xviper

I can't cite you any threads, but it was Billman250 who first posted about bent and cracked retainers on engines that had never seen an over-rev.

RED MX5

Well, that validates the retainer checks we do at every oil change.
(And I thought I was just being paraniod.)

RED MX5

Hey, XV, a funny thinged happened the other day. I checked my Modifry shift beeper to see what the highest RPM I'd hit on my last drive, and it beeped 18 times and then 5 times, indicating that I'd hit 18,500 RPM at some point. I haven't got a clue what happened, but it was obviously a fluke related to the beeper. When the tenth beep sounded my heart stopped for a second, but by the time it got to 15 I knew it was lying to me. Pretty wierd though. Have you heard of this happening to anyone else?

xviper

Actually no, never heard of this. I've never used this feature on mine, so I can't even tell you how to make it work. I just put it on so I didn't forget to shift.

walter_s

The engine was opened yesterday.

I did only take some pictures with the mobile phone.

On the 4. zylinder at least one exhaust valve is broken, so the piston and the zylinder head are heavily damaged. The broken parts of the valves were making their way through the inlet into the other zylinders.
The zylinder head can't be used anymore the pistons also.
There is no damage on the retainers, the camshafts or the valve springs.
Lean mixture wasn't a problem because the spark plugs and the colour of the valves in the not so heavily damaged zylinders were perfect.
So the rods and the crankshaft are oK, but that is the only good thing to speak about.
As far as i know not a typical failure for an F20C engine.

Walter

iDomN8U

I'm thinking the overrev combined with the increase stress from the Cams could have been the culprit.

I'm sure she will be back to normal and reliable when your all done.

Don't forget to post the dyno on dr. shick cams

walter_s

I would like to post the pictures of the engine too......

Is there no way posting pictures except hosting them somewhere in the internet ?

The overrev was 4 years ago, hard to believe for me, that something happened and the valve broke 4 years later.
The cams are not as agressive as most of you think.
There is no change in the rpm where the engine makes the most power.
So it's not a lot more agressive than the stock camshafts.

Walter

SpitfireS

walter_s Posted on Sep 27 2006, 03:48 PM
Do you mean the valve stem broke?
On all 16 valves the retainers, ect were ok?

Exhaust valves are made to withstand hot exhaust gas.
IF that valve didn't close properly it may have been surrounded by much hotter combustion gasses and may be weakened by it until it broke (or melted or something)
Why it didn't close enough (if that's the case) may be the question.

IIRC the 4th cylinder problems I have been reading about were piston & cylinder wall problems, not valves.
Oil flow to the entire valve train (even with the racing oil) should have been adequate.

As a guest I think that is the case.
IMO there are free hosts available, but then after a while your pictures here will look like a red X.
Maybe your internet service provider (where you may have an e-mail account) also allows you to use online storage?
If so, you may link from there.

walter_s

I paid for the gold membership on the 27-January 06 so i'm a little bit upset.

I contacted the admins............. wait and see

xviper

But was the money taken?