Mustang Mystery: The Noise

Hi All,

I have talked about this in a previous post but wanted to start fresh.

First, I followed Bubba's tune specs almost perfectly these are my current settings.
Spark Plug Gap: .034
Point Gap: .27 (Dwell 34 degrees) *Bubba recommended 38 degrees
Timing : 12 BTDC

Car is running well with this settings however I get a strange noise when I am in park and I step on the gas. Hoping for someone's wise ears to tell me what is going on here. Bubba had mentioned the starter and I have not checked that yet. But since the tune is complete I wanted to see what else it could be and upload a new video. I also moved my distributor to the proper location thinking that might have been the problem but it still happened. I uploaded photos of the distributor as well, could it need more lubrication?

Thanks for all your help in educating me on the car and getting to running and running right!

The Noise 2.8.2019

we went over this B4, sorry no fix.
Some said "tim. chain against case", "vibrating exh against the under body", etc.
If U can locate it & again name where that is it can help a lill.

The description is a lill contradictory 4 me:
"Strange noise coming from engine on deceleration.
Noise did not occur while driving. Only when car is in park." as it stated movement & non movement at the same time.
I assume U mean - appears "on engine revs decreasing" after rapid throttle increase.

I agree w/the 2 possibliities above'n add "flex plate bent" as its an automatic.

congrats on making some progress on your tune up! I sill will suggest that you use the 38 dwell setting instead of .027 which is just the starting point to get it running. Using the correct Dwell settings for a point type igisntion system will always give superior results in both performance and economy. Good luck

Thanks for the tips.

I’ll get back in there and check those things as well as just the dwell.

Thanks again!

like the new avatar,
handsome driver!

I'd suggest its the starter. If previously mentioned and you haven't touched it yet, I'd take a look at it.

If it were a stick id say push start it after taking the starter out to test if thats it, but i dont know if that works with an auto.

Once you determine if it is or not then evaluate again.

Put your head in the engine bay and rev it, see if you can pinpoint the noise. That may help.

Good luck,
Ryan

Hi all,

First, hope you and your families are all doing well and staying sane during this crazy time.

Second, reviving this old thread because I am still at a loss but I have some new information and a new video for this noise I have.

The noise comes in at only two situations. 1) when I am in park and get to 2200 RMPs, see video. 2) when I am going 60-70 miles per hour and let off the gas, it will make it briefly then go away.

Other than this noise the car runs fairly well. I have tuned the car quite a few times following Bubba's steps and following steps shown on the tech section. I now have the Petronix ignition installed with their Flamethrower coil. (I currently do not have a the full 12v going to the coil and my spark plug gap is stock at .034, I plan to change that in the next day with a relay I will then gap the plugs closer to .045).

As previously mentioned it could be the starter, but I have a new one and still same result. Someone said it could be a bent valve but I do not think that makes too much sense because it would be making this noise all the time, not just during the two situations listed above. My gut is telling me it has to do with the timing and when the distributor and when the vacuum advance kicks in and out. (My distributor was re-curved.)

List of possibilities:
Starter
Bent Valve
Vacuum Advance

Link to Video: Unidentified Noise @ 2200RPM

Other facts about the car:
200 Inline 6
No AC
Automatic
550 Idle in Drive

Thanks for reading and checking my video out.

Almost sounded like an exhaust thing to me. Like some kind of reverberation in the muffler housing.

Of your listed possable causes this is my opinion.
1. A starter issue is possible though probably not likely see below.
2. A bent valve is unlikely.
3. Can't be the vacuum advance, not in play when your Reving the engine up, plus the sound seems to be coming from further back.
Other possable causes
4. Yes do set the plug gaps to .045 with a Pertronix, it's quick and easy to do. Also get the voltage to it right as soon as possable.
5. What's the condition of the spark Plug Wire Set that's maybe allowing the engine to misfire at the higher RPM's.
6. Did you ever do a compression test recently? If so what were those results?
7. You seem to be getting some vibration as seen in the video as you rev the engine higher, numbers 5 & 6 could contribute to that. This vibration can over time and use can also loosen up some fasteners.

X2 This sounds like a very tinny metal type sound so it likely coming from behind the engine block and it also seems to be vibration related i.e. Higher RPM more vibration. Check the exhaust system for loose parts like Econline said internal in muffler like loose baffles and missing or loose exhaust pipe mounting points, that's all fairly easy.

Pull the inspection plate on the block plate in front of the transmission check for a cracked flex plate, loose flex plate to crankshaft mounting bolts, loose transmission to block mounting bolts, and or loose torque converter bolts. Check starter noise for any signs of rubbing and metal shavings inside the bell housing. Almost all of these things can be checked without disassembly the exception is the flex plate to crankshaft bolts, let us know what you find out. If it were me I would probably just pull out the transmission to do a through inspection of the flex plate, checking for the presents of the extra reenforcement ring and the flex plate to crankshaft mourning correct bolt torque. In any case you need to find out the cause and hopefully soon. Good luck

Awesome tips thank you very much.

