Question on 525 EFIs with over 250 hours
 

I was told by the salesman that sold me my Fountain that the 525s needed new valvesprings and a valve job at 250 hours. I also read of many header failures around that time. I bumped into a "fellow Fountain owner" at the boat ramp and he had just repladed his headers (expensive) and had to go through the engine (to the tune of 7k) due to the water damage from the leaking headers (slightly over 250 hours on the boat - a 2004). We share the same mechanic and the mechanic said the new CMI headers seemed to be much better quality than the OEM headers. He also was very impressed with the 525 engine itself. My question, experienced owners or mechanics only please, is what have your experiences / expenses been? My wife and I are thinking of moving up to a 38 or 42 Fountain and the 525 engines seem to be what most of them have. We would be using the boat 80% of the time in salt water and flushing with saltaway.

With 525s and CMIs. 200-250 is the magic number for checking into them before something goes real bad. It also depends on how hard you run them and maintain them. Best bet is to put $50 per hour in a rebuild fund

Correct. I have done many 500 HP, 500 EFI, and 525 EFIs and by 300 hours almost every one had broken springs.

I had a customer call saying he was going to do the Lake Cumberland poker run and then drop it off for upper service. Just under 350 hours.

He didnt make it, dropped a valve and destroyed the engine.

OEM headers are CMI, and are very prone to leaking also yes correct.

There is no one simple answer. If most hours are hard running near WOT then rebuild top ends sooner, such as by 250 hrs like many of the threads on here say. If the hours are high middle to medium rpm hours, with very few hrs over 4800 rpm, you have longer. Two years ago I asked everybody I could find about this question since I have 525s with over 250 hrs about 320 now. I called dealerships and asked questions on multiple forums. Most of the answers were "rebuild top ends at 250 hrs or less, and bottom ends every other top end rebuild". However interestingly when 525s are put into lower performance boats like cruisers or are used less aggressively the hours on virgin motors can get considerably higher. One fresh water dealer told me he had a larger Formula cruiser trade with 800 virgin hours on 525s. I got numerous answers of virgin motors in the 400 hours range on Cigarettes and Fountains not driven aggressively. Other factors include oil change interval, whether you buy the BS that 40 or 50W single grade is the way to go or if you follow the OEM recommendation of multigrade 25W-40 or 15W-50 which greatly improves top end lubrication on start up and reduces wear over the long term. Other factors shortening life and leading to earlier rebuilds were salt water use and failure to adequately flush after use in salt water.

This is my recent shopping experience:

Lots of 525 boats out there and SURPRISE they are for sale in the ~250 hours range. They are usually priced as if they didn't have a top end job in the future too.

If you're certain you need a 525 boat, you'll love it I'm sure, but go in to the market assuming you buy it and take it to your shop immediately to do the top ends / baseline all maintenance. After that, you'll have lots of fun boating ahead of you. As said before, probably not smart to gamble waiting.

I wussed out and bought a 496 35' boat. :)

Ditto exactly...but I ended up with a 496 32 footer :boat:

The 525 is a great motor. Merc didn't use the best valve springs. Many I have read have found broken springs by 300 hours. Headers should be checked at least annually no matter what engine they are on. I would personally pull heads every 300 on any good performance motor and keep em fresh. Big block bottom ends are beastly of you avoid catastrophic failure.

Merc Race power is all about the maintenance, just like any other built performance engine. Finding a seller that has all receipts, maintenance and top ends done when needed is a rarity on the used market.

I've owned two 525 powered boats. There are two issues: Headers and valve train. The headers you need to pressure check often. I have a system setup to be able to check them with air pressure and a leakdown tester while they're still on the boat. I typically check them every 10-15 hours. Check them regularly and you can save yourself a tremendous amount of grief and $$$. Second issue: valve train. There are many cases of these engines going for 400+ hours without any issues, but there also many that have blown up around 200-250. The safe bet is to replace springs and rockers at 200-250 hours.

I asked my dealer about used 38' Lightenings with 496 power and he said there were not many make as it would be underpowered. I realize "underpowered" is an opinion but I would think a 38' with twin 496s (425h.p.) would be a 75+ m.p.h. ride. And no header or early topped service would be needed.

