Cast Piston Failure
11-27-2015, 02:38 AM
#1
Le Mans Master
Thread Starter
Cast Piston Failure
I thought I would share this just for your enjoyment.
My Nephew called with a noise in his 99 Jeep.
I told him to drive it over and we can listen to it. He says not possible it quit running. We trailered it to my house and diagnosed something really bad had happened.
Pulled the engine and opened it up.
After seeing the damage I did some checking and it turns out these engines had weak pistons and they tend to break skirts when they get older. My 19 year old nephew learned a hard lesson in the car he saved up and purchased. When you hear something odd shut it down.
Unfortunately he thought he was close to home so why not drive it.
He is a great kid, doing well in college and sports and now he is learning Engine Rebuilding.
On this forum we have discussed the merits of Forged or Cast pistons.
A forged piston will bend in failure but not break up. This Cast piston is a poster child for why Forged Pistons are better.
The Junk in the bucket was all in the oil pan, you can see many piston pieces and Piston Ring Pieces, nothing larger than 1" in size left from a 3.785 size piston.
Note the piston pin still in the Rod but the entire piston is gone.
We are searching for a new block now to rebuild and install.
My Nephew called with a noise in his 99 Jeep.
I told him to drive it over and we can listen to it. He says not possible it quit running. We trailered it to my house and diagnosed something really bad had happened.
Pulled the engine and opened it up.
After seeing the damage I did some checking and it turns out these engines had weak pistons and they tend to break skirts when they get older. My 19 year old nephew learned a hard lesson in the car he saved up and purchased. When you hear something odd shut it down.
Unfortunately he thought he was close to home so why not drive it.
He is a great kid, doing well in college and sports and now he is learning Engine Rebuilding.
On this forum we have discussed the merits of Forged or Cast pistons.
A forged piston will bend in failure but not break up. This Cast piston is a poster child for why Forged Pistons are better.
The Junk in the bucket was all in the oil pan, you can see many piston pieces and Piston Ring Pieces, nothing larger than 1" in size left from a 3.785 size piston.
Note the piston pin still in the Rod but the entire piston is gone.
We are searching for a new block now to rebuild and install.
Last edited by Westlotorn; 11-27-2015 at 02:43 AM.
11-27-2015, 08:01 AM
#2
Race Director
Wow - I bet it was making a bunch of noise the rest of the way home.
11-27-2015, 08:20 AM
#3
Race Director
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That is an impressive fail!!!!!!
11-27-2015, 08:40 AM
#5
Racer
what a mess.... hard to tell from the pics but it looks like it may be a 4 cyl as the 4.0 6 cyl distributor would show in the pic.
I have a 1996 4.0 6 cyl Jeep Cherokee with 110,000 on it...runs like a top and a great engine...I have no clue if it has forged or cast pistons but it is certainly something I will be aware of in the future....
I have a 1996 4.0 6 cyl Jeep Cherokee with 110,000 on it...runs like a top and a great engine...I have no clue if it has forged or cast pistons but it is certainly something I will be aware of in the future....
11-27-2015, 09:26 AM
#6
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Can the block, rod, and crank be saved or not, and is it worth even trying?
Last edited by Easy Rhino; 11-27-2015 at 09:26 AM.
11-27-2015, 10:26 AM
#7
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11-27-2015, 11:47 AM
#8
Race Director
what a mess.... hard to tell from the pics but it looks like it may be a 4 cyl as the 4.0 6 cyl distributor would show in the pic.
I have a 1996 4.0 6 cyl Jeep Cherokee with 110,000 on it...runs like a top and a great engine...I have no clue if it has forged or cast pistons but it is certainly something I will be aware of in the future....
I have a 1996 4.0 6 cyl Jeep Cherokee with 110,000 on it...runs like a top and a great engine...I have no clue if it has forged or cast pistons but it is certainly something I will be aware of in the future....
I had an '87 Cherokee 4.0 6 cyl that went 225,000 miles as a family car and then for 2 daughters at different colleges. It ran like a champ until UCLA campus maintenance dropped a tree on it............
11-27-2015, 12:03 PM
#9
Melting Slicks
DANG, Another all original, matching numbers Jeep ruined! May as well put a SBC in while he's at it! I was "forced" to put a SBC in my old Toyota FJ40 since the head cracked and were $$$ back in the 80's and probably $$$$$ now.
11-27-2015, 12:08 PM
#10
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Have seen many cast piston failures. They are cheap and run quietly, so they are a favorite with the manufacturers. A 17 year old Jeep doesn't really owe you anything. BTDT. My advice, forget the rebuild and install a reman or boneyard engine and run it. The cost of you doing the rebuild will eclipse the value of the vehicle easily, unless it is a CJ. If it's a CJ, worth doing for sure. Good luck!
11-27-2015, 12:25 PM
#11
Race Director
Wow, epic fail!
11-27-2015, 01:53 PM
#12
Le Mans Master
Thread Starter
The block can't be saved without a sleeve and I don't think enough material is left to support a sleeve so I am looking for a block. Reading on line some of these engines crack pistons between 60 and 150,000 miles. A weak piston skirt from the factory.
