Balance shaft questions

[seiplej]

So tore into this some more. The upper shafts bearings are wasted. Should the entire motor be rebuilt at this point? I didnt really want to rebuild the entire motor it only has 105k on it.

[Tom]

Yikes, those are toast! If you're not burning oil, and if your oil pressure is good, I'd change those out (and the ones in the snout), change the oil, and run it.

[seiplej]

Yikes, those are toast! If you're not burning oil, and if your oil pressure is good, I'd change those out (and the ones in the snout), change the oil, and run it.

Oil pressure is good. Burning I dont know I havent had the car that long before I started the belts. The snout shows some wear but not bad.

[944m3]

I’m curious to hear other folks thoughts. But here are my 2 cents.

That looks like a lot of oil varnish in the balance shaft housing. And it’s an odd wear pattern on the bearing. I wonder if the previous owner did a good job changing the oil out at proper intervals and used the correct oil weight. Also have to wonder what the rod bearings look like if the balance shaft bearing is that bad. Or maybe one of the oil feeds for the balance shaft is clogged.

At a minimum, I would send out a sample of your oil to check for elevated metals that could point to rod bearing wear.

Btw in my opinion, it’s not 100k that’s an issue it’s that it’s 100k plus 30 years in age. A reseal/rebuild at this point is not unreasonable.

[seiplej]

Ive decided to send out an oil sample if it comes back ok Im gonna send it. I think what happened to that bearing is dry starts from these cars sitting alot. I noticed as the car sat it got harder and harder to turn the balance shafts by hand most likely due to the oil draining out.

[944m3]

As I always say, I’m always learning new things about our cars. But I don’t think what you are experiencing is normal. I’ve purchased an engine and 2 cars that sat for years and that never happened. All things being equal I don’t see how that could have happened.

I wonder if the previous owner tried to change out that bearing or removed the housing for some reason but did not reinstall correctly, maybe over torqued. Or as I mentioned before, maybe a clogged oil port. I would carefully inspect everything. Hopefully it’s nothing but for sure that is not normal even if the engine sat for a while. Though happy to be corrected.

[seiplej]

A new update to this. I removed the lower balance shaft to compare and what do you know. That bearing is worn the same exact way as the upper one. Id be willing to bet a lot of theses cars are worn this way after seeing them both like this.

[walfreyydo]

Replace the bearings and run it.

If you are worried about metal contamination you can drop the oil pan and pull the rod bearings and check those. If there were any metal in the oil youd see the damage on the rod bearings/journals. If all looks good there you Id say you are good to go.

[Tom]

Makes me wonder if the shafts were replaced without line-boring the covers and case? I have never seen that wear pattern, and have taken apart at least half a dozen well-used motors. Maybe I've just been lucky, I dunno. If you haven't checked, be aware there is small full-circle bearing in the front nose piece too (on both balance shafts). They usually last a very long time, but given the condition of the rear bearings, I'd take a close look at the front ones too.