Yamaha f250 Start Up Noise

[99yam40]

I don't think so. I take stuff apart just to see what it looks like inside, even when it is not meant to be opened up. Oil control valves, belt tensioners with hydraulic snubbers, rectifier/regulators, you name it.

Now I will say that the variable cam shaft mechanism can be a bit fiddly. My own Ford F150 truck has this mechanism. After my first oil change, when I was getting money from an ATM, the damn engine was clattering away. The building was causing me to hear the noise. Sounded awful. WTH?

A bit of research on the innerweb told me about the need to use semi-synthetic oil to make the problem go away. I believe Ford even issued a technical bulletin about the problem. I was a non-believer. Changed the oil and voila. No more clattering noise. No harm, no foul. It is just the nature of the beast.

So does this mean the Yamaha might need the semi-synthetic oil to quiet it down some?

Still sounds like Rod was the only one to point the OP in that direction on the noise, and the only one to say he has experienced the Yamaha 4 strokes with variable cams doing this.

Has anyone noticed Zeno tends to take posts in strange directions

[boscoe99]

So does this mean the Yamaha might need the semi-synthetic oil to quiet it down some?

Still sounds like Rod was the only one to point the OP in that direction on the noise, and the only one to say he has experienced the Yamaha 4 strokes with variable cams doing this.

Has anyone noticed Zeno tends to take posts in strange directions

The guy is all over the map. He reminds me of the ball in a pin ball machine flying around in 87 different directions at once.

Now to respond to your first question, I don't know. In my case the noise was there all of the time but only heard when up against a building such that the noise was reflected back at me. Outboard motors are so much noisier than automobiles are and there is wind noise that helps to mask strange sounds that might be coming from an outboard. I would just take up rodnuts suggestion and see if that makes any difference or not.

If not I might try a dose of synthetic oil just to see what happens.

[zenoahphobic]

I am still here no need for the third person reference.

Why don't we wait for what the OP Shotgun 16 reports.
We know nothing really, like sitting in a waiting room making chit chat waiting.

[zenoahphobic]

Semi synthetic/synthetic

I might try a dose of synthetic oil just to see what happens.

I would have thought all 4st Yamahas should be using semi synthetic oil anyway.
There is argument whether fully synthetic should be used as the premium. This argument will be around for many years to come yet. Oil company vested interests and human resistance to change generally.

The property I have noticed about synthetic is that it stays "stuck" to surfaces longer. Nothing to do with it as a lubricant but rather to do with its "dampening" properties, that tends to quieten things a bit more.

[shotgun16]

Will be at my boat this weekend, will report with results.

[zenoahphobic]

What causes chatter?

I am quite interested in VVT, in fact designed a simple system decades ago that simply can be described as adding a chain tensioner to the front chain section opposite the existing tensioner. It could be dialled to give retard or advance just as ignition is. It was also adaptable to throttle position. To the first M/C overhead cam engines.

So Rodbolt when you say you have examined these, what is the reason why then, some chatter and some don't. I don't wish to criticise your brievity but when one says this, and is brought before some panel as an expert "world" opinion, this would be the obvious question asked of you.

And Boscoe you have pulled one apart, what is your explanation? I need to get my hands on one and I am sure it can eventually be explained. I keep my view until then, that this noise is unacceptable.

Townsend you might be familiar with the old Honda VFR 1000F where endless cam sprockets, chains and tensioners were regularly replaced. The racket caused excessive wear, and a simple spring was all that was needed to run this engine 100000 klms. (my design never used by anyone else). Why? the cam chain tensioner had a simple "flyscreen door closer lock plate" on it that began to get slipperier from polishing - just needed some simple tension on it). The experts missed that one- made a lot of money replacing all those parts.

Sorry tangient again, motorcycles get back to Yamaha OB .

[boscoe99]

Although I have opened up several it was just to inspect the mechanism. I have not a clue what would make one chatter. Or make any other noise for that matter. The drive mechanism is locked with a lock pin until oil pressure builds up, with oil pressure being used to unlock the pin, at which time oil flow is used to control the position of the cam shaft relative to the drive mechanism.

Now, is is variable cam timing or variable valve timing?

[zenoahphobic]

Although I have opened up several

Now, is is variable cam timing or variable valve timing?

It would correctly be variable cam timing. I suppose if the cam drives the same valves inlet or only outlet then it could be twisted to mean variable valve timing.

