DrCaligari

Hi all,
I have a 2003 S2000 with about 70,000 miles. I installed a SOS supercharger and AEM ECU several years ago, and adjusted my valves at that time. I think they were all close to spec. I performed a leakdown test this weekend, and found that cylinder #1 had about 50% leakdown. a borescope inspection revealed that the #1 exhaust valves and seats are badly burned. All other cylinders looked normal. Exhaust valve clearance was still normal. Any ideas on what caused the burnt valves? I am going to pull the head and have it rebuilt, but I want to make sure that I don't have any issues that could cause this to happen again.

AP1Chief

Anything that causes incorrect valve sealealing, cooling issues (improper cylinder head cooling) or HIGH Cylinder temps AKA lean tune.
Quality of fuel (carbon deposit on the valves) maybe leaky valve seal, causing oil to build up.
Super restrictive exhaust? Clogged CAT... will toast valves quick.

This is just a few.

DrCaligari

Thanks for the insight AP1Cheif. Out of that list I think leaking valve seals might be the cause. The tune is slightly rich, and the plugs look good. I have a stock exhaust with a test pipe. All the other valves looked good.

soulicious

flanders

Do you got any more pictures on the valves?

RolanTHUNDER

Did you perform the valve clearance yourself or did you leave the car with a mechanic to do it for you?

DrCaligari

I performed the valve adjustment when I purchased the car about 10k miles ago, my memory was that they were all very close to spec and little adjustment was needed. When I checked again last weekend after finding the burnt valves lash was still about .010. Here is a pic of one of the other good exhaust valves:

RolanTHUNDER

That means the VA was not the issue.

Pinky

Amazing quality picture from your bore scope! What did you use?

F1TwoThousand

Which will help fight against burned valves. Exhaust valve adjustment on the tighter or looser specified side? With everything else functioning properly.