Top end noise?

lancec2c30 · Nov 18, 2010

I've been trying to determine what the culprit of this top end noise is for a few months now. I finished my turbo install, then shortly after blew a head gasket (uneven deck surface). I fixed that, got the motor back together, then shortly there after had this noise start.

It sounds like its coming from the upper end of the passenger side head. I pulled the valve cover and didn't find any rocker related problems.

My only guess is it being a faulty lifter, but I'm not sure how these hydro roller lifters work. If one had collapsed, would the pushrod at that valve have a lot of slop in it? Because all of them were tight.

This video is **** quality, but I figured its better than nothing. Anyone have any input, I just want to enjoy some boost.

YouTube - Top end noise

lancec2c30 · Nov 19, 2010

Anyone?

281pony · Nov 19, 2010

checked headers thoroughly? i always use the permaflex gaskets, they guarantee no leaks and they work great.

checked all exhaust flanges?

when you did the intake manifold, did all bolt's go back in? i had an exhaust leak from a missing bolt before.

if rockers are all shimmed properly, i'd look into the lifters from there. about all i can think of.

SMOKEDYA · Nov 19, 2010

lancec2c30 said:
I've been trying to determine what the culprit of this top end noise is for a few months now. I finished my turbo install, then shortly after blew a head gasket (uneven deck surface). I fixed that, got the motor back together, then shortly there after had this noise start.

It sounds like its coming from the upper end of the passenger side head. I pulled the valve cover and didn't find any rocker related problems.

My only guess is it being a faulty lifter, but I'm not sure how these hydro roller lifters work. If one had collapsed, would the pushrod at that valve have a lot of slop in it? Because all of them were tight.

This video is **** quality, but I figured its better than nothing. Anyone have any input, I just want to enjoy some boost.

YouTube - Top end noise

you dont want the push rods tight if thats what your refereing to as being tight.Back them off and with the valve closed tighten the rocker down just so there is slight tention on the push rod but it will still spin.Then go like 1/4 turn more.My motor does the same noise and all my push rods are adjusted right so IDK?Mine just isnt as loud. peace

john

lancec2c30 · Dec 7, 2010

Long time, but I've been too busy to bother with the car lately.

The noise is definitely too "metallic" to be an exhaust leak. And the other problem that leads me away from an exhaust problem is the car doesn't pull nearly as hard as it did prior to this problem. I'm still making a full 10lbs, good a/f ratio, and same timing advance as before. But im hooking in second gear now. Which was impossible before.

John, I guess I should say none of the pushrods showed excessive slop. They're just stock stamped rockers, and I just torque them to spec. I want to say 18ft/lbs?

So if I only had one bad lifter, would that dead valve create a loss of power as pronounced as I am seeing?

FoxRacer045 · Dec 8, 2010

Throw out bearing? Mine makes that noise sometimes. Dont know just a guess!

phutch11 · Dec 9, 2010

My experience has been that the majority of top end noises are hard to find exhaust leaks, followed by roller rockers hitting valve covers.

I've never had a lifter fail, but my instinct would be that you should be able to easily collapse the lifter by pushing down on the rocker with your hand. If they all feel equally hard to collapse, then that's probalnt not your problem.

The best way I have found to find an exhaust leak is to get a long section of small tubing, stick one end in your ear and use the other to probe around the headers and exhaust connections. Even pin hole leaks in welds will be very loud!

Good luck..

lancec2c30 · Dec 11, 2010

My dads 01 cobra has a TOB on it's way out, so I know what that sounds like.

I guess I'll probe around some more for exhaust leaks. I'm still 100% stock valvetrain, so rocker clearance should be fine.

Still just at a loss as to why it's so down on power.

phutch11 · Dec 11, 2010

You said earlier in the post that you're still making 10psi boost, is this the boost level that your wastegate is set to open at? Are you making the full 10lbs at the same RPM point?

Depending on your turbine wheel / housing and wastegate, you may still make 10psi of boost even if you have an exhaust leak. BUT you ought to make it later in the RPM band with the leak than you did before.

Is your wideband before or after the turbo(s)?

What kind of manifolds (i.e. material and thickness) are you running to the turbo(s)?

Good luck...

Top end noise?

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