Bent valve?

[Randy]

Daily driver, 2000 RT, 79k miles on it. Started a louder-than-normal ticking sound a month or so back. And, no, not the normal Viper engine ticking sound - I'm on around 150,000 miles on two Vipers, this is louder, and gets worse when the engine is warm. With the hood open, does not seem to be coming from either exhaust pipe area, but rather more toward the top of the engine, toward the passenger side intake or valve cover. Checked the injectors with a stethoscope, and its not coming from any of the injectors. Then, on the way home from work yesterday, about a half-mile from the house, it got much louder, and the engine started running very badly; like the typical gen-1 failed ignition wires that will cause it to run like a mis-firing four-cylinder. Checked the engine in the dark with the hood open, no corona, electrical discharge or other visible ignition leakage, and now the louder ticking has increased to more of a *clacking*.

Pulled the passenger-side valve cover off, and was going down the line of removing the rocker arms to check for a bent pushrod, and found the middle cylinder front valve stem is not rising as high as the other valves:

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Its something like a quarter inch lower than all of the others with the rocker removed.

Looks like a bent valve to me - although I've can't recall ever red-lining or downshift-overrevved the engine, and for sure not recently.

Thoughts? Am I missing something?

Randy

 

[speedracervr4]

Maybe able to pull the plug and use a bore scope to verify.

 

[Viper Specialty]

First thought in my mind its a valve seat dropped, assuming it really hasnt been over revved. It could also be a bent valve from a lifter that had failed and pumped up somehow. Is the push rod bent too?

If you need, we can rebuild the head, supply a used or rebuilt core, new or used valves, or as much of a rebuild as needed.

We also supply all of the gaskets for this job, and are the supplier for "Lifter Provision" type head gaskets, as well as AFM replacements to get rid of all of the problematic paper gaskets in the engine.

 

[SHELBYVIPER]

A wiped out cam lobe lobe will cause this as well.

 

[Allan]

A wiped out cam lobe lobe will cause this as well.

.....how? .....the valve/spring assembly is jacked up with the rocker gear off. Look again at the picture.

 

[Allan]

First thought in my mind its a valve seat dropped, assuming it really hasnt been over revved. It could also be a bent valve from a lifter that had failed and pumped up somehow. Is the push rod bent too?

Yes,.... this is probably a dropped valve seat. I have seen that a few times before. ........Something less common, only seen it twice,....is the valve guide dropping into the port, not allowing the valve to close. A bent valve would look like that as well, but is the least likely unless the motor ate something. In any event, you'll have to pull the head to fix this.

 

[Solid Red 98]

I vote for a dropped seat. I have seen this before on a Honda. The seat was following the valve up and down causing strange and intermittent misfires and clacks/ticks. finally the seat jammed in an out position and yielded an image similar to yours. I took off the head and saw the surprise. Have fun....

 

[ROCKET62]

I had not heard of or seen a dropped valve seat - and this image pretty much explains it:

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not a viper btw.

 

[Randy]

So, in any event, the head is coming off. Thanks much for the feedback; I'll pull the head this weekend and see what surprise waits for me there...

Thanks again,

Randy

 

[ViperTony]

Since the heads are coming off great opportunity/excuse to get the greg good treatment done to them. Just sayin'.

 

[Randy]

Well, I was only planning on pulling the one head.

Randy

 

[Fatboy 18]

Please post pics, very interested to see whats lurking in there

 

[dirtysocks]

http://www.viperalley.com/forum/viper-discussions-gen-i/99511-new-viper-classified-gen.html

 

[2002_red_gts]

http://www.viperalley.com/forum/viper-discussions-gen-i/99511-new-viper-classified-gen.html

Thanks for that dirtysocks!

 

[Jack B]

Looks loke coolant was leaking?? Is that what caused the problem.

I had not heard of or seen a dropped valve seat - and this image pretty much explains it:

You must be registered for see images attach

not a viper btw.

 

[Randy]

Dan, Allan, and an anonymous local club member ("Solid Red 98") were right on the money: it was a dropped valve seat.

As it was the intake valve that wasn't seating, pulling the intake was enough to show it:

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for comparison, here's one of the other normal intake passages:

You must be registered for see images attach

So, pulled the head off, and found a similar picture to Rocket62's pic of a Honda head with a dropped valve seat:

You must be registered for see images attach

You must be registered for see images attach

And, the seat did contact the piston, enough to break through the 1/16th of carbon build up in the center of the piston and put a very slight scratch into the piston face:

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Whats the wisdom on this - is this piston scratch a big problem?


Randy

 

[AZTVR]

I had never heard of that failure mode before; but, I do not work or even play much in the engine building/modification/repair arena. Just a hobbyist. It sure doesn't seem that rare after I did a google search on : dropped valve seat .

Dan & Alan, I assume that it must be due to differential heating of the aluminum head and the valve seat, and probably less than optimal interference fit ? How does one get comfortable with the rest of the seats in the head?

 

[2002_red_gts]

I Bought a set off heads that had a dropped seat. I sent them to be ported and bigger valves so all the seats had to be removed with bigger seats installed. It is from the different expansion rates of the metals. The only real way to fell better about the head is to have the seats replaced or you can just replace the one seat and hope its all good

 

[2002_red_gts]

Dan, Allan, and an anonymous local club member ("Solid Red 98") were right on the money: it was a dropped valve seat.

As it was the intake valve that wasn't seating, pulling the intake was enough to show it:

You must be registered for see images attach

for comparison, here's one of the other normal intake passages:

You must be registered for see images attach

So, pulled the head off, and found a similar picture to Rocket62's pic of a Honda head with a dropped valve seat:

You must be registered for see images attach

You must be registered for see images attach

And, the seat did contact the piston, enough to break through the 1/16th of carbon build up in the center of the piston and put a very slight scratch into the piston face:

You must be registered for see images attach

Whats the wisdom on this - is this piston scratch a big problem?


Randy

I wouldnt worry about that piston at all. If its just a little scratch like you said your good to go

 

[Viper Specialty]

Whats the wisdom on this - is this piston scratch a big problem?

Knew it.

Personally, I would not use it. Chances are will will be fine yes, but it is not impossible that the piston has a micro-crack that will come back to haunt you later. Also, the bearing would be suspect, as well as the wrist pin. Replace the rod/piston/bearing, re-use the rings from that cylinder if not doing a full rebuild.

 

[Viper Specialty]

I had never heard of that failure mode before; but, I do not work or even play much in the engine building/modification/repair arena. Just a hobbyist. It sure doesn't seem that rare after I did a google search on : dropped valve seat .

Dan & Alan, I assume that it must be due to differential heating of the aluminum head and the valve seat, and probably less than optimal interference fit ? How does one get comfortable with the rest of the seats in the head?

Nearly always the result of a compromised manufacturing/installation, unless it occurs during the time an engine was overheated. I would not repair the single seat, I would replace all of them or the whole head. Not impossible it affected more than one. If you want to repair, change all of them, and be damn sure its done right.

This would be an oppertune time to port/polish heads, and larger valves with BC seats. Call Greg Good.