Author Topic: Do main bolts have to be replaced? (Read 8219 times)

rallydiesel · « **on:** August 09, 2007, 09:18:40 am »

I am doing an engine overhaul and need to know if the main bolts need to be replaced. The manual says they aren't stretch bolts. I know the rod bolts need to be replaced.

Thanks for any help.

zukgod1 · « **Reply #1 on:** August 09, 2007, 09:30:14 am »

I've never heard the rod bolts need to be replaced.

I'm sure it's a good idea to replace all fasteners but just the same, never heard of it.

Dan

rallydiesel · « **Reply #2 on:** August 09, 2007, 09:53:37 am »

According to Bentley's, the rod bolts are stretch bolts. That's all I know. :?:

jtanguay · « **Reply #3 on:** August 09, 2007, 09:59:26 am »

well i would assume that any stretch bolts should be replaced. the bentley should say whether or not they need to be replaced...

zukgod1 · « **Reply #4 on:** August 09, 2007, 10:18:42 am »

Somebody bust out a book and tell us please?

I JUST reassembled my bottom end and dont want to button it up if those things are supose to be replaced....

I'm at work, that really doesnt matter, I've not recieved my book yet anyway

dan

Barry W · « **Reply #5 on:** August 09, 2007, 08:13:14 pm »

All factory rod bolts are stretch bolts. Replace them and save losing a rod!

A2TD · « **Reply #6 on:** August 10, 2007, 11:01:17 am »

Quote from: "Barry W"

All factory rod bolts are stretch bolts. Replace them and save losing a rod!

Actually there were some applications where they did not use stretch bolts on the mains, the bently actually talks about this, if the bolt you took out is threaded all the way to the head of the bolt, its a stretch bolt, if the bolt is only half threaded it is not a stretch bolt......

zukgod1 · « **Reply #7 on:** August 10, 2007, 11:24:35 am »

Quote from: "A2TD"

Quote from: "Barry W"
All factory rod bolts are stretch bolts. Replace them and save losing a rod!

Actually there were some applications where they did not use stretch bolts on the mains, the bently actually talks about this, if the bolt you took out is threaded all the way to the head of the bolt, its a stretch bolt, if the bolt is only half threaded it is not a stretch bolt......

Ok, that's good to know. Now I just wish I had payed attention to that when assembling the bottom end. At least it's still on the stand.

dan

jtanguay · « **Reply #8 on:** August 10, 2007, 12:38:25 pm »

yea.. i never took that into consideration when rebuilding my bottom end either.

i'm guessing TDI's have stretch... oh well at least it's still open and accessible.

clbanman · « **Reply #9 on:** August 11, 2007, 04:58:39 am »

My Bentley covers 1985 to 1992, and the only internal engine bolts that it specifies replacing are the head bolts.
I don't know about VW, but stretch bolts as a rule are not always threaded to the head. Often they will have a necked down section on the shoulder. Also, a clue to bolts being stretch bolts is that the torque specification will give you a torque value, and then specify an additional angular turn dimension. "Stretch" is a bit of a misnomer as all bolts stretch when torqued to the proper value. This is what keeps the bolt from loosening. The idea is that the bolt stretches far enough that the forces in tension are higher than any the bolt will see in shear or torsion but still sufficiently below the elastic limit in tension. What we normally call stretch bolts are single use bolts that have been designed to stretch closer to their elastic limit.

rallydiesel · « **Reply #10 on:** August 18, 2007, 06:49:49 am »

Yes, and my Bentley says to torque them "x" amount plus "x" degrees more. Therefore they are single-use bolts. I am replacing mine because I don't want my time and money going to waste when a rod destroys my bottom end.

zukgod1 · « **Reply #11 on:** September 25, 2007, 12:12:36 pm »

Old thread, where can we get some good rod bolts? ARP?

dan

dillenger1 · « **Reply #12 on:** February 27, 2008, 06:23:50 pm »

I thought this was funny,because my Chilton manual(sorry)specifies two different types of rod bolts used(stretch and non)It says the non -stretch reusable rod bolts will have notches on the nuts.It shows a picture of the nut that needs replaced and every flat on the nut has a small notch machined/forged into it.

jtanguay · « **Reply #13 on:** February 27, 2008, 06:31:33 pm »

imho stretch bolts aren't too expensive, and since its not every day that one tears into their engines... you might as well replace them and avoid rod failures (which will destroy the block)

for ARP stuff someone posted some part numbers. possibly in the FAQ?

dillenger1 · « **Reply #14 on:** February 29, 2008, 07:43:46 pm »

What i was trying to say is it seems i have reusable rod bolts.My chilton says that if the nuts have notches on the flats then they need replacing,if they dont then your ok to reuse them.