m52 main/rod bearing diy

[FredK]

The main bolts are TTY as well. I would pull the motor if it were me and check everything out good. But I guess m52's are a dime a dozen in Atlanta so if you want to cheap out on it you can always replace it cheap.

Hey, just wondering where it says the main bolts are TTY? I replaced ones that I disturbed during an oil pickup support bracket removal, but there doesn't seem to be the normal necked-down area that TTY fasteners have.

[lolcantturn]

Hey, just wondering where it says the main bolts are TTY? I replaced ones that I disturbed during an oil pickup support bracket removal, but there doesn't seem to be the normal necked-down area that TTY fasteners have.

Those are definitely torque to yield. I made the same mistake as you when I removed the oil pick up support. Then i dropped my motor in, drove it a mile, and then my friend asked "hey what did you do with the oil pick up support?" and I said "I unbolted the bolts and put them back in" "New ones right, to spec?" And I said "No?"
Called me a complete idiot and said my motor is going to eat itself if I turn it on again.
Sure enough I pulled my motor, looked at the magnetic drain plug and saw little bits of shaving, not enough to get worried but it was definitely from that main bolt because I only drove the motor for a mile and prior to that oil change it was free of shaving.
Bought new TTY bolts, torqued correctly, and have been driving my car ever since. No shavings on my magnetic plug after 10k miles

[nando]

Hey, just wondering where it says the main bolts are TTY? I replaced ones that I disturbed during an oil pickup support bracket removal, but there doesn't seem to be the normal necked-down area that TTY fasteners have.

edit for correctness: if you look at the torque specs, they list an initial torque value and then an angle. that means TTY.

[samiam3356]

edit for correctness: if you look at the torque specs, they list an initial torque value and then an angle. that means TTY.

[dirty30]

$95 for main, $45 for rod from pelicanparts.com

I said dealer bearings, not cheap Chinese replacements from Pelican. Pelican's are Glyco, Glyco's are Chinese bullshit.

[328ijunkie]

FWIW ive never had any issues with glyco's

[polkadot_boxerman]

Can someone explain the purpose of checking clearances? I know it's to find out if you need the oversized bearings or not. But I thought that was just for if the crankshaft had been taken out and reground?

[nando]

usually you don't need to worry about it too much if the crank is original and undamaged. you can fine tune it with different combinations of bearings if you want to, but normally if you just buy standard bearings (they're color coded) and check the clearance with plasti-gauge, you'll be square in the clearance ragne.

too tight - stuff will touch. that's bad.
too loose - your oil pressure will be low. also not good.

if it's not a race motor, just order standard bearings, check the clearance with plasti-gauge, and if it's in the specified cleranace range (highly likely), you're all good.

[FredK]

edit for correctness: if you look at the torque specs, they list an initial torque value and then an angle. that means TTY.

Torque angle is a technique used to reduce clamping force scatter, not necessarily that the bolt is being brought into the plastic regime.

M10x1.5 head bolts are jointing torque plus 90°, plus another 90°. Do you think jointing + 50° are making a dimensionally similar (M10x1.5) fastener yield?

[nando]

I think that depends on how many turns you need to reach the desired yield point of the bolt?

but, you could be right..

[samiam3356]

I was going off what I had read Jlevie say before and that matched up with what Chris had said. Also I have a friend that works for BMW that said I need to replace the main screws when I took off that same bracket on my s52. No expert about fastners here but I'm pretty sure they are TTY.

EDIT: http://tis.spaghetticoder.org/s/view.pl?1/00/33/51


About half way down the page it also says to replace them.

[FredK]

Gotcha. Yep, that's what the TIS says.

They used to be like $1.20 per bolt, now they're $6.