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Fixing my burned valve...


xtremerevolution
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This is on my 95 Regal, L27. This has been happening for a while now. While the car is in idle, there's a light puttering sound coming from the exahust, and its repetitive.

 

 

If you listen for it, you'll hear it during the idle clips. Its a puttering sound that's very repetitive and predictable. The car pulls hard and has plenty of power, and there aren't any SES codes thrown. It idles decently well and doesn't fluctuate much at all.

 

Any idea on what this could be? If you put your hand toward the exhaust, you can feel the exhaust blowing bursts of air during the puttering sounds. Try to listen for bursts of air. Is this normal?

 

Magnaflow straight through muffler. 4-5 years old, 80-90k miles.

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i'm not sure what's meant by puttering, and there is too much background noise in that video, but how old is your timing set? if the chain/sprockets are worn, it could have enough slack to do something like this.

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if you want to get technical, the ones for the 660s are supposed to last quite some time as well, but when the chain gets stretched enough, it can exhibit some of the same symptoms... it also acts as a slight cam retard, killing some lower end torque for higher RPM power...

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That sounds like an intermittent misfire to me.

 

My old 6000LE had an issue with that once. Drove me crazy testing and replacing parts until I found that one brand new plug wire or plug was bad out of the box.

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That sounds like an intermittent misfire to me.

 

My old 6000LE had an issue with that once. Drove me crazy testing and replacing parts until I found that one brand new plug wire or plug was bad out of the box.

 

How did you figure out which plug was bad?

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I had to do this on the corvair when it was misfiring. I dunno if the same concept applies to newer engines.

 

I removed one wire from the distributor at a time, and if it made the engine run worse I knew that cylinder was firing.

I kept going until I found the one that did not change how the engine ran and I fixed the problem from there.

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The thing is, I've heard what this engine sounds like with a misfire and it doesn't sound like its misfiring. There's plenty of power. But I'll still try your method just to be 100% sure.

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How did you figure out which plug was bad?

 

Poking around and a bit of trial and error really. I had looked at so many other bits, and had not thought that the new parts I had put on a week or so prior would be the issue. Finally, I just pulled the plugs one by one and saw that the #1 plug wire was a little burned at the end of the boot. Replaced that plug and wire, and the car ran wonderfully (after relearning the idle).

 

I should also note that mine was bad enough that the car began randomly stalling when approaching stop lights, and got real bad at idle sometimes (though sometimes it ran 100%). Once I revved it up pretty good though, it very rarely acted strange.

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Your engine is old and getting tired..

 

If you wanna know more specifically, you have a slightly burned exhaust valve and it will just slowly continue to get work just like ANY engine thats had the shit ran outta it.

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Your engine is old and getting tired..

 

If you wanna know more specifically, you have a slightly burned exhaust valve and it will just slowly continue to get work just like ANY engine thats had the shit ran outta it.

 

Work or worse?

 

Here's to hoping it will get to 300k miles. It still pulls very strong and hard. I'll probably get a valve job done when I port the heads this summer.

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Your engine is old and getting tired..

 

If you wanna know more specifically, you have a slightly burned exhaust valve and it will just slowly continue to get work just like ANY engine thats had the shit ran outta it.

 

Work or worse?

 

Here's to hoping it will get to 300k miles. It still pulls very strong and hard. I'll probably get a valve job done when I port the heads this summer.

 

worse.. oops

 

If you wanna get to 300K miles you need to never go above 4000rpm ever again..

 

Valve job wont do a damn bit of good when burning a valve normally also burns the hardened valve seat on the head on high mileage engines or wears it past the point of good use.

 

Just drive the car like grandma intended dude.. Your engine is old now.

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Your engine is old and getting tired..

 

If you wanna know more specifically, you have a slightly burned exhaust valve and it will just slowly continue to get work just like ANY engine thats had the shit ran outta it.

 

Work or worse?

 

Here's to hoping it will get to 300k miles. It still pulls very strong and hard. I'll probably get a valve job done when I port the heads this summer.

