Mahle piston top rings

Chevy1925

Chevy1925

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Ok boys, here's an interesting one.

Putting an engine together and have a brand new set of mahle 41909 piston rings here for the truck (2006 Lbz). Top rings gap out at .028-.027, way too big. Bottom gap out at .024-.023, right on par for what I'm after. Oil rings gap out at .012 across the board.

Double checked bore size and we are right at 4.056 like I measured before. Figured mahle sent me some bad top rings in this kit.

Next day air a new set of 41909 rings back out to me and same exact thing. Already sent the old set back so I can't check lot numbers. Mahle is closed so can't call them and see wtf is going on.

Now going to call guy and get a set coming from him so I know they are right but I can't be the only one that's seen this. I used a new set of 41909 std bore on an engine prior to Levi's built and they were right on at .018-.017.

Interesting to say the least. No in AZ exactly stock Dmax engine parts lol
 
Chevy1925

Chevy1925

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Harbin_22 said:
How bad is .028? Thats what my engine is at
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Depends on the build and how your getting your power. Probably not an issue in your truck as long as the second ring isn't tighter than the top. This engine won't see over 600hp and will most likely live around 400-450 with more air than fuel so things are staying tight/close to stock specs
 
Chevy1925

Chevy1925

don't know sh!t about IFS
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seems im not the only one seeing this as an issue in the std bore rings. Mahle is inquiring for a set from their aftermarket facility to test and go from there.

anyhow, i have a set coming from socal diesel (thanks lorenzo) that i know will be where i want them :D
 
Chevy1925

Chevy1925

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Im going to bump this up with fair warning to those that buy these rings and use them on cast pistons.

in talking with Mahle, the 41909 is what they send with all FORGED pistons, not cast. thats for standard and over bored. all their std/over bored CAST pistons come with 42160 that uses a stainless steel top ring. For what reason they are selling the 41909 as a stock replacement ring set and letting distributors call it the, they wont tell me. I would not use the 41909 knowing its a softer ring setup for forged and wont last for engines looking to put mileage on them (adam's truck is one that shows this).

As for the ring gap difference, they just got my first set of rings back and tested, second set is on their way. They say the ring gaps are within their spec which is .024 max gap for top ring and .024 for the second ring gap. I agree with them that these rings do in fact fall within their tolerances given the .003 increase in ring gap increase for .001 bore size increase and ill even allow .001 increase for variance in my feeler gauges. I have explained that GMs top ring gap tolerance is .012-.018 and for a stock ring set, they are still outside GMs spec.

but my biggest issue that i have not heard back on is why two set of rings have gone out with the second ring needing so much filing to make a looser ring gap than the top that it would put its gap far outside that of any stock truck would use and far outside their specification for the gaps.

Now im not bashing Mahle, im not throwing them under any kind of bus. I know of many companys that have had QC issues before and is nice to see mahle looking into this even just me calling and reporting about it. But what i would like guys to look at is the 41909 ring and based on what i have been told, i would at no point use this ring for a cast piston.
 
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henery97

henery97

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My mahle rings that came with my race casts were right on the high side of spec directly out of the box. I didn't file any of them, but I attribute some of that to using a stock bore piston on a 200k block.
 
TheBac

TheBac

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Chevy1925 said:
Now im not bashing Mahle, im not throwing them under any kind of bus. I know of many companys that have had QC issues before and is nice to see mahle looking into this even just me calling and reporting about it. But what i would like guys to look at is the 41909 ring and based on what i have been told, i would at no point use this ring for a cast piston.
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Ah shit. Wouldve been nice to know this in 2010. Ive got 56,000 miles on the rebuild now. Might be time to do a compression check?
I was planning on tearing it down anyway once I swap to the other engine.
 
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Chevy1925

Chevy1925

don't know sh!t about IFS
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Oct 21, 2009
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henery97 said:
My mahle rings that came with my race casts were right on the high side of spec directly out of the box. I didn't file any of them, but I attribute some of that to using a stock bore piston on a 200k block.
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Without knowing your final bore size after hone, it's hard to say if it was rings or the fact you have a larger bore that caused it. The last engine I did had 175k and started out with a tighter bore than I've seen in most engines with that many miles (4.0548 to be exact)

TheBac said:
Ah shit. Wouldve been nice to know this in 2010. Ive got 56,000 miles on the rebuild now. Might be time to do a compression check?
I was planning on tearing it down anyway once I swap to the other engine.
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It wouldn't hurt. At least it would tell ya how much life you have left
 
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