Original, never touched 1966 425. I am finishing restoring the whole front end, It started very easily after 3 years of inactivity. No issues with timing and carburator. I ran it 2 or 3 times a say fro a period of no more than 10 minutes and all was fine. Having an issue with the brake master cylinder, I remove it but forget to reconnect the vacuum line to the power booster so it started rough, I reconnect it and it continue better but not as smooth as before, and then all of a sudden a hammer noise appeared, please look at the attached video. Any help on how to IMG_3863.MOVdiagnose what is going on or what you guys think is highly appreciated. One word of caution, the gas in the tank is 3 years old and was not replaced, yes I know, but it is what it is. Best Regards. Raul

 

Taking a stab at this, it could be a few possibilities. A remote one is piece of carbon has broken loose in a cylinder and is getting smacked by one of the pistons every time it gets to top dead center. The sound is too metallic to give total confidence in this though. A rocker arm bridge could have broken, or even a cracked valve spring. While not the most quick valve covers to remove due to accessory brackets being in the way, this could help see if it is valve train related. Something else which could cause this is the fuel pump arm return spring has become dislodged, the result being the arm of the pump knocking against the eccentric on the front of the cam timing gear. Everything is speculation, the first thing to do is too loosen/remove all the belts to eliminate the water pump, A/C clutch bearing and power steering pump. Did something fall into the crank pulley while you were working on the car, and now rubbing? The sound comes very suddenly after silence at the beginning of the clip. Nothing is ever certain dealing with noises, eliminating the more easy to fix things helps to keep our sanity. Failing to trace the above parts as being source of the noise, this will need to be delved into deeper. Hopefully some of the really seasoned folks on the 425 can chime in!

 

You have a valve or lifter sticking. If the gas smells like varnish it can be like glue and cause all kind of havoc to anything exposed to fuel as the engine cools.

 

It wouldn't hurt to examine the bolts holding your torque converter to the flex plate.

 

Thanks Gents, useful suggestions, I will start removing belts and physical inspecting around the engine in detail, BTW I had lost in the rebuilding process the front brace for adjusting the A/C compressor, maybe just maybe. If all this do not supress the noise I will remove the valve covers to look at the train. Sincere Thanks!. Regards, Raul.

 

The noise is valve related, you need to take the valve cover/s off and inspect.

 

Hi Eric: If its a lifter or valve sticking is there a way to solve this without removing the intake manifold?. Regards. Raul.

 

Maybe, you need to look at the rocker arms and see what is going on as a first step.

 

understood, will do that during the week end and update with my findings!. Regards. Raul.

 

Remove both valve covers and all seems correct for me, please take a look at one of the trains in the attached video. What to do next?, using an stethoscope the noise seems to becoming from the rear side of the intake manifold. Close to the distributor, there there is a much "thinner" metallic with the same rhythm, like a small piece of metal clanging. Please any further advice is highly welcome. This situation has me really down since I was almost finishing this project and all of a sudden this unexpected problem points toward a dim future. Regards. Raul.

 

I have a set of 455 heads in the shop right now that have a bunch of stuck open intake valves due to old fuel. The fuel with ethanol in it starts to turn to glue after a few years This is about the 5th set I have seen in the last few years. If you can pinpoint which side it is just pull the valve cover. I bet you will find some loose rockers where the valves are stuck.

Personally I would not run it another second until you find out what the noise is. A bent valve is an easy fix. A broken one makes a mess

 

Evidently you did not like my suggestion in Post #4? You do know the converter/flex plate is located nearly directly below the distributor correct?

 

Listened to the video, and it sure sounds like rockers making noise.

