Classic cars forum & vehicle restoration.

[rcx822]

I'm fixing up a Toyota 1UZ V8 engine, it's a 4.0l, in the UK commonly called "The Lexus Engine". Two of the spark plugs took quite some force to come out. They have some goo on them. The spark plug threads in the cylinder head seem ok, but the plugs are stiff going in. I can see that the threads on the stiff spark plugs are slightly out of pitch.

I've looked around for spark plug thread chasers. A lot of them look too cheap to trust. Or there's no way of gripping them while they're deep down a twin cam spark plug hole.

Draper Expert do one that LOOKS reasonable quality. The hex on it is very big, I can mill it down to a size that would fit into a spark plug socket.

I really don't want to mess this up and have to be doing repairs or removing the cylinder head. I thought I'd ask for tips before I do this.

Am I right in saying that a "thread chaser" is more blunt than a tap?

[img]http://www.drapertools.com/product/51767/Expert-10-12mm-Spark-Plug-Chaser[/img]

[Rick]

That's my understanding, although as I've said many times before - I'm no engineer

A chaser tidies up existing threads, whereas a tap is more aggressive. I bought a chaser a while back, I think to use on the replacement (all iron, no inserts) head I fitted to big Dodge. Being a sidevalve, with the plugs on the top, with the head on the bench, made it quite a straightforward job.

RJ
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[Phil - Nottingham]

I always found an old spark plug with 4 saw cuts down the threads used well greased is perfect for tight/damaged threads especially alloy
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[Peter_L]

[ukdave2002]

I had to chase a plug thread on the Stag (alloy head) bought an off the shelf plug thread chaser. I made sure that the inlet valve on the cylinder was open, connected an air line to the carb to create a bit of positive air pressure. With some grease on the thread chaser any swarf come out with the chaser rather than finding its way in to the cylinder.

Dave

[emmerson]

Or use an old plug with a groove ground in the thread, same job as the saw cuts.
If all else fails, then a Helicoil might be the only answer.

[Peter_L]

Has anyone ever noticed that the success of a fix is inversely proportional to how close it is to those offering the cure ?