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Roughly 75% power loss and metallic slapping noise

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Old 07-09-2018, 10:33 PM
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Roughly 75% power loss and metallic slapping noise

I have an 86 pickup with a 22r. I rebuilt the motor 17,500 miles ago and it's been running perfectly until a sudden failure today. Without any warning signs at all it suddenly lost about 75% of it's power and the motor started making a very noticeable metallic slapping noise that went along with the engine RPMs. I of course pulled over and had the truck towed. Any thoughts on what this possibly could be? One possible guess that I had was that maybe the timing chain tensioner somehow failed and the timing chain slacked off and skipped a tooth. Perhaps? That may be the best scenario. Or perhaps a piston rod broke? This seems less likely but I'm not sure what else would make the slapping noise I was hearing. These things just seem so unlikely because it's such a fresh rebuild... But perhaps I didn't tighten something properly... Or a random premature failure has simply taken place... The oil level was perfectly full and the engine temperature never went outside the normal range. Will have to tear into it when I get a chance.
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Old 07-10-2018, 12:32 AM
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Red face

Easy to pull the valve cover and look down at the timing chain
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Old 07-10-2018, 04:15 PM
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So here's what I found after popping off the valve cover. Broken valve spring. The slapping I heard was clearly the rocker arm slapping loosely back and forth. Perhaps also the valve hitting the piston head? What are the chances that the valve collided with the top of the piston? These were all brand new valve springs from engnbldr 17,500 miles ago. What may have caused a valve spring to break like this? The truck was running beautifully until out of nowhere this happened. Well... I'm off to drain the oil and see if it has a story to tell...



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Old 07-10-2018, 04:30 PM
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Just drained the oil. It looks great. No metal bits or silver metal particles whatsoever. Just a nice medium brown color.
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Old 07-10-2018, 04:53 PM
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Originally Posted by irv View Post
What are the chances that the valve collided with the top of the piston? These were all brand new valve springs from engnbldr 17,500 miles ago. What may have caused a valve spring to break like this? The truck was running beautifully until out of nowhere this happened. Well... I'm off to drain the oil and see if it has a story to tell...
Us guessing won't really accomplish much. But, is the valve stuck or will it move up/down?
Simplest thing would be to pull the spark plug and look in there with a scope. However, to thoroughly inspect and repair you'll have to pull the head off.
Also, thoroughly look at the spring and rocker etc to see if there are any pieces missing. You know where they will go.That may tell you they why.
A very close up of both ends of the spring break would be interesting to see.
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Old 07-10-2018, 05:06 PM
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Originally Posted by L5wolvesf View Post
Us guessing won't really accomplish much. But, is the valve stuck or will it move up/down?
Simplest thing would be to pull the spark plug and look in there with a scope. However, to thoroughly inspect and repair you'll have to pull the head off.
Also, thoroughly look at the spring and rocker etc to see if there are any pieces missing. You know where they will go.That may tell you they why.
A very close up of both ends of the spring break would be interesting to see.
Well I don't know a ton about this kind of stuff. I do the work myself but I'm always learning as I go. I didn't know if perhaps someone would inform me that it's not possible for a valve to hit a piston head on a 22r. That would be good news but I'm not holding my breath. The oil is nice and clean which is a good sign that a hole wasn't punched through the piston. But, however, I can't pull up on the valve stem very far at all which seems to me as a sign it may be bent.
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Old 07-10-2018, 05:17 PM
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One big thing I'm wondering is whether this new valve spring was faulty and just broke out of nowhere for no apparent reason or if the broken valve spring is a consequence of some other primary factor... Even though they are all brand new, I'm now suspect of all these valve springs.
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Old 07-10-2018, 06:14 PM
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Originally Posted by irv View Post
Well I don't know a ton about this kind of stuff. I do the work myself but I'm always learning as I go. I didn't know if perhaps someone would inform me that it's not possible for a valve to hit a piston head on a 22r. That would be good news but I'm not holding my breath. The oil is nice and clean which is a good sign that a hole wasn't punched through the piston. But, however, I can't pull up on the valve stem very far at all which seems to me as a sign it may be bent.
It is possible for a valve to hit a piston head on a 22r - like if the timing chain slips/breaks. Can you see into the cover to see if anything is wrong?
Yeah the valve sounds like it's bent - can you turn it at all?

