!!!rod help!!!!

[Drewet88]

Well to make a long story short.
My car threw a rod and I was going to attempt to rebuild the engine but someone suggested I just pull a donor engine so I did. I pulled another engine and dropped it in and it ran roughly but ran. Now that was just a temporary fix because I want to put my original engine back in after I fix the thrown rod. So my question is...
Can I pull the rods from the donor engine if they are good and put them into my original engine?
Can I just take my old rod out of the broken engine, go to the junk yard and match it?
Or should I just poney up the money and buy a rod and piston rebuild kit?

[MagicRat]

Engines that have actually thrown a rod are simply junk and should not be rebuilt.

The thrown rod tends to flail around during the last few rotations of the crankshaft and hammer away on other crank case components, including the block, oil pan, adjacent rods, pistons etc. Inevitably such components are chipped, cracked and weakened.Also often the cranks are twisted or broken.

Even if they look okay, the damage/stress these parts have suffered opens the door for future failures.

[Drewet88]

Let me correct myself. I didn't mean thrown a rod I meant a rod was cracked, I didn't know there was a difference.
The long story was the previous owner had cracked a rod when he did an oil change, started the engine with the oil plug and filter off because he thought that whould get every drop of oil out for a full oil change and the rod cracked right on start up.
He didn't move it when it happened he just left it in his driveway where it sat for a lil less than a year when I bought it and had it towed to my house. I didn't drive the car or anything, I just pulled the engine out and dropped in a donor engine.
But by looking at it the rod is cracked, but everything else looks good.

[GTP Dad]

You can use the rod from the engine you put in the car. Just make sure to use the rod cap from the donor rod as well. If you are going to go to that length why don't you pull the entire engine apart and put new rings and bearings in it as well. Not to mention new head gaskets and lower intake manifold gaskets. You will have everything off the engine anyway to replace the rod so this would be an ideal time to do this and since you have it out of the car you won't have any space considerations.

I also caution you that if he cracked one rod he probably damaged the crank and other rods not to mention what he may have done to the cylinder walls and the pistons. Take advantage of the opportunity and you will have a good engine ready to go back into the car.

[Drewet88]

Thank You GTP DAD for your help.
Should I just buy a rod and piston kit, the one I was looking at at Kragens said it has all of the items needed to basically replace my Rods and Pistons back to a new engine.
Or would an entire rebuild kit be better?

[tri-power]

If you're going to do a rebuild on an engine, it's always smartest to do it right, meaning do everything. The engine is only as strong as it's weakest part. Since you're going to have to tear the engine down, it's better to spend a few extra dollars now that have to spend a lot more later because you didn't do it right the first time.

[GTP Dad]

I have to agree with Tri-power. If you are going to rebuild the engine then purchase everything you need to do it right. So I recommend the entire rebuild kit. Make sure that you check the cylinders for taper and wear before you purchase the kit because if the cylinders are out of round you will want to have it bored oversize and then you will need larger pistons and rings. You will also want a new oil pump! Good Luck!!

[tri-power]

Not to mention if there's a crack inside the cylinger wall, the only way to save it would be to have the cylinders sleeved. Before you do anything else to it, have the block magnafluxed to make sure it's still worth using. Then you can have it machined and then you can rebuild it. The more work you put into it now, the less you will in the future.

[Drewet88]

Thanks everyone.
Now I just have to find a good machine shop around here. To get everything done to it so I can have a nice smooth ride. After I get all of this done I just have to work on putting in a nicer suspension so my ride can be smooth as possible.
Does anyone know about how much it'll cost to get the block magnafluxed and machined?

[GTP Dad]

Like everything else it depends on the amount of work that is needed. Extensive machining can cost lots of money but just to magniflux and rebore if necessary will probably cost in the $400 range. Magnifluxing will cost about $150 depending on the shop. Unless you really want to do the work yourself you may want to search for a reman short or long block it may actually be cheaper and a whole lot less time consuming. And it will come with a warranty!

(By the way what size and year is this engine?)

[Drewet88]

What is a reman short?
The 87 Oldsmobile ninety eight.
The engine is a 3800 6 cylinder.

[GTP Dad]

Sorry for the abreviation. A remanufactured short block. That is the block with the cam, crank, pistons, rods, timing gears and chain.

[Drewet88]

O. I could've guessed that I was just half sleep. Do machine shops sell them or would I just have to search around?

[tri-power]

Or the other option of getting the long block. Where you only ned to add the oil pan, intake, valve covers, and water pump, with gaskets. Everything else comes off your old motor.

[GTP Dad]

Most machine shops do not sell them. Search the net remanufactured engines. You can find one on e-bay from time to time. You can also search rock-auto.com or gmpartsdirect.com for a short or long block.