Seized piston rings - JeepForum.com
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post #1 of 26 Old 06-30-2019, 04:37 AM Thread Starter
Dutch Arjan
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Seized piston rings

Hello, before explaining my problem I will first tell you some prehistory about what has been done about my XJ. It all started with a torn head (0331). The engine had 320,000 kilometers on the clock. In the end I chose to overhaul the entire engine myself. Everything is new except for the piston rods. The first start-up went fine and the engine ran very nicely. After less than 500 kilometers the engine wanted to start poorly and I replaced the fuel pump. The fuel pressure was much too low, but this was not the cause. It turned out that the compression was much too low! After I removed the pistons, it turned out that the piston rings were stuck and that the pistons were deformed. I have already checked the timing and this is correct.

You probably don't have enough information yet, but I hope we can start the dialogue and get to the cause of my problem.

Here some pictures:

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post #2 of 26 Old 06-30-2019, 06:57 AM
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Well, the photo shows a sizeable chunk missing from that one piston. I don't see any seizure or much scuffing on the visible side, but there isn't much to go on. I am curious as to why you stated "seized piston rings"? All of the damage I can see appears related to that chunk.

Can I assume you did the assembly work? Were the rods resized? Were the cylinders 'honed to fit'? Did you do a dummy-up to check for interference? Did you 'drop' a piston while working, or squeeze it in a press while doing wrist pins? Have you recovered the chunk or did it get under the valve? Were the rings installed upside down? Did you 'gap' and file the rings on install/? Were any rings bent or problematic on install? Did you pre-lube (oil) the rings before placing the head on?

Can we get pics of both sides and the other units?
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post #3 of 26 Old 06-30-2019, 07:51 AM
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ABOVE IS A NICE REPLY - I also have A lot of questions...
>>Pistons are +.030 - was this bored or used same size as removed?
>>Rings, the position, single dot double dot top bottom, chamfer*, to position ring, was end gap set?

As mentioned an luck finding missing piece?


*different ring manufacturer have different methods to ID top or lower ring and sometimes are mixed together, some lower rings with upper rings.

When I see the price of OEM I think aftermarket.
When I see the quality of aftermarket I think OEM.
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post #4 of 26 Old 06-30-2019, 09:05 AM Thread Starter
Dutch Arjan
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Hereby finally the answer to the questions asked. Sorry for the delay..

1. Well, the photo shows a sizeable chunk missing from that one piston: There is no piece missing. It is the angle of the photo that suggests that the piston is damaged.
2. Can I assume you did the assembly work?: Yes!
3. Were the rods resized?: The rods are stock, is that what you mean?
4. Were the cylinders 'honed to fit'?: The cylinders are bored +.030
5. Did you do a dummy-up to check for interference?: There was no interference while assembling the engine.
6. Did you 'drop' a piston while working, or squeeze it in a press while doing wrist pins?: No, I assembled the engine with the upmost precaution.
7. Were the rings installed upside down?: The rings are installed according the guidelines from the manufacturer. (Enginetech)
8. Did you 'gap' and file the rings on install/?: Yes, gapped it with a feelergage and all gaps are within spec.
9. Were any rings bent or problematic on install?: The rings were not bent. Installation wasn’t easy due to “escaping” rings from under the tool but eventually I succeeded.
10. Did you pre-lube (oil) the rings before placing the head on?? Prelubed cilinderwalls with WD40 and the rings with some oil.
11. Can we get pics of both sides and the other units?? Yes!
12. Pistons are +.030 - was this bored or used same size as removed?: Pistons were oversized delivered and new because the cylinders were also bored out.
13. Rings, the position, single dot double dot top bottom, chamfer*, to position ring, was end gap set?: See answer 7. Or perhaps I do not understand the question correctly?
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20190630_163838_resized.jpg   20190630_163829_resized.jpg   20190630_163845_resized.jpg  

Last edited by Dutch Arjan; 07-01-2019 at 04:53 AM. Reason: Completing post
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post #5 of 26 Old 07-01-2019, 06:28 AM Thread Starter
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I have just reacted to the questions asked. Please see previous post.
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post #6 of 26 Old 07-01-2019, 07:28 AM
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Is it normal to use WD40 upon assembly, being that it's a solvent and not a lubricant?

D3<!L!>3D
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post #7 of 26 Old 07-01-2019, 07:54 AM
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YES I am old and the eyes are not what they were.
But I see damage in picture - see attachment.
The piston has the same 'missing' appearance on all 6 pistons?

Gotta say I never heard of using WD40 as a break in oil, did you need to use starting fluid fluid to get engine running?

IDK "wasn’t easy due to “escaping” rings from under the tool but eventually I succeeded. " - this is confusing to me can you explain.

I am mentally searchig for a cause - nothing in my experience is helping make sense of images.
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When I see the price of OEM I think aftermarket.
When I see the quality of aftermarket I think OEM.
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post #8 of 26 Old 07-01-2019, 07:57 AM
jtec
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how did you check ring end gap?

When I see the price of OEM I think aftermarket.
When I see the quality of aftermarket I think OEM.
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post #9 of 26 Old 07-01-2019, 11:06 AM Thread Starter
Dutch Arjan
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Hi, I've only used it for the bores. The piston & rings got lubed with engine oil.
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post #10 of 26 Old 07-01-2019, 12:19 PM Thread Starter
Dutch Arjan
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YES I am old and the eyes are not what they were. But I see damage in picture.
The piston has the same 'missing' appearance on all 6 pistons?: The pistons are not damaged. I'll post a picture from another angle.

