Interesting sounds coming off highway

[Benjam]

So ever since I put the engine back in my exploder I've been having an interesting sound when I come off the highway. I've been living with it for probably 5-6 months now but I feel like its time to take care of it.

The engine specs are as follows:
Stock rebuilt 90tm bottom end. new pistons, rings, main, rod, and cam bearings. 98tm heads from alabama cylinder head, opened up exhaust ports.
422 cam
Smith Bros pushrods at 5.550"
Stock style new rocker arms.
Borla Headers, wrapped.
Probably 10k miles on this rebuild except for the cam, probably 5k on that. 410 wasn't enough


Now for the sound.. It mostly makes itself known when I'm coming off an on-ramp, waiting for traffic in front of me. So at idle. It sounds like a terrible heat-shield rubbing against marbles in a can rolling around. It seems the sound comes mostly from the pass. side of the engine bay. If I give it gas it just gets "sharper" in sound until it revs up enough to overcome it, and sounds normal again.

Also worth mentioning, occasionally at idle I have a slight metallic sound, almost like a heat-shield rubbing somewhere. Now this is odd because there aren't any heat shields on this truck that I'm aware of.. I have to believe these two issues are related.
I've had these borla headers on before this specific build of the engine, but same truck and not wrapped with no issues. Part of me wants to believe the header wrap increased the diameter of the pipes and is rubbing against the engine block when it heats up and expands?

It's hard to describe the sound but I did my best .

The sound doesn't change on 87 octane or 93.. I was thinking spark knock for a while but there is no change at all between different octanes.

Any ideas, gentlemen? This thing has been drivin me bananas.

Benjam

 

[malohnes]

I have JBA headers. Your issue sounds like mine before I figured out my split Y Pipe needed tightening. I have no clue if Borla header have a split Y Pipe also, but if they do, that would be a good place to look.

Has this sound always been there since the rebuild? Since the 410 - 422 swap?

 

[Benjam]

Malohnes,

The Borla headers do have a split y-pipe. Although this setup has been on the truck for a solid 10 years with no issues until now. I will double check this though. You are referring to the clamp connecting the two "banks" of the y-pipe together,correct?

I hadn't heard this until I had the exhaust ports opened up and put the 422 cam in.

Forgot to mention,I have the comp dual springs to match the bigger cam.

Benjam

 

[Anime]

Marbles rattling in a can - valve clatter?

Usually if the rocker arms are good, it's the pushrods, sometimes they are too short/long for the 422 cam. Can also of course be bad/collapsed lifters.

 

[Benjam]

Anime,

I would think slop in the valvetrain would produce more of a ,"tap,tap,tap."
This is like a growling coming from the pass. Side engine bay. When it first started I tried getting out of the truck for a closer listen but it was done by the time I got out.

Lifters are also as new as the bottom end,probably 10k miles. Not that it means much,being I had a lifter fail the first 5 thousand,prompting the second teardown and 422.

Benjam

 

[Anime]

It sounds like a terrible heat-shield rubbing against marbles in a can rolling around.

This is like a growling coming from the pass. Side engine bay.

Which is it?

The air filter/intake makes a deep 'growling' sound with an intake or airbox mods.

Perhaps you're getting the howling/whistle from the IAC valve? That's the one that happens at idle, gets louder with slighty higher RPMs, then goes away at driving RPMs.

 

[Benjam]

My apologies Anime, this is difficult to explain

It's almost like both of those characteristics in one.

The Intake noise is a good point. I've dealt with that before on a 4.0 ranger and I know exactly what you're talking about. It doesn't sound the same as that but I do have a modded airbox and the ranger I've heard this on does not, so it is possible..

Hmmmm..

Benjam

 

[Benjam]

Okay so while the truck was on the rack this evening for radius arm bushings I gave it a quick look and believe this whole problem lies with the pass. side header. Keep in mind these headers have been on this truck for a long time, just never wrapped, and never with the 422 cam. I can't remember how tight the header fit to the engine block without wrap, but it looks like the wrap bumped the diameter of the header up that much more and is now rubbing on the block.

I can't see how the header got bent so this is the only conclusion I can come up with..Though I do find it hard to believe a couple layers of header wrap made this an issue.

Of course I am assuming this is the entire problem, so it is still anybodies guess.

I snapped a few pictures but they are from a cell phone and one with a not so good camera. :thumbdwn:

The area in question, pass. side bellhousing

You can just see the "ear" of the bellhousing rubbing here

Rubbing the oil filter adapter bolt, perhaps?

And the whole reason I had the truck up today, "Ooh Shiny!"

So those are my thoughts.. From here I think I will be finding time to remove the headers and header wrap.. as much as I don't particularly want to.

Thoughts, everyone? Am I on target here?

Benjam

 

[malohnes]

I doubt the wrap would make any noise or cause any noise. But it might be a good idea to rewrap them tighter so they don't wear by rubs.

I would still venture to suggest retightening all your header/collector flange bolts, clamps and header bolts to the head to rule that out. I didn't think I had loose ones until I crawled under with the engine running and heard the tinging.clanging noise. Then with some heavy gloves started moving the exhaust piping around form the tip, to muffler moving back to front and found the noise with a slight, maybe 1/8 - 1/4 inch movement of the driver side y-pipe moving inside the pass side y-pipe.

Other than that, I don't have any other guesses.

As a side note, my motor mounts are in sad shape and need ot be replaced. This makes the noise worse since the motor flexes more and this tweaks the exhaust system. I mention this as I don't know if you have new or reused old motor mounts.

 

[Benjam]

So a couple weeks ago I'm leaving work for the day and fire up the exploder.. Immediately I hear the metallic sound at idle, and it's even louder this time. So I pop the hood and narrow it down to the belt tension-er.

Pulled it off last week and although the bearing wasn't entirely gone, no slop in it at all, you could hear just a slight creaking when you turned the pulley. Put a new tension-er on, and wala.

No more funky sounds at idle, and more importantly, coming off the highway!

It's been a little over a week now since I replaced the bad tension-er, with no strange noises since..

I am a happy camper so far!

Benjam

 

[sport97]

Glad to hear. I replaced mine recently. It was ready to implode it was so wobbly but it was quiet as could be. You have to love when the issue turns out to be something much easier and cheaper to fix than you originally thought. Seems this rarely happens though...

 

[malohnes]

Great news! Glad it was a simple fix, though a maddening one to handle.