Is this piston okay to run? (pics)

[gieri002]

Is this piston okay to run? Ive seen some pretty good sized marks but never one like this. All the other pistons are fine.

 

[92AWDHX40]

Looks ok put pull it out, and look over again.

 

[dsmrebel084]

Agreed....pull it out and check it over

 

[JusMX141]

I wouldn't. Those are some pretty serious grooves from the valve. If you were just talking about the marks near the valve recesses that show the piston has contacted the valves before, I'd say OK....but that damage in the center of the crown is more than I'd like to see.

 

[gieri002]

I'm sure the rest of the piston is fine. The damage is due to a timing belt snapping while starting the car. The cylinder walls look excellent as well. Do you think there would be any adverse effects of running this piston? The gashes are fairly deep.

 

[92AWDHX40]

worst case scenario get some replacements with rings for under 200 bucks.

 

[gieri002]

JusMX141 could you explain your response a bit more thoroughly? Is the center of the crown a worse place to have damaged than the outer portion of the piston? I have seen some pretty beat pistons run just fine and make decent power.

 

[mx730md]

i could be wrong but the one look pretty eroded from runing lean others look like droped valve but i never seen the inside of one of these motors so i may be wrong

 

[99gst_racer]

Damage to the center of the piston will usually not affect the rings, which is a good thing. But, deep marks are difficult and sometimes impossible to smooth out. Leaving a crater or any type of edge can cause a hot spot - especially in the center of the piston.

Judging from the pictures, the wider mark could probably be smoothed out OK, but the deeper one near the lettering looks way too deep to smooth out. If it were me, I'd probably replace that piston. It's looks to be beyond reasonable repair.

But you could try smoothing it out, then taking some pictures and reporting back to us.


Tip of the day- These alumina zirconia pieces are absolutely perfect for deburring the dings in pistons. And they only cost about a buck at your local hardware store.

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[MadDashImports]

If you have the money I'd buy some new one's or a good pair of used. If your building on a budget Smooth it out. But used piston's are cheap. And even if you smooth it out it will still create a hotspot especially i'f your running lean.

 

[gieri002]

By "smoothing it out" you mean getting rid of the edges, correct? I am very familiar with the lumina zirconia pieces as you can see on the rest of my pistons (haha). How much heat do these heat spots generate? Do you have a link so I could see some calculations/facts and see what I am up against?

 

[goodbuds]

npr pistons are like 80 bucks on eBay oem factory replacement,

 

[gieri002]

I'm not looking to make more than stock hp with this car, it is my daily driver. I am looking for more specifics on what the effects of these hot spots would be.

 

[ed1380]

More knock under load.

 

[Alex7747]

I'm not looking to make more than stock hp with this car, it is my daily driver. I am looking for more specifics on what the effects of these hot spots would be.

If thats the case, just smooth out the pistons and put it all back together.

 

[99gst_racer]

The sharp edge is a perfect catalyst for a hot spot. A hot spot is exactly what it sounds like. It's a area of a piston dome that glows hotter than the rest of the piston. The hot spot area can and usually will promote pre-ignition (detonation), which can eventually destroy the piston and/or rod bearing among other things. Many people even go as far as to smooth out the edges of valve reliefs on brand new pistons to reduce the chances of hot spots. In many cases when the valves contact the pistons, it leaves a mark that is decently wide and not very deep. These are easy to file smooth and reduce edges. Your one mark there is narrow and deep, and it will probably not be possible to clean up well enough.

 

[gieri002]

Ah gotcha, well in your expert opinion how much could this chip potentially decrease the life of the piston due to detonation?

 

[99gst_racer]

Ah gotcha, well in your expert opinion how much could this chip potentially decrease the life of the piston due to detonation?

It's pretty well impossible to determine. It really depends on a host of varibles including but not limited to the quality of fuel you run, how much ignition timing advance you run, how much boost you run, and how well you can clean up that hole. Detonation is always bad and must be corrected or the engine won't last long at all.

As others have mentioned, NPR pistons are around $20-30 per hole. Seems like a cheap solution to avoid gambling on your engine. And as I previously mentioned, you could try to clean up that piston and see how it looks afterward. It would be easier to make a 'yes or no' determination after it's cleaned up as best as possible.

 

[gieri002]

Any advise on swapping in 1g rods and new 2g pistons while the engine is still in the car?

 

[bryanwheat]

You are gonna want to pull the engine to hone the block and clean it. You will also need to have the small end of the rod narrowed and the hole increased a mm for the 2g pistons to fit on 6 bolt rods. I would just get the kit from mizzumo for like 160 dollars. It has npr pistons and rings, acl or king bearings and a full gasket set.

 

[XiKeiyaZI]

You're not smoothing that out without causing adverse effects- And I'm usually one to look for any reason to give good news.

Replace the Piston. Otherwise you're going to end up with 2 craters in that piston.

 

[bryanwheat]

The piston could be cracked also. When exposed to combustion conditions it could come apart and you will end up having to pull it apart again.

 

[XiKeiyaZI]

If you end up wanting to try to salvage it - Grind it down and then take it to a machine shop and have them check it for unseen cracks or damaged.

 

[MilwaukeeGSX]

if on a serious budget, i wouldnt mind reusing them after a wirebrush cleaning

 

[bryanwheat]

If you end up wanting to try to salvage it - Grind it down and then take it to a machine shop and have them check it for unseen cracks or damaged.

It will be atleast 40 bucks to have it checked for cracks. You will have to hone the one cylinder and buy new rings for it also. Right there you are looking at more than it cost to buy a new set of pistons and rings.