View Full Version : cj5 v6 damage

July 20th, 2021, 10:51 PM
No not mine...but a friend of mine who just finished running the rubicon and is in Leadville for our upcoming early cj5 gathering. Pulled his jeep off the trailer today and it didn't sound good. Pulled the valve cover and:

Missing valve and spring! I think the real carnage pictures may come once the head is off and we can see the bottom of the head and down into the cylinder...

July 20th, 2021, 11:11 PM
Hold muh beer and run it like a rental - it's got five others still work'n!!

err... bummer.

carnage pix of the piston and valve would be nice when that comes around. Hope the cylinder walls aren't trashed.

July 20th, 2021, 11:18 PM
Hold muh beer and run it like a rental - it's got five others still work'n!!

err... bummer.

carnage pix of the piston and valve would be nice when that comes around. Hope the cylinder walls aren't trashed.

This is Scott's jeep - the guy we ran Red Cone with last year. He's hoping to swap out the piston, but I am thinking there is either going to be too much damage to the underside of the head as the valve is hammered up on the bottom of it, or fell down down into the cylinder and thus trashed that. In both cases, there is a good chance of a hole in the piston....FWIW, I volunteered to help him out in any way possible, so thurs might be a bit more up in the air depending...

July 20th, 2021, 11:38 PM
If he needs more hands - I could help. Some motor tools available (long unused).

He might bet lucky and not have any serious cylinder wall issues. I hope the valve guide didn't get trashed with the valve partially in the guide, well extended, with the piston hitting the valve at an angle. Any rough marks on the inside of the head might be able to be ground smooth and call it good.

I had a lawn mower (https://www.jimwilliamson.net/misc/tractors/yazoo-2-07.jpg) (12HP Wisconsin, long stroke / low RPM) that would (repeatedly) burn off the top land of the piston (near the exhaust valve) and then the top ring would chip out and the second land would start to break. This was in the fall when I was in school, weekends were short, and grass / leaves needed to be tended. I worked the motor more than it could take. At idle I could hear the tinking of ring (steel) and piston land (aluminum) bouncing up and down in the cylinder. There was no time for downtime until the season was done. The motor (it happened twice) never missed a beat. When I'd pull the head for the replacement the aluminum and steel bits were beat down to smooth grains of rice and the top of the piston and inside of the head had no carbon on'm - clean. The cylinder walls weren't harmed (odd - even where the ring broke - that I found curious). I'd pull the piston for replacement and put it together for the next season.

July 24th, 2021, 04:16 PM
Yup...its not looking good...here is what was found in the oil pan:

And looking up toward the piston from the bottom:

no pics of the bottom of the head or of the cylinder walls yet....

July 24th, 2021, 04:59 PM
tasty bits

July 24th, 2021, 05:40 PM
Tentative plan right now is to remove the blown out piston, hone the cylinder by hand with dingle ball hone (still haven't seen down the cylinder so...), throw in a used piston, ring and valve, and go with it for a week or so. It might last a day, it might last the whole week...I think the big concern is how much metal and fine powder has moved through the oiling system and has plugged up something important. The connecting rod bearing is probably bad as well, but I think the hope is even with a knock and all, if it'll just run for a few days it will be worth it, and then it can be dealt with more properly later when he gets home to FL. When i killed my v6, it was the main bearings (and specifically the thrust bearing) that started loosing oil pressure and eventually sent finely ground babbitt powder through the system and plugged it all up and the engine basically lost all power, but didn't seize up or overheat to the point of damage. In this case, that probably hasn't happened yet, but guessing it may happen before its all said and done.

July 24th, 2021, 06:10 PM
Yup...its not looking good...here is what was found in the oil pan


The StRanger
July 24th, 2021, 11:02 PM
Ohhhhh dat look uuuuuuuugly !!!!!!

July 28th, 2021, 08:39 AM
How's this for a campground repair:

Scott pulled the head - a pic from the top end...

Scott put in a used piston and ring (I would assume the connecting rod as well) mailed to him from a connection on the ecj5 forum (borrowed a ring compressor from FLAPS):

Installed a used valve into the head - apparently the valve seat wasn't pretty, but did the best he could with a small Dremel grinder type thing. There is going to be blowby around both the ring and the valve - it's probably going to be a good mosquito fogger.

Cleaned up and reused the head and intake gasket:

And it runs...good enough hopefully for a bit of wheeling next week with a group of ecj5's....then it will get a complete tear down and rebuild (or maybe a complete engine swap/replacement) when he gets it back home. The cyinder wall isn't pretty either - not sure if it will need sleeved during a rebuild or not. He cleaned up the oil pick-up screen and of course new oil filter etc - will run it a bit today and then change the oil again. Hopefully it won't trash the crank journal...Scott said he's not that concerned about saving the engine for a rebuild (I kinda think he may have bigger plans for it - plus he has a 3b he's looking to build at home that might be the new focus).


July 28th, 2021, 09:10 AM
Thumbs up to salvaging some vacation!

I'll put money on it holding / running well enough for'm.