Publisher's Note: Welcome to our 28th edition of Tech Tips Tuesday on "Precision Engine Care: Mastering Bearing Clearance Measurement".  We'll be re-publishing an edition of AMSOIL Tech Tips for you every Tuesday.  Click on the Blog Category "AMSOIL" to see everything published to-date.

Precision Engine Care: Mastering Bearing Clearance Measurement

John Gardner: Engine manufacturers have been making the part fitment and tolerances tighter and tighter, and with that, well, you need to know about plastigauge and bearing clearances.

That's what this AMSOIL Tech tip is all about. For bearing clearance measurement, well, you can use a strip here called plastigauge. You can see it right here on the graphic. It's actually a plastic piece that goes right across the actual bearing or the journal. And what you do is you put it on there and then you smoosh it. You put it to factory specifications and torque it, and read it.

Now, you can see our engine right here. We actually have a dual overhead cam engine right here, and you have cam bearings underneath. You have crank bearings. They're all over the place. So what you would do is basically take one of these caps off, get you a little strip of that plastic, put it on there dry, don't spin it, torque it to specifications, and then read that bearing clearance.

Very, very important that you have the proper bearing clearance. Why is that? Well, you can see right here, I got a few bearings. This one, well, it's worn here in the middle. That's going to be a problem. This one right here, totally have a hole in it. It's been wearing metal to metal, not a good thing. This one, well, it's totally shot. This was actually a thrust bearing. On both sides, you have no protection with that whatsoever. And this is what a good bearing looks like.

Now, it's important to use the right oil because you want to have a film between those. Len from AMSOIL, tell us a little bit about that.

Len Groom: It's interesting that you look at those bearings because in the plastigauge thing, you're actually instead of plastigauge, when your engine is running, there's oil in that small space, which is why we're measuring it. Oil is that cushion that's going to ride between the bearing and the crank or the rod or the camshaft, and it has to hold up to combustion pressure. It has to hold up to a whole bunch of different forces, and that requires the oil to have film strength.

And one of the things that you get where you get really good film strength is a high-quality synthetic. And AMSOIL Signature Series products have an extremely high-quality base oil that we use that automatically gives you a really good film strength. It's going to hold up, and it'll keep those bearings from touching together because anytime metal touches, you get wear. So, they're going to help with that.

John Gardner: Yeah, you see the results in the bearings. Now, the proof's in the pudding. Len, take a look at this right here. You can see the leading competitor. Man, those bearings are shot. AMSOIL? They look like new.