compression reeds or rings?

[slimjohnson]

83 johnsonv4 j140tlcte motor was running great at wide open throttle and bogged down and shut off in about ten seconds without reducing throttle. refired ounce and ran really rough. towed it home and checked compression. it was 120lb on 3 cylinders and 20 on the last one. wondering if this a sure thing that the rings/piston is done or could it be a stuck reed of some type. little advice prior to tearing this thing apart would be appreciated.

 

[slimjohnson]

Re: compression reeds or rings?

sorry to the veterans in advance for my forum ignorance. after i posted this a similar thread comes to my screen at bottom that i couldnt find doing a normal search. im guessing after reading those threads that i need to add oil to cylinder and recheck my compression.

 

[metriccrescentwrench]

Re: compression reeds or rings?

With that much of a drop you might just as well go ahead and pull the heads, it's serious.

 

[slimjohnson]

Re: compression reeds or rings?

thanks metric. I'm still waitin on my service manual. do i need to gradually reduce the torque on the head bolts in any specific order or does it really matter on these engines. I normally work on toyota 4cyls. This is all new to me. wishin i had a 4 stroke. I know how to work on those.

 

[oldybutagoody]

Re: compression reeds or rings?

Might be blown head gasket. Is that spark plug "steam cleaned" from water getting into the cylinder?

 

[slimjohnson]

Re: compression reeds or rings?

plug looked normal and piston top that is visible is not very clean. good idea but i dont think im that lucky.

 

[daselbee]

Re: compression reeds or rings?

High speed lean condition causes the piston to swell up a bit and sieze in the cylinder.
If you try to start immediately, it acts like the batt is dead. Then as the cyl cools, and it doesn't take long, then it will turn over and start again.
You will need to pull the head, you will find a scored cylinder.
You will also need to find out the cause of the lean condition, most likely a dirty carb, or fuel restriction on the cyl affected.

You don't have to gradually remove head bolts...just watch out for breaking them!!!!

 

[slimjohnson]

Re: compression reeds or rings?

yup thats what happened. it was siezed up immediatly after it quit. thanks.

 

[daselbee]

Re: compression reeds or rings?

PM sent.

 

[daselbee]

Re: compression reeds or rings?

You know...this also could be due to overheating caused by swelled up or mislocated water deflectors.
When you get the head pulled, shoot a few pics of the water deflectors and post them up.
Don't disturb the position of the deflectors before you shoot the pics.

I am very interested in what you find.

 

[slimjohnson]

Re: compression reeds or rings?

will post pics in a little bit. gonna tear into it tonite.

 

[emdsapmgr]

Re: compression reeds or rings?

Agree with daselbee. Probably a high rpm overheat lockup. A mislocated water deflector is a definite possibility. Debris/resriction in the high speed jet on that side of the carb. Also look for excess carbon around the ringsets and the pistons skirts. Carbon prevents the cooling fuel/oil mix from lubing the rings.

 

[slimjohnson]

Re: compression reeds or rings?

still waiting on my service manual so im feeling kinda stupid that i dont no what the water deflector is. Ipulled the head off and the rings definately broke. piston and head is chewed up pretty good. cylinder wall doesnt look gouged but there is some metal deposits smeared on the walls. pics coming soon.

 

[slimjohnson]

Re: compression reeds or rings?

I pulled the carbs off and found a piece of my broken air silencer cover about 3/8" by 1" in the intake had gone past the carb butterfly and was in the intake. it was in the bottom left carb air outlet. is that the air/fuel path for the bottom right cylinder. (opposite side of motor from piece of debris but both on bottom) I promise to get better terminology when i get my book. Hopefully today!!!

 

[slimjohnson]

Re: compression reeds or rings?

trying to add pics lets see if this works.

 

[daselbee]

Re: compression reeds or rings?

This is one of the most common failures of a V4 crossflow. Overheating, coking up, etc breaks a ring.

Classic.

You didn't get the deflectors in your pics. Back off a bit to see the water jackets that surround the cylinders. DO NOT DISTURB the deflectors before you take pics. Please....

Edit...AND, I cannot tell which cylinder this is....

 

[slimjohnson]

Re: compression reeds or rings?

Im guessing the deflectors are the squished down tube things in the 7oclock position of each cylinder in the water jacket. I have not repositioned them in any way. its hard to see the bottom one but its the same position as the upper cylinder as far as being at 7oclockalthough it is recessed down from the mating surface of the head by approximately 1/32". also standing at rear of boat it is the lower left cylinder that had the ring failure. service manual showed up while typing this post. YAAAAAAA!!!!!

 

[daselbee]

Re: compression reeds or rings?

See that crap between the rubber deflector and the head bolt hole on the center deflector? Is that blocking the water passageway completely? If so, probable cause of your porblem.

And, that is #4 cylinder, the cylinder that drives your fuel pump. I am surprised you made it home....

 

[slimjohnson]

Re: compression reeds or rings?

it is prabably 50-60% blocked. It didnt make it home. I got towed by another friendly boater about six miles back to the ramp. Only ran about ten seconds when it did finally crank after the initial shutdown/bogdown.

 

[Solittle]

Re: compression reeds or rings?

trying to add pics lets see if this works.

I assume that these are three picturess of the same cylinder?? If not this is a puzzle due to the 120 lbs on the other three.