What is this sound?

[Master_Spazez]

Now I've had rod knock before, and this doesn't sound like it! I've listened to the block (2 different places), head, and exhaust manifold with an extension and the noise is loudest from the head. The oil pressure rises and falls normally, and isn't any harder to start than normal. I thought it was a lifter, but then I remembered it just uses lash pads! Any ideas?

http://www.facebook.com/photo.php?v=2960232299161

 

[suprarx7nut]

Hard to tell, but i'd wager on a leak. Either exhaust manifold or intake.

 

[IJ.]

Sounds like loose valve clearence, try holding it around 2500 and see if the sound changes.

 

[SRZMK3]

either exhaust leak at the header which it most likely is because those doughnuts go out pretty often, or you have carbon tracing on the spark plug wires.

 

[Supracentral]

Sounds like loose valve clearence, try holding it around 2500 and see if the sound changes.

Yea, I'd agree with Ian on this.

You have a vacuum gauge handy?

Hook one up and check here:

http://www.supramania.com/forums/showthread.php?21167-Boost-leak&p=249145#post249145

 

[Master_Spazez]

Actually I have one hooked up to the manifold and I remember at idle it was always around 25in Hg.

 

[MPR]

That is definitely NOT an exhaust manifold leak. When the camera is near the back of the block above the head you can clearly hear metal on metal ticking. It's gotta be something in the top end/ valve train...

 

[Master_Spazez]

Also, this noise started when I switched to using a lighter oil (10w-30 from 15w-40). Could this be the cause?

 

[IJ.]

Pull the Cam covers and check the valve clearences with feeler gauges when each cam lobe has it's back to the bucket, for it to be this noisy it should be apparent.

Lighter oil could be a factor but check the basics first (lighter oil will displace easier so it "might" be rod knock but I'd run the buckets first before hitting the panic button)

This is why I asked you to run it up and hold it around 2500 to see if the noise changes.

 

[Master_Spazez]

When I held it around 2500 the noise got quieter, completely nonexistent at idle. I'll be checking clearances today.

 

[IJ.]

When I held it around 2500 the noise got quieter, completely nonexistent at idle. I'll be checking clearances today.

Ok NOT a good sign sadly

Run the engine and pull 1 injector clip at a time then replace it and move to the next, post back here what happens noise wise.

 

[Master_Spazez]

Why what is that a sign of? When I pulled spark plug wires the noise got equally quiet for each one. I checked clearances today stone cold and they were all within spec. It just seems too rattly/tinny/rhythmic to be knock because when it was knocking last time it was a deep "KNOCK" and it didn't have a pattern to it.

Also I didn't hold it at 2500, I just revved it up a few times (don't know to what rpm) and the noise got quieter.

 

[IJ.]

Why what is that a sign of? When I pulled spark plug wires the noise got equally quiet for each one. I checked clearances today stone cold and they were all within spec. It just seems too rattly/tinny/rhythmic to be knock because when it was knocking last time it was a deep "KNOCK" and it didn't have a pattern to it.

Also I didn't hold it at 2500, I just revved it up a few times (don't know to what rpm) and the noise got quieter.

If you're not going to try what I suggest I can't help you... :nono:

 

[Master_Spazez]

I will but I drained all the oil out of it so I wont be starting it until Monday, I didn't get to NAPA in time to grab a filter.

 

[AJ'S 88NA]

Why what is that a sign of? When I pulled spark plug wires the noise got equally quiet for each one. I checked clearances today stone cold and they were all within spec. It just seems too rattly/tinny/rhythmic to be knock because when it was knocking last time it was a deep "KNOCK" and it didn't have a pattern to it.

Also I didn't hold it at 2500, I just revved it up a few times (don't know to what rpm) and the noise got quieter.

I've spun a rod bearing 3 times now and it sounded different each time.

What's your oil pressure doing, each time for me it dropped quite a bit.

 

[Master_Spazez]

As I've said its still normal oil pressure. I won't be able to run it again until Monday, I didn't get to NAPA in time to get the oil filter. -_-

 

[Master_Spazez]

I've pulled each injector plug like IJ. said to and the noise does not drop at all, aside from becoming quieter from the RPM drop. However I put my hand around where the exhaust manifold and the downpipe meet and I can feel the exhaust coming out there, which may explain why it is so loud. I guess my punishment for not having a proper header, haha.

 

[SRZMK3]

please replace exhaust doughnuts and then repost what happens after if fix or not.

 

[suprarx7nut]

I've pulled each injector plug like IJ. said to and the noise does not drop at all, aside from becoming quieter from the RPM drop. However I put my hand around where the exhaust manifold and the downpipe meet and I can feel the exhaust coming out there, which may explain why it is so loud. I guess my punishment for not having a proper header, haha.

Ding, ding, ding. Winner.

I've always been surprised how much an exhaust can sound like physical metal on metal contact. Actually feeling the exhaust leak is about as much proof as you can get.

 

[MPR]

I've never heard a manifold leak sound like that in my life. (and I've heard many). If it turns out to be a manifold leak, I stand corrected and very surprised.