Merc Racing 525efi
 

I'm in the process of selecting engines for a repower. I've been getting a lot of negative feedback from owners of the Merc Racing 525efi. They tell me there are reversion problems with the headers due to the aggressive cam and the heads are damaged within 80 hours. I understand there may be a class action suite?

Anyway, can anyone verify the problem or recommend a good alternative for engines. (Chief, Sterling...?)

Thanks

As far as I know, the engines are solid, it's just the leaky POS CMI headers that come with them that cause the problems. Throw some other exhaust system on them and they are fantasic engines...

Yeah the cam is not the problem. Any motor can suck in water if the headers leak in the right spot. Mercury got CMI to build cheaper headers to save money and screwed what would have been a near bulletproof engine

I love the 525's in my Donzi. They fire right up every time, idle perfect, and run great around the docks. They push my big boat to mid-90's as well. I did install the better headers and have had no problems.

Mike,
When you refered to the "Better Headers" are you talking about the CMI Gen'X headers?
Thanks,
Dean

What headers did you install?

mike A.

I was told Merc changed the bolt pattern and you could not switch out the headers. If you can then this is good news. What Headers fit the block?

+3 on the 525's. $hit can any used CMI's. even the gen X's.
None of the CMI's or Merc/CMI will last long enough. (unless you do some preventive "stuff". )
Not sure the status of the legal stuff, but I think it just fizzled away.
One of these days when I have some more time I will post all the ways to make headers last longer, and do some "stuff" to avoid leaks.

There were/are reversion problems with this type engine ,Mercury even have a service bulletin out for this ,I did some digging last week in Midas /Mercury bulletins ,and Mercury mentioned the use of a silent choice systems can cause reversion problems with some boats ...depending what type boat ,and how low it sits in the water

250 hours, original headers, no problems. Run great. Don't use the silent choice above 3000 rpm.