Somethings amiss

QGolden said:
Hi Dusty
I sincerely hope that this issue turns out to be a non-issue or an easy adjustment for you. Your Green A is one of my favorites. I travel through Morgantown a few times a year on the way to Grayson KY to see my In-laws, I would love to see it in person some day.

100 of us will all diagnose a 100 different malady's that seems to fit our perception of your problem through 100 different personal experiences, and I am no different. I do have an old chart from one of my Vintage (1940's) Motors Manual that I have used to help me to diagnose noises. Bear in mind, Marbles in a thick metal box to you is something different to me. What I call a knock you may call a Rap or a loud tap, or a marble in a heavy tin box. :rolleyes: Subtle, Deep etc all suspect to personal opinion.

But here is my go to list (mostly plagiarized) for engine noises some of the symptoms below obviously do not apply to your issue, but it is a good list and might help someone else some day:

Subtle Knock at half engine RPM no load on the motor:
Frequently Lifters. A faulty lifter can be found by listening to each rocker pivot point with a stethoscope while the engine is at idle. Also can be caused by, damaged valve spring, pushrod, rocker arm or even excess valve lash. Noise is caused by metal components "Floating"

Deep metallic knock:
This noise is caused by excessive main bearing clearance. Usually when the engine is under load for instance while accelerating, or climbing up a hill. Low oil pressure accompanies excess main bearing clearance because as clearance increases pressure decreases. Of course if you do not have an Oil Pressure Gauge, then you do not have a benchmark, Particularly in a low pressure, splash A.

Sharp metallic rap when releasing or engaging clutches Or letting off or stepping on the throttle:
Crankshaft end-play wear. Again caused by a momentary float as the pressure is removed or applied to crankshaft. This can be checked with a dial indicator or sometimes shims. Try to move the crankshaft from one side to another recording the amount of play. Check that with the factory specs.

Metallic rap when the engine is running under a light load:
Probably connecting rod clearance. The noise may become louder and will increase in frequency as the engine speed increases. Then go away if you go up hill and put the engine under load. Under load the cylinder pressure keeps the parts tight, under light load they can "float". You can isolate the defective connecting rod bearing by using a Stethoscope (I like the metal probe end inserted into a real rubber hose best myself). Work the throttle until you can repeatedly and predictably create the noise. Remove the spark from one cylinder at a time. When spark is removed from the defective cylinder the metallic rapping will noticeably decrease. .

Dull metallic rattle heard at idle and sometimes under light engine load.
Piston slap is usually the culprit. This noise is caused by excess piston/cylinder wall clearance, and usually goes away if you rev the engine a little. Sometimes the noise will go away completely when things warm up. This noise will not affect the engine’s reliability. However, if the noise remains after the engine is up to temp then a current or imminent piston or ring failures is likely. You cannot diagnose this by removing spark because the piston travel is not individual cylinder dependent.

Light metallic rap at idle and at low speeds:
Usually caused by excessive piston pin clearance. The cylinder with the worn pins can be isolated by grounding spark plugs. However, the affect is different than too much rod clearance. Noise from a loose piston pin will actually increase with the spark grounded, because there is no downward push from ignition and the piston "floats up" as the rod moves down. This sometimes occurs if piston rings are replaced and the pins are not.

While these are some of the most common noise sources, noises can come from areas such as Drive belts, water pumps, generator, timing associated parts etc. It might help to disconnect the Water pump and Generator while listening to a motor, it will reduce some of the ancillary noise.
Click to expand...


Thanks so much for the lengthy input and the time it took to do this. I have a great non Model a mechanic that is going to help with me with the valve clearance adjustment...I hope this is the problem.
 
Just as a follow up there is also a ticking noise that has been present for about a couple of months. I thought it might be an exhaust leak or that's what it sounded like but it seems to be coming from under the left side of the valve cover as well.

thanks to all again

dusty
 
Hi dusty,

Many thanks for update.

Original tappets for valves last a long time before they get out of adjustment; however, some new adjustable threaded tappets have been known to need adjustment more often.

Many non-Model A mechanics who never saw a Model A engine can easily figure out what is going on -- kinda like a guy who never went to Kindergarten -- he already knows his A,B,C's & can count to 10..

