v-4 head off tell me what you think

[fishingdave]

So I decided to pull the head off , of my 89 90hp and to my surprise the pistion was all chewed up, tell me guys what do you think must of went wrong <br />thanks <br />dave<br /> http://supercool3598.tripod.com/johnson/index.album?i=0 <br /> <br />It going to be the begining of a long rebuilt process and i will keep all you guys up to date

 

[Ross J]

Re: v-4 head off tell me what you think

It strikes me that there's a build up or deposits on the head and piston. If that's so then there could be a water jacket problem, or broken rings. Have you stripped it down yet? I would expect that kind of deposit to be evenly dispersed over all the cylinders otherwise. I'm no expert but it's an opinion.<br />Ross

 

[Dhadley]

Re: v-4 head off tell me what you think

Just guessing I'd say thats a result of coking. Broken ring. Typical.<br /><br />I'd also bet the top rpm was in the low 5000 range.

 

[rodbolt]

Re: v-4 head off tell me what you think

hello<br /> looking at the eroded piston dome I would lean towards a carb lean out. the skirts will tell the story .

 

[Dhadley]

Re: v-4 head off tell me what you think

All that black sticky goo is coking. The bottom ring will be broken. The coking will extend down the side of the piston, especially on the exhaust side. The bottom ring on the top piston will be stuck in the groove. Worse on the side oppsite the end gap. The underside of the dome will have a (relatively) large patch of burned carbon like substance. The wrist pin will be brown and blue if not slightly purple. <br /><br />Usually boring will clean it right up. Oversize pistons for that motor go up to .064 over so unless its been bored a couple of times already, it should be no problem.

 

[fishingdave]

Re: v-4 head off tell me what you think

the head of the piston and motor head is all mashed up, and i think it was from over heating, but im hoping that the sleves are able to be bore, but any advice would be great

 

[jy118lfd]

Re: v-4 head off tell me what you think

Looks like Just under the exhaust side by the deflector is the piece of piston that broke off and that is what did all that damage. Coking or the piston got too hot and the pin that locates the ring gap backed off allowing the ring to turn and catch the exhaust port. Thats what happened to my crossflow. Either way Dhadley is right lugging the motor was the cause<br /><br />Plus find a new head for that side the old one is junk there is no way to repair it without running the risk of carbon getting in the dings and becoming red hot under load.