Inboard Ignition Coil Replacement for MerCruiser Thunderbolt IV and V Ignition Systems with HEI - Replacing 18-5438, 392-805570A2, 392-7803A4, 392-805570A1, 72115, 40511 Review

These coils will cause intermittent misfires in your engine. I had 1 bad coil but decided to swap the right and left motors. Approximately every 2-5 minutes the engines die and misfires occur. Sometimes so bad that they ignite unburned fuel through the air intake. Garbage. Buy a well-known brand so your boat doesn't explode.

Installed on Mercruiser 4.3 with Thunderbolt 4 ignition Perfect light matching. Fixed an issue that prevented my boat from starting when warm. Boat starts IMMEDIATELY when cold or warm. Couldn't be happier. The fact that it was less than 20% the cost of the original part was nice, and I ordered a replacement just in case and still saved over $60 compared to the OEM.

The replacement coil looked like a Mercruiser coil but was slightly larger in diameter. Fits easily under a bonnet designed for a 3 year old. Also had an issue with the first coil where the negative contact sheared off during installation and was replaced quickly with no questions asked - great customer service!

Mercruiser owners beware - the specifications on this do NOT match those listed in the owner's manual for a Mercruiser 4.3 engine with a Thunderbolt iv or v system. Bench tested at 1.5 ohms and Mercruiser specs are 0.6-0.9 ohms. The main seller offered a full refund after several emails trying to explain that the product was not up to specification for a 4.3 or even 5.0 Mercruiser.

It was nice to see that this coil for my Mercruiser 5.7L actually has brass connectors. After problems with bad connections on coils from other manufacturers, namely aluminum or some metal that broke easily when tightened, this coil had stronger brass pins and even came with tightened nuts and compressed lock washers. This told me that this coil had a good chance of getting installed without breaking anything. What is there to lose with a two-year warranty?

I bought this aftermarket to install while my heavy duty hand made coil distributor is being manufactured and shipped. It took me ten minutes to install. Wow what a difference. I immediately heard and felt a deeper and stronger rumble while idling on my indoor Malibu ski boat. My problems with procrastination have been resolved. Also, it took several long holds to get it working in front of this new coil. Now it lights up immediately. Love it. I will still use my expensive heavy duty coil but…

Both the primary and secondary coils did not meet the requirements of the flash ignition system. I'm not going to ruin my ignition system with a non-standard coil. Not even installed, just returned and bought one that fits the manufacturer's specs. After contacting the seller and unimpressed by customer service, he couldn't and wouldn't answer questions about unqualification, instead being advertised and sold for a flash ignition system. I'm worried that the warranty won't be better. I'm glad I

I have purchased a remanufactured pulley for my Stingray boat. According to the description on the Revain platform, this is the correct replacement spool. Unfortunately, the resistance of this coil was never tested prior to sale. This was my loss as according to the card included in the box it is non-refundable. The resistance of the resulting secondary winding is 11.3 ohms. The primary coil resistance ranges from 7.2 to 70 ohms depending on how hard the coil is shaken. This refurbished spool…