Lotus casting core plug questions

In an effort to preserve original lotus head castings I'm curious as to what the latest thinking is on leaving the original steel core plugs in place, that is untouched as installed from factory.
Is it's advisable to loosen the steel plugs(remove them, clean the head with a tap, re-install as loose as possible)? What kind of risk am I looking at? Are they able to be re installed and not have an issue with leaking? Recommended sealant? Etc... This is one of my concerns, the other being the removal. I've read they can be very tight. To be honest I've been afraid to touch them. Also keep in mind they're lower mileage lotus castings, one with 65k and the other with 35k, so in my opinion they're still in the window for failure.

Has anyone heard of a head cracking after having the plugs loosened? I'd hate to up my risk due to touching them.

I have read through the old threads and have my thinking is that torque is what's responsible for the cracking issue. I've also read that the amount of thread showing isn't necessarily an indication of how tight they may or may not be.

So in short is it best left alone? If it's not broke don't fix it, right?...but this is a TIII so I'm not sure this rule applies.

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Originally Posted by spirit1991

In an effort to preserve original lotus head castings I'm curious as to what the latest thinking is on leaving the original steel core plugs in place, that is untouched as installed from factory.
Is it's advisable to loosen the steel plugs(remove them, clean the head with a tap, re-install as loose as possible)? What kind of risk am I looking at? Are they able to be re installed and not have an issue with leaking? Recommended sealant? Etc... This is one of my concerns, the other being the removal. I've read they can be very tight. To be honest I've been afraid to touch them. Also keep in mind they're lower mileage lotus castings, one with 65k and the other with 35k, so in my opinion they're still in the window for failure.

Has anyone heard of a head cracking after having the plugs loosened? I'd hate to up my risk due to touching them.

I have read through the old threads and have my thinking is that torque is what's responsible for the cracking issue. I've also read that the amount of thread showing isn't necessarily an indication of how tight they may or may not be.

So in short is it best left alone? If it's not broke don't fix it, right?...but this is a TIII so I'm not sure this rule applies.

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Since nobody else has chimed in ...

When I bought my Spirit R/T a year or so ago, I checked to see what condition my core plugs were in. The valley where the plugs are at is bone dry with no cracking or other deterioration evident. My car has just under 80K miles on it.

I have a good friend that worked at Chrysler as an engineer and is very familiar with the problems these plugs develop. I told him that I still had the stock iron plugs in the head and that it didn't leak. He said the best thing I could do to prevent problems was to unscrew them, clean the threads, put on a layer of teflon tape and screw them back in. But to torque them a bit "softer" than the original spec.

Chrysler claimed that the heating/cooling cycles of the engines over time caused the cracking since the iron plugs expand at a different rate than the surrounding aluminum of the cylinder head. My buddy thinks that they were also installed too tight, contributing to the problem.

So, there's my $.02.


Barry

Somewhere I thought I heard there was a 'thread count' spec, that is how many threads are showing on your factory plugs tell you how hard they were turned in and how much stress they are putting on the casting. I've had 4 TIII motored cars, all were cracked to some degree so I guess I'm one of the lucky ones:p

Thanks guys! I'm still concerned about the actual removal process and how the re-installation will go.
Anyone happen to have a pic of a removed plug? Curious as to how long they are

I've had quite a few TIII heads over the years and have been pretty lucky to only have one that was cracked. Most of them still have the steel plugs. One was repaired once before (before I got it). If it hasn't cracked I would just leave it alone.

How do you get the plugs out without stripping the plugs and having to drill them out or something? I tried taking the ones loose in my 2.5 TIII that's going in the Lebaron, but they are so tight even with the correct size allen they want to round out.

For those plugs I have been able to get out, I clean up the threads and coat them with teflon pipe dope and thread them in by hand. Once the car is running and up to temp, I tighten the plugs just enough to stop any leakage. It doesn't require much torque and I haven't had any leaks across any of my cars since using this method.

One note about how tight these plugs are when installed; When I had a head replaced under warranty back in 96, I drove the car home (12 miles) and tried to remove the plugs right away. I could only get 1 plug out, the other 2 wouldn't budge using a 1/2 drive breaker bar with 3' extension. I just left those 2 in place and so far no issues.