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Engine Specific Info and Questions => IDI Engine => Topic started by: mercedesjones on September 30, 2006, 08:43:30 am

Title: 1.9 cap bolts
Post by: mercedesjones on September 30, 2006, 08:43:30 am

Can someone confirm if the cap bolts for mains and rods are stretch bolts and have to be replaced if removed? If so, can I still plastiguage with the new bolts and re-use them as long as the engine wasn't run?

Thx.

Title: 1.9 cap bolts
Post by: 935racer on September 30, 2006, 09:34:14 am

Which engine and which year are you reffering too?

Title: 1.9 cap bolts
Post by: mercedesjones on September 30, 2006, 10:19:43 am

1.9 aaz

Thx.

Title: 1.9 cap bolts
Post by: 935racer on September 30, 2006, 10:33:54 am

Need to know which year, call your local vw dealer with the engine year and serial # of your car and they will tell you. Or if you have the old bolts take a look at them, if they are a fully threaded shank they are stretch bolts, replace them, If they are only  half threaded shank you can reuse them.

Title: 1.9 cap bolts
Post by: QuickTD on September 30, 2006, 03:50:24 pm

The rod bolts are always stretch type but there are 2 different kinds based on year. The early rods had locating pins in the caps and took a normal looking bolt. They are about $12 each. The later engines don't have locating pins in the rod caps, they use a ground portion on the shank of the bolt to locate the cap. Oddly enough they're the cheap ones at $3-4. Both types can be torqued to the first stage for checking clearance. As long as you don't put the 90º turn on them they do not stretch and may be reused. Of course, you must put the 90º turn on them during final assembly.

 Like 935 said, the main cap bolts are either all thread or partial thread. the partial thread ones are not stretch bolts and can be reused. The all thread stretch bolts can be torqued to the first stage for clearance checking.

Title: 1.9 cap bolts
Post by: mercedesjones on October 06, 2006, 12:40:02 pm

Just picked up the rod and main cap bolts from the dealer. $70 - OUCH!
I can't see a diff in length btwn old and new. Do stretch bolts return to their original length when not under torque? Or did I spend $$ for natta. The mains are threaded up to the bolt head btw.

Title: 1.9 cap bolts
Post by: jtanguay on October 06, 2006, 03:53:05 pm

the bolts shouldn't stretch... i believe just the threads 'stretch'.

Title: 1.9 cap bolts
Post by: mercedesjones on October 07, 2006, 08:47:42 am

Right, thanks. Can someone tell me the correct torque specs for the mains and cons on this bottom end? 1995 1.9td. Thanks.

Title: 1.9 cap bolts
Post by: HarryMann on October 07, 2006, 05:52:53 pm

When they say 'stretch' bolts, it means the bolt is taken through elastic deformation limit to an estimated but small permanent strain. This might be 1, 2 or just a few % plastic strain. You'd hardly be seeing this, though it could be measured (if you had measured those original bolts first).

Will try to dig out thsoe figures unless someone else does first, but they do vary a bit by year. Had a hell of a job finding the right big end shells and bolts for my AAZ, think there is more than a single year split in thes engines' bottom ends, could be wrong though.

Title: 1.9 cap bolts
Post by: andy2 on October 08, 2006, 04:15:52 pm

As per Bentley:

Main bearing cap bolts

-new type bolt (replacment) with fully threaded shank tighten to 65 Nm (48 ft-lbs) plus 1/4 turn (90*).Note: do not reuse this type of bolt!
-old type bolt with partially threaded shank tighten to 65 Nm (48 ft-lbs).This type of bolt can be reused.
-do not mix old and new type bolts!

connecting rod bolt

-streach bolt-always replace
-oil threads and bolt head surface during installation
-AAZ and AAA engines:tighten to 30 Nm (22ft-lbs) plus 1/4 turn (90*).