River Ratt

I just picked up my '04 Fever with the 525efi this fall, before I picked it up I had Merc certified mechanics survey it. The engine has 280hrs. on it, 100+ hrs under 2000 rpms and very little time wot, from what they seen it wasn't beaten on. They performed an engine leak down test and said all off the cylinders had great compression and all were almost exactly the same. So my question is when people suggest replacing valve springs on these motors around 200-300 hrs is it because the valves springs are getting weak which will affect compression when the valves don't seat as good or is the worry a spring breaking and dropping a valve and totally f-ing up the summer. So Im just wondering whats the main concern when these valve springs get hours on them, compression or breaking?

Budman II

iTrader: (1)

Both. Perhaps the bigger issue is not outright breaking, but springs losing seat pressure over time from heat cycles and compression cycles. If the correct pressure is not maintained, it can allow the lifter to lose contact with the cam lobe and even "loft" over the nose of the cam. That puts tremendous pressure on the lifter wheel and can lead to early failure. You can also have harmful harmonics develop in the valvetrain with weak springs that can lead to damage.

Budman II

iTrader: (1)

It is possible to check spring pressure with a special tool without removing the head, if you are worried that you may be on the edge. But a good set of springs like the Isky Tool Room series might be worth the investment to set you mind at ease and ensure a trouble-free summer of boating.

jbraun2828

I think the concern is the junk parts mercury built the valve train with. There are much better springs and lifters for less money than the stock stuff. With 280 hrs I would definitely look into updating the valve train.

HyFive578

iTrader: (3)

I am going through a valve spring replacement right now on my 525's. I can tell you what I've learned in the process and pass along the info from the pros that I've been speaking to. The 525 OEM springs install at a short height and do not have enough pressure to handle the lift of the 525 cam. The springs are really too light on the seat. Despite the fact that the Merc manual indicates an install height of 1.850, all three of my motors have installed heights of 1.810; all factory stock. Given that the springs lose pressure over time and that they start out being too light, eventually you run into a problem where they cannot effectively control the valve train and then other bad things can happen.. I bought my current boat with 120 hours on it and all three engines had excellent compression and leakdown tests. At 204 hours, I had a rocker arm failure on my port motor resulting in a new long block. My reason for changing the valve springs started out being the result of what I heard about hours but the more homework I did, its more about putting the right components in there period.

On a related topic about the 525, if you have Silent Choice exhaust, you should seriously consider removing the headers and look for signs of reversion in your exhaust ports. I've also discovered this recently and apparently is very common with rear mounted 525's with Silent Choice exhaust. I mention this in the context of valve springs because if the valve train is not being controlled properly, you can also have reversion.

ALL_IN!

iTrader: (1)

Do a search on posts from Eddie Young about 525 spring / valve train issues. It's not just springs.

http://www.offshoreonly.com/forums/g...ml#post4203256

Our boat has 575's, and a rocker arm was starting to fail (loose needle bearings) and one valve spring had failed both motors at 260 hours. Luckily, I shut it down and took it to Eddie before any further damage. ...and we're picking the boat up in the morning - will be so glad to have it back!

HyFive578

iTrader: (3)

Yup.. I started that thread and Eddie is one of the "pro's" that I was referring to. I am also changing the rocker arms..

River Ratt... aren't you glad you asked??

Orange quatro

What kind of exhaust do you have? If they are CMI. Check them also.

River Ratt

Thanks for all of the info fellas, I can learn so much so fast on this forum, it rocks! I am glad I asked. Yep I've got the CMIs which are currently sitting on my toolbox in my garage, I pulled them off before putting the boat in storage to pressure check them this winter. If they pass I will be pressure checking them after every cruise and be replacing them with Stainless Marine exhaust the second I don't like what I see. I don't have silent choice which I'm glad. Now the question is since Im pretty mechanically inclined do I do the springs/rockers my self or pay the big bucks for someone else to do them? I know there is a way to do it with the heads on the motor by pressuring up the cylinder with air to hold the valves then swap stuff out but Im not sure how complicated it is? Since my headers are off now would be the time. Decisions, decisions......

HyFive578

iTrader: (3)

I am pretty mechanically inclined as well but was initially afraid to it myself. But I did a little research, talked to some friends with experience and bought the right tools and it's pretty easy to do. I am doing it with the heads on the motor, pressuring each cylinder to swap the parts. You also need to set the valve lash after changing the springs whether you replace the rockers or not. You also need to measure the installed height of the springs as they are now before you replace them..