A better cast piston would have survived no problem but this one has a defect.
I did read it happened in 4.0L and 2.5L engines and the aftermarket pistons have corrected the weakness.
So no matter what block we find with high or low miles we have decided to install new pistons and rings plus Main Rod and Cam bearings. I have a great Machine Shop I trust that gives me modern cylinder finish. I have never built an engine with his work on the cylinders that used any oil at all. The sad thing is the rest of this engine looked great internally at 135,000 miles, it could have run a long time as most modern engines will.
I was leaning to an upgrade to the 4.0L but discovered the Trans, Transfer case and Rear end are all lightweight parts that work well with the 4 cyl but are not strong enough to handle the power in a larger engine so we will build it back to factory stock.
Thanks for letting me vent. BTW my Vette is still waiting for time to rebuild it while other priorities keep stepping in front of it. The good news is my nephew seems to really enjoy wrenching so I have gained a helper and he is getting better with tools.
Hope you all had a great Thanksgiving.
Mark
A better cast piston would have survived no problem but this one has a defect.
I did read it happened in 4.0L and 2.5L engines and the aftermarket pistons have corrected the weakness.
So no matter what block we find with high or low miles we have decided to install new pistons and rings plus Main Rod and Cam bearings. I have a great Machine Shop I trust that gives me modern cylinder finish. I have never built an engine with his work on the cylinders that used any oil at all. The sad thing is the rest of this engine looked great internally at 135,000 miles, it could have run a long time as most modern engines will.
I was leaning to an upgrade to the 4.0L but discovered the Trans, Transfer case and Rear end are all lightweight parts that work well with the 4 cyl but are not strong enough to handle the power in a larger engine so we will build it back to factory stock.
Thanks for letting me vent. BTW my Vette is still waiting for time to rebuild it while other priorities keep stepping in front of it. The good news is my nephew seems to really enjoy wrenching so I have gained a helper and he is getting better with tools.
Hope you all had a great Thanksgiving.
Mark
11-27-2015, 02:11 PM
#13
Team Owner
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A long time ago, I was cruising in my '56 Bel Air. It suddenly developed and engine miss. No noise, just a dead miss.
I found the offending cylinder. NO compression, plug was crappy. Couldn't figure what was wrong unless I just blew a big hole in a piston but I kept drving it until the week end when I could work on it.
When I pulled the head, the top of the piston from the ring lands up with the rings intact were sitting in the top of the cylinder. In the meantime the rod and piston skirt were merrily running up and down in the bore without hurting anything.
265's were notorious for cracking just above the steel insert cast in the piston skirt for reinforcement and that's where the piston broke.
A new piston and ring set in that cylinder along with a little sandpaper finish on the bore and I was on my merry way again.
I found the offending cylinder. NO compression, plug was crappy. Couldn't figure what was wrong unless I just blew a big hole in a piston but I kept drving it until the week end when I could work on it.
When I pulled the head, the top of the piston from the ring lands up with the rings intact were sitting in the top of the cylinder. In the meantime the rod and piston skirt were merrily running up and down in the bore without hurting anything.
265's were notorious for cracking just above the steel insert cast in the piston skirt for reinforcement and that's where the piston broke.
A new piston and ring set in that cylinder along with a little sandpaper finish on the bore and I was on my merry way again.
Last edited by MikeM; 11-27-2015 at 02:12 PM.
11-27-2015, 03:50 PM
#14
Le Mans Master
Thread Starter
A long time ago, I was cruising in my '56 Bel Air. It suddenly developed and engine miss. No noise, just a dead miss.
I found the offending cylinder. NO compression, plug was crappy. Couldn't figure what was wrong unless I just blew a big hole in a piston but I kept drving it until the week end when I could work on it.
When I pulled the head, the top of the piston from the ring lands up with the rings intact were sitting in the top of the cylinder. In the meantime the rod and piston skirt were merrily running up and down in the bore without hurting anything.
265's were notorious for cracking just above the steel insert cast in the piston skirt for reinforcement and that's where the piston broke.
A new piston and ring set in that cylinder along with a little sandpaper finish on the bore and I was on my merry way again.
I found the offending cylinder. NO compression, plug was crappy. Couldn't figure what was wrong unless I just blew a big hole in a piston but I kept drving it until the week end when I could work on it.
When I pulled the head, the top of the piston from the ring lands up with the rings intact were sitting in the top of the cylinder. In the meantime the rod and piston skirt were merrily running up and down in the bore without hurting anything.
265's were notorious for cracking just above the steel insert cast in the piston skirt for reinforcement and that's where the piston broke.
A new piston and ring set in that cylinder along with a little sandpaper finish on the bore and I was on my merry way again.
The engine will be built again with Cast Pistons, Hypereutectic this time around, most passenger car engines today run this type piston and they work just fine. In our Vette engines that run high compression and old technology fuel and ignition systems the Forged Piston is money well spent to protect all those "numbers matching blocks". You can see how a cast piston can quickly move your numbers match engine into a scrap heap.
