F40 rebuild yes or no ?

[almetelo]

Hi!

Need some advise please!

Bought a cheap damaged 2001 F40 with the purpose of recover it if be worth (if not sell parts and have some profit) to have a project on hands, learn a little more and replace my loved yami 2 strk 30 x3, I’m not in hurry to fix it.

Have a look on fotos to see what I’ve found when dismantled the motor.

The 1st cylinder wall is a little cracked, cylinder head damaged.

Here is what I supose that happened:
The exhaust valve broked, the piston compress it against the cylinder head damaging it, the cylinder wall cracked, the piston almost disappeared in 1000 pieces (pieces were almost on the oil sump) and the rod crooked (theory of backyardigan lol would like hear from you what could cause this and how this happened)









Now the most importante, worth fix the block?

I’ve been on a proper machine shop that fix the cylinder crankcases, they said can fix the cylinder head as new, weld the cylinder wall and feat a new linner sleeve, they said that will be good but is always a risk of failure (but unlikely) they asked 200€ +/- $250 for the job on cylinder head and crankcase.

Have you ever fixed a cylinder cranckcase like this with good results?

If I’m in US I would buy a used block but used parts here are rare on sale and very expensive and thats not the type of stuff my friends or family can bring me from US on the luggage to save on postage and costumes.

If I had to buy parts here defenitily would not worth it… Compared Yamaha parts with Mercury parts for this motor and most Mercury parts are half of the price here on boats.net from Yamaha parts for this model.

Already bought a used piston and rod in US but I want to be sure I’m doing the right thing before fix the crankcase...

[almetelo]

[TownsendsFJR1300]

Fixing the block itself, removing the liner and heli arc welding would be a bit tight. If that wasn't cracked, the liner and head fix, wouldn't concern me.

Only $250 for all that welding, machine work, liner, sounds cheap to me...Definitly magnaflux the head/block etc to find the extent of the crack..

Does the big rod end on the crankshaft look ok?

I suppose you need to add up everything its going to cost to re-assemble, gamble that the block is ok, and see if its worth fixing.

Why that exhaust met the piston, I don't know, maybe an over rev big time? That or perhaps the valve seized up(pretty un-likely) however the valve staying open(when it should have closed) definitly started the course of events.

If the cam belt jumped, all the exhaust valves(at least) would have been damaged, so it likely wasn't that.

I suspect you probably have a parts engine, but add all the #'s up.

Please post what you end up doing/find..

[almetelo]

Hi Scott!

Thanks for your reply!

Agree with you... what concern me is if the cylinder wall will be good and hold the use in case I'll rebuild it, thats why I need hear opinions about this...

The machine shop I've been is the one with better reputation around here and I got better price because is by my best friend that have a auto workshop and he work with them, can´t forget in US labor must be more expensive than here...

Cranshaft looked to be good...

If I know block would be free of problem where it have/had? the crack I guess would be worth it... but like you said can be a gamble!

Payed 500 for the motor + 250 to fix block and head + 300 in parts (bought in US) I guess still would be worth it as labor will be mine and my friend will reassembling the cylinder head as I don´t have the tools (but also free)

Like you do, the any possible cause I can see an over rev to this happen.

All other valves are good.

As I'm not in hurry to fix it I can wait untill find use block here in EU at good price.

Found 2 cylinder crankcase/block here at 400€ but don´t want spend that much and still have to repair the cylinder head... Sometimes cheap is expensive...

For now I'll wait...

Other opinions are wellcome!

Rodbolt or Boscoe have you ever fixed a block with this similar problem with good results?

[TownsendsFJR1300]

Absolutly, please have others chime in. I don't think I've seen the block (with a sleeved cylinder) actually break, there some serious forces going on in that combustion chamber.

I have seen on some Yamaha motorcycle engines, (FJR1300 and FZ600) where the cam chain, or cam chain tensioner has failed/jumped time and caused similar damage.

These engines are NOT sleeved. Of course, it damaged the cylinder badly but NEVER cracked the block. The cylinder surface is coated (again NO iron cylinders), so the block, if damaged, was toast... Damage was often to the piston(besides the head) poking a hole thru it.

Looking at your rod, the piston didn't puncture, the rod bent and the next weak point was the cylinder/block.. I'd rather have a piston with a hole in it than a cracked block/cylinder...

Good luck and please post eventually how it works out..

[arny]

You also have to change all valve guides,as they probarly are worned out and cause the valve-head to break .Yamaha came out with a better type(steel) in 2004. Take a look

[rodbolt17]

my opinion of the merc built F40 wasn't high to start with.
judging by the rust I would guess you had water in that cyl at one time and stuck the valve open.

one that badly damaged here in the states would be in the scrap aluminium pile.

repairing the block would be about 300 or so and the head another 5-700.
add in bearings,gaskets and the rest your looking at 1500 or so to start reassembling. then add about 18 hours at 90/hr and you way exceeded the value of a 10yr old+ 40.

[almetelo]

Hi!

Thanks for your comments.

Yes, the forces involved were really severe.
A stucked opened valve could be the cause of this failure but I tend to belive it was other cause like over rev, who knows...

In a possible repair (if I will do) are included (provided) 2 guide valves for the 1st cylinder in the budget as cyl #2 and # 3 didn´t suffer any damage I'll keep all parts.



The rust in cyl is because I wash it to remove grease and the little parts of the piston and had no rust when I open it..
The motor failure was more than 1 year ago.

Labor is not included in this bill for reassembling the motor as I will do everything I can, just will need some help to reassembly the cyl head as I don´t have the tools.
Even if I repair the block or get a used one at good price just will worth it if I buy parts in US.

If I sell the motor by parts I belive I can do at least twice the price payed for it but may take some time...

For now I'll wait and see whats come up.

Thanks.

[almetelo]

one more question...

In a possible rebuilt should I feat new piston rings on pistons #2 and #3 or can I save a few bucks using previous ones?
(I belive I do but if is not really necessary better for the wallet) but is something I was expecting to spend on this bill.

Bearings will be replaced in case of.....

[ausnoelm]

Get what you can for what parts are still OK, and forget you ever saw that motor, it's toast. You can rebuild it, and maybe it will be OK, but it will for ever be a welded, patched, bits and pieces pile of questionable parts.

[rodbolt17]

if the bearings are not damaged and still plastigage in spec I would reuse them.
the rings I would replace.

[ausnoelm]

whatever you decide to do find out what happened to it, or you will be rebuilding it again, don't believe it was from an over rev like you stated.

[TownsendsFJR1300]

don't believe it was from an over rev like you stated.

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

[arny]

Have seen this on "some" pre 2004 F40.The valve head fall off,caused by worned valve guides-a sort of yellow metall were used pre 2004 and was not the ideal quality for this purpose. Plenty Mercury in this engine

[99yam40]

Have seen this on "some" pre 2004 F40.The valve head fall off,caused by worned valve guides-a sort of yellow metall were used pre 2004 and was not the ideal quality for this purpose. Plenty Mercury in this engine

If you pay attention to the the pics the valve head did not fall off or he is showing a different valve in the pic