What is platiguage?

[blakebmxr3]

ok sounds good, i think I'll go with auto zone probably. they have HI Tech I think

one of you said something about a crank kit, what does that include?

 

[5-90]

ok sounds good, i think I'll go with auto zone probably. they have HI Tech I think

one of you said something about a crank kit, what does that include?

I'll use Clevite77 bearings when I can get them, but I've been using them longer than my kids have been around...

A "crank kit" is a crankshaft (with either a cleanup grind or a resize grind) and bearings to match. While it's still not going to give a GUARANTEED oil clearance on anything, it's a good way to go - because you'll not have to order bearings separately.

The only way I can think of to get a guaranteed oil clearance value is to install the bearings, torque the caps (assuring "bearing crush,") and measure the resulting bore. However, this is something you don't need to worry about for a street engine, it's only an issue for extra-high-endurance or extra-high-performance (and those dial bore gages with NIST-traceable setting rings come into play on this one...)

 

[blakebmxr3]

ok kool.

where is the code you said was stamped on the block, about the crankshaft???

 

[cwstnsko]

My stock rod bearings had the STD (and a bunch of other numbers) stamped on the back. I used Clevite 77 bearings from Autozone ($5 each)

 

[blakebmxr3]

well what i was talking about is that there is supposed to be a code stamped on the side of the block(from what i read in other threads) and I dont remember where it was supposed to be located????

 

[5-90]

What year? I'll see if I have an FSM close to it, and I'll get it to you either before I take off for errands (if you're really fast) or after I get back (if you're not.)

I should look this up anyhow, I know...

 

[blakebmxr3]

its a 1989 xj sport 4.0 auto blah blah blah.....

(i was slow)

 

[5-90]

OK...

There should be a machined boss on the pax side of the engine near the distributor. Look for:

"P" - one or more connecting rod journals ground -.010"
"M" - all crankshaft main jounals ground -.010"
"PM" - both of the above (all mains and one or more rods.)
"B" - All cylinder bores +.010"
"C" - All camshaft bearing bores +.010"

Codes are stamped into the flat boss.

 

[blakebmxr3]

Thats great! Helps a lot, but when i looked earlier there was nothing there, but i wasn't sure where to look.

I'll check it out tomorrow cuz it's raining preytty hard now.

 

[blakebmxr3]

that code next to my distributor is: 902MX24

 

[xjbubba]

Personally, I wouldn't trust that the presence or absence of codes stamped on that boss to be an accurate indicator of journal or bore size. I know of one instance where there were no codes stamped ('88 YJ), and in fact one journal was 10 under. Nobody bothered to mike the rod journals, or use plastigauge to check clearances; bought standard bearings and slapped them in. Won't go into the consequences. With an engine with as many miles on it as you say, I would pull the engine an do a rebuild, unless I was planning on doing an engine swap in the near future. I had my SBC sitting on the floor next to my '88, when I busted a compression ring in my 4.0. Since I wasn't ready to do the swap, and needed to use my Jeep, I opted to do the least possible; that included a ring job and rod bearings. I ran a compression test before pulling the head; it was in spec on all but one cylinder. That cylinder was at 30 psi. Upon pulling the head and pistons, four of the six had at least one busted ring!. The "bad" cylinder had two busted rings. The moral? If your engine is bad enough to need new rod bearings, it more than likely needs every thing. You can do an overhaul while the engine is still in the truck, but the quality of the rebuild will probably suffer. I'd suggest you pull it and do it right the first time.

 

[5-90]

that code next to my distributor is: 902MX24

Should all be standard, then.

Mike a main and all the rods to be sure. They sometimes forget to stamp the code at the factory, so be a little sceptical when working with stuff like that.

The "902MX24" is just the engine build data - per FSM, that's "4.0L/241.5cid w/MPFI, build 24FEB1990" You must have a "late" 1989 rig...

 

[blakebmxr3]

yeah I'll double check everything, and do a compression test before the rebuild.

