F40 rebuild yes or no ?

[ausnoelm]

Your best "guesstamate"? (not being a smart a...)

well... it certainly didn't over rev one cylinder only, and it's only one cylinder that is scored/damaged. might have been an over heat, cracked the cylinder, then water intrusion from the crack, motor sat for a while and rusted a valve open, next start, valve bends? possibly lots of other things too, but not an over rev (in my opinion)

[almetelo]

Hi!

The horn valve on the pic is the intake valve of the 1st cyl, the exhaust valve head disappeared in pieces...

Definitely an over rev can cause this... (horn or broked valves)

Why on 1 st cyl ??? duno! Maybe was the weakest point.

but...

when this motor came to me had no thermostat. (or was running without it or was removed in the meantime as it was in storage for +/- a year)

1st cyl run cooler can cause this kind of damage???

May affect valve clearance??? I guess so but I duno!

The broked exhaust valve head caused this damage (we all agree here) but what cause it to broke... ???

[almetelo]

The horn valve on the pic is the intake valve of the 1st cyl, the exhaust valve head disappeared in pieces...

the valve that caused the damage was the exhaust valve as the valve in the pic is the intake valve (horn) after collide with the broked exhaust valve head (IMO)
But this intake valve on pic was in place.
The exhaust valve head was missing but the rod valve was in place secured by the cotter valve.

The exhaust valve head I didnīt found it as it should be mixed with fragments of the piston (most in the oil sump)

[TownsendsFJR1300]

Thanks for the update..

[rodbolt17]

that's not typical over rev damage.
it is typical of a valve stuck open due to rust/corrosion on the stem.
the rev limiter will grab the RPM way before the valves float.
these little 4 strokes are easily cabeable of 7000 RPM if the rev limiter would allow it.
unlike the self adjusting hydraulic valve lifters that can pump up and alter overall valve lift, Yamaha outboards use a solid mechanical valvetrain.
some with cam driven rockerarms and some that the cam operates the valve directly.
that type of damage is also typicall on the 8.1 and 7.4 big blocks.
I do see the occasional valve collision in the 5.7.
most times its due to water intrusion that causes corrosion.
etier from reversion or a bad manifold or riser.

[almetelo]

Please post what you end up doing/find..

Hi!

Have some news on my project

Bought a used block and a cylinder head by the price of the repair of the old block and head
Even for me is hard to belive how did I got this price here (even cheaper then US)
Bought it to a local fisherman that the motor was "drinking oil" and after the mechanic open it the repair was so expensive that didnīt worth it so he bought a new one and had the old one at home for some time until now.

Just took it to polish the cylinder walls as already had a little rust (but not scratches)

Removed valves from cylinder head to wash it, clean valves, springs etc and will replace the valve stem.





When removed the cyl head cover found this:



and asked my self:

"What is this!?!?!?"

The motor must had thousands hours on it (the camshaft is eated about 3.3mm / 0.130in but the block and head seems to be good thats the most important as I have a almost new camshaft and rocker arm to fit on it.

On last week on January I have a friend in US for 1 week of business and he will brings the parts from here(site)/there(US) most will be Mercury as are much more cheaper.

[rodbolt17]

***
that cam is munched.
hopefully you will have enough stuff to make two into one.

[almetelo]

Hi!

The exhaust / muffler is suposed to be all that black / dirty on the outside?





Apologise if this is a dump question

[TownsendsFJR1300]

Is it wet with oil?? (it appears so).

Black carbon is expected, but that looks like its been burning a bunch of oil...

[almetelo]

Is it wet with oil??(it appears so). Yes, wet oil...

Black carbon is expected, but that looks like its been burning a bunch of oil...

What can cause burn oil? Bab piston rings, bad valve stem, what else?

Even if motor was burning oil I was not expecting all that carbon on outside of the exhaust but after clean it looks like have passage/contact with the outside of exhaust / muffer

[almetelo]

Hi!

What T/T terminal assy (6H5-81920-00) is suposed to do on this model?
Asking because I'll be building a PTT harness

What the Pilot Light (62Y-84301-00) do? some models have it others donīt.

[boscoe99]

The terminal assembly, item 15 in the first linked illustration below, appears to be a junction fitting for the positive battery cable, the trim and tilt relay power feed wire, the main engine harness power feed wire and the starter relay power feed wire.

Are both posts of the terminal assembly common to each other?

2006 and Later F40TLR Yamaha Outboard ELECTRICAL 3 Diagram and Parts

The pilot light is the low oil pressure/over temperature warning lamp that is used on a tiller steered model. Item 47 in the linked illustration below.

[almetelo]

Hi Boscoe!

Thanks!

Both posts are not common.


I'm planing build this PTT harness



So I'm planing keep the original harness to save some money and add this wiring for the PTT (I'll be using it with a tiller handle so I donīt think is really necessary change harness and I already have 2 PTT solenoids from a Tohatsu which also saves some money)

This schematic doesnīt have any terminal assy and I think I'll not need it.

Agree?

[boscoe99]

Agreed.

I actually prefer the relays that you propose to use (at about ten bucks a pop over here) versus the multi-hundred dollar relay assembly that Yamaha uses.

If one fails just replace the defective one. Heck, I can replace many of them for what a relay assembly costs from Yamaha. Not that they are any more prone to failure either.

Yam doesn't use a circuit breaker in the trim circuit by the way. If they did it would be 400 Euros.

[rodbolt17]

all that carbon/oil on the muffler/oil pan assy indicates a gasket or muffler seal leak.
its NOT supposed to be there.
my advice would be a complete disassembly and inspection of ALL mating surfaces with a straight edge and feeler guage.
.004" is about the maximum allowable warpage on any surface there.

on the trim, to make it neater look about the motor boneyard for the old style jonny/rude inline 3 or crossflow v4/v6 that used two relays in a bracket.
water resistant and can be remotely mounted.