So I just bought an 07 with 84k miles to replace my S that was totaled by a drunk driver right at the start of winter. Before I drove it at all I did a valve adjustment, new oils, new spark plugs, new belt, and new battery. Haven't really drove it over the winter and it finally got warm enough to take out of the garage. While doing a few datalogs running the same tune I had on my old s2k corrected for a/f on the new one I noticed some knock on cylinder 2 around 7k rpm. It isn't crazy amount maybe 3-4 count max at WOT and non while cruising. The car still pulls and no CEL light the only thing I would mention is the injectors seem to be noisy and have a tick to them but maybe it could be something else?

So I decided I would do a compression test and did each cylinder 3 times the numbers I got where around 220, 180, 210, 210. So cylinder 2 does seems to be a bit low, is this anything I should be worried about?

I am going to do another valve adjustment this week just to double check that my clearances are correct, is there anything else I should look for while I have the cover off? Then retest compression again

Thanks for always helping a sucker out

 

You should do a leakdown test next, not another compression test. This will tell you if its a burnt valve, or piston ring/cylinder wall issue.

Either way, if it runs well, just drive it. If its a valve issue, you can remove the head and lap the valve. Not easy, but not awful.

If its the cylinder, not really much you can do, short of a full rebuild, and these motors aren't easy to rebuild.

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I would adjust the valves, my guess is you have a tight one, hopefully it isn't burnt.

 

In for future results.

 

He already did a valve adjustment, when he got the car, before he even drove the car. Reading comprehension.

But agreed, sounds like a burnt valve. Exhaust valve too tight, due to dbw cars running lean.

OP, what were the valve clearances before adjustment? Were any excessively tight?

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Yeah they where tight I am sure the previous owner never did one after 84k miles. Once I noticed it was tight I just respec'ed it never checked how much. If I am not to lazy I will re check the adjustment tomorrow and make sure I did them all correct.

Fingers crossed I just did it wrong and it fixes it all but I am going to bet its a burnt valve. Car is still plenty of fun so hope it doesn't get worse.

 

Finally got around to rechecking the specs...They all seemed to be good from the first one and loosened one exhaust valve up to see if that will help. I currently have the car jacked up and trying to hunt down a tick I am hearing only at idle. I am not sure if it is related to the engine and cant really pinpoint what the noise is. It is coming from either around the exhaust manifold or where the engine and tranny meet up. I am honestly not experienced enough to tell what the sound is or where it is coming from. Any ideas? It is a tick I hear only around idle, if I give it gas the sound drowns out and picks back up about a second after idle kicks in. Ill try and get a sound clip but I don't think it would really catch the sound well.

 

No luck pinpointing sound and compression numbers remained the same. I might do a dyno day at the end of next month and see what kind of number the engine is still putting out after a gernby tune and update you all.

 

Ever do a leak-down test? May want to do this before dyno test.

 

I have done a leak down yet as I don't have an air compressor or the gauges.
Maybe you all could fill me in on my different options at this point? I really don't know much about engine internals and costs. If I did do a leak down and figure out the problem would it even be worth it? I always see people saying these engines are not worth getting worked on and the most cost effective option is to swap a new engine in. So far there is no check engine light and the car still runs decent so I figured I would see how much jam it still has left.

My guess is the exhaust valves are burnt up due to tight valves how much would it be for a shop to fix it up like new again?