Engine/Transmission (1994 - 1998) Burned Piston?

[TWhetten]

I am swapping a 12 Valve into my jeep. I got the complete engine from a friend that owns a garage. I only paid $400 for the entire engine minus the vacuum pump and power steering pump. Anyway the engine was taken out because it was knocking, the pump has never been turned up and the engine has 250,000 miles on it. I pulled the heads and the #6 piston is burned and contacting the head. The cylinder walls look good, could I get away with just swapping in a new piston. What could have made that cylinder get hot enough melt the piston.

 

[CodySanders]

you said the pump wasn't turned up but what about the injectors? or mabey they had a water meth kit with lots of meth. not likely but possible for the injector of #6 to be stuck open. six is always the hottest but i would say some body abused the truck i would go threw it and make sure no bearings are cooked and other cyclinders are ok. it is easier to do it wright once.

 

[Rhondasway]

A defective intercooler will do that too. Whether turned up or not without a functioning intercooler (or boot for that matter) there's just too much heat especially under load (like towing a grade).

Also blowing a head gasket and running oil through the coolant system for too long (minutes) can give you this little gift.

Can't make a recommendation as far as what to do. One of my incidents left me with that knock that most people couldn't hear. I chose to rebuild and that piston wasn't really melted, just shrunken like a witchdoctor's necklace. :-laf

 

[cruiser_2]

Now the most interesting thing you wrote is that the truck engine was making noise a knowcing soiund and #6 is contacting the head... sounds like a rod bearing may be going bad too. I would at least pull the pan or drain the old oil put a magnent in it and look for pieces of metal. Looks like you are in for some work whatever you do. Take the head and have it magnafluxed and find out if there are any cracks too. Just a precautionary step.

 

[hsmith]

Sure can't beat that price for a re-builder. Don't try to cut corners though.

 

[Cummins Thunder]

I have a knock upon start up after sitting for several hours I am sure mine is due for an overhaul:{

 

[6BT-Dakota]

Just curious what kind of Jeep are you putting the 6BT into

 

[BAnsley]

Had a 24 valve with the same problem in my shop last fall. oil gauge in the truck didnt work and customer ran engine out of ''bad turbo seals'' and continued for a bout 3 miles with the loud knock before he checked the oil. engine looked good except for #6 rod bearing,gound about . 070 thousands off the crank.



good luck, Brian

 

[TWhetten]

Just curious what kind of Jeep are you putting the 6BT into

I am putting it into a 1967 jeep Kaiser 1. 25 ton M-715

 

[12V Ford]

Check to make sure the piston cooling nozzle is still in place too. Sometimes those fall off and the piston doesn't get cooled as good. You going to turn this one up some? Or are you afraid it'll smoke your CR:-laf. J/K, that jeep probably only has gearing to run 55 mph:-laf.



All the above comment sound good too. If any pistons get burnt, it's usually the #6.

 

[TWhetten]

HAHA,I'm tempted to spend my jeep money on my CR just to outrun you:-laf not to worried about the jeep outrunning the CR, the 5. 98 gearing the jeep has now might let it get to 55mph but not much more. An axle swap is on the to do list to. You know me I am definitly gonna turn it up. What the heck is a cooling nozzle?



I was in your neck of the woods for thanksgiving, froze my butt off.

 

[12V Ford]

You should have looked me up. Oh well. Each cylinder has a cooling nozzle that's pressed in the block and you have to have the pan off to see them. I'm not sure exactly how they look, because I've never seen one.

 

[gitchesum]

FYI, when you re-install the piston, if it has an indention cast on one side of the piston, make sure the indention on the piston on the correct side to allow room for the cooling nozzle.

Had a guy come in with a handful of bent cooling nozzles one day because he had the pistons installed on the connecting rods 180* out.

 

[TWhetten]

FYI, when you re-install the piston, if it has an indention cast on one side of the piston, make sure the indention on the piston on the correct side to allow room for the cooling nozzle.



Had a guy come in with a handful of bent cooling nozzles one day because he had the pistons installed on the connecting rods 180* out.

Thanks for tip, that sounds exactly like something I would do.