2 power heads in 3 years

95 225 looper motors. First power head sent a rod thru the block on cylinder number 3. Installed new power head, cleaned all carbs. lync and sync. Ran good for two years then clang clang. With the carbs,intake and reeds removed I can see cylinder 5 has pulled the wrist pin and the top of the connecting rod is bent.
I was cruising about 4k RPM and stopped and idled along for about 10 minutes, when I throttled up to take off is when it threw the rod.
Crazy thing is it is similar to what happen when the first block thru a rod. idling slow then throttle up and clang clang.
It has always had a good pee stream and wasn't running rough at at all. (Not coughing or kicking at all)
After the first head blew I installed a new VRO2 to rule that out.
When I removed the recirc tubings and blew thru to make sure they were clear I could taste the oil AND the oil tank was going down so I'm pretty sure not an oil problem.
Going to go thru the carbs again with a fine tooth comb but dont suspect they are the problem..Anyone have any insight ? Coincidence, highly unlikely.
How would you go about determining what is causing the problems?

It would be good to see some pictures. If it was an oil problem you would have scoring on pistons and cylinder walls and I don't think the wrist pin would be the first failure, ultimately the wrist pins only rotate through a fairly small angle, unlike bearings on crankshaft. Is there evidence that the wrist pin hit a port in the cylinder? Without knowing i would guess that the first engine was old and tired and the second failure had to do with the rebuild and parts used (or not used).

For some reason it wont let me upload photo. Though the photo I have is not great, You can see the bent rod and the wrist pin laying there. A lot of metal, I suspect from the wrist pin ripping out of the piston. Since it still under warranty I wasnt able to remove the heads or go any further without voiding the warranty.
I feel like it was a problem with the re manufactured motor also. Bought from OBR, they seem to have a good rep but who really knows.

How much time did you have on this 2nd powerhead before the failure took place? Was this a used powerhead, a rebuilt powerhead or a factory new one? If rebuilt... by who?

Failures like that are normally caused by lack of lubrication over a long period of time. Next time around on cleaning the carburetors, make sure that the brass high speed jets are "all" perfectly clean. They lay hidden horizontally in the bottom center portion of the float chambers, way in back of the drain screw.

If constantly running the engine with say one cylinder NOT firing (no spark)... That would eventually result in what we call a "Wash-Out" condition where due to the ratio, the gasoline eventually overcomes the oil mixture in that one cylinder, and the improper mixture tears the hell out of the piston and cylinder wall... but this has not been the case with your engine in either failure, hence the reason why I would be questioning the lubrication route(carb feeding that cylinder)... However.....................

What caused that connecting rod to bend? Usually that is due to a hydraulic lockup condition... the piston encountering something it cannot compress. See what you can find there as the rod bending reason.

Too late now with the present powerhead, but with the next... occasionally do a compression check so as to be warned of a oncoming problem if it exists.

Also, do a drop test from time to time.... while running, remove a spark plug boot from the spark plug, one at a time, to see if the result is a identical rpm drop on each cylinder.

To do a spark test, a proper "Air Gap" tester is needed (nothing else will do!) whereas the gap can be set to 7/16". The spark should be a strong blue lightning like flame... a real SNAP! The gap is important.
********************
(Spark Tester - Home Made)
(J. Reeves)

You can use a medium size philips screwdriver (#2 I believe) inserted into the spark plug boot spring connector, then hold the screwdriver shank approximately 7/16" away from the block to check the spark or build the following:

A spark tester can be made with a piece of 1x4 or 1x6, drive a few finishing nails through it, then bend the pointed ends at a right angle. You can then adjust the gap by simply twisting the nail(s). Solder a spark plug wire to one which you can connect to the spark plug boots, and a ground wire of some kind to the other to connect to the powerhead somewhere. Use small alligator clips on the other end of the wires to connect to ground and to the spark plug connector that exists inside of the rubber plug boot.

Using the above, one could easily build a spark tester whereas they could connect 2, 4, 6, or 8 cylinders all at one time. The ground nail being straight up, the others being bent, aimed at the ground nail. A typical 4 cylinder tester follows:

..........X1..........X2

.................X..(grd)

..........X3..........X4

This can obviously be modified to a 6 or 8 cylinder setup tester.
********************

FYI the second power head lasted almost exactly 2 years. It was a re manufactured motor from OBR. They have it now, awaiting their assessment of what happened. Its warrantied but I''m sure they will figure out a way to blame me

They may surprise you with the warranty... Wish you luck in that area.

Wasting your time if block don't have the water modifications... some rebuilders don't know how to do it or heard of it.

What are these "water Mods" you are referring to? I'm one that has never heard of them. Are these a requirement ? Was there known issues with these blocks? I dont race my boat just a weekend warrior on the chesapeake .

Time to upgrade.

faztbullet said:

View attachment 21479

Click to expand...

Bullet... None of the following is intended to be insulting or of any offense to you personally as I have the highest respect your knowledge. It simply pertains to my opinion due to past experiences that conflict with that pdf bulletin.

I read all of that info... interesting. However, to have that done, one has to ship the powerhead crankcase to "MarFab"... they do not say what the mentioned procedure consists of (secret?)... and it is worded in such a way that the end result, in their not so many words, that the procedure may correct the problem, and then again, it may not, and therefore regardless of how their warranty is expressed... there is no warranty on this particular procedure.

In my 30+ years at the bench, I've had a few of the much earlier model crossflow V4's and V6 powerheads fail due to having the ring location pin being driven in which of course allowed the ring to turn out of place and become caught in one of the ports, but of course having retired in 1991, I never encountered a 1993 (and up) V6 looper with that problem. I'm sure that it took place but I seriously doubt that it became a epidemic as MarFab sort of suggests.

Of the V4's and V6 crossflow engines that I encountered with with this ring location problem, a new piston and correction of all known associated problems in the rebuild resulted in a engine that ran for many years without a repeat of the problem... and may still be for all I know. With that past knowledge in hand, I'd be far pressed (as the saying goes) before I'd be going to the trouble to ship off a powerhead for a no warranty procedure that may or may not correct a insinuated problem.

The failure are block design/water flow problem. It a modified copy of the Ficht cooling system. I will not build a 90° looper without it nor will I build a 60°without pressure testing block. Block runs wayyy cooler.