1992 engine rebuild--need new connecting rod, how to separate?

[spinne1]

Hello, I am in the process of rebuilding the engine in my wife's 92 LeSabre Limited. I found that my piston six connecting rod had a problem with the hole and screwing in the bolt ruined the bolt (it broke off in the hole). I tried to drill it out and tap the hole and get a different bolt from Lowe's. This worked fine until I installed my camshaft. The bolt stuck out the top of the bolt hole and would not allow rotation because it was hitting the camshaft. I tried to remove the bolt to perhaps get a shorter one or to perhaps saw it off, but it too broke off inside the hole. I now need a new connecting rod and of course a new bolt. The bolt I can get easy enough at the junk yard. The connecting rod I plan to get at the junk yard as well because a remanufactured or new rod for this car is apparently not available for sale (I've tried several places and also partsamerica.com). The questions I have are:

Should I:

Get a replacement rod from the junkyard and attach it to my present piston six?

Get a replacement rod and piston and use it even thought the wear pattern in the piston will be different than my cylinder?

Get a new piston and attach it to a rod I get from the boneyard?



Here's the big one:

How do I separate the piston from the rod. There is a pin there, but I haven't tried to remove it yet. Can I get it out with an impact socket of just the right size and a hammer? Or will it need to be pressed out at a machine shop?

Thank you

[HotZ28]

Originally Posted by spinne1

Should I:

Get a replacement rod from the junkyard and attach it to my present piston six?

Get a replacement rod and piston and use it even thought the wear pattern in the piston will be different than my cylinder?

Get a new piston and attach it to a rod I get from the boneyard?

Here's the big one:

How do I separate the piston from the rod. There is a pin there, but I haven't tried to remove it yet. Can I get it out with an impact socket of just the right size and a hammer? Or will it need to be pressed out at a machine shop?

Thank you

First, never try to substitute a regular hardware store bolt for a rod bolt! Rod bolts are a special alloy, heat-treated and have a special head for tightening the bolt, as you found out! New rods should be available at any Buick, Olds or Pontiac dealer. If you insist on using a used rod, press off the used piston and press on your existing piston. This will allow you to use the same piston and rings that were in the cylinder. Any automotive machine shop should be able to press the wrist pins in/out for you.

The rings develop the wear pattern inside the cylinder, not the piston. The piston skirts rock back & forth at the base of the stroke and the skirt of the piston will make contact with the cylinder at that point, however, in the area where the rings do their job, the piston should not contact the cylinder wall.

Of course, you will need new rod bearings and the crank journal should be as smooth as glass. You can use your fingernail to “feel” for scratches on the crank journal when moving your nail horizontally across the journal. Compare the feel with a piece of glass. If you feel any ridges (high/low) spots, you will need a crank kit. If you install a new rod & bearing on a damaged crank journal, it will not last long!

If you have the engine out of the car, it would be better to install a new crank kit, rings and hone the block. Of course, it is imperative that proper torque procedures be used in this area, if not, failure will soon occur!

[rexter3]

I have to agree with Hotz28. do not try to cut corners,do it right once or pay twice.

[spinne1]

I went to the boneyard today and got a piston/rod out of a 92 Lesabre with only 117000 miles on it and the parts look to be in very good shape (yes I grabbed the two connecting rod bolts as well). [It was raining part of the day which was no fun. It took me about 3-4 hours to get the parts out of a complete engine--no power tools are allowed so it's all elbow grease.]

As part of this rebuild I am putting new piston rings in. I have five pistons installed already with the new rings and the sixth I had to remove to fix the connecting rod issue. After reading your post HotZ28, it seems as though there is no need to swap my original piston for the one I just got. It seems I can just use the piston from the junk yard car and put my new rings on it (after thoroughly cleaning it of course). Would you agree? I checked out my crankshaft carefully when pulling it out and also when cleaning it with acetone and it looks perfect (and I've checked the oil clearance with plastigage with the new bearings installed). No nicks or scratches whatsoever. My camshaft on the other hand had pitting. I've replaced the camshaft. I am using new main and rod bearings. The timing chain and belt were put on new by me not long ago.

And finally, I did hone the cylinders before beginning the reassembly. I got a nice crosshatch pattern on them, then I cleaned them with hot soapy water and towels and also a toilet brush. Then I wiped and wiped them until perfectly dry, then I used acetone until I got no more color on my white cloths. Then I rubbed fresh motor oil in them to prepare for the pistons.

Thank you both for your helpful responses.

[HotZ28]

I can just use the piston from the junk yard car and put my new rings on it (after thoroughly cleaning it of course). Would you agree?

Yes, I would agree if the used rod & piston are in good condition, you should be able to use them with new rings and a honed block. Sounds like you are doing things the way they should be done. Remember, follow all the torque procedures & specifications during assembly and you will be ok. Keep us informed on the progress!
Good luck!