.060" Crank endplay... Ouch!!

[88GThatchback]

I had a thread about a clutch noise a couple days ago and figured out the problem. I have a 347 with 500 miles and when I built it, the crank endplay was .007" IIRC. Now it is .060"!!!! What would have caused this? The engine seemed to run great. The only thing I can think of is the thrust bearing didnt hold up and broke somehow? I did find some nice slivers of metal on my drain plugs about .75" long. I figured I could of been somethin from the breakin but I guess not. Im going to pull it tomorrow and see whats damaged. What do you guys think happened and what could be damaged?

Thanks,
Clay

 

[88GThatchback]

ttt

 

[Rick 91GT]

Sounds like you took the thrust right out, was it properly seated? What were the clerances, rod side clearance, bearings, etc... What crank, brand and material and what bearing was used?

Usally thrust issues are not common on a manaulk trans car, auto and converter balooning can cause that issue.

 

[88GThatchback]

I dont remember exactly what we did to seat the bearing, but i think we jammed it one way and back the other and then torqued it. What do you recommend for seating the thrust bearing? I didnt check the rod side clearances, but the bearings were .001"- .0015". The crank is a Probe cast steel 347 crank. Bearings are Clevite 77's that came with the kit. This was my first engine build so i was expecting something like this to happen. I got it ready to pull, just need a hoist. Will have an update tomorrow night after we get it out and apart.

Clay

 

[Modular2v]

damn....your making me nervous lol i just got through building my 331......i have not found and metal in the oil yet though!......i plastiguaged mine and everything was to spec, hope it works out for your....hopfully the bearing is just a little beat up

 

[88GThatchback]

Got some bad news!! Pulled it out and the crank has a nice deep groove in it from the thrust bearing face on the clutch side. Now I need a new crank, bearings, and whatever else I find. Why whould the bearing cut into the crank? I thought the bearings were soft and they would go first. We still cant figure out what caused this. I dont want to buy new parts and just put it back together without knowing and then have it happen again. Any ideas? Ill post pics later.

Thanks,
Clay

 

[88GThatchback]

Heres the pics. The first of the crank is the grooved side and the other is the good side. Tell me if you need any more/better pics.

 

[Rick 91GT]

Never seen anything like that.....

 

[ECU5.0]

damn! well the motor looks pretty clean, if that makes you feel any better. doesnt look good man. youre making me scared to put my motor in even though i checked and double checked and tripled checked all my clearances. good luck man.

ps. now that i think about it, im gonna check everything one more time tomorrow

 

[88GThatchback]

You think there could have been something wrong with the crank? I dont see how anything could have done that. My clutch cable wasnt tight all the time or anything, so nothing was pushing forward other than when I shift. Would you rebuild with a new crank and bearings and call it good? What else would I check? Im going to take it to the machine shop that machined the block on saturday to see what they think.

 

[Rick 91GT]

That looks like a SCAT crank, Probe machined beam rods and pistons. I build a lot of motors with that exact combo with no issues at all, P series bearings.

Time to talk to your motor builder to get some imput, .007 is plenty of clearance, actually a tad to much for a manual. The bearings look like **** from those pics...but it had a lot of metal floating around.

Were the mains/caps checked for alignment? What was the rod side clearance?

 

[Rick 91GT]

You think there could have been something wrong with the crank? I dont see how anything could have done that. My clutch cable wasnt tight all the time or anything, so nothing was pushing forward other than when I shift. Would you rebuild with a new crank and bearings and call it good? What else would I check? Im going to take it to the machine shop that machined the block on saturday to see what they think.

I measure and check every single part before and after machining when building a motor, part of the blueprinting.....

 

[88GThatchback]

I built the motor so if anyones at fault its probably me as its my first. The mains were line honed. By rod side clearence, do you mean the clearence between the rod and the crank? If so, i checked before I pulled it and it was .023". I dont know what is normal, but it looks like a lot. And yes, it is a SCAT crank, Probe pistons and rods. I forgot Probe used SCAT cranks.

 

[Modular2v]

now what really makes me nervous is that im using probe pistons/rods and scat crank too!!.....maybe your crank wasnt up to par when they sent it out?

 

[Modular2v]

not trying to sound like an a$$ but.....there was assembly lube on there right?

 

[ECU5.0]

lord you guys are freakin me out so bad with this. im gonna empty like 6 bottles of assemply lube on my crank tomorrow and measure everything with a freakin microscope...hell i might even use a telescope if it will help

 

[Rick 91GT]

No amount of assemble lube will prevent wear like that, don't go crazy with the lube it won't help.

You guys just because one person has an issue do not jump into the "oh **** that will happen to me" mode. Measure all your parts, check all the clearances before you install. If your worried about have a professional take a look at your parts, or build the motor for you.

.023 is high but it will not cause that. With that set-up I end up in the .017-.024 range usually.

Did you check the thrust with the center cap off and on? Tapping the crank forward then back will seat the crank.

What is the PT on your main bearings? 590P What about the rods? 634P

 

[Boss 351]

Did you turn the crank freely with your hands once you torqued the mains? I rebuilt my engine for the first time too, so far so good. That bearing looks like it was used uneven, I mean my high mileage motor had the same type of wear where yours only had 500 miles?

Where they the right sized bearings? Stupid questions but I'm not very good at these things yet. How was everything torqued down? Did you follow the steps?

 

[Modular2v]

i would like to know if the crank was easy to spin by hand with all the mains and rods torqued to spec...it shouldnt be to hard to turn

 

[88GThatchback]

The rod bearings are CB634P and all the mains except the thrust bearing are MB2121P. The thrust bearing is MB2122P. I cant find this bearing on Summit anywhere. Could this be the wrong one? The crank turned fine after everything was torqued. When I checked the thrust I had the center cap on. Is this wrong?

Clay