ALH Possible bent rod advice?

DCELL

Veteran Member
Joined
Apr 15, 2002
Location
Sheridan, IN
TDI
'01 GOLF 2DR, ‘15 Passat SEL TDI
I'll try to make a long story short.

The car I am currently working on is the first I've seen that actually had timing belt strip itself and then the owner restarted it and let it run trying to figure out what was wrong with it. I've had others with suspected "slipped timing" or tensioner failure, but never one where my piston protrusion measurements didn't match up. As there are slight impressions from valves on the piston tops, I was suspecting the worst.

I used a variety of measurement techniques to try to determine what was going on with these pistons. I used both a magnetic dial base and a magnetic deck bridge as well as checking with both a dial gauge and caliper. Measured at the thin shoulder above the wrist pins after a conversation with franko6.
What I found was (left/right): #1=.041/.040, #2= .039/.040, #3 .039/.040, and #4 .042/.035

After measuring more times than will admit, I pulled #4 and #3 pistons for inspection, as I understand rods are weight and length matched in reciprocating pairs. What I don't know is what I'm looking at? Both of these rods look identical, and neither look bent to my eye. I don't have a surface plate at my disposal.

MY Question:
Is there any other way I can quickly determine the status of these rods without sending them to Frank? It's not that I don't want to send them out, it's more of an issue of time. He's already got the head rebuilt and on the way back to me.
Can anyone tell me in what way rods "normally" bend in a valve collision?

Many thanks!
 

Mavrick

Veteran Member
Joined
Feb 16, 2012
Location
Ontario
TDI
2003 VW Jetta TDI
The set of rods I replaced in my buddies ALH were very obviously bent upon visual inspection. The first 3 being within .002" I would not worry about. #4.. I personally would not even worry about that one as it's within somewhere between .001 and .005" - that could very well be from the factory..
 
Last edited:

DCELL

Veteran Member
Joined
Apr 15, 2002
Location
Sheridan, IN
TDI
'01 GOLF 2DR, ‘15 Passat SEL TDI
my concern is that by measurement, the piston head on #4 itself is actually tilted, I pulled them to check for bends, but also to look for cracks or other signs of distress, but have found none. Perhaps I am being overly cautious.
 

greengeeker

Vendor
Joined
Feb 8, 2006
Location
Cambridge, MN
TDI
2002 Jetta GLS
Does the tilt coincide with your worst valve impact mark (and most trashed cam follower)?

I'm not used to seeing bent rods when the belt goes but I suppose anything is possible.
 

DCELL

Veteran Member
Joined
Apr 15, 2002
Location
Sheridan, IN
TDI
'01 GOLF 2DR, ‘15 Passat SEL TDI
No, the tilt is opposite the impression, that's what was throwing me. The cam followers actually not spidered. I don't think it hit hard at all, so I'm kind of thinking it's just been that way since it was built
 

DCELL

Veteran Member
Joined
Apr 15, 2002
Location
Sheridan, IN
TDI
'01 GOLF 2DR, ‘15 Passat SEL TDI
156k. Original belt is the one that broke.
I've decided I'm going to re- ring and throw them back in with new bolts. Fingers crossed.
 

Vince Waldon

Top Post Dawg
Joined
Apr 25, 2009
Location
Edmonton AB Canada
TDI
2001 ALH Jetta, 2003 ALH Wagon, 2005 BEW Wagon
I personally think you'll be fine... very fine. :)

Those protrusion numbers look great to me, and if in fact a piston was tilted I'd suspect a worn bore or piston skirts rather than a bent rod, which you'll be able to check for as part of honing/re-ringing. :):)
 

Pat Dolan

Veteran Member
Joined
Apr 19, 2002
Location
Martensville, SK
TDI
2003 A4 Variant, 2015 Q7
No, the tilt is opposite the impression, that's what was throwing me. The cam followers actually not spidered. I don't think it hit hard at all, so I'm kind of thinking it's just been that way since it was built
Since you don't have measuring tools to do rod out, what I suggest is swap the #3 rod onto the #4 piston and vice-versa. If the error moves to the #3 hole, you have a bent rod.
 
Top