 

Dear Norm: Far from it, actually at first I didn't realize what you were talking about, later I realize what you called Flex Plate is my old good Flywheel!. I was, and possibly still I am,somewhat biased toward valve issues or worst but after seeing the valve train working it doesn't seems to be there the issue. I always kept your suggestion rumbling on my head and after looking at it more an more it make very good sense to try. Also, at first it looks it may be difficult for me to do check them but after some analysis I certainly can do it so I will give it a try possibly today or tomorrow. The other thing that kept me skeptic is the fact that when the engine is cranking there is no noise but then it hits me that possibly and on the contrary when the starter engages into the Flywheel it push it firm and later when disengaging it becomes loose, maybe wishful thinking but certainly worth a try. I will let you know the results as soon as i get them. All the Best. Raul

 

Hi Eric: I didn't hear that noise coming from the rockers, its too loud!. How can I identified a valve is stick, I understand if springs are being compressed by the rocker the valve should be opening and that is what is happening ot all of them. Best regards. Raul.

 

Hi Bill: For sure, I was aware, I initially test the fuel somewhat and compared to new fuel and it didn't seemed bad at all, also it ran on it no more than 10 minutes. I have some logistical issues here in my country due to COVID-19 that precludes me form getting new fuel easily, no excuses here but.. as soon as possible i will check it. Do you see from the video evidence of stuck valves?, Best Regards. Raul

 

I listened to the video on my phone, but now after watching it a bit on my laptop I'm not seeing a whole lot of oil flow.

 

Eric; me too but I am assuming not enough time for it to flow, it was just running the length of the video, is this correct?

 

Technically, it would be called a flywheel if it was a manual transmission. If it is automatic technically it would be called a flexplate. Flexplates are generally much thinner than a flywheel - they are designed to "flex" as they transfer motion from the engine to the torque converter. In effect they isolate & transfer motion. A manual transmission lacks a torque converter & therefore lacks a flexplate since the coupling of the motion from the engine to the transmission is accomplished via the clutch pack assembly. At any rate, there should be a dust/debris cover (metal or plastic) covering the torque converter where it meets the flexplate - generally held on by four small bolts or screws. The original cover on your car is most likely metal considering it's a 1966. It's possible someone may have replaced it w/ a plastic cover over the years - I don't know. If you remove the torque converter cover (my suggestion), you can readily visualize the flexplate itself and it's mating to the torque converter/engine.

The flexplate is designed to flex and under normal operating conditions it would flex appropriately. You may have snapped/broken a flexplate to torque converter bolt (or several), you may have a broken or cracked flexplate (cracked in numerous places) which can cause the flexplate to seriously become "warped" and out-of-balance as it rotates. I'm not suggesting this "is" the issue, broken bolts, cracked/broken flexplates can emanate different sounds depending on what's broken. I would examine that area if it were me. The flexplate is barely spinning as you start the engine - most likely it is barely flexing. When the engine starts, the flexplate is rotating at a much higher speed. "If" the flexplate is broken, cracked, or bolt(s) have broken - you'd expect more rotational flexing of the flex plate.

If you have a manual transmission you can forget about it being a flexpate issue entirely.

 

Thanks for the explanation Eric, unfortunately after looking at it, all 3 bolts, they were all in one piece and tightly adjusted, cannot evaluate the flex situation but it looks perfectly straight. I only looked at it while cranking or still since I am avoiding firing the engine until I found the cause. Thanks again for this.Best Regards.

 

I agree with Vintage Chief, in the first first video it sounds like a cracked (auto trans) flywheel sound to me. Had it happen once , on one of my (+43) Oldsmobile engines.
Of course, other things are possible, but am going by what I remember

 

Update on this issue: I run a compression test and all cylinders almost identical reaching 150 psi, so I am discarding valve train issues, am I right?