I've seen one later model full stagger. I've also seen a full stagger 42 with 496s. 1 of each ever. Lol. I know what you mean beck see 38 fevers came with 502 mags forever.

There is no reason to fear the 525. They are awesome motors. Easy to work on, easy to get parts for and generally very reliable. Mine start every time I turn the key. If you take care of them, them will take care of you.

Header,s & long heavy tails need support or tie bar,s , someone need,s to put a gopro in the engine compartment & watch that stuff move and shake .

Springs and rockers are not a real big deal or expense, especially if it avoids a catastrophe! Some folks have suggested a full valve job though.... What's your take on that?

The other week I spoke to a reputable engine builder on the West Coast of Florida. I was ready to drag my boat to Florida to have valve springs, etc. done. He told me to save my money and wait until rebuild time at the 450ish hour time frame. He said installing new springs / valve job is a waste of money as it will be replaced when you rebuild and you run the change of pushing oil. His recommendation was change oil every 20 - 25 hours, new plugs every year, pressure test or replace the headers.

Everyone has an opinion I assume and if it is mechanical there is the chance something could always fail.

I have a 2005 35 Lightning with 525's and 466 hours on them. Never been touched. Getting ready to do the top ends and pressure test the headers. and maybe the ECU's while I'm in there DO NOT be scared of the 525's with 250+ hours.

I did leak down test at 400 hours. Inspected each cylinder with remote camera. All was good. I replaced the springs, keepers and retainers. Stayed with stock spec springs. Original '07 vintage headers still fine. Fresh water boat. Single engine so no long pipes.

I am just over 300 on mine. Oil changes every 25 +/- hours, used but not abused, they still run as strong or stronger than when I first bought the boat. I have wrangled with this freshen up question for some time now. Feel like the top ends would be a reasonable direction to go in but have had some tell me " if it ain't broke! " This boat had 40 hours on it when I bought it almost nine years ago and it has never given me so much as a hiccup in all these years. Respectable care is one thing but tearing into a pair of perfectly good running engines just for chits and giggles is just plain stupid, in my book.


Side note here. I did have a pair of carb 500's that took the valve spring dump at 187 hours. So I am not living in lala land.
But 525's are not 500's, not even close.

I had a rocker explode at 200 hours sending needle bearings everywhere. Cost me a new long block. Guys that work on dozens of 525's have seen a trend in spring / rocker failures around the 200 - 250 hour mark leading them to believe there is a systemic issue with OEM components. Some even less than that. There are also plenty of 525's that run for 100's more hours without a single problem. Had I not had that failure, I probably wouldn't have touched mine until I got to 300+, but I did and decided to redo the top end preventatively. Cost me the money for the parts, but I did the work myself. IMO, was worth it.

I don't think a full valve job is warranted unless there is a reason. ie: do a leakdown test and see what your results are. When you change the springs, you should also change the valve seals so you can inspect the guides (from the top at least).

Out of curiosity how did the needle bearings take out the long block? Get into the lifter bores or something?

Just went thru complete rebuilds on 2003 525's with 460+ and 470+ hrs, never been apart. My builder found 1 broken piston ring, both cam's had damage/gauling, at least one head gasket (another problem area on early 525's I believe) about gone and 3 out of 4 headers with cracks.
That seems to agree with full rebuilds at the 500 hr mark.

.......and this is my second 525 boat, love these motors as mentioned by others.

Agreed, I was thinking the same thing. Thanks!

Got into the lifter valley and pan. Tore up the crankshaft, camshaft and bearings. This engine had been rebuilt previously (prior to my ownership) and when we tore it down, we discovered that the crank had already been turned once before so that was out of the question, that it had mismatched pistons with wrist pins that had been superheated to get them in and bunch of other stuff that made my engine builder say...."I'm not touching that thing"... so it became more cost effective to replace the long block. Point still, that a rocker blowing up can do significant damage.

Thanks for the info. I'd always heard that, but didn't know the reason why.

For the guys that have whipplized these motors, how dramatically does that change the maintenance intervals?