Hey guys I am new to the forum and have a few questions

I bought a 1996 gmc jimmy sle from a good family friend the vehicle was well taken care of. I bought it so I could store my car in winter and knew that the jimmy has been a very reliable vehicle to the family I bought it from. It has 107,xxx miles on it. I drove it up north and back which is roughly 700 miles and drove it all week so total i put on 1,000 miles on it. I was at a stop light and noticed a little motor noise. After investigation it spun a rod bearing as I found evidence in the oil.

Now Im debating whether to rebuild the current motor with a new crank assembly or swap a used one into it. The motor is out already.

Will a 2000 blazer motor work as a direct drop in? or do I have to change anything?

Or would rebuilding be a better choice?

Any and all input would be nice since I am not familiar with this motor yet.

Thanks Brandon

 

The only thing that may be different on the 2000 motor is the ECT (engine coolant temp) sensor. In the '96-'98 motors, I believe this was located in the lower intake manifold just below the thermostat. The coolant temperature sending unit for the gauge cluster was located in the driver side cylinder head between cylinders 3 & 5. In the 99+ motors, the engine temperature sending unit & ECT sensor were combined to one sensor located in the driver side cylinder head.

You could drill/tap the LIM for the ECT sensor from your '96 motor or swap the lower intake manifold. Swapping the manifold would be a good chance to upgrade the LIM gaskets to the metal framed Felpro gaskets to stem off another failure point.

 

Swapping the intake manifold seems easy enough for me since the old one is already off. Im going to look at this new motor tonight to see how it runs. Ill look and see if they are in the same spot or not.

Thanks for the input and help!

 

Cool. If only all problems were as easy to answer.

Word of advice: If the truck ran good otherwise before it barfed the bearing, reuse everything connected to the PCM. Should be pretty much cake since you're using the 96 manifold.
But keep all the stuff that swaps.
To find out easily look up the application for the later year part and see if it also fits the 96.
Easy to do on rockauto by clicking the part number.

Opinon on the fail: that bearing likely spun because of oil coolant contamination eroding the bearing surface and creating ridges which overheated by friction and carbonized the oil at the high spots. Later the carbon breaks loose and wedges. This probably wouldnt happen if the owner had started using Mobil 1 or any other high ash temp synthetic.

 

I didnt seen any signs of coolant in the oil. I think it was a piece of carbon that broke loose and clogged something? I know they drove it like my grandma drives her car. He also said to use mobil 1 because thats all he put in it.

Another thing I thought of wouldnt oil pressure change if theres an issue (like a spun bearing) or if something is wedged some place blocking oil.

 

Huh.. go figger! Is there any sign of carbon on the spun bearing? Should be none of that build up if they used mobil 1. I did a mild teardown on my turbo 4 cylider at 190 Kmile and no sign of any deposit anywhere. Even in the oil galley of the turbo itself.

If you have the curiosity to track down the fail cause, it would be interesting to see what the situation was .
Oil Filter brand?

 

I havent taken the pan off yet that was my plan for tonight. I plan on tearing it down for experience. He used fram tough guard or something its the orange one.

 

Here and update on the issue it spun the rod bearing closest to the oil pump nothing seems to be clogged and the bottom end looks very clean no sludge or coolant. Im getting a new crank and matching bearings to hopefully be back on the road next weekend

 

I came across another motor i might be purchasing for my jimmy its the same cost in parts to fix my motor. but its a 2004 is it the same as a 2000 motor?

 

The 2004 and 2000 motors would be an identical swap. I think the 4.3s from 2003 up have roller rockers- I'm guessing this would be an improvement. You will have to drill and tap a larger hole in the block for the knock sensor from the 96 motor. This is the sensor near the distributor and oil pressure sensor at the back of the block.