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Rod/main Nuts And Bolts

Redcarsonly

By Redcarsonly
in BMW 2002 and other '02

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Redcarsonly Explorer

Redcarsonly

Posted
Posted

Are these nuts and bolts one time use? This is my first engine build but I'm under the impression that when it all goes together I need to assemble and disassemble each rod and main cap more than once to check for oil clearances. Does this mean that I need a new set of nuts and bots for each round of measuring and then for final assembly? What do you engine builders do?

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skipsfcr Veteran

skipsfcr

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No, they are not plastic region (stretch) fasteners. I'm not saying that you shouldn't replace them during a rebuild, particularly if it's a high performance engine or simply makes you feel better, but you certainly do not need to between checking.clearances and re-torquing.

Budweiser...It's not just for breakfast anymore.

Avatar photo courtesy K. Kreeger, my2002tii.com ©

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Redcarsonly Explorer

Redcarsonly

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Well it's going to be a completely stock rebuild. New hone, rings and all bearings. Just trying to get a budget put together for the project. Thinking deves rings. But where do you guys recommend buying parts? Autohausaz?

Ace Andrew, what have you seen fail? The rod bearing stud or the nut?

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TobyB Grand Master

TobyB

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Listen to Gordon- these fasteners are reusable.

 

The rod bolts are good to 7500 rpm all day long, year in, year out.

 

In fact, some of the problems that have come up have been with the

new stuff...

 

That said, if there's ANY sign of damage, replace the rod bolts.

And check pistons carefully- I have very seldom found any used

piston to be worth re- using.

 

Otherwise, don't sweat it.

 

I have used Deves rings with good results, on a 'hone with decent used pistons' refresh.

 

one person's 02.

 

t

"I learn best through painful, expensive experience, so I feel like I've gotten my money's worth." MattL

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Redcarsonly Explorer

Redcarsonly

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Toby

Thanks for your input. It backs up my thinking that if the nuts and bolts have made it this far and are still perfectly in tact, they should still be good. They will of course all go thru a pretty tough visual inspection (20/20 vision), and I'll verify lengths if I can. As far as I know, the nuts and bolts holding the engine together are not what failed and forced the car to be parked.

About the pistons... Sad news. We'll surely measure them and replace if necessary.

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TobyB Grand Master

TobyB

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Well, you can have them ground- but I think the spec is maximum only, so I wouldn't bother.

 

UNLESS the bearings are getting hung up on the crank radii- then the radii of the 

bearing surface of the crank needs to be reduced... or the racer method, which is to simply radius

the edges of the bearings to match.

 

hth

 

t

"I learn best through painful, expensive experience, so I feel like I've gotten my money's worth." MattL

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AceAndrew Grand Master

AceAndrew

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Listen to Gordon- these fasteners are reusable.

 

The rod bolts are good to 7500 rpm all day long, year in, year out.

 

In fact, some of the problems that have come up have been with the

new stuff...

 

That said, if there's ANY sign of damage, replace the rod bolts.

And check pistons carefully- I have very seldom found any used

piston to be worth re- using.

 

Otherwise, don't sweat it.

 

I have used Deves rings with good results, on a 'hone with decent used pistons' refresh.

 

one person's 02.

 

t

 

 

I'll disagree with Toby and Gordon on this one ... but it seems I'm the odd one out on the message board this time.  At LEAST very very thoroughly inspect each one.

ADAMS Autosport

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TobyB Grand Master

TobyB

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Whoopsie- Tommy, you're right- I misread as .025, not .25.

 

New bearings WON'T eliminate side play, as that's set by the rods touching the sides of the crank journals.

And most likely is that the crank's wide from a regrind- although, the rod could have been narrowed too, I guess.

Are they worn?  I've never had an issue with rod side clearance...

 

And Andrew, I don't think it's a BAD thing to put in new rod bolts- I do it when I build a new engine from an unknown core.

It's prudent, if it's going to be stressed significantly.  I just don't think it's necessary on a motor that's going to see normal street use.

Unless something's happened, like a significant overrev.

 

Not mentioned, and very useful, is to simply measure the lengths of the bolts both relaxed and installed.  If you find one or two (or 4 or 6 or

eight) that are way out, or don't behave when torqued, then you can swap them.

 

fwiw.

 

t

"I learn best through painful, expensive experience, so I feel like I've gotten my money's worth." MattL

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