Valve Adjustment/ loose valves

[Toulla]

2001 F25 Yamaha (Merc) Checked the valves at fif****, 200, 300 and 400 hours. Adjustment was only needed at the fif**** hour check.
Now the engine has 550 hours and here is what happens. starts and runs ok. after the engine reaches normal operating temps, at low RPMS, say 1700 to 2800 RPM I hear what I think is the noise of loose valves. Above 2800 RPM I don't hear the noise because it gets masked by the roar of the engine.Its bothersome because the noise was absent till 3 things changed:

1. The engine now operates in South Florida instead of Northern CA.
2. It now uses 90 octane Non-Ethanol gas instead of 87 octane ethanol gas.
3. It now uses 20W40 Yamalube instead of 10W30 yamalube oil.

I suspect the valves finally are loose and need to be adjusted and the question is this:
Do you guys think one of the three changes above is causing the noise and not loose valves? and what are the dangers of operating the engine with loose valves? I can't pull the boat for a while and I do want to use it in the meantime.

[boscoe99]

I don't see any of the three things mentioned as causing the noise you are hearing.

It is real easy in that model to to a valve clearance check. The adjustment is pretty easy as well.

Better operating with too much valve clearance than too little valve clearance. But I would inspect the clearances just to be sure.

[TownsendsFJR1300]

+1 ^^^

Especially with the screw adjustment, it can't get any easier. There's nothing to fall out / etc with them being slightly loose..

Those changes mentioned above wouldn't cause it.

Its likely just an adjustment however I would run some Yamaha RingFree before hand thru the engine to help clear up any carbon build up.

Excess carbon build up would cause larger clearances. (valve not seating quite fully). Its a great product, works really well too..

[Toulla]

Thank you both for your input. I thought of doing a shock treatment with ring free, however, I am hesitant due to the fact that I have been using ring free ever since I got the engine new. Plus I am not sure what the proper way of doing it is any more...Done a shock treatment once at 300 hours. I will do the adjustment first and go from there. TownsendsFJR1300, I am in Fort Myers.

[TownsendsFJR1300]

Thank you both for your input. I thought of doing a shock treatment with ring free, however, I am hesitant due to the fact that I have been using ring free ever since I got the engine new. Plus I am not sure what the proper way of doing it is any more...Done a shock treatment once at 300 hours. I will do the adjustment first and go from there. TownsendsFJR1300, I am in Fort Myers.

If you've been running Ring Free all this time, I would disregard any shock treatment.

Most folks don't know of the product, don't want to spend the money for it (as it isn't cheap) but IME, works extremly well and is much cheaper than cleaning carbs, injectors, etc.. I always have a quart in the garage..

PM sent

[ausnoelm]

Why is it that people think some sort of decarb, shock treatment, fuel stabilizer and all that sort of stuff is going to cure all problems?

[TownsendsFJR1300]

Why is it that people think some sort of decarb, shock treatment, fuel stabilizer and all that sort of stuff is going to cure all problems?

Because some of these products do in fact work very well. Some don't. Ringfree@ $50.00 quart is a bit expensive however it does indeed work.

Before I learned of fuel stabilizers decades ago with my my old 140, v4 Evinrude looper, I had to clean the carbs, varnished up. the next week, go to take the boat out, clogged up AGAIN.

Cleaned them again went to the marina and asked what product is out there to help with this. I got "Gas Shok" as recommended. Put it in, NO MORE CARB VARNISHING UP as long as I owned the boat engine-NONE.... I still use it.

I've never had the VST apart on my F150 engine, never pulled injectors, with the K100 I run, never pulled the PU (or tank) in the 50 gallon built in tank in my 1996 Angler. (all original).

Drain fuel from the VST and the previous moisture that WAS THERE(built up over time, almost 20 YEARS), is NOW gone (with using K100 and NON-Ethonol fuel). The fuel is as clear as if I pumped it yesterday.

On a chipper / shredder I use maybe twice a year (8HP Tecumseh), the last time I used it, it wouldn't idle down and had a slight misfire at WOT(3600 RPM).

As I was busy trying to mulch a bunch of limbs, I just put a heavy dose of Ringfree in the fuel tank. I was done in about an hour and in that time, the misfire went away and low and behold, it NOW idles normally. Didn't take a wrench to it, just one hour of running with RF... If that doesn't prove it works, I don't know what will...

Don't believe me, ask Rodbolt. Ask him what two products he uses in his own , personal vessel (also an F150). Ringfree is one of them..

I've been wrenching on anything with spark plugs since I was 12, 56 now..

You may want to try some of these products, some do indeed work...

[ausnoelm]

Not saying they don't work, but most see them as an easy fix to something that no amount of sprays and fix alls in a can/bottle will ever fix, they are meant for routine use.

[TownsendsFJR1300]

Not saying they don't work, but most see them as an easy fix to something that no amount of sprays and fix alls in a can/bottle will ever fix, they are meant for routine use.

Agreed 100%.

That's why I posted in post #5 to disregard if he's been using it regularly...