Spark Plug Module Mounting Bolt

There is no T27.5. T25 is the right size. It can be a problem getting them out. You might try letting some good penetrating oil soak in and a good rap square on the head of the screws with a hammer before taking them out. Anti-seize on re-install.

Bill Putney (To reply by e-mail, replace the last letter of the alphabet in my adddress with the letter 'x')

I didn't know about the existence of T27 torx. That would explain why people post a lot on the LH forums of problems getting those screws out (T27 is an odd size in your generic - i.e., cheap - torx sets). I've read that on the later years of LH production, they don't use torx screws. Not sure what they went to - maybe hex cap - but they must've gotten a lot of complaints about the torx's.

(Hmmm - Before I hit "send", I went and checked the set I have. It is a cheap set, but it does in fact have T25, T27, and T30. Probably unusual, but would explain why I didn't have the problems a lot of others have had with those screws.)

I have found that it's best not to go the full 100k on plugs. More chance of a plug binding in the threads, gas mileage definitely drops considerably during the later parts of the 100k even though it may run fine (probably some drop in performance if it were to be meaured), and probably idle quality suffers.

I definitely think it's a worthwhile gain to change no later than 80k (I've been doing mine about every 70k - even then, there is a genuine jump in mileage when I change them).

Bill Putney (To reply by e-mail, replace the last letter of the alphabet in my adddress with the letter 'x')

tim bur wrote:

Seems we both need to backpedal a little on this one. I just went out and checked the fit of the torx bits in the coil mounting screws on my '99 Concorde. The T27 was definitely too big. The T25 is the right size. Either your saying it's a T27 is wrong, or they changed the size from one year to the next on the LH cars.

It's definitely T25 on mine.

Bill Putney (To reply by e-mail, replace the last letter of the alphabet in my adddress with the letter 'x')

Bill and Tim Thanks for the input. I was concerned about the 100,000 mile plug replacement. It seems like after 8-10 years of my typical driving, the plugs would be impossible to get out. My first thought was to pull the plugs and see what they looked like. I will try to find a T27 because the T25 definitely spins on my LHS.

Ron Munroe Falls

Normally what happens is over the years that #27 hole gets corroded and the shape changes. That causes the bit to strip the screw.

Whatever size it is, normally over the years the screw becomes corroded and the bit no longer fits

Or get your allen wrenches out, I forget which one will work but you will be surprised how it fits when your torx bit doesnt work