What's this loud tapping sound from my new engine?

[robroy]

Good afternoon!

At the risk of having redundant threads I thought I'd ask about this here.

#50's new engine is now running but makes a bad tapping/cracking noise. Here's a video that shows off the noise pretty well. EDIT: This video is encoded using a very modern format. New video software can play it, such as VLC 1.0.3, Windows Media Player 12, Apple Quicktime 7, and the iPhone, but older software cannot.

http://www.robroygregg.com/Number50/Num ... dRun_A.avi

I'm hoping this is just exhaust leaking at the collectors, but I'm not sure. It seems like it sounds loudest all around in the engine bay (not as loud under the truck). That narrows it down a whole lot doesn't it?

Anybody care to take a listen and guess? Also, any suggestions on anything feasible I can do to determine whether it's an exhaust leak or not?

Thanks very much!
Robroy

[DuckRyder]

It is very hard to tell from the video.

Take a long (and I mean long like pry-bar long) screwdriver, place the handle in your ear and place the other end of it on the alternator, valve covers water pump and so forth. It will act like a stethoscope and should help with isolating it. (Of course if you happen to have a stethoscope use that...) I realize this sounds crazy but it works well.

You can check for exhaust leaks by running your hand near the meeting surface of the head and header (obviously don't touch them or get your hand too close) you should be able to feel any leaks.

[robroy]

Hey Robert thanks for your excellent reply!

It is very hard to tell from the video.

Yeah I know what you mean. Thanks for checking it out though!

Take a long (and I mean long like pry-bar long) screwdriver, place the handle in your ear and place it on the alternator, valve covers water pump and so forth. It will act like a stethoscope and should help with isolating it. (Of course if you happen to have a stethoscope use that...) I realize this sounds crazy but it works well.

Okay, this is what I'll try next! I'll try a piece of long iron pipe, since I have that handy already.

You can check for exhaust leaks by running your hand near the meeting surface of the head and header (obviously don't touch them or get your hand too close) you should be able to feel any leaks.

Okay great! I thought about that but wasn't sure if exhaust leaks could be felt that easily or not. I'll give this a whirl.

Robert, thanks again for your great advice!
Robroy

[70_F100]

Too rapid for an exhaust leak.

It sounds like something hitting thin sheet metal.

Check the inspection cover on your bellhousing.

[robroy]

Hey 70_F100, thanks very much for your excellent advice!

Too rapid for an exhaust leak.

Now that you point it out, I can imagine this being true. I was imagining that the rapid clicking could reflect the exhaust ports opening, but perhaps that's unlikely.

It sounds like something hitting thin sheet metal.

I see what you mean!

Check the inspection cover on your bellhousing.

That I will do! You know, I think your suggestion may be highly insightful. Now that you've mentioned it, I remember that I never achieved a fully satisfactory fit on the clutch inspection cover area. It just didn't fit very well, and I had to bend the starter location plate somewhat to suit. I didn't see any clearance problems at the time, but I'll pull this area apart and do a thorough inspection to be sure.

Robert, getting back to your earlier advice, I used a long piece of steel pipe to listen to various parts of the engine. Here's what I covered so far:

1. Headers at the exhaust ports on both sides: OK
2. Valve covers: OK
3. Fuel pump: OK
4. Oil filter adapter area: OK
5. Alternator: OK
6. Heads nearby the spark plugs: OK

I may fire it up again tomorrow and use this method to listen to the clutch inspection cover area!

Regarding the exhaust leaks, I followed your advice and felt around. It was actually hard to find an area of the exhaust that wasn't leaking! Those temporary, flexible, stainless stretches of tubing I used leak all over. I also felt leaks around the collectors, since they're not tightened down (to preserve the uninstalled profile of the ball-and-socket joint).

Yet while I was under there, it just didn't seem like any of the leaks were the kind that could produce a sound like that. I think 70_F100 may be on to something by saying that the sound is too rapid and suspecting a sheet metal clearance issue.

Robert and 70_F100, thanks for your super helpful advice!
Robroy

[DuckRyder]

I tried to play the video on my desktop but it says a codec is missing, so I'm reduced to listening on the laptop.

I do agree it sounds like something on sheet metal, My first though was something perhaps hitting the alternator fan. Could also be the inspection cover. You can run it without the inspection cover for testing purposes.

It sort of sounds like two noises to me, in addition to the sheet metal noise it sounds like it has some valve train noise as well.

I wouldn't worry much about anything in the exhaust past the head to header joint at least not now.

[hazelnut]

I havent seen the video but you might want to pull the coil wire(motor cant start) and the inspection cover and have someone bump your motor over while your under the truck and see if you see any fresh looking rubs anywhere inside the inspection area and have a look around with a flashlight.Sorry left out the most important part,block your wheels so the truck cant roll.

[robroy]

Good day Robert and Hazelnut, thanks for replying!

I tried to play the video on my desktop but it says a codec is missing, so I'm reduced to listening on the laptop.

Sorry about that. I know that the encoding I used wasn't widely supported, since it's so new. Next time I post a video I'll try to use an older, more established format.

I do agree it sounds like something on sheet metal, My first though was something perhaps hitting the alternator fan. Could also be the inspection cover. You can run it without the inspection cover for testing purposes.

This I will do!

The alternator fan looks OK and I couldn't hear anything unusual through my iron pipe (physically touching the alternator case and my ear).

This said, I did make a somewhat unpleasant discovery. When I put the pipe to my ear and touched the OIL PAN, the tapping sound came through loud and clear! Now I'm imagining the crankshaft hitting the windage tray in there or something.