Bubba,
In the video do you hear the engine misfire at the higher RPM? I haven't noticed that.But my #6 plug wire is a little challenging to get on sometimes and I wouldn't be surprised if there is a misfire.

I have not done a compression test but I will.

The flexplate sounds like a good call to me. As much as removing the transmission scares me I think it would be something cool to do. But I wont probably be able to do it for a few months. I will check all the easy stuff you mentioned below, then do a compression test, then, change my plug wires, then if nothing changes from that, pull the tranny and check it out.

No I didn't hear a miss fire but whatching the Tach I can sure see that it's vibrating or shaking as you bring up the engine RPM. Bad or loose plug wires can cause an intermittent misfiring that also introduces imbalance. Many times this is noticed at RPM's just a little above idle, it's also possable that because of the other much louder rattling noise it's making it real hard to hear if there's a misfire. You could try only bringing the RPM up somewhere between idle but before the 2200 were the noise gets so loud like maybe 1200 to 1500 than you might hear or feel if there is a misfire. You can test the plug wires and Distribtor cap with volt / ohm meter (if you have one) to measure the resistance, or if they are a really old set you might just replace them with a new and higher grade set to be able to take full advantage of your new Pertronix's Ignistion's extra power.

One other test you can try useing your tach is to first loosen the plug wires then with the engine runing pull one plug wire off (use an insulated plug wire pliers for safety) note the RPM drop then do the next cylinder. If you happen to see one that's not any differance then note that, if they are all about the same RPM drop this would tell you that all the cylinders are fairly balanced in compression. I personally will only use the higher quality ignistion parts on my vechicals they give the best performance and economy plus they will last.

Anyway in the above that's the first potential problem which would be a tuning issue, next is that noise which is another seperate problem and is either caused by a mechanical part or as Econoline first suggested a muffler. Have also seen them many times make these rattling noises too. A really bad one you can hit with the palm of your hand or a rubber mallet and hear the baffles rattle inside. Good luck

Alright, great thanks again for the detailed response.

I successfully installed a relay and my coil now has the proper amount of volts.

I changed out my spark plugs (which were completely fouled which was due to a poor tune on my part but hopefully we are all squared away now and may have caused the vibration Bubba pointed out). I will still test my wires and likely get new ones because I don't like the red ones I currently have.

Bubba, what brand of ignition wires do you prefer? I am assuming 8mm thick as well?

Back to the noise, here is another video, this time with a view of the flex plate. Perhaps wiser eyes than mine can point something out to me. Don't mind the loose wires or oil pan. I was testing my oil pressure and the wires were left over from the relay install, but removed now.

Noise Video #2 - Flex Plate

can't see anything conclusive in the video some more lighting might help it's a bit dark. Does your engine still have the tin block plate between it and the transmissions bell housing? I can't tell, they are about an 1/8 inch thick the lower inspection plate should als clip into it at the top near block and oil pan. Did you find any loose bolts anywhere? Yeah that sure sounds bad! You could use a mechanic's stethoscope or a broom handle to listen to different areas and find the exact location of this noise I always carried them in my service truck. Always use extreme caution when using these near any moving parts like the cooling fan and the spinning flex plate. In this last case you could just put it on the outside of the bell housing.

Yes 8 MM would be excellent I have used many brands. My picks for use were mostly the NAPA Echline ignistion parts their top line Caps and Rotors as they have the better brass contacts and thicker construction material of the cap, and plug wires top line ones (Lifetime). My reasons were because of guaranteeing my work using only the best parts when possable, also of the convenience of locations in the many areas I did these Mobil Repairs, plus I had an account there. I also used lots of the MotorCraft ignistion parts but there are some other very good brands too you just need to compare their features and construction details. Good luck I hope you find the cause of that noise it's sounds like some fairly serious trouble.

Well after almost 2 years of trying to figure this out I only needed some basic common sense . The bolts connected to the flex plate were loose. I tightened them up and noise gone when rev'd!

As I tightened the bolts the flex plate would spin, hoping that is normal and I don't have a compression issue. I plan to do a compression test soon when I can pick up a tester.

I do have the inspection plate but when I had put it on in the past it would cause a different noise and just left it off. I will put it back on and see if it fits better now, which it should.

Thanks for your input and helping me through this. It went from transmission removal to tightening some bolts.

Bubba is one smart guy. Way back in post #9 he said to check for a loose flex plate. This forum is a great resource.

Hey, be happy it was a simple fix and it's done! Next!

Yes bubba is a genius id be still chasing my tail on basic problems if it weren’t for him.

Yes! I’m very happy thanks Econoline.

Well,,,Yes he is!

"...Next! ..."
Let's get this gleaming White Stead onto the nxt issue.
Running, stoppin well, 'funnin' out the door~

Congrats MustangDadDrake, i am glad it was a quick easy fix for you, should make it more enjoyable to drive now. And thank you everyone for the kind words I do appreciate it.