 

Rocket Launcher & Vintage Chief: I have attached a new video where you can see the Flexplate somewhat running, the main purpose of the video was to confirm or rule out if the starter pinion is the culprit, which unfortunately doesn't look so. I do realize the housing of the starter seems too close to the flexplate, and I am not sure if this is correct, I cannot visualize if it is touching it lightly. I recall in the CSM, specifically page 12-10 figure 12-10, drawing of the electrical components of the engine, there is a spacer between the starter and the block,which I do not have, I do not remember it or losing it, does anyone recall if it is mandatory?. At the end of the video I tried to get a closer look at the flexplate but it was a little dangerous, please any comment or advice is highly welcome!. regards. Raul

 

It appears you've narrowed down the location of the issue - at least based upon the exceedingly loud air hammer noise. I wasn't going to throw a wrench into this thread earlier by suggesting starter, pinion, alignment, shims, etc. unless you first went downstairs to examine the flexplate condition & more or less ruled out rocker arm bridges. I don't have a 1966 CSM, so stating pages & figures (for me at least) won't do me any good. Others might have a 1966 CSM and they can provide additional guidance. Are you referring to alignment shims (spacers) where the starter attaches by any chance? That might very well be the case. I haven't had to shim my starter on my '71 CS, but I know others who have had to shim their starter. It is not clear to me if the shims are required for OEM starter applications or the shims are required to accommodate aftermarket starters.

I'll examine my own '71 CSM just as a reference, but IMO, I believe you've located the jack hammer sound and it's emanating from the flexplate - perhaps not a bolt, or a crack, etc. - but perhaps non-alignment w/ the pinion might very well be the case. Others will hopefully provide additional opinions. Honestly & hopefully this "is" where the issue resides instead internally to the engine.

EDIT: Is your starter an OEM application starter or an aftermarket starter of nefarious origin?

 

I definitely don't want you to place yourself in an unsafe position, but it would be nice if you were able to place your hand on the starter motor itself or I believe you said you had an engine stethoscope? If you can "feel" something "hammering" against the starter that would suggest it's most likely where the jack hammer resides.

Is this starter a different starter than what was previously on the vehicle or same starter which was always on the vehicle? I listened to the video again, it sounds like the pinion is ratcheting within the starter clutch & is "ratcheting". The clutch only spins one way and it makes a distinct ratcheting sound when it engages. It certainly sounds, at least, as though the pinion has remained "engaged" with the flexplate (the pinion is spinning inside the clutch) and the pinion has not retreated back down the starter armature.

 

Listen to this video at the 24 second time mark. Tell me if this is nearly the same sound as you are hearing when the pinion is contained w/in the starter clutch. It sure sounds like it to me.

 

The starter is the original one VC.

 

I don't know. Many different styles of starter motors and solenoids, I just don't know. It does sound like that pinion (or I guess it could be called what, a bendix?) is hitting the flexplate almost like it hasn't released. There are solenoids which have that nylon sprag(?) or lever which slides the pinion out and into the flexplate (engaging the flexplate to start the engine) and then it is supposed to slide the pinion back down the armature shaft into the starter motor once the engine starts. Could that nylon lever be broken? Is the clutch/pinion assembly mis-aligned? I don't know.

 

Unfortunately, looking at the video in detail I can clearly see the pinion disengaged and retreated while the noise continues, that’s Why I turned to the possibility the flexplate is interfering with the starter case, and yes I was referring to the shims when I mentioned spacer.

 

Oh, ah ha, right - I understand now. So, you could see the pinion retreat and you think maybe the actual flexplate is hitting what? The starter motor casing? I don't know. Well, if a normal flexplate in good condition was hitting the starter motor casing, I would think it would produce a more rapid clanking. By that I mean there are what, like ~115 teeth on the flexplate and only about what 6 or 8 teeth on the pinion gear? You'd think if the flexplate was hitting the starter case it would produce more hits per unit time. Just thinking out loud here.

EDIT: I just listened to it again - it is awfully rapid I'll give you that. Maybe the flexplate is hitting the starter casing.

 

Again, not unless you feel comfortable with this, I'd sure like to put my hand on the starter motor to see if I could actually "feel" the vibration emanating on the starter motor - whether internally inside the starter motor or externally on the casing. Just the ability to actually "feel" the slapping/ratcheting would say a lot about the noise/vibration.

 

You are right, I was not thinking clearly here, I have in mind a wobble flexplate for some reason!, the stethoscope shows a loud clicking sound on the starter housing where the pinion resides but also in the converter and bell housing, I am still lost here.

