Cam lobe wear mark
04-19-2012, 11:18 AM
#41
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The OP was lucky to not lose the engine.
Another question is:
When it comes to the valves?
I mean, together with the misfires and low compression numbers....
Just replacing retainers is like (to stay in the oil analogy) topping up oil after you find a dry dipstick and seeing the oil warning light during hard cornering and hope you're allright.
It might be, it might not be.
The OP knows how short & sweet the overrev really was, was it low enough to not have piston - valve contact but high enough to crack retainers.
IOW the valves slammed shut for some time - may only be seconds - and seat damage is possible.
My old MY'00 head - 144k km - was fine as far as I knew, just used, lightly overreved only a couple of times but not that severe.
The engine ran fine with it, no missfires, no nothing.
If the bottom end would not have developed issues on a track (on semi slicks) I would be using this engine & head today.
Still, the seats, and the exhaust seats in particular, turned out to be not in the best of shape, IMO.
In any case, after the polish it looks a lot better, I think there is no-one to disagree about that.
Unless there is factual evidence an overrev gives you nothing but cracked retainers and certainly no damaged seats I would not just swap cotters & retainers and call it a day.
Another question is:
When it comes to the valves?
I mean, together with the misfires and low compression numbers....
Just replacing retainers is like (to stay in the oil analogy) topping up oil after you find a dry dipstick and seeing the oil warning light during hard cornering and hope you're allright.
It might be, it might not be.
The OP knows how short & sweet the overrev really was, was it low enough to not have piston - valve contact but high enough to crack retainers.
IOW the valves slammed shut for some time - may only be seconds - and seat damage is possible.
My old MY'00 head - 144k km - was fine as far as I knew, just used, lightly overreved only a couple of times but not that severe.
The engine ran fine with it, no missfires, no nothing.
If the bottom end would not have developed issues on a track (on semi slicks) I would be using this engine & head today.
Still, the seats, and the exhaust seats in particular, turned out to be not in the best of shape, IMO.
In any case, after the polish it looks a lot better, I think there is no-one to disagree about that.
Unless there is factual evidence an overrev gives you nothing but cracked retainers and certainly no damaged seats I would not just swap cotters & retainers and call it a day.
04-20-2012, 03:36 AM
#43
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Thanks for clarifying Billman. My heart skipped a beat since my cams are polished. I know I didn't overrev while I've had the car and I already had changed my retainers to the AP2 ones.
04-20-2012, 10:32 AM
#44
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How much can you do while looking at them from above, still in the head, head on the block?
Remove stem seals and wiggle the valve and guess if the play is too much or ok?
Borrow a borescope and look at the seats through the sparkplug hole?
One thing you can certainly NOT do without removing the valves = check if they are bend.
Sometimes you just want to know, especially after an overrev.
At least, that is what I would do on my own car.
And what I would recommend anyone asking me.
Remove stem seals and wiggle the valve and guess if the play is too much or ok?
Borrow a borescope and look at the seats through the sparkplug hole?
One thing you can certainly NOT do without removing the valves = check if they are bend.
Sometimes you just want to know, especially after an overrev.
At least, that is what I would do on my own car.
And what I would recommend anyone asking me.
06-05-2012, 10:46 PM
#45
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Thread Starter
sorry for the late update.
my friend and I finally got to work on the retainers.
here is a picture of the retainers. almost all of them have cracks.
here is a picture of the retainers during the swap out. the two on the left has old retainer and the one on the right has new retainer, see how low the valve stem seats on the left compared to the one on the right.
anyways, on to the story...
after everything were put back together, we when for a test drive.
while test driving we noticed that the car feels very sluggish and also code 1399 came up. So we drove it back to the shop waited for the motor to cool to redo the valve adjust. (We thought maybe the valve adjustment were off but that wasn't the case.)
we did some troubleshooting and found out cylinder one has low compression (before we swap out the retainers compression were all around 210)
looks like tomorrow the head will come off so we can check out the valves.
my friend and I finally got to work on the retainers.
here is a picture of the retainers. almost all of them have cracks.
here is a picture of the retainers during the swap out. the two on the left has old retainer and the one on the right has new retainer, see how low the valve stem seats on the left compared to the one on the right.
anyways, on to the story...
after everything were put back together, we when for a test drive.
while test driving we noticed that the car feels very sluggish and also code 1399 came up. So we drove it back to the shop waited for the motor to cool to redo the valve adjust. (We thought maybe the valve adjustment were off but that wasn't the case.)
we did some troubleshooting and found out cylinder one has low compression (before we swap out the retainers compression were all around 210)
looks like tomorrow the head will come off so we can check out the valves.
06-06-2012, 11:18 AM
#48
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My girlfriend missed a shift about two months ago and very briefly over revved. The car has been running fine so I didn't think too much about it. After reading this post and others like it I decided to pull the valve cover and take a look at my retainers. They really all appear fine according to Billman's good/bad example photos. Should I be satisfied that they pass visual inspection or should I take additional steps? I didn't see the tachometer when she over revved so I don't know how bad it really was but I could hear/feel that she missed and she admitted that it redlined.
Any and all advice appreciated. Thank you.
Any and all advice appreciated. Thank you.
06-06-2012, 12:07 PM
#50
Registered User
My girlfriend missed a shift about two months ago and very briefly over revved. The car has been running fine so I didn't think too much about it. After reading this post and others like it I decided to pull the valve cover and take a look at my retainers. They really all appear fine according to Billman's good/bad example photos. Should I be satisfied that they pass visual inspection or should I take additional steps? I didn't see the tachometer when she over revved so I don't know how bad it really was but I could hear/feel that she missed and she admitted that it redlined.
Any and all advice appreciated. Thank you.
Any and all advice appreciated. Thank you.
I would also be a little concerned about cracked retainers, even if you couldn't see any obvious evidence of them being cracked. AFAIK, it doesn't take much of an over-rev at all to crack them.