Experience with Broken JE Pistons

Mahler9th · 10-13-2006, 07:54 AM

Anyone out there have experience with broken JE pistons? Particularly in high compression ,3.4 to 3.8 liter engine applications? If you know of instances, please describe details, and post pics if you have them.

Steve@Rennsport · 10-13-2006, 08:33 AM

LOL,...I've seen my share of broken JE's.

Ring lands (not detonation related) and pin bosses are the main issues.

In one case, it cracked under the domes but those were experimental ones.

TimT · 10-13-2006, 11:50 AM

We never did figure out what caused this failure. There was to much carnage to perform a good forensic exam.

id911T · 10-13-2006, 12:28 PM

Tim,

How much racket did that make when it came unglued?

Otto · 10-13-2006, 03:58 PM

Wrist pin boss pulled out. I had several failures like this, MAHLE ONLY!

kenikh · 10-13-2006, 04:12 PM

The only bad thing with Mahle is that if you want a banana split, you get vanilla. If you want chocolate, you get vanilla. If you want ANYTHING, you get the flavor of their choice, then they charge you like it was custom mixed. Both Mahle and JE are disappointing in so many ways...

Steve@Rennsport · 10-13-2006, 04:44 PM

Quote:

Originally posted by kenikh
The only bad thing with Mahle is that if you want a banana split, you get vanilla. If you want chocolate, you get vanilla. If you want ANYTHING, you get the flavor of their choice, then they charge you like it was custom mixed. Both Mahle and JE are disappointing in so many ways...

Kenik:

Having used both products for a very long time, I think some perspective is needed here.

Your flavor analogies are correct but I'd disagree about pricing/value.

JE's are darn cheap for what you get and an economical alternative for those who either cannot afford Mahle's or need a custom configuration (which Mahle doesn't do in small quantities). One should never forget that JE's are made and intended as racing pistons and as such, perform their mission pretty well. Race engines get maintenance regimens that no street engine sees, (at least they should),........

Thankfully, JE will make anything you want for reasonable cost. Remember, you get what you pay for.

Mahle's comes in their own flavor, but they are still the best choice for those who demand longevity and reliability. If someone wants a Mahle in a size or CR that they do not currently offer, these must be be ordered in larger quantities (for substantial money) and patience is required for delivery. Still,.......there is nothing better as nobody has matched their metallurgy.

sww914 · 10-14-2006, 08:10 AM

Quote:

Originally posted by TimT
We never did figure out what caused this failure. There was to much carnage to perform a good forensic exam.

I think you can just hone that cylinder a little and slap a used piston in there. No problem.

JimCulp · 10-14-2006, 04:17 PM

Wow that's hard to look at.

MBEngineering · 10-15-2006, 10:29 AM

HI I pulled this out of a running engine with no prob's , no miss fire or under power, pulled the engine in bits for routine maintenance and found this?

It's a JE out of a 3.0lt engine.

regards mike

Brother · 10-15-2006, 05:59 PM

Quote:

Originally posted by sww914
I think you can just hone that cylinder a little and slap a used piston in there. No problem.

Motor Meister is hiring.

beepbeep · 10-15-2006, 11:37 PM

Quote:

Originally posted by MBEngineering
HI I pulled this out of a running engine with no prob's , no miss fire or under power, pulled the engine in bits for routine maintenance and found this? It's a JE out of a 3.0lt engine.

regards mike

Looks like typical pre-ignition/knock damage. I doubt Mahle would live trough that either.

turboteener · 10-16-2006, 07:34 AM

TimT, you need to check your wristpin boor clearance. I would bet it got too hot and siezed. Then yanked the pin out the bottom of the piston. You may also look at having all of your wristpins DLC coated. It will make a difference.

MBE, looks like it was run lean at some point and burned through the thinnest point. Perhaps the sharp edge created a hotspot right at the top of the valve pocket. I would radius the valve pockets. ALso notice the scuffing on the skirt. May have detonated the piston and forced it down. Is that the intake or exhaust side?

kenikh · 10-16-2006, 08:03 AM

I think the bottom line is that you should know your application. If you are using JEs in a street motor, run a CR commensurate with street use. A good quality piston should live a long and happy life as long as you aren't riding the line.

MBEngineering · 10-16-2006, 10:40 AM

HI Brett the meltdown is on the inlet side of the piston, the only thing I could find with the engine was the inlet valve guide was worn-out on that No 5 cylinder. Not any prob with the rest of the pistons.

regards mike

Boxer 6 · 10-16-2006, 11:42 AM

I always thought that a forged piston (i.e JE's) are much better than cast pistons such as the Mahles?

kenikh · 10-16-2006, 12:39 PM

Mahles are forged, except the lower end T and E pistons.

turboteener · 10-16-2006, 02:03 PM

A bad valve guide can allow oil into the cylinder. Oil will always lower the octane rating of any fuel. If the guide was bad enough I would venture to say the cylinder suffered some pre-ignition. This combined with a possible lean mixture and you really see some super high combustion temps. Although it is unusal to see this on the intake side of the piston.

Perhaps there was some contact with a foreign body, maybe a spark plug electrode or something going through the carb. How did the valve seat look? What about the spark plug?

MBEngineering · 10-17-2006, 02:33 AM

HI turboteener the engine is on MFI and the plugs are OK, the valve seat is also ok , and no damage to the head

Do you think this car has a engine prob', as the engine was inspected after this event, with no complaint from the driver of any loss of power.
I would also like to apologize to "Mahler9th" for hijacking the thread with the Q&A's.

regards mike

beepbeep · 10-17-2006, 05:57 AM

Apologize for hijacking the thread too.

Only thing I don't like with JE's is that material they use doesn't grow at same rate as cylinders, leading to lot's of piston slap on cold start until they heat-up.