Bent Rod Or NOT?

I'm rebuilding a 2002 vw jetta tdi and cylinders 3 and 4 connecting rods have a slight bend on them. I have looked online and I see pictures with a similar look to the rods. However, It does not look right to me.
I purchased the car from a dealer and there was a timing belt in the trunk. However the timing belt was not changed and it broke. =(
I'm replacing pistons because they hit the valves and they had a lot of carbon build up on the rings, that's when I notice that 3 rod had a slight curve to it and less on #4.
Suggestions? My hunch is replace the rods on 3 and 4, but not sure.
If they are bent does any one have some used rods????
Thanks,

Get ahold of " franko6 " on here......he will have everything you need and the best advice you could hope for........you might also need a head if the valves hit......he can rebuild them and is an expert on this subject.





Frank's VW TDI's, LLC
1007 Olive St.
Lockwood, MO 65682
417-232-4634
FranksTDIs@sbcglobal

Check piston protrusion above block.

There's no difference in the rods .......... they will work in any hole!

If you pick up a couple of used rods, have them weighed (all 4), to determine if they need to be balanced (all same weight within spec).

Ditto on recommendation for Franko6.
If the engine was running when the timing belt broke, then the head should be rebuilt. Often when that happens, the damage is limited to the head and the bottom end is ok to continue. But... I am no guru on engine internals like some of the others here. What you're describing sounds unusual, and I agree it's worth questioning.

AndyBees said:

Check piston protrusion above block.

There's no difference in the rods .......... they will work in any hole!

If you pick up a couple of used rods, have them weighed (all 4), to determine if they need to be balanced (all same weight within spec).

Click to expand...

If I recall correctly, the rod/pistons are weighed to be balanced between sets, so piston 1 and 3 should be exact and piston 2 should weigh in the same as #4.

Franko6 will have the details.

Although there are "two pairs" of pistons, they are all the same in weight (should be within spec) and all the rods are the same weight ...... the rods will work in any hole as I stated above (they do have a specified orientation).

The piston pairs are 1 & 2 (function in either of those holes) and 3 & 4 (function in either of those holes) as far as interchangeability.

As far as relationship on the crankshaft, they are paired as follows: 1 & 4 (each end of crankshaft) and 2 & 3 (in the center of the crankshaft).

If they are not balanced (weight, within spec), then the engine will be out of balance!

Take your rods to a machine shop and have them checked for bend, twist, dimensions and while you are at it have them Magna-Fluxed to check for cracks. Always a good idea with any rebuilt. My guess is that if they appear to be bent to the naked eye, they are probably scrap.

Seriously, spend some money on doing it right. Just throwing some new parts in without proper machine shop work on the bore, pistons crank and rods is a waste of time and might only last 5,000 miles.

Replacing pistons just because of some carbon build up is not a valid reason to replace them. What needs to happen is you clean the carbon and measure the bore for diameter and taper and then measure the pistons for wear as well as measuring the OD of the crank main and rod journals while you have things apart.

Depending on the measurement numbers the machine shop comes up with will determine what you will need to do to have a rebuild that will last.

Hope you get my drift. You cannot rebuild an engine successfully by just guessing on the condition of the parts which sounds like you are doing........

csstevej said:

Get ahold of " franko6 " on here......he will have everything you need and the best advice you could hope for........you might also need a head if the valves hit......he can rebuild them and is an expert on this subject.





Frank's VW TDI's, LLC
1007 Olive St.
Lockwood, MO 65682
417-232-4634
FranksTDIs@sbcglobal

Click to expand...

VG advice. You may not need a full blown rebuild, IDK. Frank can help you map out a strategy that fits the work you actually need.

Oh, did I mention that Frank Irving is the brains behind probably the only place I would send my TDI stuff for machine work?

supposed to be different lengths too ...