My actual understanding is the variable valve timing alters the duration the valves are open as well as when they commence opening.

Good point, is it just language again, what system does Yamaha call it?

[rodbolt17]

on the Yamaha system to date, the variable cam timing simply alters where the intake camshaft is positioned.
they are a pain to reassemble the sprockets but if not under warrenty I will try to clean them if the filter was covered in powderd metal due to a thrust bearing failure.
Yamaha does not offer any parts for the sprocket.
sprockets are almost 500 bucks.
why some chatter more than others I have no clue.

but when you reassemble a 3.3,4.2 or 5.3 with VVT they raise all kinds of cain until you get oil pressure.
did 11 of them just this summer for various reasons.
some had bad manifolds,some leaking ex valves that injested water and a few with thrust bearing failures.

that chatter doesn't seem to affect anything.

[99yam40]

Interestingly Rod used variable cam timing and VVT in his last post.
So I am not sure what Yamaha actually calls it in the manuals or other literature

[boscoe99]

Yamaha and some other engine makers refer to it as VCT for variable cam shaft timing. Whereas other engine makers refer to it as VVT for variable valve timing.

In my view, and at least in the case of a Yam, it is the cam shaft that is being varied. The valves them simply follow the cam shaft. So, the correct term is VCT.

Now if some way, some how, the valves themselves can have their openings and closings (maybe lift and duration as well) varied without the camshaft being involved then that might truly be called VVT. Anyone got diagrams for this type of an arrangement?

I go back to the days when the cam shaft was installed before the valves and head were installed. The cam shaft was degreed to the crankshaft. Some cam shafts and drive mechanisms were designed such that the cam shaft timing could be advanced or retarded just a bit. But the valves still simply did what the cam shaft told them to do. They always were in phase with the cam shaft. It was always the cam shaft that varied.

[zenoahphobic]

The cam shaft was degreed to the crankshaft. Some cam shafts and drive mechanisms were designed such that the cam shaft timing could be advanced or retarded just a bit.

This was done to adjust for stretch and wear, to get back to specs. Toyota (that I know of) provided this feature but abandoned it in future upgrades of the engine variants

[shotgun16]

Swapped ocv filters and still made noise, definately chattering of vct sprockets upon inspection at start up. Power head on motor was replaced last year due to melt down from blown water pump, power head was not fully dressed, don't know if this is a factor leading to symptoms

[shotgun16]

Okay, so as I operated the engine throughout the fall it continues to make the chatter noise coming from sprockets after cold start ups. Definative proof came after first start up after oil change before winterization and it made a ton of noise even after being warm, makes sense this is an oil pressure thing. I pursued this issue with the place I use for service, and whom rebuilt the engine three seasons ago after powerhead meltdown down to failed water pump, and they didn't have any knowledge of something like this occurring and weren't much help. My question is to what extent should I pursue this? Can this be the cause for failure like three years down the line when the engine is out of warranty?
Another question, for the past two seasons I have been getting a small amount of water intrusion in my engine oil. Not a ton, but present, definately white streaks and small water droplets. My other engine shows no symptoms of this. Because the engine has been rebuilt I am very sensitive to any issues with this engine. Had it checked out last season when first noticed, passed compression and leak down tests, had the Yamaha rep come out and look and he said if it isn't a bad head gasket or cracked block, only way it could occur is through water injestion or stuck themostats/condensation. He said change tstats and just run it and keep an eye on it. Did as recommended and I keep getting water in there (did not put engine in any situation where I could get water injestion). Motor preforms fine, just worried that it could cause significant issues down the road, especially out of warranty. Everybody tells me not to worry about it now, or just keep an eye on it, but these issues don't sit well with me especially as I use my boat primarily for offshore. Feel like I have to build an argument that something is wrong with both the chattering sprocket and water in oil.

[zenoahphobic]

Thanks for report.
You seem to say it has a further three years warranty?
If that is the case keep perusing it, but with a dealer it appears wants you to go away.
If you were operating in fresh water maybe one might accept the proposition to wait and see, but not if the water getting in there is salt laden.
Low oil pressure often is as a result of wear increasing tolerances allowing too much oil escape leaving little for what is at the end of the oil passage.
This ends in accelerated wear at the points having less pressure, and leading to the expiry of the engine commonly referred to as "worn out".
Sorry as previously intimated I would not be happy without further investigation. Gone are the days with fingers crossed hoping to get "perhaps another year or two". Address it immediately when something is noticed to be amiss.