 

worse.. oops

 

If you wanna get to 300K miles you need to never go above 4000rpm ever again..

 

Valve job wont do a damn bit of good when burning a valve normally also burns the hardened valve seat on the head on high mileage engines or wears it past the point of good use.

 

Just drive the car like grandma intended dude.. Your engine is old now.

 

Hmm, I doubt I'll be able to do that. Too much fun going WOT.

 

Can't you replace a valve seat? I know you could on aluminum heads, but I never bothered to check if it was possible on iron heads.

 

Looks like I'll have to start saving for an L67 swap. :biggrin:

 

How many more miles do you suppose I can continue to drive this thing? I'd think a burned valve would cause a huge reduction in compression, but like I said, the car still pulls very hard and strong.

 

For the record, low mileage L27 cylinder heads go for pretty cheap.

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it can be done on iron heads... back in the early 70s when leaded gas was getting phased out, you needed hardened valve seats because of the new gas. not too many manufacturers were using aluminum by then...

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something interesting i read lately: EGR helps cool the exhaust valves. makes sense seeing that EGR reduces peak combustion temps...

 

That is true. I did replace my EGR valve once as it had failed, and it only ran from Vegas to LA with that bad EGR valve. Can't imagine it would have done much damage in that time.

 

I'm very tempted to do a compression check. One would think that if I have a badly burned exhaust valve that I would have pretty bad compression on one of the cylinders. One would also think that my performance would suffer.

 

Edit...I'll do a compression test tomorrow. That should definitely determine if I have a burned valve.

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it can be done on iron heads... back in the early 70s when leaded gas was getting phased out, you needed hardened valve seats because of the new gas. not too many manufacturers were using aluminum by then...

 

My Corvair doesn't need lead gas. :mrgreen: Another win for the Corvair.

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Edit...I'll do a compression test tomorrow. That should definitely determine if I have a burned valve.

 

Not a bad idea at all. I wasn't going to jump to the conclusion that there was a burned valve until checking other easy things, but the sound of a burned valve is definitely like the sound heard in the video.

 

My old '86 Fiero burned a valve, and it ran just like your car does now. I noticed over time that it didn't get the same fuel economy more than anything else, since it ran fine with the throttle open. Believe me, with the barely 90 horsepower the Iron Duke in that car put out, it still saw WOT all the time out of necessity! :lol: At any rate, I drove it nearly at least 10k miles like that and it was still running when I sold it (ironically enough to someone who planned on L67 swapping it).

 

I say if you plan on L67 swapping, just keep driving it and gather up the parts you need. If you want to fix it, get a low milage head and stick it on there (or rebuild the ones you've got now).

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My best bet will be a new set of heads if it is a burned valve, since doing a valve job on the current heads will probably be a lot more expensive. I'll pick up a compressor while I'm at it and port those heads a bit as well.

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Valve is burned, 100% sure. Did the old dollar on exhaust trick, and it sucked it in and blew it out repeatedly. Found a local shop who will do a valve job for $240 plus parts. My $2500+ tax return will pay for that. Alternately, I can get heads with 85k miles for $150 plus shipping. New valve and valve guide would be $40 per valve in parts. What do you guys think?

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Valve is burned, 100% sure. Did the old dollar on exhaust trick, and it sucked it in and blew it out repeatedly. Found a local shop who will do a valve job for $240 plus parts. My $2500+ tax return will pay for that. Alternately, I can get heads with 85k miles for $150 plus shipping. New valve and valve guide would be $40 per valve in parts. What do you guys think?

 

 

$2500 tax return?? holy h&$$, how do you get so much? lol...i only get like 700-900.

 

i would go with the lower mileage heads if there in good shape.

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Student loan interest writeoff.

 

That $150 includes the whole 85k mile engine, including alternator, coils, icm, you name it. Only problem is that the whole engine is in northern Wisconsin and I don't have a truck so I'd have to get the parts pulled and shipped and he could scrap the shortblock.

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