Frustrated, discouraged and don't know what to do

[derotoreut]

Originally Posted by budman k20

I remember having to clearance my stock oil pan with a ballpeen hammer when I built my 383. There is not much rod bolt clearance right where the pan bolts to the block. This is just a guess...but I would bet the (thick) cast aluminum pan is being hit by the rod bolts.

The cast aluminum pan is on my TH350 trans. The 383 has a painted steel 7-quart deep pan, so I don't believe there is an issue with the rod bolt clearance. You make a good point though. I have heard of this clearance issue in the past.

[chipflyer]

If you have someone "power break" it while you listen with the hood opened up can you hear it? If it does it you should be able to use an engine stethoscope or a piece of broom handle and get a pretty good idea exactly where its coming from or at least rule out areas.
I had a loose wheel weight once that made a terrible knock at only low speeds that was a pain to diagnose, might check those for fun.

Jeff

[Sammy]

Had a stock water pump that had play in and out on the shaft. Made a strange noise under a load only. Didn't leak but just happen to find it before it let loose into the rad.

[GASoline71]

What are you using for an air cleaner? Anything wild and out of the ordinary?

That definately sounds like an air leak or some sort of belt slipping.

It doesn't sound internal to me. Do you have a fan clutch installed?

Gary

[derotoreut]

Originally Posted by chipflyer

If you have someone "power break" it while you listen with the hood opened up can you hear it? If it does it you should be able to use an engine stethoscope or a piece of broom handle and get a pretty good idea exactly where its coming from or at least rule out areas.
I had a loose wheel weight once that made a terrible knock at only low speeds that was a pain to diagnose, might check those for fun.

Jeff

We tried to power brake the truck the first time this appeared. It was hard to hold it from moving, so we put it up on jack stands to power brake it. We were able to hear the noise, but it was too dangerous to stand near it in case it came down off the stands. We weren't able to get close enough to put any type of stethoscope on it.

What I think I'm going to do is to take it to a local chassis dyno shop. That way I can run it loaded and should be able to repeat the noise I'm hearing. I talked to a friend of mine today who is a close to the owner of a local speed shop. We are hopefully going to work something out to get it onto their dyno stand.

[piecesparts]

You did not say that you have done anything with the fuel pump. If you have an engine mounted fuel pump, have you tried replacing the fuel pump? If there is rod play in the pump drive rod, due to a weak spring in the fuel pump, then you get a noise from the engine that will sound like knocking or pinging, under load.

[austinstocker]

By listening to the videos, it sounds like whatever is making the noise is affected by engine load or rpm. Is the noise always occurring at a certain rpm, or only under a certain amount of load? I noticed that when the trans shifts, the noise becomes very noticeable at the beginning of the next gear. Have you tried putting a stock pan and filter on the TH350 just to rule it out? Did you put this pan and filter mod on the truck at the same time the engine was built?

[magwakeenercew2jh]

One thing for sure, there are a lot of moving parts to consider.

A friend of mine asked me one time, in response to my noise-seeking quandry:

"Anything leaking?"
I said, "No."

"Any performance/driveability issues?"
I said, "No".

"Overheating?" "Using an obviously larger amount of gas?" "Burning oil/smoking?"
"No. no. no.", I responded.

"Everything tight and torqued in the suspension and driveline?" "Exhaust hitting anything?" "How about the
brake, e-brake, oil cooler, and fuel lines?"
"All good", I answered.

"Check your speedo cable?"
"For God's sake," I yelled, "I'm not stupid!"

"Well", he said, "you *do* have a noise don't you?"

"Yeah." "What do you think I'm asking you about?"

"Well", he told me, "you seem to have all the answers". "So I guess you have two good options left...."
"Okay, Okay, what are they?" I humbled.

"Well, you can open your ears, eyes, and mind and look for the noise where you don't expect it"
"...at least look in the places you 'haven't' looked", he rudely suggested.

"Doha, Sam." I responded. "What's the other option?"

Sam said, "Let it clearance itself."



I'm not suggesting that your experience here isn't frustrating or that you are doing anything wrong. But there's just so much stuff that can make noise. Good noise *and* bad noise.

To get a fix, there needs to be a starting point on the malady. The engine, while suspect, and still an intelligent potential for *bad* noise, seems to have been sussed out pretty well.
At least the long-block portion....or whatever portion that your builder tested.

Disclaimer ON: I'm an Idiot. And I've been here so many times, that I'm simply doing a yell out to myself. Disclaimer: OFF

I, personally, think that sound suggests something revolving...and expanding when it's under enough load so that it hits something solid...like a housing.... Of course, that's about
67% or 82% of everything in the running gear.

However, it could very well be a bolt left rattling in one of those middle-earth holes at the bottom of the front fenders...or something stupid like that that just hits the correct harmonic
every time in order to drive you from your right mind.

Pulling back to assess the situation using the last point of no-bad-noise is a must. Secondly, more eyes and ears on the offending general area will be the golden path to the solution.

Unless you decide to let it clearance itself.

[midniteblues]

after listening too the videos it sounds more like a rattle an it sure does sound like a tough one to find. If they dyno'ed the engine the way it sits in the truck i would look else where I'm sure they would've had let the engine go after the second time around with a noise like that.

few things too check would be both dipsticks
dust cover on the trans,pcv,dizzy&cap, speedo cable&assmembley,fan&shroud,starter drive gear,

before i paid anyone i would risk useing the hose,broom handle or stethascope too pin point where its coming from sometimes even a finger on the part can feel it. if you can find where its coming from thats half the battle cause you would know where an what too look at.

keep at it an think outside the box an you'll find it you might be a lil' more gray and frayed but you'll find it

[54belair]

If you put the rear up on jack stands and rotated the drive line and heard the noise,
you have a rotational issue, not necessarily an "under load" issue.