Originally Posted by irv View Post
One big thing I'm wondering is whether this new valve spring was faulty and just broke out of nowhere for no apparent reason or if the broken valve spring is a consequence of some other primary factor... Even though they are all brand new, I'm now suspect of all these valve springs.
Check the timing chain - if that slipped the valve could just have been the victim of that.
A very close up pic of the broken spring ends would be interesting.
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Old 07-10-2018, 06:36 PM
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The spark plug had a bad story to share with me.

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Old 07-10-2018, 06:42 PM
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Originally Posted by L5wolvesf View Post
It is possible for a valve to hit a piston head on a 22r - like if the timing chain slips/breaks. Can you see into the cover to see if anything is wrong?
Yeah the valve sounds like it's bent - can you turn it at all?



Check the timing chain - if that slipped the valve could just have been the victim of that.
A very close up pic of the broken spring ends would be interesting.
The timing chain looks ok from what I can see. Tensioner seems good and everything seems tight and in place like it should be. I am however not able to turn the motor over by hand at the moment. Not sure why. Here is a pic of the broken valve spring. That one break is the only damage to the spring. Just a single break right in the middle.

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Old 07-10-2018, 07:13 PM
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Originally Posted by irv View Post
The spark plug had a bad story to share with me.
Originally Posted by irv View Post
The timing chain looks ok from what I can see. Tensioner seems good and everything seems tight and in place like it should be. I am however not able to turn the motor over by hand at the moment. Not sure why. Here is a pic of the broken valve spring. That one break is the only damage to the spring. Just a single break right in the middle.
When I saw the spark plug I had a thought that the piston came up to do that. Saying not able to turn the motor over by hand follows that pattern. The noise you heard may have been a rod loosening. Is dropping the pan easy on your truck?
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Old 07-10-2018, 08:59 PM
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I am able to turn it over by hand, my mistake.

However I have removed the head. The entire engine is toast. The valve was snapped off and jammed into the piston which is beat to death. The block is cracked. The head is marred up beyond salvaging.

This is pretty unbelievable. This was a brand new rebuild with less than 20k miles on it. It had brand new piston heads, rings, valves, valve springs, water pump, oil pump, timing chain, bearings, etc etc etc. Every single part was brand new. It had been running absolutely beautifully. I have no idea how this happened. All I can gather is that that one valve spring inexplicable broke in half and dropped the valve down onto the piston head and all hell broke loose. I'll share pictures tomorrow when I've got some daylight.

Last edited by irv; 07-11-2018 at 01:16 AM.
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Old 07-11-2018, 12:34 AM
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Red face

I would guess just pure bad luck about like what I have.

A flaw in the steel the valve spring was made from just got to the point it failed .

Looking forward to the rest of the pictures

Was this block bored ??
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Old 07-11-2018, 12:47 AM
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Originally Posted by wyoming9 View Post
I would guess just pure bad luck about like what I have.

A flaw in the steel the valve spring was made from just got to the point it failed .

Looking forward to the rest of the pictures

Was this block bored ??
Yeah what a bummer, huh? Maybe it's time for a 2.7 or a 3.4 swap... Nope the block wasn't bored over. Just honed the walls for the rebuild and used brand new stock sized pistons. Yeah I'll def share some pics.
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Old 07-11-2018, 11:19 AM
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Old 07-11-2018, 11:23 AM
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Old 07-11-2018, 11:24 AM
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Pictures of the carnage above. Interestingly a little piece broke off the front of the engine block - right where that small additional bolt connects to the block from the head.
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Old 07-11-2018, 12:45 PM
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From looking things over further it's clear that broken bits of the intake valve and piston head from #2 cylinder were kicked back up into the intake manifold and were then distributed into the other cylinders.
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Old 07-12-2018, 06:44 PM
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How long did you run it like that?
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