'Wrist pin noise'? How serious an issue?

[OceanRuns]

A lady not far from me is selling a Geo Metro convertible for very cheap (perhaps $300-400). She said it runs, but has a ticks sometimes (not loudly, according to her).

She says her mechanic told her that it might either run for a long time like that, or fail. No way to tell. My understanding is that if it fails, it's new engine time.

My question is, is it possible wrist-pin noise can just go and go? I've also read it can be difficult to actually even pin down that is where the noise is coming from.

Thanks for any insight.

 

[Klutch9]

I owned a '97 Grand Am a few years back, and put about 40,000 miles on it (from 133,000 to 174,000). It had wrist pin noise the entire time between about 2,000 rpm to 3,500 rpm. It never changed or worsened during the time I owned it, and the motor was very reliable. Who knows how long it was making the noise before I bought it. I have heard the similar opinion that it'll either die right away, or keep going indefinitely with the wrist pin slap. In my case, it kept going just fine.

 

[SwampSurvivor]

It'll run until it doesn't any more.

 

[lubricatosaurus]

You have to really know what your ears are hearing to pinpoint a diagnosis of wrist pin noise. Thats going to sound like piston slap, or maybe some lifter noise or worn journals.

Run a thicker oil, like mobil1 15w-50 and hope to cushion whatever is making that noise in there.

 

[OceanRuns]

I think for something I may potentially be able to get for $300 to $400 it might be worth looking at.

 

[SwampSurvivor]

Originally Posted By: lubricatosaurus
You have to really know what your ears are hearing to pinpoint a diagnosis of wrist pin noise. Thats going to sound like piston slap, or maybe some lifter noise or worn journals.

Run a thicker oil, like mobil1 15w-50 and hope to cushion whatever is making that noise in there.


I can't speak for the Geo Metro engine, but thinner oils (20 grade) will often quiet 4.0 wrist pin noise down to almost nothing.

 

[Trav]

It depends on a few things, if it is wrist pin noise (i would check that out first, not just take someone's word for it) it could be from a work thrust bearing cause the rod to twist slightly, assembly error which is not likely to show up now in this vintage, lack of splash lubrication.

If it is a press fit pin and it has come loose in the rod its going to cause cylinder damage fairly quickly but if its the piston being loose on the pin it probably go on for a long while.
If its a floating pin a lock could dislodge and tear the bore up.
Listen to it, pull or short the plug wires with a test light one after the other with the engine running, if the noise goes away on one you know that's the effected cylinder, like diagnosing a rod knock when there is no load on the piston it gets quieter.
If it doesn't go away it could be just a simple valve adjustment.

IIRC that's a 3 cyl engine and it should be easy enough to change if the car is even worth it.

 

[bigt61]

It runs? And it's $3-400? Just buy it. Wrist pin clearance will never get "better" but it may survive for a long time if driven gently. RPM is your enemy, so shift early without lugging the engine in the next higher gear. Let it warm up for a minute after cold starts and you have a low cost alternative to walking. I'd use 5W-30 dino or HM in California. Don't waste money on synthetics with that beater, you'll just cause a leak. Keep it topped off - low oil level is not your friend.

 

[SwampSurvivor]

How hard would it be to throw a new piston it it? I have seen some videos on youtube of the cars. Seems like you can drop the pan easy, there's definitely enough room to pull the t-belt off and remove the head (the 3 cyl head can't weight much at all).

 

[lubricatosaurus]

Originally Posted By: bigt61
It runs? And it's $3-400? Just buy it. .

Thats right. Hey, try a load of Moly (LiquiMoly MoS2 from NAPA autoparts or Amazon) and run a thick oil like any conventional 20w-50. In California, the climate allows it no problem. Thicker oils create thicker oil films, great for older cars like that.
With that, get it to last as long as possible for cheap. Then way later replace the engine.

Thats got to be the most fun car on the planet to drive in good weather with the top down. A huge bonus.

 

[hansj3]

Buy it and drive it til the engine blows. Then replace with a turbo engine out ta a firefly or jdm, and enjoy 100HP In a metro

 

[splinter]

Geo Metro 'vert? Sweet!

 

[Eddie]

Wrist pin noise is a double click when the piston reverses at BDC. It is usually easy to separate from piston slap and valve gear noise. I light double tap can go forever but, a loud double tap can brake a piston and the engine will need a rebuild or worse. Ed

 

[CHARLIEBRONSON21]

Get it, swap in a SBC and run with it. Anyways, for that little, you could sell it for scrap and make pretty much that back. I'd say get it.

 

[SteveSRT8]

Originally Posted By: lubricatosaurus
You have to really know what your ears are hearing to pinpoint a diagnosis of wrist pin noise. Thats going to sound like piston slap, or maybe some lifter noise or worn journals.


You really hit this straight on the head. Precisely who decided it was a wrist pin? Why not a piece of valve gear? I seriously question the diagnosis, like Trav said it may just need a valve adjustment!

 

[zach1900]

That's like one car payment. Quit being so cheap. When gas shoots back up you could probably get at least 1500$ out of it.

 

[OceanRuns]

Ok, I'm back from checking it out. Seller is a really cool lady, she's had it since 1991.

It sounds to me like a 'ticking'.

It doesn't do it all the time.

-When I revved the engine in neutral, it doesn't do it at all...even up past 4000 RPMs.

-When in gear it does it sometimes. It seems most noticeable between 2000-3200 or so RPMs. It also seemed more noticeable it some gears than others.

Aside from that the car drives well.

The clutch did seem harder than it should to be press in, but after a few minutes of driving I'd forgotten about it.

The heater works. It also has AC, which works, that's cool. It's an 'LSI model'.

More description...

-Headlights only work on high (and you have to hold the lever in the high position. Both bulbs could be burnt out on low, or a wiring issue.)

-Door latches don't work on the outside, inside is fine. I'd take door panels off and mess with it.

-Missing chintzy interior trim pieces, I don't care at all.

-Side was scraped and repainted poorly. Body is good. No rust. One one taillight cover broken. Hello Pick N Pull.

-Top is solid with exception of one tear I'd just tape over. Back window is cloudy.

-Could use a cleaning

.

 

[OceanRuns]

Here are photos. We went on a long test drive.

It's actually pretty fun, feels almost sporty. The one missing wheel-cap is in the vehicle.

 

[sciphi]

Buy it and run it until it's dead. A "new" engine is what, $500?

 

[asand1]

Swap in a Japanese 4cyl/5spd.