lx250txra ox66 engine knock

[Snow Bird]

Just replaced ox66 250hp engine seized and connecting rod on number 1 and 2 cylinder made 2 holes in block. Number 1 cylinder had white aluminum powder on piston grey color not black and no trace of oil piston ceased and number 2 cylinder was rusty due to salt water coming into motor.
The other 4 cylinders and pistons looked in good condition cylinders have oil on cylinder walls. The motor did not overheat no alarms went off for temperature or oil. I figured at the time the motor was 10 years old and had lived its life.
Just replaced entire block with new one complete with pistons crank and heads.
Transferred all the electrics pumps injectors & put on new CDI unit. Started new motor would not run very smooth, let idle for 2 minutes, figured it would sort itself out running slow when I put the boat in the water.
Before launching yesterday started engine after engine idled for 2 to 3 minutes engine began to knock. Never even put the boat in water. Thinking that whatever damaged the old engine has now hurt the new short block (crank cylinder block) took out spark plugs and there is not much traces of oil. Drained VST and there is oil in the fuel checked oil pump and this is also working. How does oil get to lubricate these 2 stroke ox66 motors? That is lubricate the piston rings connecting rods and crankshaft? Not by the gas and oil that comes in the motor by the fuel injectors? Now if for some reason an injector stopped working and the other 6 worked fine there would be no fuel coming into the cylinder if the injector stopped working and there would be no oil to lubricate that cylinder piston overheats or connecting rod bearing gets no oil and bang engine damage? Well the new block has a knock looks like I will have to get it pulled down. Do you think the crank could have been hurt by idling motor if there was no gas and oil going to cylinder?
Should I replace number 1 and number 2 fuel injectors with new ones to be safe and sure fuel going to these cylinders if i find damage.
An engine knock is usually what connecting rod bearing? hope i don't have to replace crank.
Well lots of questions, any answers to these questions would be much appreciated.

[rodbolt17]

ALL the lubricating oil comes from the oil pump,through a one way check valve and is mixed with gasoline in the VST then injected via the fuel injectors.
clog an injector filter or have an injector failure and the rods,bearings and pistons suffer.

[Snow Bird]

Thanks Rodbolt 17 guess I will have to crack the block to see extent of damage to bearings on connecting rod and also crank journal. It was at idle for a short time if injectors are replaced or serviced will knock go or this is an overhaul job I am looking at?
I have 3 of these motors what can I do so this doesn't happen to another have all injectors serviced? Any signs before you hear a motor knock to look out for to know injector not working correctly? maybe lost of power?
Thanks for your help.

[Snow Bird]

Hi Rodbolt 17 if i have the fuel injectors serviced ( if they can be serviced maybe Boats.net may know where i can send them) or if i should replace the no 1 and 2 cylinder injectors do you think the noise will go away when fuel and oil lubricates motor correctly? or do you think i have damaged the motor already as it is knocking? what do you think is making the knocking noise? could it have significant damage as it was only idled for short time and is a new block?

[Snow Bird]

I posted the questions to Rodbolt 17 but input from anyone would be much appreciated.

[boats.net]

Need to find out what damage was done to engine first, did you bleed oil pump and oil lines when put new engine on, did you run on oil/gas premix? If not engine probably didn't get any oil.

[Snow Bird]

ran engine on oil premix from separate tank then switched back to normal gas. Bled oil lines before starting engine by slackening bleed screw on oil pump. I am guessing one of the injectors not working and no fuel oil mis going to cylinder. Oh when i heard knock shut down motor and drained fuel out of VST and there was oil in fuel, fuel light blue my first thought was oil pump not working but it is working as it has delivered oil to the gas in VST. Does anyone know where i can send the injectors to get them serviced to see if they are all working. If an injector is found not to be delivering fuel this can damage engine even at idle?? The motor has never gone over 1500 rpms how can I check the damage pull the motor down or if I replace injectors will knock subside? Should i change the injectors and restart motor? Thanks for your help guys.

[ranger521]

You will have to tear down to see if there is any internal damage, usually you would squirt some 2 stroke oil into the intake and unto the crank and connecting rods to give it some lube when you first start the motor. Not knowing where you are there is a place in Florida that does injector service, "Flagship Marine", you will have to google to get info.

[Snow Bird]

Thanks Ranger 521 for your response I am in the Caribbean not many Yamaha dealers pretty non existent so any advice is much appreciated. Will check with Flagship Marine as I go to Florida quite often. You guys don't think I should service or replace injectors and restart motor at idle with functioning injectors? You don't think noise will go away when it gets the oil and gas mix? Anyone would like to take a guess what this knocking sound could be? engine was only idled for 3 five minute intervals. Could crank be hurt? So go strip it down rather than restart with serviced injectors. Looking forward to your responses.

[jb123]

have you checked compression?
pull heads first

[99yam40]

Thanks Ranger 521 for your response I am in the Caribbean not many Yamaha dealers pretty non existent so any advice is much appreciated. Will check with Flagship Marine as I go to Florida quite often. You guys don't think I should service or replace injectors and restart motor at idle with functioning injectors? You don't think noise will go away when it gets the oil and gas mix? Anyone would like to take a guess what this knocking sound could be? engine was only idled for 3 five minute intervals. Could crank be hurt? So go strip it down rather than restart with serviced injectors. Looking forward to your responses.

Knocking could be the rod bearings either at the piston wrist pin or the crank.
It sounds like loose tolerances in bearings because of no lube.

But maybe some one else can come up with other reasons for knocking

[Snow Bird]

Thanks guys, will do compression test looks like i will have to lift off and strip down. if crank bearings are compromised do you think crank will be damaged as well?

[rodbolt17]

that knock could be as simple as the O2 sensor draw tube to a bad bearing.
mechanical damage cannot be fixed by adding oil.
I send my injectors to flagship marine in punta gorda FL.
very good folks.
however if there is already mechanical damage its damaged.

[AlSmythe]

I have a 2002, Yamaha 4 stroke with 1700 hrs. Yesterday without warning after backing off the trailer I placed the control in clutch ahead only to hear some muffled grinding. A few hours later a striped out crank shaft was located. This problem came without any warning and occurred during mild operation. I guess i should be thankful it didn't happen offshore. This is going to be a costly repair. The motor has been meticulously maintained and still bears original paint on the skeg. What happened?

Al Smythe

[99yam40]

Al,
Start your own thread with all your motor info and questions. It has nothing to do with this one