Blown a Spark Plug

watersidemat · 22 October 2016, 16:27

Ok so...
Bought a ZapCat, the voices told me to do so!

Took it out today to test and it wast sunning at top speed but anyway that's something for another time, for this thread i have the following problem:

Spark plug blew out of the bottom cylinder, the thread on the cylinder has been striped.

Question one, can it be re tapped or threaded.

question two, if answer to question one is no, do i need to replace the cylinder head?

Thanks in advance.
(I know very little about engines so layman's terms if possible!)

breezeblock · 22 October 2016, 16:39

yep easy repair go one eBay and look up sparkplug inserts try and get the ones that are like a tube with a thread outside and inside they seal better than the helicoil types

breezeblock · 22 October 2016, 16:42

252367849078
is the ones on eBay that you need

watersidemat · 22 October 2016, 17:32

Awesome, cheers, I've ordered on for the sake of £6, erm....how do I use it!?
If i cant do it i can probably find someone more cleverer than me to!

breezeblock · 22 October 2016, 17:50

cover the tap in grease to catch the swarf screw the tap in unscrew it and clean the thread out of all grease and crap screw the insert in with a bit of loctite leave it to set for a few hours and that is it good to go

watersidemat · 22 October 2016, 18:10

Legend! thanks

Nos4r2 · 22 October 2016, 19:12

If you need to ask on here how to use it, get someone who knows what they're doing to use it or you'll be buying a new head...

spartacus · 23 October 2016, 10:12

Hang fire. You want the job done properly, so my advice is to go to an engineering machine shop and get them to use a steel insert.

The lower plug on my Tohatsu was cross-threaded at some point before I bought the engine, so careful as I was I subsequently stripped the thread during a routine service.

I took the cylinder head off, as you can clean the water passages which is no bad thing. You'll need a new gasket, and new head bolts, which need to be tightened in sequence and to a specific torque. Do it this way and it's as good as new. If the plug pops out at full chat when you're miles offshore you'll know why it's important not to cut corners. Clean both the head and the cylinder head thoroughly. Use a Stanley blade to scrape off the old gasket so both mating surfaces are clean as a whistle.

watersidemat · 23 October 2016, 14:09

Cylinder head now removed, surprisingly simple! I'll have someone make an insert based off that eBay kit and have it put in professional like! I'm looking forward to cleaning it all up now the heads off, loads of gunk has built up in there!

watersidemat · 23 October 2016, 14:25

When I put this back together do I need a sealant for the gasket? Any recommendations if yes.

spartacus · 23 October 2016, 14:51

Quote:

Originally Posted by watersidemat

When I put this back together do I need a sealant for the gasket? Any recommendations if yes.

No sealant required. Use a genuine Tohatsu gasket and torque bolts in sequence. There should be guides online. Can't stress enough that you need to use new bolts.

watersidemat · 23 October 2016, 15:25

All on order.

breezeblock · 23 October 2016, 16:49

Quote:

Originally Posted by watersidemat

Cylinder head now removed, surprisingly simple! I'll have someone make an insert based off that eBay kit and have it put in professional like! I'm looking forward to cleaning it all up now the heads off, loads of gunk has built up in there!

paint stripper works quite well at cleaning crap off cyl heads then put it in the dishwasher when her indoors has went to the shops

Fred. · 23 October 2016, 18:28

Quote:

Originally Posted by breezeblock

then put it in the dishwasher when her indoors has went to the shops

Nos4r2 · 23 October 2016, 22:07

Don't paintstripper it,or dishwasher it. Gunk and a stiff bristled brush (NOT a wire brush!) will do enough unless it's really carbonned up.
You really don't want to lose any of the original coating on the outside or the waterways. It's rather important that it doesn't corrode

jyasaki · 24 October 2016, 15:11

Dishwasher detergent doesn't play nice with aluminum. If you do put it in a dishwasher, use a small amount of regular sink type dish soap rather than dishwasher detergent.

jky

Poly · 24 October 2016, 15:17

Quote:

Originally Posted by jyasaki

Dishwasher detergent doesn't play nice with aluminum. If you do put it in a dishwasher, use a small amount of regular sink type dish soap rather than dishwasher detergent.

jky

The good news is that doing this will create so many bubbles your floor will get a nice wash too...

...don't ask how I know ;-)

watersidemat · 03 November 2016, 16:48

Right so slight update, still waiting on some new cylinder head bolts they will be a few weeks again unfortunately but the head is fixed and i have a new gasket, just need to clean off the piston heads as they have some carbon really baked on.
in terms of re fitting it all back together, i can see the order the bolts go in and i have the torque setting but; the bottom bolt when i removed it i couldn't get a normal socket around it let alone a torque wrench, therefore, any advise on tightening up the lower bolt, and how accurate does the setting need to be, could i guess it with a spanner, id rather not remove the engine! thanks again.

Seaflyer02 · 03 November 2016, 18:07

Are you using a standard 1/2" drive socket and wrench, if so can you get a 3/8" drive socket and torque wrench in using a universal drive?

breezeblock · 03 November 2016, 18:42

couldn't you remove the cowling to allow better access