romponit

I've heard that 575 engine has had problems and was told to watch out for them. I'm interested in finding out what kind of problems people have had. I am looking at used boats and have been checking out 525s and 575s. Off course i'd like the most power and speed, but need reliabilty for my wallet. Any help would be appreciated.

Here's Johnny

I love mine.......had a little over 300 trouble free hrs at the end of last season and did a complete overhaul this winter. When we opened them up they were in pretty good shape and could have gone a bit more, but I like to be on top of stuff before it blows, Season here in NY is to short to lose a engine over the summer. If you do find something you like that has 575sci's I would always get a survey 1st then pick the owners brain on what maintenance was done to them. If you do a search here on OSO you will see the 575's biggest problem was bearing failure in the blower itself........ I change my blower oil every 25 hrs and have them rebuilt every 100-150 hrs by The Blower Shop. I could go on but if you have any specific question just do a search..... if you don't get any answers from a search then feel free to ask here.....

Pesky Varmint

Two 575SCi's in my 35 Nordic.

I pulled the heads at 400 hours for a head overhaul, and since I still saw crosshatching on the cylinders and had excellent oil pressure I'm not going to worry about the bottom end until after around a 1000 hours.

Head gaskets are the only weak link inside the engine.

Early blowers seem more reliable than the late ones (late ones
have a sight glass for oil level). I have had one blower rebuild in 400 hours and regularly change blower oil.

Also watch oil in diaphragm fuel pump drive on the raw water pump. I change it yearly.

So those precious few of us who've actually put hours on 575's would really like to hear these stories, and where they come from. And all bets are off for those genius's that run smaller pulleys or modify them.

Pesky Varmint

BillR

Very soilid motors. Ran mine for 280 hours, did a rebuild at that time - basically didn't need it. Had blowers rebuilt / upgraded by blower shop.

Run great. Would not hesitate to by them again.

BTW: those that have changed oil in blowers, it is time to change mine. How is that done? What oil should I use?

Pesky Varmint

I built a little rig using tiny plastic tubing and the Merc drive oil hand
pump to pump out the reservoirs. Maybe doesn't get 100% of the oil,
but I compensate with frequent changes (say 25 hours or so).

Pesky Varmint

Quinlan

iTrader: (1)

Depends what you want. The 575 is a strong motor. Very cold natured, but you cant beat the scream of the blower. Plan on more maint, depending on hours and previous owner.
If you want true turn key, and less issues 525s
And I have 575's
Ck out SOS and see what I have been doing.
Quinlan

Steve Zuckerman

The 525s are very nice motors. One big advantage (if you are a saltwater boater) is the closed cooling system.
The 575s are the older "open" cooling system.
If the blowers are run at a reasonable speed (4" pulley, about 4PSI stock) they hold up well. For some of us, who just can't leave things alone , there is plenty of HP to be found by increasing blower speed and boost. That's where some of the blower issues have come up.
It is a very strongly built motor, with forged internals, and there is plenty left (bigger cams, aluminum heads, higher compression (only 7.5 stock), intercooling, reprogramming, bigger blowers (I have a BS 871), etc if you want more. 700HP is easy, and even more if you are willing to get a little more exotic.
The 525 will absoloutely rip with a Whipple 3.3 on it.
Personally, I think if it's a blue Merc, you can't go wrong.
Regards,
Steve

JaayTeee

Mine had 388 hrs on them when 1 started
loosing a head gasket.

Everything else looked good inside,
I decided to freshen them up though,
and was able to go back with std.
rings and bearings.

We decided to upgrade them a bit
( heads, cam, ecm mods)
Courtesy of Mr. Horsepower1,
and should have them done in a couple of weeks.

They're a great engine, but like others have mentioned
head gaskets and blower problems are the most common
problem with them.

525's havent been trouble free either
( header leakage problems)

JaayTeee

I just take them ( the superchargers) off and
take the plugs out and dump the oil out.

They recommend merc. drive oil in them.

I've used Amsoil drive oil in mine without
any issues.

Vinny P

I rebuilt Johns 575's this past winter. Along with what was said above I have a few issues I would like to bring out.
My biggest concern : I cant understand why did Mercury use flat tappet cam shafts? While rebuilding these engines, I was going to replace the cams with hydraulic rollers. The key was, we didnt want to re-map the ecu's. After several phone conversations with RMbuilder, it was determined that he could not exactly duplicate the flat tappet cam profile, to hydraulic roller. It would be real close, but not exact. Our concern was not having the correct vaccuum signal to the MAP sensor, possibly effecting the fuel curve. So, rather than take a chance, flat tappets were made and installed. One other issue is the throttle bodies. We wanted to get new injectors, but found they are not available from Merc anymore. There are a few posts here about using replacement injectors. but since there seemed to be no issues with the original injectors, I just bolted them back on.