metal/epoxy which I had to remove with a hammer and chisel and the other one was covered in red mastic, got the old plugs out by knocking one side down and tipping them and grabbing the other side with pliers, the one that was covered in mastic also had a big slug of mastic under the plug!
Fitted the new plugs with a bit of gasket sealant around them, would have been easier if I could have got a straight hit directly above them but managed in the end, used a socket on a short extension.
Gave all four spark plugs a good clean and when I removed the coil to check for cracks (wasn't any) I cleaned that with degreaser as well.
Also read online about reducing the spark plug gap from 1.3 mm to 1 mm, didn't measure my gaps but it was definitely bigger than that so set them to 1 mm.

The misfire is now gone on and the engine is running as well as ever.
maybe it just needed a really good clean around the spark plug area although before fitting the new coolant plugs I'd already cleaned and dried around number 4 plug to no avail, or maybe tightening the plug gap has reduced the load on the coil and it's not breaking down?

In the meantime the new replacement coil arrived but I've not fitted it yet, that's my next step but only if the misfire returns, don't like guessing and just changing parts without a fault present, I'll leave it in the car for now with the code reader.
Thanks for all the advice

[Zener]

Good Job you was right not to fire the parts cannon

[tinhead]

[quote=Zener]Good Job you was right not to fire the parts cannon [/quote
]
Yeah, I diagnose faults on machines all day and you have to follow a logical process, unless you work at a main dealer and you can just throw parts at the fault and charge the customer, but not when you're running a shed.
Still a bit annoyed I may have wasted money on the coil, it was only £16 though so probably not worth paying the postage to return, and it's a good backup in case the fault returns, the only other cost was £8 for the core plugs and I've still got three spare left.

[Peanut Gallery]

May I just add a note to check its not the windscreen washer jets leaking water down onto the spark plugs, filling the whole area with rainwater. I know you have changed the freeze plugs, but thought I would add this!

[tinhead]

Peanut Gallery said:

May I just add a note to check its not the windscreen washer jets leaking water down onto the spark plugs, filling the whole area with rainwater. I know you have changed the freeze plugs, but thought I would add this!

Thanks, I'll definitely check this, even though in this case it was water from the coolant plugs the washer jets get mentioned a lot.
I assumed people meant the washer fluid leaking but you're talking about rain water from the outside leaking into the engine bay?
So it's the seal between the washer jets and the bonnet that needs checking and possibly sealing with silicone?

[Peanut Gallery]

tinhead said:

Peanut Gallery said:

May I just add a note to check its not the windscreen washer jets leaking water down onto the spark plugs, filling the whole area with rainwater. I know you have changed the freeze plugs, but thought I would add this!

Thanks, I'll definitely check this, even though in this case it was water from the coolant plugs the washer jets get mentioned a lot.
I assumed people meant the washer fluid leaking but you're talking about rain water from the outside leaking into the engine bay?
So it's the seal between the washer jets and the bonnet that needs checking and possibly sealing with silicone?

Yes, it is rainwater that leaks down to the groove between the inlet and outlet cams. Mine had filled the area with water completly before I bought the car to the extent of rusting out the plugs - evidence of broken ceramic was there. I used to open the bonnet and remove a couple of spoonfulls of water after each rainy day. Not a problem on the 1.8 and 2 litre engines as these had engine covers.

There is a new version of washer jet that stops this, or as you say, a splodge of silicone would seal it.