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4.3l Express 1500: replace rod bearing without dropping engine?


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January 10th, 2012, 3:35 PM   #1  
4.3l Express 1500: replace rod bearing without dropping engine?

I've got a bad rod bearing in my 4.3l 2003 Express 1500.

Mechanic says replacing the bearing is a PITA because you have to remove the whole front of the engine or some such thing.

But when I look under van, it looks like the oil pan will just drop right out. Maybe have to remove the frame cross member, but that's all.

So what I need to know is: Can I replace a rod bearing by just dropping the oil pan?

Also, if there is a good service manual I should get, please tell me which one. I can't find a decent manual. The haynes is fairly useless.

Thanks,
Paul

 
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January 11th, 2012, 6:40 PM   #2  
Wow, 105 views and no replies.

Anyway, it looks doable. I've taken off the starter, cross member and tube mounts, and will loosen the oil pan and see what happens tomorrow.

 
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January 12th, 2012, 7:33 PM   #3  
Ok, I'll make my own reply...

Yes, you can take the oil pan off a 2003 4.3l Chevrolet Express 1500 and get to the rod bearings without dropping the engine. Here's how you do it.

1. Don't listen to what the haynes manual says, it is useless and misleading.

2. Take off the front frame cross member that crosses under the oil pan and detach the wires running across it (not absolutely necessary, but worth it)

3. Remove the starter (2 bolts) and starter cover plate 2 bolts.

4. Remove the tranny cooler mounting bracket on drivers side (1 bolt).

5. Remove the oil pan bolts.

6. VERY IMPORTANT: There are 2 hidden bolts at the back of the oil pan. They are accessible only when you remove the 2 rubber plugs hanging at the back of the oil pan. Just pull the plugs down and they come out. Then you can put an extension in and remove the 2 nuts inside there.

7. Remove the 2 horizontal bolts from the bottom of the tranny to the back of the oil pan

8. That's it. Oil pan should come off with a little persuasion.

Took me a long time to find those 2 hidden bolts. HAynes says you have to remove the engine cover and jack up the engine, and remove the torque converter cover. What a load of BS. They obviously never did it.

In case you're also looking for the rod bearing clearance it is 0.01 to 0.025". Also not in the haynes manual. Why did they even write it?

My rod bearings are reading 0.03, so I'm going to put a 0.01 oversize bearing set in. The crank journal is a bit scarred on 2 of the rods, but I'm just doing this to keep her going for a bit. Had way worse scarring on my toyota and put oversize in and it's still going after about 40K.


Last edited by pdrayton; January 12th, 2012 at 7:35 PM.
 
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February 26th, 2012, 9:55 AM   #4  
How did this pan out for you? (Pun intended! )

Going outside now to drop the pan on my 3500 Express 5.7L.

 
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February 26th, 2012, 10:04 AM   #5  
Van is still running OK. Oil pressure is at the bottom end of acceptable. I ended up putting regular size bearings in -the oversize made the crank so tight I couldn't turn it.

 
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February 26th, 2012, 1:27 PM   #6  
That's great - glad to hear it! Thanks for the reply - your thread was the one that led me to give it a whirl... with the rod knocking I really didn't have much to lose compared to the $1800 used / $3500 rebuilt installed quotes.


Not to be a total idiot... but it's been a while. How do you slide out the old rod bearings? I "think" all that's holding it in place is the oil surface-to-surface tension (bearing to con rod)... can I tap it out with a flat punch to start it rolling around the inside of the rod? (By tapping on the end edge of the bearing - like installing a rear main seal.) First rod journal looks great w/ no grooves but bearing has 'dry start' look to bearings. (Just got van out of shop for intake gasket & oil change... No knocking before they 'fixed' it.)

Edit: I'll add this - there were a LOT of metallic particles in the oil. Based on the first bearing (closest to oil pump)and comparing the condition to the crappy Hayne's manual pictures, I'm thinking the guys who repaired my leaking intake gasket didn't put oil back in before they fired it back up. They also told me they'd put in some Lucas Oil Treatment to "quiet the lifter down". (Asked them to take care of lifter while intake was off for gasket repair... their idea of 'fixing' it was to mask the noise.)



For anyone reading this thread you can easily remove the pan on the 5.7L 3500 Express van as well for this job. I didn't have to remove starter, exhaust or transmission/flexplate dust cover (although I did remove dust cover for more room).


Last edited by lunghd; February 26th, 2012 at 3:17 PM.
 
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February 26th, 2012, 1:42 PM   #7  
Yes, bearing should come off easily by hand when you have the connecting rod nuts and bottom piece off.

Sometimes they do 'suction' on with oil pressure, but pushing the rod and piston up to give some play around the bearings and rotating them around the journal is often enough to loosen them up.

 
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February 27th, 2012, 1:36 PM   #8  
Thanks - got all but front most bearing swapped out. Front most bearing is worn down to point I'll need an undersize bearing.

 
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February 27th, 2012, 5:04 PM   #9  
You mean oversize bearing?

I would suggest you get a set of regular size bearings and put them on and see how the crank turns by hand. Just because your bearing is worn down, doesn't mean the crank journal is worn down. Check the journal for scarring.

My crank journal was worn on a toyota 22RE and I sanded it with super fine sandpaper. Yes, I know, terrible idea. But it's still going after 40K...

 
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February 27th, 2012, 6:20 PM   #10  
Yup - under/over - depends on which parts counter I go to... one has them categorized as oversize & then lists them in their descriptions as undersize. Oversize as in larger numerical size of bearing... to make the hole smaller; or undersize as in smaller OD of a turned crank journal.

Have replaced all but the front most bearing - TON's o slop in that one. May have been replaced in the past at some point as it doesn't have the same tab to keep it in place as the ones marked GM.

Crank turns fine - no grooves / scarring,. Front most bearing is definitely not a standard size and journal is definitely smaller too. I have enough play with a new standard bearing that I can physically move the rod on the journal so if the crank can be saved it's going to need an oversize bearing. Enough 'slack' that I couldn't get a good plastigage reading w/ the standard new bearing. I used the sandpaper trick as well but crank really doesn't feel/look that bad. I'll mike the journal & check to make sure it's not egged tomorrow & check the mains.

Looks like a 'dry start' or might have had some starvation to front journal. New oil pump ordered. Appreciate the feedback.


Last edited by lunghd; February 27th, 2012 at 6:22 PM.
 
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