Hole in the block. 77 J 140

[AntiqueTbird]

For your review is an image taken of the block of my 1977 Johnson 140. Had a seize on #1 and the sb side ran hotter than port.. Pulled her apart replaced piston #1 cleaned the cylinder wall of all left over aluminum with acid and a q-tip very carefully. Didn't pull that top water jacket cover. Put her all back together nice and clean replaced the grossly misshapen rubber diverter tubes with 3/8" solid silicone o-ring cord stock a70 toughness. Assumed that the tubes were just bad because the mech who put it together 5 years ago used axle grease to slip them in and it degraded the rubber. Turns out I have a 3/16" hole at the top of that center column assuming it opened up due to corrosion and sitting unused for 6 months. Then on the first use this year it just opened and kablewy. The hole opens near the the top inboard side of the sb #1 piston. That's the one that seized and has obvious signs of seizing both on the "old"

 

[AntiqueTbird]

Even after the edit my message is cut off.

Both the "old" (around 5 years) and brand spanking new pistons.

 

[interalian]

There are bleed holes between the upper cylinder water jacket and the water chest. Per:

http://smg.photobucket.com/user/int...d-4345-bf22-149fd3897c30_zpswljjopiz.jpg.html

 

[AntiqueTbird]

Ok sho'nuff. Looks like those are that.found the other one on the port side. Now more head scratching. What would cause a perfect running '77 140HP that was put up for 6mo's suddenly start running hot on the sb side and four corner seize the #1 piston? Carbs are apart on the bench. All clean main jets are .065" idle jets are .027" via wire gauge. Reeds are great looking. Exhaust housing is clear all the way down.water paths seem to be all clear as much as can be seen and blown out etc...

The sb side is just running hotter all the way. Seals are certainly good, no fuel on top of the block or the bottom. No reaction to starter fluid squirts around the block seals , carbs etc...

Seriously head scratching situation.

It has new impeller, new thermostats, new thermostat housing, spacer, gaskets, springs, bypass valves and seat grommets, upgraded diverter tubes of a70 solid silicone 3/8".

Last year it ran perfect. We would idle out to the running area, run on a plane for about 7 minutes, idle for about 5 minutes then run for a good 10 minutes to the scalloping grounds. Idle around dragging a couple snorkler/scallopers for a couple hours. Anchor up and eat something have a cold beverage then idle around some more scooping up scallops. Then sit anchored for a bit relaxing maybe some more cold beverages then run back in. No problems at all. Started right up every time (still did, not right now due to its torn down on the bench.). Checking every detail of carbs pulling lead shots out etc... Etc...

Is there a major gotcha about the sb side of these motors?

 

[interalian]

I'm reaching, but sometimes you can get a lean condition on the topmost cylinder (#1) if the crankcase seal is bad. I would expect a lot of oily residue around the timer base, stator and under flywheel area if that's the case, along with #1 plug looking different from the rest.

 

[AntiqueTbird]

nothing around the timer base very clean no oilyness anywhere except the tops of the pistons and inside the crankcase. I'm beginning to think that there is a vapor lock situation on that #1 cylinder waterjacket. I read that the 73-77 v4's were known to have excess air around the top side (#1) cylinder and the solution is to tap a vent into the water jacket from up top of #1 and run it down to the lower cowl half as a pisser. that's a grasp at straws in and of itself I think maybe. But I'm bringing the block into a machine shop tomorrow to have the cylinder cleaned up and the bore checked for round and size. I have a sneaking suspicion that #1 cylinder clearance is maybe a touch smaller than it should be and is shrinking too much when I come off of WOT and grabbing the piston. It did seem to run perfectly, before this season, last year through the whole operating range from 800-5800 RPM but maybe my memory is unduly colored.

One thing I can say for sure is that at higher RPM the SB side gets Really Hot, The port side stays cool. when I put my hand under the blubber holes even at idle the SB blubber hole water is considerably hotter , it doesn't make sense to me as it seems that the discharge water after it gets past the t-stats and poppets would have a chance to mix before making it to the blubber holes. Still not sure what the root cause is nor can I find any obvious thing else that is like "A-ha That's it"

I'll know more after the machine shop puts their snap gauges and mic's to it.

 

[interalian]

I put dual pissers on my motor, tapped off the cylinder head water covers, right at the top. The only potential "problem" I see from this is that the pisser water would present a scalding hazard should the motor overheat. I can live with that.

 

[Bosunsmate]

Have you checked your sb head for flatness?
So is this problem not evident at idle, only at high rpm?

 

[AntiqueTbird]

Its warmer throughout all engine speeds. But at planing speed the #1 and sb side as a whole are just much much hotter. I can run her to ~3000 without a problem.

Plugs are evenly brown when pulled.

I'm believing that the #1 bore is just undersized. The block is at the machine shop where they will hot tank, deglaze, lightly hone then measure it. I'm guessing it will be ~3.523".

 

[Faztbullet]

If anything it will be tapered oversize..If its 3.523 that's .023 oversize!!!!!......need to reinspect the t-stat area as sound like problem is there if that side is getting hot.

 

[interalian]

You can also remove the rubber hoses from the bottom of the heads and see if you're getting roughly equal amounts of water from each side at idle, in the event there's some blockage somewhere.

 

[Bosunsmate]

You can also remove the rubber hoses from the bottom of the heads and see if you're getting roughly equal amounts of water from each side at idle, in the event there's some blockage somewhere.

yes id give that a go, it could be a blockage feeding into the start of the cooling circuit in the cylinder case, ive seen that before

 

[AntiqueTbird]

it was previously gone through 5 year ago. in that service they did a bunch of stuff. one thing was to have two cylinders pushed and resleaved. Then all were bored to .020 over. Maybe I've just babied it too much to realize it was having overheat problems. Maybe I've never come up to 6000 before a few days ago in the years since the work was done. The way it's seizing though something is way out of whack and it's in the machine shops hands at the moment.