1986 truck, 22r, carbureted. One owner since new, me. I had a local machine shop rebuild the engine because my shop in the Sonoran desert faces west and the wind blows in sand from the west. Boy was that a mistake. Cylinder #3 performs zero work at idle. I still haven't torn the head down, I replaced it with one from 22RE Performance and my compression on all 4 cylinders nearly doubled so that solved that problem. The engine has 5000 or 6000 miles since the rebuild. I was towing my Yamaha Rhino and the engine started running hot. Not overheated but hot. I slowed down and temp returned to normal. On my way home same scenario but by the time I got home the engine wouldn't idle and when I would restart it was clear one cylinder was doing nothing. I compression checked it and #4 was at 90 pounds. Dumped some oil in there; it returned to 240 PSI so rings. Pulled the head, pulled that piston/rod.Top ring was fine but if I rolled the second ring around the land from outside there was one point where it was high and would not remain in the bottom of the land. I looked into the land with a jewelers loupe, very high magnification, and there was the most beautiful zig zag crack in the bottom. That land is collapsed. The cylinder looks fine, cross hatching strongly evident. As best as I can measure it with a good quality dial caliper the bore size is perfect.
I bought a set of NPR pistons and rings, gonna replace all four. Upon checking initial end gap on the new NPR rings, the gap was something like .012 above the maximum allowed in my Toyota factory manual. So I bought a set of Hastings rings and they are a full .010 below the NPR rings, right at the maximum gap allowable. Been too hot here to get into it any further but big temperature drop Monday so back to it. The only explanation I can come up with is my .020 over NPR pistons were packed with a set of .030 or .040 rings. I checked the original (NPR) gaps on the two cylinders with the piston down, about 2" down, same result. Same result on the Hastings rings, .010 less gap. I am slow to make an accusation unless I have real evidence but I don't have hundreds of engine builds under my belt. Anyone have any other ideas about why the NPR ring end gap is so wide? They do not appear to have been ground.
Finally would you hone the cylinders at this point? I have a hone and can but not sure I should. I'm 70 years old, still do everything myself and still always learning. Thank you for any insight you may have. Oh, the people who sold me the kit said "if you have any doubts about installing this kit return it". So in other words it's my responsibility to solve their problem.

 

If the cross hatching is still good
I'd put in the new pistons and rings
Use a good breakin oil for about 500 mile to seat them good. Then I switched to Amsoil in my Turbo 4runner
sorry your having to do this.

 

I'd give a light hone with a coarse stone hone To insure the new rings will seat. I like 180 to 220 or so.

I have had bad luck seating rings in 22r engines when using finer grit stones than this.

Here is a thread concerning some of my ring seating woes:: '87 22RE blowing smoke on acceleration - YotaTech Forums

I had got this block back from the machine shop that bored it and they gave me some line about 'plateau honing' that is finished with 400 grit stones.

I had asked for a coarse hone and I suffered from my failure to hone the block myself after they hadn't done as I had instructed.

There's about 15 thousand on this engine now, and no troubles with the NPR pistons and Hastings moly rings

I'll be 70 my next birthday.

 

Update: I installed the Hastings rings on the NPR pistons. My compression is 180, 185,185,185. Engine runs extremely rough though. Revs fine but will not idle. I ran through the cam timing procedure without pulling the cover and everything lines up as it should. I can't find a vacuum leak anywhere other than the Red Line spacer plate leak that has always plagued me. I remember when I got the truck home after my initial problem the plugs were black and sooty. This 4X4 has been delivering 21.5 MPG recently so I'm now suspecting something in the Weber Red Line carburetor let go. Something stuck in the needle/seat or power valve failure? I never have been impressed with this Red Line carb and spacer setup. I'm willing to buy a new carb, a 32/36, and I will remove the spacer and flatten it to get rid of the small vacuum leak that has always plagued this setup but I am lost on what carburetor to buy. I see a ton of them out there. I know I don't want another Red Line.

 

I would pressure test the coolant system just to make sure you haven't cracked the new head or blown a head gasket.

Fix those vacuum leaks once and for all so you can set up the carburetor correctly. If you decide to buy another carburetor stay away from the cheap junk sold on ebay and amazon unless you just want to rob some of the new parts from it to rebuild a good Aisin. Spend the money on an Aisin. You can rebuild it yourself if you're so inclined but use the GP Sorensen rebuild kit from Autozone. Most of the other kits sold are only partial kits and don't have all the parts needed. I have a post on here where I list the kit Part #.

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