How does this crank look?

[suprarx7nut]

So we got the rod caps off the other day on the 88 auto and this is what the crank and bearings looked like. The car never knocked or had low oil pressure. It had a blown head gasket so we wanted to check bearings to make sure they were healthy.

Plastigage said bearings were well within spec. Std spec is up to .05mm, we were at .035-.05 and all bearings looked great, IMO. None of the crank pins showed ANY scoring that I could tell. They all looked pristine to me.

What do you guys think?

This one has some smudging, but that's all from us wiping away the plastigage.

This was the worst bearing. It had some minor pitting and got a few tiny scratches from wiping away the plastigage.

 

[toyotanos]

Officially, I'd have it checked by a good machine shop, but the journals looks good to me. I'd just have them polished and install a new set of bearings! You will also want to clean up the rusty front snout section. That will make pulley install/removal very difficult in the future.

 

[87nasupra]

+ 2 i would still have a shop check it and atleast polish it.Looks good though.

 

[CyFi6]

Bearings look to be worn pretty evenly, but the one you really want to look at is the upper half, that half takes more of the load.

 

[ohiosupramst]

Make sure the crank is straight also. Put mains on v-blocks spin crank and check each journal for runout with dial indicator. Crank does look to be in great condition though.

 

[Poodles]

Crank looks fine except for the keyway for the front pulley...

 

[IJ.]

Make sure the crank is straight also. Put mains on v-blocks spin crank and check each journal for runout with dial indicator. Crank does look to be in great condition though.

If it isn't straight there will be evidence on the edges of the mains..

 

[ohiosupramst]

Oh didn't know it could be done that way thats just the way I learned.

 

[suprarx7nut]

Cool, thanks for the responses everyone. Reaffirmed what I thought for the most part.

Need to debate whether I should send the crank in tomorrow with the head or wait to do it later when it's not 20 F in the garage.

 

[Poodles]

Gonna have the keyway fixed while it's out?

 

[Another MkIII]

Personally, I wouldn't lose any sleep over using that crank as is. However, if you really want to do things 100% right, sending it to the machine shop and getting new bearings is the only way to go.

I forgot about the keyway. You will want to get that fixed.
-AM3

 

[Mk3runner]

I'm with Poodles on this one.. The crank snout will be a huge headache down the road if its worn.

 

[CyFi6]

If the keyway is actually deformed and its not just the picture, its probably not worth it to try and save it. Had one crank like that, the snout was .015" smaller than it should be, keyway was bad, and the threads for the pulley bolt were stretched out/widened. Obviously, even if the keyway is fixed, there are still other problems that come with it

 

[suprarx7nut]

Gonna have the keyway fixed while it's out?

I'll check it again, but I think that pic might be deceiving.

Personally, I wouldn't lose any sleep over using that crank as is. However, if you really want to do things 100% right, sending it to the machine shop and getting new bearings is the only way to go.

I forgot about the keyway. You will want to get that fixed.
-AM3

I'm with Poodles on this one.. The crank snout will be a huge headache down the road if its worn.

If the keyway is actually deformed and its not just the picture, its probably not worth it to try and save it. Had one crank like that, the snout was .015" smaller than it should be, keyway was bad, and the threads for the pulley bolt were stretched out/widened. Obviously, even if the keyway is fixed, there are still other problems that come with it

I think it might just be the pic angle and the fact that the snout was quite dingy at that point.

I assume you guys are referring to the front keyway for the harmonic balancer and NOT the timing gear one?

The woodruff for the balancer was a little funny looking when we pulled it out. It had a dent almost in each side going along the top side, parallel to what would be the slot of the crank. :dunno:

 

[CyFi6]

Take a close up of the key and keyway of the front slot in the snout

 

[suprarx7nut]

So I checked it today and it's definitely worn a little. Can a shop easily weld material on and cut away a new keyway? It's barely worn/rounded on one side only, but it's noticable.

This would explain the worn key as well. I thought the key was supposed to give well before the crank material does? That's what we were always told in my engineering classes. The key should always be the weakest point so you dont damage larger parts.

Oh, and we pulled whole crank out and every bearings looks very even. No uneven wear that I could tell and the upper bearings weren't any worse looking than the lowers. Looks like it's pretty straight.

 

[CyFi6]

It depends how bad it is, if just the keyway is slightly bad and the actual size of the snout (measured with a mic) is the same on the end as it is where the crank pulley doesnt ride, you might be able to get away with it being welded. They supposedly put a carbon key in there, weld it up and then pull the dummy key out.