Gotta say I never heard of using WD40 as a break in oil, did you need to use starting fluid fluid to get engine running? I used an American engine oil (Gibbs?) breaking oil high in ZDDP. The engone started right up with the first crank.

IDK "wasn’t easy due to “escaping” rings from under the tool but eventually I succeeded. " - this is confusing to me can you explain.: To insert the piston I used a ring tool to compress the rings in the piston. This wasn't easy means that it gave some troubles but in the end, when I got the hang of it, it worked just fine.

I'm also searching for possible faults but everything checks out. I've also been to a Jeep mechanic and he says he has not seen anything like this. But... when I told him the pistons were from Enginetech he said he didn't have good experience with this brand.

I've also suspected the CPS but it must be okay because the startup would not be possible. The engine worked fine during the breakin procedure. (10min 2000 rpm, 10min 2.500 rpm and 10min at 1.800 rpm)

Please advice!
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post #11 of 26 Old 07-01-2019, 12:32 PM
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Well, I guess we should ask you what was happening that caused you to shut down and disassemble the motor? Giving out an explanation of what occurred to cause you to stop may be useful.
That portion of the piston pic below the oil control looks to be unfinished/not machined/broken off a bit. You are absolutely certain that each piston looks like that?
The carbon residue and flame pattern look pretty normal for a center-fed 6 cylinder, but maybe a tiny bit rich.

What is 'deformed' about the pistons as you stated?

Reconditioning the rods is necessary when re-using parts. Were the big end and little end checked for runout?

Boring the block .030 over is only part of the new piston process. The pistons should be measured for individual fit to each bore, and typically the machinist would make a final pass to gain proper clearance for later heat expansion.

Yes, I've sprayed WD-40 on cylinder surfaces for storage, but it should be removed for pre-assembly lubing with oil. The pistons will friction drag a little because the oil won't stick at first.

The end gap on the #1 piston upper ring (1st pic) is considerably wider than the gap I see on the #3 upper ring. Did a piece of ring break off above where the (apparent ring land) damage seems to be???
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post #12 of 26 Old 07-01-2019, 12:35 PM Thread Starter
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Quote:
Originally Posted by jtec View Post
how did you check ring end gap?
I used a feelergage the measure the ring gap
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post #13 of 26 Old 07-01-2019, 01:33 PM Thread Starter
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Quote:
Originally Posted by gutthans View Post
Well, I guess we should ask you what was happening that caused you to shut down and disassemble the motor? Giving out an explanation of what occurred to cause you to stop may be useful.
That portion of the piston pic below the oil control looks to be unfinished/not machined/broken off a bit. You are absolutely certain that each piston looks like that?
The carbon residue and flame pattern look pretty normal for a center-fed 6 cylinder, but maybe a tiny bit rich.

What is 'deformed' about the pistons as you stated?

Reconditioning the rods is necessary when re-using parts. Were the big end and little end checked for runout?

Boring the block .030 over is only part of the new piston process. The pistons should be measured for individual fit to each bore, and typically the machinist would make a final pass to gain proper clearance for later heat expansion.

Yes, I've sprayed WD-40 on cylinder surfaces for storage, but it should be removed for pre-assembly lubing with oil. The pistons will friction drag a little because the oil won't stick at first.

The end gap on the #1 piston upper ring (1st pic) is considerably wider than the gap I see on the #3 upper ring. Did a piece of ring break off above where the (apparent ring land) damage seems to be???
Hi Gutthans, thanks for replying!

I've decided to rebuild the motor because the head (0331) was cracked. Then discovered that all the bearings were worn out. The motor has 323.000 kilometers on the clock and the rebuild was necessary.

I'm absolutely certain that the pistons are not broken or missing a peace. All the pistons look this way.

The pistons look a little wet because I performed a dry and wet leak down test to establish were the compression was lost.

With deformed I mean that the piston were under so much pressure that the pistons were pressed in what caused the top ring to get seized up in the groove.Thats what the machinist told me after he examined the pistons.

Reconditioning the rods is necessary when re-using parts. Were the big end and little end checked for runout? Yes, this was done by the machinist.

Boring the block .030 over is only part of the new piston process. The pistons should be measured for individual fit to each bore, and typically the machinist would make a final pass to gain proper clearance for later heat expansion. This was also done by the machinist.

The end gap on the #1 piston upper ring (1st pic) is considerably wider than the gap I see on the #3 upper ring. Did a piece of ring break off above where the (apparent ring land) damage seems to be??? I see what you mean but the first ring is completely stuck in the groove but the second ring is not. It is not broken.
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post #14 of 26 Old 07-01-2019, 02:11 PM
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If all or most of the rings are 'stuck', and the pistons are deformed from the top down (squished) then I would have to guess that only one of 3 things caused this: 1.the decking height was incorrect 2. the gasket used was not for the 4.030 opening or 3. While running the motor suddenly hydrolocked (sucked in water) and caused all 6 pistons to marginally compress

I have never seen a motor put together with either condition above, and the one hydrolock I saw bent rods. But I would have to guess one of those 3 errors.
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post #15 of 26 Old 07-02-2019, 02:47 AM Thread Starter
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Quote:
Originally Posted by gutthans View Post
If all or most of the rings are 'stuck', and the pistons are deformed from the top down (squished) then I would have to guess that only one of 3 things caused this: 1.the decking height was incorrect 2. the gasket used was not for the 4.030 opening or 3. While running the motor suddenly hydrolocked (sucked in water) and caused all 6 pistons to marginally compress

I have never seen a motor put together with either condition above, and the one hydrolock I saw bent rods. But I would have to guess one of those 3 errors.
Thanks,

Hydrolock is out of the question because the rods are still straight. I will check the other 2 options...
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