Wrist Pin

Muskoka · June 30, 2003

I had my truck in for AC work last week and the mechanic commented that he was concerned with a bit of a rattle on startup - there's a bit of a clatter - like two to four 'hits' as the engine catches, then nothing; it starts up and away we go.

Anyway, he says it could be the wrist pin then slowly shakes his head like he was telling me it has an inoperable tumor .

So, what the hell is a wrist pin, what function does it serve, could it be as expensive as I'm being led to believe, and how do I know if it even needs work/replacement?

lrymal · June 30, 2003

I would certainly find out what the tech is thinking and what should next be done. The wrist pin is a steel pin that attaches a connecting rod to a piston.

cyrylyn · June 30, 2003

I had my truck in for AC work last week and the mechanic commented that he was concerned with a bit of a rattle on startup - there's a bit of a clatter - like two to four 'hits' as the engine catches, then nothing; it starts up and away we go.

Anyway, he says it could be the wrist pin then slowly shakes his head like he was telling me it has an inoperable tumor .

So, what the hell is a wrist pin, what function does it serve, could it be as expensive as I'm being led to believe, and how do I know if it even needs work/replacement?

it's cheaper (for a dealer) to replace the engine with new or rebuilt engine than to rebuild your current engine to replace a wrist pin.

MarkD · June 30, 2003

Ross Pistons

Wrist Pin

Muskoka · June 30, 2003

Thanks, guys. Now that I know what it is, where it goes & what it does, how common a problem is this?

It would stike me that if a wrist pin (see, I'm learning - I didn't say the wrist pin like I did in my oroginal post ) was worn or loose, it would clatter all the time with the piston action. It doesn't though. Only a little bit at startup. Why is that (if it is a pin, of course)?

It's a little concerning that a $10-15 part could ultimately mean a new motor .

I'd like to sound like I at least know what he's talking about when it comes up again.

Jon

SteveCZ · July 1, 2003

Sounds like the good ol' start up knock to me........ You are one of many with the same problem.....

Muskoka · July 1, 2003

Sounds like the good ol' start up knock to me........ You are one of many with the same problem.....

I'm very familiar with this on the current generation of Vortec's as I had a '99 Silverado with the 5.3L & eventually grew to tune it out. My lease ran up and they got the truck back.

I've not heard anything about a similar problem with 1st generation Vortec's like my '96 5.7L, though. Is this a known condition in these motors? I've only had this truck for two months so I have no way to know if it's had this forever, or if it's just now developing.