3.2 Connecting Rod Bearings

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tanstaafl.

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My beloved ShoWagon is showing signs of age after 180,000 miles.

Last month the differential pretty much exploded on an out of town trip (in Alaska, the next town is over 300 miles away!) and while I got the best gas mileage ever (45 MPG) it really doesn't count because the last 160 miles were done on the back of a wrecker! With the planetaries and other big pieces churning around in the transmission, we were lucky to salvage the case. (automatic transmission) Damn near nothing else was saved. Big bucks repair job!

Now I notice a problem that is telling me my connecting rod bearings are wearing out. When the engine is started after sitting for six hours or more, there is a fierce, hard rattle that lasts about 1/3 to 1/2 a second as the engine fires up. If I carefully hit and release the starter so the engine cranks over a turn or two but doesn't start, then start it, there is no rattle.

This is telling me that when the engine sits, whatever oil is keeping the connecting rod bearings off the crankshaft is seeping out after six hours, and I am effectively dry-starting the engine. Obviously this situation is not going to improve by itself, and crankshaft damage cannot be too far away.

Thus, the questions.

1) Can I R&R the oil pan without removing the engine?
2) If so, can I then replace the connecting rod bearings?
3) If so, how many of the main bearings can I replace?
4) If so, what is a source for these parts and a new oil pan gasket?
5) What caveats should I be aware of? What "gotchas" do I need to avoid?

I realize fully that this is not the optimal solution to the problem. In reality I should really be replacing piston rings and valve guides, honing the cylinders, removing cylinder ridges or even reboring, etc. But the upper end seems serviceable (although one cylinder is enough lower on compression than the rest that it really should be dealt with) and the car is consuming only about half a quart of oil in three thousand miles. A full overhaul is just not in the cards at this point, especially after spending all my disposable income on the transmission!

So, given the assumption that I am just trying to keep from wrecking the crankshaft and do not want to R&R the engine, what do I do now?
 

Racer X

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The rod bearings on these motors, as it turns out, is a maintenance item, for lack of a better term.

You can R&R the oil pan with the motor in the car, but you have to drop the Y-pipe. Prepare to have to drill out some broken manifold studs.

You can do the rod bearings in car also. Be mindful not to knick the crank when pushing the pistons up.

I wouldn't bother with the main bearings, as they don't really wear at all (I've seen them at 213k miles, and they had less wear than the 30k rod bearings in the same motor).

Seeing as you're in AK, more than likely you're gonna be ordering these parts. I've had excellent experiences with RCM Automotive, personally.

As far as caveats, if you order the rod bearing kit from RCM, you also get a plastiguage. It's really just reassurance that your journal is within spec, which is almost always is unless you actually spin a bearing. The rod caps are torqued in 2 stages, I do 25ft.lb. and then 35ft.lb.

TORQUE YOUR HARMONIC DAMPENER TO CRANKSHAFT BOLT TO 120 FT.LB.!!!!!! Anything less, and your car will develop crank cancer. Ask me how I know. :frown:

I'm sure others will chime in with more advice, but I think I nailed most of the basics. Good luck!
 

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