Author Topic: Replacing Rod Bearings in Car  (Read 4533 times)

September 12, 2017, 05:42:56 pm

thomas m

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Replacing Rod Bearings in Car
« on: September 12, 2017, 05:42:56 pm »
When replacing the connecting rod big bearings with the engine in the car, is it ok to re-use the nuts??
I'm planning on pulling the caps, inserting new bearings and re-using the nuts if that's not a problem.

How about the bolts?? Do they get replaced???? Are they easily removed??
I don't know how I would get them out if they are pressed in.
Bentley says 22 ft-lb plus 1/4 turn. So, I guess they are one-time-use stretch bolds????? Yes...No??? Bentley is not clear on this.

I'm not building a performance engine. Just putting another finger in the dike to address marginal oil pressure.

« Last Edit: September 12, 2017, 09:56:44 pm by thomas m »


Thomas, Original owner since new:
1991 MK2 Jetta Non-turbo 1.6 diesel, Engine Code ME, 5 speed 020 AWY 04120 transmission, Hydraulic Lifters,
320,000 miles
Location: Vancouver, WA
LOOKING FOR REBUILD OPTIONS IN PORTLAND, OR OR ON THE WEST COAST

Reply #1September 12, 2017, 11:22:39 pm

ORCoaster

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Re: Replacing Rod Bearings in Car
« Reply #1 on: September 12, 2017, 11:22:39 pm »
Are you replacing the pieces next to the crank between the piston rods or the main crank?  I think the term rod big bearings is throwing me here. 

All the nuts and bolts I am looking at in the picture can be used again and again.  Just torque them right.  The bolts that have the nuts on them on the rod caps are set and don't move in circles, the nuts do but that is all.  So you can undo the end cap, rotate the engine enough to push the piston up and when you rotate the engine some more the crank comes away from the piston and you can get up in there to bring the piston back down and slip the bearing out.  Pay attention to how they came out as they are a set and have a notch or something that aligns them together.

Now if you are talking the bolts that hold the crank up and in place I have not done anything with those in the car. I removed them once to get a crank out of a bad block but that was it. 

Reply #2September 13, 2017, 10:42:17 am

thomas m

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Re: Replacing Rod Bearings in Car
« Reply #2 on: September 13, 2017, 10:42:17 am »
For now I am going to replace the rod bearings, not the main bearings. That's for the next time.

Now, I'm just addressing the rod bearings under the rod caps. The ones with the nuts.
So I will  replace the bearings, reuse the nuts and torque to Bentley specs.

The extra 1/4 turn seems to imply stretch bolts like the head bolts. But I guess not.

I'll address main bearing replacement in a separate post.
Thomas, Original owner since new:
1991 MK2 Jetta Non-turbo 1.6 diesel, Engine Code ME, 5 speed 020 AWY 04120 transmission, Hydraulic Lifters,
320,000 miles
Location: Vancouver, WA
LOOKING FOR REBUILD OPTIONS IN PORTLAND, OR OR ON THE WEST COAST

Reply #3September 30, 2017, 08:02:53 pm

libbydiesel

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Re: Replacing Rod Bearings in Car
« Reply #3 on: September 30, 2017, 08:02:53 pm »
When faced with that exact same quandary, I  actually took a set of mk2 rod bolts and torqued them to spec then loosened them several times, measuring their length with micrometer each time.  They permanently deformed measurably with each time they were torqued.  It's hard to say definitively whether or not the mk2 rod bolts should be replaced each time.  I'm inclined to say they should.