It sort of sounds like two noises to me, in addition to the sheet metal noise it sounds like it has some valve train noise as well.

Okay! Welp I'll try to figure out them one at a time. Hopefully one of those sounds is just an artifact of my video camera's poor microphone, but we shall see!

I wouldn't worry much about anything in the exhaust past the head to header joint at least not now.

Yeah I see your point!

I havent seen the video but you might want to pull the coil wire(motor cant start) and the inspection cover and have someone bump your motor over while your under the truck and see if you see any fresh looking rubs anywhere inside the inspection area and have a look around with a flashlight.Sorry left out the most important part,block your wheels so the truck cant roll.

Hey Hazelnut, that's a great idea. I may try that later today when I have a helper on duty!

Since I heard the sound pretty clearly from the oil pan area, it seems like I may need to rip that apart again.

But since that's a huge job, I'll take the clutch inspection cover off first and look around in there as well as I can.

If that sound truly is coming from the inside of the oil pan, what potential causes come to mind?

Thanks very much for the expert advice!
Robroy

[70_F100]

Since I heard the sound pretty clearly from the oil pan area, it seems like I may need to rip that apart again.

But since that's a huge job, I'll take the clutch inspection cover off first and look around in there as well as I can.

If that sound truly is coming from the inside of the oil pan, what potential causes come to mind?

Thanks very much for the expert advice!
Robroy

Since the engine was run on a dyno prior to you getting it back, I wouldn't expect the noise to be coming from within the engine. If it is, I would call the rebuilder before pulling ANYTHING back apart. They should be responsible for anything and everything internal, since you have just fired it up for the first time. If you pull it apart without contacting them first, they may refuse to do anything for you if there is, in fact, a problem with the engine internals.

I'd first check the clutch area, as I said before. It's very possible that your pressure plate bolts are slightly too long, as I have a strong feeling that you may have replaced them with new ones. If you did, I hope you used the special bolts that are supposed to be used there. There's a good chance that they are hitting either the inspection cover or the engine spacer plate, and that sound could be transmitted to the oil pan due to their relative closeness.

Since I know that pipe you've been using has to be somewhat cumbersome, you might try using a length of heater hose. You'll get the same results, and a lot more convenience.

[robroy]

Hey 70_F100 thanks for replying!

Since the engine was run on a dyno prior to you getting it back, I wouldn't expect the noise to be coming from within the engine. If it is, I would call the rebuilder before pulling ANYTHING back apart. They should be responsible for anything and everything internal, since you have just fired it up for the first time. If you pull it apart without contacting them first, they may refuse to do anything for you if there is, in fact, a problem with the engine internals.

I see your point!

In this case though, I actually did replace the oil pan, windage tray, and oil pump pickup tube. They shipped the engine with a rear sump, 4x4 pan on it, so I needed to swap those things out.

I'd first check the clutch area, as I said before. It's very possible that your pressure plate bolts are slightly too long, as I have a strong feeling that you may have replaced them with new ones. If you did, I hope you used the special bolts that are supposed to be used there. There's a good chance that they are hitting either the inspection cover or the engine spacer plate, and that sound could be transmitted to the oil pan due to their relative closeness.

Could be! My pressure plate bolts were these ARPs:



About the sound being transmitted due to closeness, although this certainly could be true, I didn't hear much in the way of bad sounds from the inspection cover. It was a lot more prominent from the oil pan itself.

Since I know that pipe you've been using has to be somewhat cumbersome, you might try using a length of heater hose. You'll get the same results, and a lot more convenience.

Oh okay! Yeah that will help a bunch. Thanks for the tip!

Thanks for the great advice 70_F100!!!
Robroy

[robroy]

I just called Steve at Proformance Unlimited, and he says that it's the windage tray hitting the crankshaft.

He said that this is a typical thing to happen, and that folks are supposed to rotate the engine all the way around by hand before buttoning the oil pan up. He mentioned that very often, the windage tray needs to be modified or bend somewhat to keep it from hitting the crank.

I noticed that the clearance between the crankshaft and the windage tray was pretty tight, but I didn't think to actually turn the engine over to see if it would hit anywhere. I trusted that the Milodon parts wouldn't be made incorrectly or have any manufacturing flaws. Ouch!

Steve agreed to listen to the video clip and get back to me, so maybe he'll have additional advice at that time.

Robroy

[robroy]

I've begun pulling off the inspection cover. Is it normal to have some clearance issues with the headers getting those off?

Thanks!
Robroy

[Ranchero50]

Welcome to headers...

Sounds like the windage tray whacking just from the description (I can't see of hear the video...)

[robroy]

Hey Jamie thanks for your reply!

Welcome to headers...

Thanks! I guess that's just the way these charming things are! So far I've unbolted the ball-and-sockets, disconnected the clutch linkage, and tilted the inspection cover around in every conceivable fashion. I'll figure it out yet!

Sounds like the windage tray whacking just from the description (I can't see of hear the video...)

Yes I think that's the most probable thing at this point! Now that I know that I was supposed to check for crankshaft clearance after installing the tray, it makes sense. This may be painful but that's how inexperienced guys like me gain experience! Plus, if I need to remove the pan, I will have a custom drain plug installed this time (really)!

Thanks again Jamie!
Robroy

[DuckRyder]

Refresh our memory about which windage tray you used? I remember some discussion about an Milodon one and the Factory Cobra Jet style.

With the fact that it seems to be coming from the pan, I would not run it any more. It should be possible to manually turn the engine. (Pull the plugs, chock at least two wheels [on both the front and back of the wheel], and place the transmission in neutral).