I just found an engine (used) from a phoenix az recycler for $500
so might do that, but the thing is i have enough $$$ for the bottom half rebuild but not the engine yet. should i continue the rebuild if the compression and crank is good? Or do a used engine???

i heard a lot of good things from doing the bearings, but then I've also heard some risky things(like from xjbubba) that could be even worse for my beautiful engine!?

Is it seriously that complicated to do the bearings and restore an engine if i just get the same size bearings that is stamped on the back of them?

I'm going to be doing this with an awesome mechanic and he says it souldn't be that big of a deal.

More advice plz

 

[5-90]

A bearing service isn't that difficult, and not that risky - but it's also a very good opportunity to inspect everything else. If you're going to pull the cylinder head (not exactly necessary, but definitely advisable!) then you're going to have the big ends of the connecting rods unbolted - so why not pull the pistons and check?

Broken rings like that are a relative rarity - I've not caught them without noting larger problems anyhow. I've done a few sets of bottom end bearings over the years - I still inspected everything else, but didn't note any major problems otherwise. At least if you check things out, you'll know.

 

[blakebmxr3]

ok i didnt think it was that hard(thanx to tour advice 5-90)

i wasnt going to pull the head, but i was going to put a new valve cover gasket on, and water and power steering pump, along with that nifty aluminum radiator reservoir and heater hoses ect... in the near future.

 

[Flash]

if the compression is bad, buy the used eng.......the compression should be good on that used one before buying.

If the compression is good then....... care, patience,and knowledge will make the bearing replace successful!


Flash

 

[5-90]

ok i didnt think it was that hard(thanx to tour advice 5-90)

i wasnt going to pull the head, but i was going to put a new valve cover gasket on, and water and power steering pump, along with that nifty aluminum radiator reservoir and heater hoses ect... in the near future.

It's not actually necessary, but you may have to set up the timing and rotate the crankshaft to get the pistons all connected back up - or just remove the spark plugs. You don't want a compression seal when you have to move the pistons in the bores, or it will hinder you greatly.

Me being me, I'd want to pull the head anyhow, and visually check the bores and pistons anyhow. I'd honestly have everything torn down before I bought anything other than gaskets as well (and, to clean the cylinder head mating surfaces, I have found that Scotch-Brite pads work well - either hand pads, or discs you can use with a drill motor.)

 

[blakebmxr3]

alright I'll take the advice on the used engine.

I think all I'll do is the bearings for now but if my buddy thinks its a good idea, I will pull the head. which means I"ll be on here for more advice again.

what if the compression and the crank is good? would you still recommend pulling the head? Well you told me that "you" would. but im on a budget(i never go cheap on parts) i got like $350 that I'd like to spend, but i have a lot more stored up for college. if it really needs an engine i will do that. Plus I'm trying to make this a weekend job.

 

[Flash]

It's not actually necessary, but you may have to set up the timing and rotate the crankshaft to get the pistons all connected back up - or just remove the spark plugs. You don't want a compression seal when you have to move the pistons in the bores, or it will hinder you greatly.

Me being me, I'd want to pull the head anyhow, and visually check the bores and pistons anyhow. I'd honestly have everything torn down before I bought anything other than gaskets as well (and, to clean the cylinder head mating surfaces, I have found that Scotch-Brite pads work well - either hand pads, or discs you can use with a drill motor.)

Thats the problem i have with replacing the bearing!!!!! Hmmmm how the ridge on the cylinder Hmmmmm might as well throw a set of rings in it while I'm there Hmmmm maybe i should pull the crank and have it polished Hmmmm maybe i should just put a stroker crank in it while I'm this far head, port and polish


flash.

 

[xjbubba]

My advise, is don't buy a used engine without doing a compression check on it. I would not install a used engine unless my engine was not rebuild-able;IE, busted crank, busted block--something bad that would cast doubt on the basic foundation of the engine. The used engine you install may have worse problems than the one you're removing.