Last edited by Westlotorn; 11-27-2015 at 03:54 PM.
11-27-2015, 05:30 PM
#15
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Yep and a dropped valve on a cast piston is usually a disaster too.
After the above fiasco, I dropped a valve in one cylinder and many of the parts and pieces from that blew back through the intake and took out six more piston tops. Hammered the tops of the pistons down to seize the rings in the ring grooves.
Again a little more sandpaper on the bores, seven new pistons/rings and I was on my way again.
It was cold that day that I fixed it. About 20*F laying on my back on railroad gravel in a parking lot. Saving grace was I think piston were only $2.50 back then.
After the above fiasco, I dropped a valve in one cylinder and many of the parts and pieces from that blew back through the intake and took out six more piston tops. Hammered the tops of the pistons down to seize the rings in the ring grooves.
Again a little more sandpaper on the bores, seven new pistons/rings and I was on my way again.
It was cold that day that I fixed it. About 20*F laying on my back on railroad gravel in a parking lot. Saving grace was I think piston were only $2.50 back then.
11-27-2015, 09:00 PM
#16
Le Mans Master
The block can't be saved without a sleeve and I don't think enough material is left to support a sleeve so I am looking for a block. Reading on line some of these engines crack pistons between 60 and 150,000 miles. A weak piston skirt from the factory.
A better cast piston would have survived no problem but this one has a defect.
I did read it happened in 4.0L and 2.5L engines and the aftermarket pistons have corrected the weakness.
So no matter what block we find with high or low miles we have decided to install new pistons and rings plus Main Rod and Cam bearings. I have a great Machine Shop I trust that gives me modern cylinder finish. I have never built an engine with his work on the cylinders that used any oil at all. The sad thing is the rest of this engine looked great internally at 135,000 miles, it could have run a long time as most modern engines will.
I was leaning to an upgrade to the 4.0L but discovered the Trans, Transfer case and Rear end are all lightweight parts that work well with the 4 cyl but are not strong enough to handle the power in a larger engine so we will build it back to factory stock.
Thanks for letting me vent. BTW my Vette is still waiting for time to rebuild it while other priorities keep stepping in front of it. The good news is my nephew seems to really enjoy wrenching so I have gained a helper and he is getting better with tools.
Hope you all had a great Thanksgiving.
Mark
A better cast piston would have survived no problem but this one has a defect.
I did read it happened in 4.0L and 2.5L engines and the aftermarket pistons have corrected the weakness.
So no matter what block we find with high or low miles we have decided to install new pistons and rings plus Main Rod and Cam bearings. I have a great Machine Shop I trust that gives me modern cylinder finish. I have never built an engine with his work on the cylinders that used any oil at all. The sad thing is the rest of this engine looked great internally at 135,000 miles, it could have run a long time as most modern engines will.
I was leaning to an upgrade to the 4.0L but discovered the Trans, Transfer case and Rear end are all lightweight parts that work well with the 4 cyl but are not strong enough to handle the power in a larger engine so we will build it back to factory stock.
Thanks for letting me vent. BTW my Vette is still waiting for time to rebuild it while other priorities keep stepping in front of it. The good news is my nephew seems to really enjoy wrenching so I have gained a helper and he is getting better with tools.
Hope you all had a great Thanksgiving.
Mark
Put a 5/32 wall sleeve in it and let her rip.
11-27-2015, 09:21 PM
#17
Melting Slicks
11-27-2015, 09:27 PM
#18
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Because forged pistons don't have the cast-in steel reinforcing strut used in cast pistons to manage expansion and reduce piston-to-bore running clearance; forged pistons don't have that compensating strut, so they require more running clearance, which can result in "piston slap" at cold-start condition. 
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SI67 (11-28-2015)
11-27-2015, 10:16 PM
#19
Le Mans Master
Thread Starter
The newest Forged Piston Designs, at least the Sealed Power design is not shaped like the old 1960 piston. There is good knowledge today about what parts of the piston grow under heat and they can use the new CNC machines to cut the piston in a shape that leaves clearance where needed. Given that the new forged pistons can be installed at .0015 to .0025 in general, see the exact recommendation by part number.
This allows the forged pistons to run a quiet as a cast piston today. A big improvement.
In the old days forged pistons would always rattle on cold start and then quiet down.
The old pistons needed .0045 or more. The newer forged are much better.
This allows the forged pistons to run a quiet as a cast piston today. A big improvement.
In the old days forged pistons would always rattle on cold start and then quiet down.
The old pistons needed .0045 or more. The newer forged are much better.
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SI67 (11-28-2015)
11-28-2015, 11:43 AM
#20
Le Mans Master
If you run the stock CAST pistons in either a Chevy small block or a big block and rev the engine over 6000rpm regularly, they will ALL do that.
Last edited by 63Corvette; 11-28-2015 at 12:16 PM.