I have a 2000 GMC Jimmy 4 dr 2wd. It's got about 140k miles on it and lets just say I've done way more maintenance on it than is required since I got the car (at 33k miles in 2003). I want to keep the car for 3-5 more years at least.

My transmission pan has been covered in oil every time i've gone to change the tranny filter over the past 40k miles, and about 2 months ago I started getting the oil spots on the driveway. I was also having to top it off with a half quart about once a month. So i decided that it was time to finally change the rear main seal and oil pan gasket if necessary. i quickly learned that the engine had to come out for that to happen so i went ahead to do that.

After lots of cursing i finally got the thing out and swore that was the last time i was ever going to do that. I do want to keep the car for a while so i decided that while its out i better replace the main and rod bearings along with the rings since the engine started knocking while cold this past winter when it was below about 50 in the mornings and there was a few times over the past couple months where i got worried about my oil pressure being low while going down the road at 70 mph.


Everything looked good in the engine except for a little bit of water that looked like it was getting in the #1 cylinder. The old bearings and the cylinder walls looked good with a pretty decent cross hatch still visible. I got all the rings and bearings standard size from sealed power.

I'm to the point now where i am putting the pistons back in and i noticed that when i put the bearing in the rod cap that the edges of the bearing arent flush with the machined deck of the cap. the bearing edges stick out about 1/32 of an inch on each side above the deck. however the bearing on the rod size is actually recessed from the deck a little bit to where it matches up perfectly with the cap side bearing when its bolted on. 5 of the 6 rods are like this, with the 6th one having the bearings fit flush to the deck on both halfs.

I called a machine shop about this and the guy thought that there was a problem and that the bearing edges should've lined up flush with the machined mating surfaces of the rod and the cap. However i read in a general engine building guide that rod end bores have a slightly smaller diameter than the OD of the bearings that go in them to create a small amount of bearing crush when they are torqued.

Also i put the old bearings back in the caps and it turns out they have the same fit as the new ones except not as much stick out above the deck of the caps. i checked the diameters and roundness of the big ends of the rods with the caps bolted down lightly with a socket and they were all within a thousandth with a micrometer as best as i could measure.

i have very limited engine building experience however a very experienced friend is helping me and we are going by the Haynes manual step by step (with the exception of only checking some of the more critical clearances and diameters). My experienced friend thought the bearing issue was a problem which is what led me to calling a machine shop.

does anyone think there is a problem with how these bearings fit in the big end of the rods?

 

This doesn't sound right to me but you say that the old ones are similar in fit as well? I would be curious to see a rebuilt long block to see if it may be the same. When everything is put together and torqued, how does the engine "feel" when spinning it over by hand? I would take the engine to someone and get another opinion just to ease your mind.
Also, you do realize that you could have just pulled the tranny to change the rear main seal right?

 

the crank "feels" good when you spin it over by hand. nice and smooth rotation. the assembly lube is definitely doing its job. i noticed that when we took the rods back off that bearings had been kinda pressed into the caps a little bit and were "almost" flush with the machined mating surface of the cap and rod. still not totally flush, but about 75% better than fitting them in by hand.

its like the center of the bores are slightly off of the parting line of the rod and cap. however much of the bearing is sticking out above the parting line of the cap is recessed below the parting line on the rod. they match up perfect when the cap is bolted on.

we couldnt get the tranny out without lifting the engine really high. we thought about taking it off from there but decided that we got so far that we might as well do another 15 pumps on the hoist to take it out and clean everything up and check everything out. turns out the oil pan gasket was leaking a little bit anyways.

 

You are gonna have to get that shortblock to someone who can put an eye on it and answer your questions, this sorta thing just can't be done without "seeing" whats going on...