dave1123

If you want my opinion, replace the cam chain gear as well, ESPECIALLY if it's aluminum. IDK because I've not had one apart, but a lot of engines have aluminum timing gears or nylon covered ones. The crankshaft gear also if it's worn. If you can see grooves in the teeth, replace it.

Again, my opinion, ditch the Autolite plugs, go with Champion Copper Plus.

js03wj

Ok guys, so I managed to remove head by myself which wasn't all that bad at all while intake and exhaust mani's in place (way easier than trying to remove in engine bay) I found the collapsed lifter and it was bad! All the other lifters seemed fine but will still replace them. Also couldn't find a 12 point 1/2 deep. Zone, Napa, o'reilly no luck. Home depot to the rescue!!


Advice needed. The 1st piston pic is piston 1 closest to radiator and the 2nd pic is the following piston and the 3rd is a pic the piston after that one, well piston 1 and 2 look kinda bad on the tops to me but I don't think that was my initial problem, (knocking) Should I replace the first 2?



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dave1123

I don't like the looks of those knarlies around the top edges of those pistons. It looks like they seized and scuffed metal up the sides. You should at least pull out #1 and look at it. Nope, don't like them at all!

Ya Know, you've gone so deep into this motor that if you need pistons, do them all and put a set of bearings in it too. A new oil pump would be a good idea. At least regrind the valves.

Here I am, spending your money, lol!

js03wj

Ok, so what do I look for once I pull piston.? I mean what if nothing else wrong like cracks and such other then the slightly melt spots?? Can I do with a little melted piston top?

bigbadon

Hate to be the bearer of bad news but that engine is overdue for a rebuild or replace. The Cylinder walls look worn and scored. The pistons have melted crowns which means it overheated by lean fuel mixture (doubtful since 4,5,6 are ok) or cooling problem. Also check the CAT and exhaust system. Since 1,2&3 are grouped into the same cat you could have a possible restriction.

moparchero

Odd that the walls didn't look so bad. Do you need to regrind the valves every time you change the pistons? I imagine you wouldn't get the ideal pressure as before, because of the scarring.

js03wj

Jeep was over heated which resulted in the knock tap on video page 1.

charliec

look for the rings to be seized. especially the top one. There was serious detonation going on. I,d say 2 pistons ,rings and rod and main bearings,and I would also throw in an oil pump, but like Dave said it,s easy for us to spend your money.

js03wj

Ok. Well at this point I think I'm just ganna order 2 new pistons, rings, and maybe main bearing. Why is it that the rings come as a pack and not by the piston.?

js03wj

Will these work.? Sealed power
H802cp rock auto has em for $28 a piece.

js03wj

http://www.rockauto.com/catalog/more...nid=470&jpid=2

js03wj

Ok. Delima. Ihave 2 new pistons, all new rings. I'm debating whether or not to just replace the rings on new pistons or pulling out the other 4 pistons that I'm not going to replace and re ring them.? Should I replace the rings since I have them or should I just replace the rings on the 2 new pistons.?

Also I'm going to replace all the main bearings for all 6 pistons.

js03wj

Ttt

dave1123

I think you mean the rod bearings, but yes, it's a good idea. And do the rings as well. Otherwise, you're liable to have an imbalance in the compression. That way you'll know for sure if your pistons are scored or not. What you are looking for is melted aluminum that attached to the cylinder walls and then dragged against the pistons. I believe that's what caused the raised dimples on the first 2 pistons.

What you're going to have when you're done is a just-about total engine in-place rebuild. The only thing left would be the main crankshaft bearings.

js03wj

Yes I do. Well it's ganna have more new parts than old but rockauto is very reasonable and full price for everything under $350 including spectra radiator . Summit came thru with the pistons as they where the cheapest. I gotta say the tear down wasnt that bad. Easiest part was removing the head, intake, and exhaust mani of as one piece.
I'm also going to clean the cyclinders a little, just the surface.