blown #6 cylinder on Johnson 225

[jdicke6]

Re: blown #6 cylinder on Johnson 225

We got things torn apart and discovered #6 cylinder(bottom left) would funtion with low compression but had a piston that was broken apart. Shards of metal were compressed into the head/cover. We also discovered scarring on cylinder number two possibly from a pin according to iboat forums.


options were the following:

Rebuild motor on our own for first time and hope it works. Cost $1500

Buy a used motor for $3500-$5000 that is slightly newer but then also pay $1000 for new controls. (I was told anything newer than 1995 would require new guages and controls)

Option we chose- buy rebuilt power head for $1800 out of Rico Beach NY with a one year warranty. Install it ourselves and replace all critical parts such as rebuild carbs, replace thermastats, new water pump, and new gaskets and seals for entire engine.

Two major questions.

1. We had a hard time getting fly wheel off and broke two pullers. When it finally did come off it cracked like a gun shot and flew into the air.
We also noticed magnets on bottom looks like they were glued at one time to the underside of the fly wheel. Does anyone know if these magnets should be glued and also what should there spacing be. Any ideas why this fly wheel pulled off so hard?

2. Are there any critical things we should keep in mind when working on this project. We have never put a boat motor back together and I am sure there are little secrets people have learned. Is there anything else we should replace while everything is torn apart.

Also, a repair manuel from IBOATS was ordered today...Im sure that will answer some questions.

Thanks and awaiting opinions.

Still working on uploading pictures.....having difficulty.

 

[daselbee]

Re: blown #6 cylinder on Johnson 225

We got things torn apart and discovered #6 cylinder(bottom left) would funtion with low compression but had a piston that was broken apart. Shards of metal were compressed into the head/cover. We also discovered scarring on cylinder number two possibly from a pin according to iboat forums.

Good to see you back. I always wonder how a poster's repairs turn out.

There are a whole lot of things to consider, but from the above quoted:
You cannot use the damaged head. It will have hot spots on the dented areas and will cause detonation. If the rebuilder is saying re-use the heads, don't.

Two major questions.

1. We had a hard time getting fly wheel off and broke two pullers. When it finally did come off it cracked like a gun shot and flew into the air.
We also noticed magnets on bottom looks like they were glued at one time to the underside of the fly wheel. Does anyone know if these magnets should be glued and also what should there spacing be. Any ideas why this fly wheel pulled off so hard?

Flywheels can be impossible to remove at times. It is not unusual for it to be stuck as hard as yours was. To prevent it flying off in the future, leave the large flywheel nut installed, but loose, maybe 1/4 inch of gap. When the flywheel lets go, the nut will stop its flight.
Check out numerous posts on flywheel removal here to see all the various difficulties ppl encounter.
The magnets are known to break and come off. Most times, if one comes off, there is stator and timer base damage. There is a magnet epoxy kit available, and it seems as if someone has already gone that route.
I am only speaking of re-gluing the large outer magnets.
There is an inner magnet ring that comes loose too. There is no approved way of re-gluing that ring, but I have seen it done successfully. The placement of it is very critical, and is is generally recommended to not try to re-glue that inner ring. If it is off, it will affect the engine timing.

2. Are there any critical things we should keep in mind when working on this project. We have never put a boat motor back together and I am sure there are little secrets people have learned. Is there anything else we should replace while everything is torn apart.

Wow, where to start...
Remember, the engine failed for SOME reason. That reason should be absolutely determined and corrected before you re-install parts from the old powerhead. Critical to your failure are the carbs. Dirty carbs mean lean running cylinders, and eventual piston failure. As you clean the carbs up, you should examine/inspect very very carefully to see if there were any clogs etc that may have caused a lean running condition.

The oil mixing fuel pump (VRO VRO2 OMS) is not generally a cause of such a failure, because if this part fails to mix oil, it will affect ALL cylinders, not just one.
I would absolutely run 50:1 in the fuel tank, along with the normal VRO mixing to provide 25:1 oiling ratio thru the break in period. Mark a line on the oil tank and calculate the oil usage to the gas usage before discontinuing the pre-mix in the fuel tank. The oil mixing fuel pump can also be bypassed if you want to always run pre-mix. Plenty of posts on that subject here.

The guys that sold you the powerhead must have undoubtedly given you a strict break in procedure.

Be sure to torque that flywheel back to 145lbs, or you can shear the key and then be debugging a no-run condition.
Add a water separating fuel filter to the incoming fuel line.


I have sent you a PM.

 

[trendsetter240]

Re: blown #6 cylinder on Johnson 225

Hey welcome back and good luck with your outboard. I recently did a complete teardown and rebuild of a 95 70hp and posted the details here http://forums.iboats.com/showthread.php?t=374011 . Unfortunately not many pictures of the last stages assembling the carbs and electrical as I had my mechanic do the final touches. Some pics on there may be helpful.


I have more pics that I didn't post so just ask if you need a reference I might have it.

Buy a used motor for $3500-$5000 that is slightly newer but then also pay $1000 for new controls. (I was told anything newer than 1995 would require new guages and controls)

This is not entirely true. You can buy an adapter for the engine harness for about 100 - 150 bucks and your old controls will work fine. The only difference is instead of the new "System Check" warning system you still have the beep warning alarms in the 95 control box. Throttle and shift cables are interchangeable.

 

[jdicke6]

Re: blown #6 cylinder on Johnson 225

We finally discovered why #6 had blown.
In the process of putting the motor back together we were replacing oil lines and realized the configuration of the oil lines did not match what the manual was showing us. We quickly figured out that there was no line going to #6 which would easily explain why the motor blew so quickly after the last rebuild. We replaced all the lines the way the manual showed and performed many function checks. So far so good and hoping to have this thing in the water with in a few weeks. Thanks again for everything from everyone. I used much advice off of this site and could not have done this project with out a manual which I purchased here off of IBOATS.

Hope to post a picture when I get everything up and running.

 

[Fl_Richard]

Re: blown #6 cylinder on Johnson 225

I think you mean recirculating lines? I dont think this would cause a failure.

Anyone?

 

[daselbee]

Re: blown #6 cylinder on Johnson 225

I think you mean recirculating lines? I dont think this would cause a failure.

Anyone?

Yeah, there are no oil lines. Recirc lines will cause poor idle....look for another cause. You never posted pics of the #6 cyl and piston...would love to see them.

 

[jdicke6]

Re: blown #6 cylinder on Johnson 225

More questions:

Motor was reassembled with rebuilt power head. Everything typically replaced was replaced.

We tested the motor with water muffs and everything seemed to run great.

Yesterday we took it on the water for the first time to break the motor in. We had a mixture of 50/1 gas/oil plus the vro pump also pumping in oil.

It fired right up without a problem but upon upon trying to give more throttle it would not go above 3000 rpms on the tac. The boat would not get up on plain and max speed was between 9 and 11 mph.
We immediately checked for spark and discovered that plugs 2 and 4 were not sparking at all. The plugs were wet with gas/oil bug unfired. All other plugs were firing.
We replaced all plugs, wires, and two coils for cylinders 2 and 4 and still no spark or increase in performance.

All throttle cables/nuts were also checked in the control and back on the motor side and they were not limiting the amount of throttle that could be given.
We are now thinking there is something wrong with the power pack/module.
Has anyone heard of anything like this before and what can I do to diagnose and fix it. (I have already learned a good bit from other articles on this site but none cover my exact situation.)

I am all ears.