I know its splitting hairs but--- I would start looking from the engine back. With the rear wheels up on stands you werent putting that 383 under any appreciable load.

[derotoreut]

Originally Posted by piecesparts

You did not say that you have done anything with the fuel pump. If you have an engine mounted fuel pump, have you tried replacing the fuel pump? If there is rod play in the pump drive rod, due to a weak spring in the fuel pump, then you get a noise from the engine that will sound like knocking or pinging, under load.

piecesparts, No I haven't done anything with the fuel pump. It's a mechanical fuel pump that was provided new by the engine builder as part of the turnkey engine. They used it when dyno'ed and said they didn't hear the noise during the dyno. Worth a try though I guess. Thanks.

Originally Posted by austinstocker

Have you tried putting a stock pan and filter on the TH350 just to rule it out? Did you put this pan and filter mod on the truck at the same time the engine was built?

austinstocker, This is a good idea and worth trying. It's really the only thing I changed since the noise started. Thanks.

[austinstocker]

Well hopefully everyone's input helps you out. Let us know if you make any head way.

[jorgensensc]

Is your alternator new? Sounds like Bearings grinding. Or possibly an AC clutch, Could even be the water pump bearings..Did they dyno it with accessories?

[Lastson03]

Check your starter. I had one rebuilt once and the guy left out a return spring in the solenoid. It soul rattle like spark knock or rod knock under load. Even changed the engine before I figured it out. The starter would not fully disengage so under load when the flex plate would flex it would knock. There was hardly any noticeable damage to the flywheel.
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[derotoreut]

Originally Posted by jorgensensc

Is your alternator new? Sounds like Bearings grinding. Or possibly an AC clutch, Could even be the water pump bearings..Did they dyno it with accessories?

All my front end accessories are new. I have a new alternator, water pump, power steering pump and A/C compressor. They are part of a March system. All are driven off of a single serpentine belt. I eliminated these items as a possible cause by removing the serpentine belt and taking the truck for a quick drive, just long enough to find out it still makes the noise. To answer your question, no it was not dyno'd with the accessories.

[austinstocker]

Anything new yet?
Posted via Mobile Device

[derotoreut]

Originally Posted by austinstocker

Anything new yet?
Posted via Mobile Device

Hey Austinstocker, it's ironic that you ask. Last night I went out to work on it a bit and decided to brake torque the truck again. I could definitely hear the tapping/knocking noise, but could not tell where it's coming from. Again... I can only get it do it with load on it. It will not do it when sitting idling or revved. This does tell me it's not anything rotational though like drive shaft.

I will continue my quest for an answer.

[jorgensensc]

Are you absolutely positive it's not the timing? If its too far advanced it will knock under load pretty badly.
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[derotoreut]

Well I want to thank everyone for their input and ideas into this noise problem. I finally solved the mystery of the engine noise. Well here goes...

As it turned out it wasn't any problem with the engine. Actually, Laston03 was pretty close with the solution. Because the noise was evident when it was brake-torqued, a friend laid down along side of the truck, looking underneath while I brake-torqued it (crazy huh?). What he found was sparks coming from the flex plate. As it turns out, when the truck was under load, the flex plate would flex enough that it hit the pinion gear on the starter. I would have never thought this would happen because I looked at this before. I have a Power Master high torque mini starter that was shimmed to manufacturers specs. Even though it was installed as suggested it still rubbed under load. Last night I removed the starter and looked at the gear. I found evidence of contact on the starter gear, but never could see any on the flex plate. The starter gear was worn slightly on the gear face. So I re-shimmed the starter back some more and what do you know? Problem solved.

Through all of this United Racing Engines (URE) has been excellent. When I originally heard this noise, they took this engine back and totally rebuilt it. They also upgraded the crankshaft and pistons and re-dynoed it for free. They covered all of the costs. Even when it was returned to me and I had the same noise (Duh!) they were there to support me. I feel foolish and embarrassed to even tell them what it was.

Well again I want to thank everyone that contributed to this solution. This site is awesome.

[rsavage]

So happy you found it. Your persistence in finding it was key. Congrats Dan.

[ole dollor]

good to hear you solved the problem....i hate it when we have a noise and cant locate it....ya did good.

[desertnick69]

So now what are you going to do with ALL that spare time! That had to drive ya nut for the last 4 or so months w/no results. Really glad you found the problem.

[derotoreut]

Originally Posted by desertnick69

So now what are you going to do with ALL that spare time! That had to drive ya nut for the last 4 or so months w/no results. Really glad you found the problem.

Oh I'm sure I'll find something to fill the time slot. Lol. You can't imagine how much I racked by brain trying to figure this out. The number of people I talked to about it was ridiculous. I was at wits end with this thing. I was thinking (and hoping) it would be something simple, but just couldn't put a finger on it. Now I can get it ready for summer. YES!

[domeier]

I chased a problem like that on a plane engine some years ago. It would intermittently lose 80 rpm at cruise about once every five hours. Drove me NUTS trying to figure it out, because it would never repeat when tested on the ground. I took that thing apart and apart and apart and changed everything... my buddies all thought I was crazy, but I finally isolated it by replacing the valve springs.

Glad you figured it out. That's the kind of puzzle that will make you tear your hair out.

[desertnick69]

Originally Posted by derotoreut

Oh I'm sure I'll find something to fill the time slot. Lol. You can't imagine how much I racked by brain trying to figure this out. The number of people I talked to about it was ridiculous. I was at wits end with this thing. I was thinking (and hoping) it would be something simple, but just couldn't put a finger on it. Now I can get it ready for summer. YES!

If nothing else we have a lot of information to fall back on if some one else would run across the same or similar type of thing.