Is my 96 Blazer motor shot?

The obvious question...............have you checked the oil and is it full?

If the oil is full, with zero oil pressure and noises from the motor, sounds like you blew something out in the bottom end.

Doc

>

Oh yeah, Doc's probably right. I would say you have a rod bearing spun. I've seen motors idle quietly and smooth but as soon as you raise the RPM's, knock knock knock. Your probably in for a rebuild as it's not much use to put a crank and any rods in the engine with out doing the rest of it. You've already got it tore down. That is if the lower end is the problem.

nospam

Sounds like a spun rod bearing:

But without being at the scene of the crime, it's hard to give a proper answer. But I'm sure both Doc and my self are correct.

Have you changed the oil and filter at normal intervals, like 2500 or 3000 miles? That has a lot to do with engine longevity, and low oil levels around turns cause the oil pump to cavitate (Draw air) and let the oil pressure drop and run the bearings dry for a while.

Causing a lack of oil film between the bearings and crankshaft, and excessive wear begins.

I hope this helps?

Refinish King

Don't push rods have bushings, or am I thinking of a different kind of rod? Or am I just used to hearing a main bearing (for the crank) being spun? I didn't think a push rod had much-if any- rotational force on it.

~KJ~

I think your referring to the connecting rod. Some have a bushing in the small end (not many do, mostly motor cycles) mostly they are heated and the piston pin is pushed into the rod while it's hot. Then when it cools it will hold the pin and piston in place. The push rods sit on your lifers and press up into the rocker arm to open the valves. They some times have guide plates to keep them where they belong.

nospam

I see, he never said "connecting" so I inserted "push" for it to make sense to me. Now what the two of you are saying makes sense, sorry my deduction skills aren't up to par.

~KJ~

No problemo, mine aren't always at their height of use either.

nospam

Hi!

What is this, or what does it mean, exactly?

William The Guesser -- Trying To Learn More (a rare moment!)

The bearings in an automotive engine are of a type called a babbitt bearing, which is a two part bearing. In other words it's realy two halves that make a whole bearing. Basically they are more like a precision bushing than a bearing as we think of them. When we say a bearing spun, that's usually is from excessive clearances between the crank and the bearing. And the bearing actually moves from it's position in the connecting rod. As a result greater clearances are created from the bearing breaking down. That's when you get the knocking sound.

What causes this is the crank and the bearing wear into each other from lack of lubrication, dirt in the oil, old oil etc.

nospam

WTF?????? "Babbitt bearings" was not a type. It was what the bearings were made out of. Babbitt Metal!

Babbitt was a low temperature melting metal compound made of tin, lead, copper, (maybe some aluminum) and cadmium. (The fumes from the melted Babbitt was a low level poison). You could melt Babbitt in a pot on a wood stove or a hot plate. When you rebuilt old engines, you melted the old Babbitt out of the bearing shells/block and poured in molten Babbitt to make new bearings. You could make one piece bearings or split bearings.

You used a bearing scraper to get cut them down and to get your clearance. In case people have seen a bearing scrapper and didn't know what it was it looked like a triangle file, without the teeth. The flats were smooth. You didn't use the flats like with a file, you used the edges which were knife sharp. You held the scraper across the bearing and pulled it sideways to scrape thin sections off the bearing.

Large Babbitt bearings were cast in one piece for ships and locomotive engines. These bearings had a large shell that was like a donut or ring, and the inside edges had lips. You would put a round "false shaft" in it that was the correct size, and then pour the molten Babbitt in through a hold in the side of the ring. The Babbitt would fill in the empty space and when it was cold you would remove the "false shaft", and you had a bearing inside the ring. The ring would be slipped on the ships prop shaft.

Jim, The term Babbitt bearing is for the type of bearing it is not the application. There are also more than one way to install them, such as in automotive applications they merely snap in place and are aligned by a protruding notch that matches a tab in the bearing retainer, in this case the connecting rod large end.

See this web page:

This is from their web site: What we Offer: We can provide you babbitt bearing for Main, Connecting Rod, and Camshaft. Standard design steel-backed, babbitt-lined, split Sleeve bearings are offered from 1 to 15-inch shaft diameter. Thrust surfaces are available on either or both ends, in flat plate, tapered land, equalizing or non-equalizing tilting shoe styles. Special Sleeve bearing can be produced in a wide range of materials, from 5/8 to 60-inch shaft diameter.These bearings are engineered to meet the toughest service requirements in corrosive and abrasive marine or industrial applications. And the fluted rubber bearing surface will outlast hard surface bearings by more than 10 times. We specialize in the manufacture and machining of bearings for antique automotive, truck, tractor, car and auto rickshaw engines.

nospam

They are now generally refered to as "plain bearings"

I call 'em bearings. However when the copper is gone, I've been told that is the "babbit material".

Either way, sounds like the OP needs a new 572CUI for under (and probably through) the hood....

~KJ~

Yeah Yeah that's the ticket.

nospam

What is, the Babbitt or the BBC?

~KJ~

BBC of course.

nospam

spam, spam, spam, spam, spam ,spam, eggs and spam

Do you like green eggs with your spam? I like green eggs with spam, Doc I am.

Per my signature I like nospam, but that's who I am.

nospam