 

I am trying to ascertain how to diagnose the issue while the engine is running to better get a grasp of the noise, but nothing short of removing the starter itself comes to mind unfortunately. Obviously, you won't be able to start the engine, however there may be a tell-tale sign of rubbing metal-on-metal if you remove the starter and can visually see metal abrasion somewhere. Once the starter is removed you'd have a little more visualization of the flexplate itself. You can wedge a crow bar or long heavy duty screwdriver along the side of the flexplate and make shallow attempts to see if the flexplate is possibly out-of-round, making a clinking noise as you leverage it vertically side-by-side with moderate force to see or hear something. I think you're in the correct area relative to the noise - would you agree? I think the starter most likely needs to be removed next for a better diagnosis?

 

Agree completely, actually that was my plan today but decided to film the video first and then got a little disappointed by the prospects, I will try to do it ASAP.

 

I forgot to mention that this noise started to happen after I run the engine with both front wheels elevated since I need to purge the power steering. It did not happened while but later as I put all 4 wheels on the ground. FWIW.

 

Just curious, how did you lift the vehicle - with a floor jack located under the cross-member below the front suspension forward of the oil pan? Which would be the normal position to hoist the front of the vehicle.
Did you hoist the front end via an area on the engine itself by any chance?
Did you perform any work on the motor mounts or hoist the engine itself for any reason?

 

Lifted with a floor jack under the crossmember.
I did raise (incline the front upwards using home made tool as described in the CSM) the engine 3 years ago to remove the carter for repair and use the opportunity to replace the motor mounts.

 

BTW this is the first time I ran the engine since that work.

 

In & of itself, there should be no issue running the engine with the front-end of the vehicle hoisted residing on jack stands. I am familiar w/ the procedure you're referring to regarding the front engine hoist. As long as it was done properly, that shouldn't be an issue. IOW, as long as it wasn't hoisted on the crankshaft itself (which be the worst place to perform that particular front engine hoist). The screw which runs through the engine support tube should be applied to the base of the engine and not the crankshaft. I can't speak from experience regarding a 425 cid engine, but I note for a 455 you are "supposed" to remove the transmission cross-member, transmission & flywheel/flexplate prior to raising the engine (as outlined in the 1971 CSM for a 455 cid). That is NOT the case for the 350 cid. I raise the front of my engine (350 cid) via an engine lift when required instead of the tool you are referring to. I can't say if you strictly followed the procedures according to the CSM but there are reasons for strictly following the procedures.

This is the first time you've run this engine since you hoisted it 3 years ago to replace the motor mounts and I'm not clear what you mean by you removed the "carter" for repair? What is a carter?

I don't know what the tolerances are regarding the hoisting of the front of a 425 cid engine (in particular with the lower homemade engine hoist tool). There are obvious reasons CSM procedures should be strictly followed e.g. removal of transmission cross-member, transmission & flywheel/flexplate. If the procedures were not followed (I'll mention again when using that homemade tool you have to use the bottom of the engine case and NOT the crankshaft) it leaves areas open to suspicion. I would start by removal of the starter and go from there. Examine the flexplate thoroughly, examine the starter thoroughly, if that sound is emanating from "that" area and you haven't found the issue or resolved the issue: (1) transmission shop or (2) start removing the flexplate and torque converter would be my next guess. I'm not sure what else I can suggest.

 

Looking back at what you said....
Examine this video. Listen to the noise at 45 seconds when he tightens the bolt. As he tightens the starter bolts the noise becomes very similar to your noise. I wonder if you need that spacer. In this video, where the starter bolts are loose, you do not hear any sound. As he tightens the bolt, the sound becomes apparent. It's very similar to your situation perhaps. Imagine if you had that spacer between the block and the starter, you wouldn't be driving the bolts as deep & you wouldn't be drawing the starter up as close to the block. When he drives the bolts deeper, the noise begins. Spacer might be your issue? A quick diagnosis might be to simply loosen the bolts on the starter and see if the noise disappears?