If you have a bad Thunderbolt-IV module...

[Captain Crispy]

If you have a bad Thunderbolt-IV module, bite the bullet and install a new ignition system rather than replace the bad module. Here is why:

1) COST- a new T-bolt-IV module, if you can find one, is going to be north of $300, if you can find it. A used one is...USED; how long is it going to last ? A used one will also cost a couple hundred dollars, and you may may need to buy a new wiring harness for it, too. A new EST ignition SYSTEM- distributor w/ built-in ignition module, coil, spark plug wires, cap & rotor- can be had for less than $350.

2) EASY- installation is NOT HARD if you follow the instructions to the letter.


Because of a bad T-bolt IV module, I just installed Delco Voyager EST systems in my two 1987 Mercruiser 454 Bluewater inboards for a total of $674 for both engines. Bought the systems on e-bay from ATP Engines in Florida.


Also, if you need any used Mercruiser 454 ignition parts [distributors, caps/rotor/wires, coil, T-bolt-IV module] I have my old parts listed in the Classified section.

 

[hottoddie]

Agreed. As an alternative I installed DUI (Davis Unified Ignition) on my 2 Crusaders 3 years ago. Flawless.

 

[SCORPIO]

I'll have two used but working Thunderbolt IV modules and complete distributors from a 5.7 to sell in a few weeks. I kept my old one from a port engine repower last year thinking I may need it on the starboard. Since the starboard is now getting replaced, I'm going to offer them for sale.

 

[rph1225]

I just did the same as the original post. People on other posts swore up and down that the Thunderbolt would never fail and to keep it. I proved them wrong. Ha Ha

I went with a Mallory and the boat runs better than ever.