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Changing lower bearings on 4.3 Blazer 4x4


Negoshe8n's Avatar
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05-14-03, 11:41 AM   #1  
Negoshe8n
Changing lower bearings on 4.3 Blazer 4x4

I have a not so bad but bad enough rod or main knock. I want to change out the bearings before it ruins the rods or mains. No blow-by and the motor has great pick-up. SO Can I just pull the motor and the then the pan and be able to change all the lower bearings. Mains and rod bearings. What is the best way to do the change? All at the same time? Rods first? Upper bearings and then lower part? I have to remove the flywheel also I guess? Pretty straight forward....right? Where should I remove the exhaust at. Manifolds or Y-pipe? Thanks for any help.

 
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05-14-03, 12:30 PM   #2  
Joe_F
If the bottom end is wasted the top end usually isn't far behind.

Best bet is to buy a GM Goodwrench engine and swap over what doesn't come with the new engine. Barring that, ATK or Jasper have decent engines with a warranty.

For the R&R of the engine, you should consult a good service manual such as a GM one or an Alldata.com subscription.

 
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05-14-03, 01:15 PM   #3  
If you have a knock replacing just the bearings without measuring the clearances is a waste of time. The shaft has to checked for being round, taper,finish, oil clearances etc. The rods need to measured and checked for being straight.

Not DIY job

Joe's right about entire engine replacement

Larry

 
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05-14-03, 01:22 PM   #4  
redneck
LOL!, yep once the bearings are gone your crank is not far behind--it maybe able to be saved by machining. Price pulling the motor and rebuilding vs a crate motor--I think the crate is the way to go--and alot less down time--with a warrenty! Ain't no machine shop gonna give you a warrenty!

 
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05-15-03, 06:49 PM   #5  
Negoshe8n
motor

I have been looking into just picking up a TPI 350. Not going to waste my time. What do you guys think about the 4.3 V8 motors?

 
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05-15-03, 09:52 PM   #6  
knuckles
You might want to pull the pan and check the oil pump screen.

These engines were well known for plugging the screen with sludge, especially if they've not had regular maintenance.

You can clean or replace (recommended) the oil pump screen and replace both the rod & main bearings for less than $100. IMHO it's time and money well spent.

You have about a 50/50 chance the screen will be clogged & the original bearings will have minimal wear. If the bearings are worn to the copper, you can pretty much assume the crank is worn and you need a new engine (or a crankshaft & bearings at a minimum).

Save yourself some time and pull the #1 main bearing and the #1 rod bearing caps first. These bearings are farthest from the oil pump and most likely to see the worst wear.

A new or reman engine is very expensive and will probably take you a weekend or 2 to install.

Replacing the oil pump, oil pump screen, connecting rod bearings & main bearings will probably take you the better part of a day.

 
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05-16-03, 05:55 AM   #7  
Joe_F
I'd agree, but I'd hazard a guess you've got wasted valve stem seals on the upper end, so it will be futile doing the bottom and then finding out it's a puffer anyhow .

You'd be money ahead with a new engine. These S/T Blazers keep their value, even in poor shape. I've seen ones with rust and dents going for $3000 bucks or more in the local papers!

 
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05-17-03, 01:02 AM   #8  
Just for info- I've installed 10-12 Jasper engines in the last year or so. We also purchased what they (Jasper) calls an installation kit.. SOO sweet.. It came with EVERYTHING..Filters, clamps, hoses, belts, plugs, ect.. All the stuff that "nickel and dimes" a person to death..So far, no "come backs" on these engines for any reason..No leaks, no drips, just oil changes.. VERY happy customers..VERY happy mechanic!

 
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05-17-03, 07:05 AM   #9  
Joe_F
What brand of parts are in this kit?

 
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05-17-03, 08:16 AM   #10  
The last one I did was an S-10 pick up, the filters were AC-Delco, the plugs AC-Delco, belts and hoses were Gates.. Basically the same parts GM would have recommended for an S-10.. If memory serves correct, the kit was an extra $290 or so.. But we totaled up the kit versus having to buy the stuff part by part, and it came out ahead having it all right there and OE stuff.

 
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