Let us all hope it is something simple.
 
Here is a long shot but sounds like this can travel. Loosen the fan belt and try to wiggle the water pump shaft front to back and check the pulley too. A loose or broken pulley can cause a knocking noise.
 
Cool Hand Lurker said:
Here is a long shot but sounds like this can travel. Loosen the fan belt and try to wiggle the water pump shaft front to back and check the pulley too. A loose or broken pulley can cause a knocking noise.
Click to expand...



thanks Cool Hand, I do have a fairly new leakless pump installed and the noise is definitely coming from the rear and side of the engine. But like you said it could be coming from anywhere. I did have a squeaky fan belt...could have sworn it was something metal rubbing.

thanks again
dusty
 
Last edited:
Another follow up, mechanic friend is coming up tomorrow to have a listen and add his opinion. Also it came up if these are indeed adjustable lifters?? I guess there are Model A engines that do not have adjustable lifters???

thanks
dusty
 
Had a very similar problem with my A. Noise came on slowly, and seemed to be a little worse at around 30mph in high gear, but could be heard otherwise as well. Very hard to localize. Turned out to be a bad center main bearing, something actually chewed the babbitt up. Needed a whole short block. Hope that's not your problem.
 
rosenkranswa said:
Had a very similar problem with my A. Noise came on slowly, and seemed to be a little worse at around 30mph in high gear, but could be heard otherwise as well. Very hard to localize. Turned out to be a bad center main bearing, something actually chewed the babbitt up. Needed a whole short block. Hope that's not your problem.
Click to expand...


Me too as there is no block of any length in my foreseeable future:(

dusty
 
Just to clear things up, The right side of a car, airplane, or what ever is as sitting in the drivers seat not standing in front looking at the fan blade etc.The Right front fender is on the right as sitting in the drivers seat. I learned that way back in 1963 when I went to work at a Pontiac Dealer Body shop.
 
Marvin/TN said:
Just to clear things up, The right side of a car, airplane, or what ever is as sitting in the drivers seat not standing in front looking at the fan blade etc.The Right front fender is on the right as sitting in the drivers seat. I learned that way back in 1963 when I went to work at a Pontiac Dealer Body shop.
Click to expand...

I'm talking about the side of the engine that the valve cover is on and its the left side of the cover which is to the rear of the engine.
 
Dusty said:
Another follow up, mechanic friend is coming up tomorrow to have a listen and add his opinion. Also it came up if these are indeed adjustable lifters?? I guess there are Model A engines that do not have adjustable lifters???

thanks
dusty
Click to expand...

Dusty,

How did you make out today?

Q
 
1. some A lifters are not adjustable, but yours prolly are
2. remove the fan belt totally and restart the motor to see if the noise goes away. If so then it is the gen or water pump. I know exactly where your noise 'sounds' like it is coming from, and prolly is, but sounds can telegraph thru a motor
3. A main bearing knock is a very dull sound and nothing like you describe
4. use a screwdriver with a plastic handle and short out one plug at a time to see if the noise goes away or diminishes. If so, possibly a rod knock. Shorting out plugs will not make main bearing knock go away.

Having said all the above, the 5 most likely issues are:
a. valve lash too loose. Pull valve cover and adjust on a COLD engine. .011 intake and .013 exhaust. Can be a bit looser but never tighter. Do this first which you have indicated you are going to do
b. distributor drive is tight and the cam is 'walking up' the gear and jackhammering back and forth in the block. Mitch/PA has written some good stuff on this, search under his name. Remove distributor and be sure the shaft is free. Maybe the top bushing has not been lubed
c. Cam timing gear loose or if the two piece gear, coming apart
d. Cam thrust plunger and spring issue (Inside the timing gear cover; the spring can break; the plunger can seize
e. Piston slap from a shrunk piston, typically cyl 3 or 4.
Coolant does not circulate around all cylinders equally due to a design flaw. For example owners often report that their blown head gasket (when it happens) is between 3 & 4: why: those cyls run hotter. The pistons in those 2 cyls are most prone to overheating and then shrinking, giving piston slap. You can drive a car with piston slap for a long long time. GM cars in the 70s and 80s all had it.

I have worked on 2 such As in the last month doing just what you are describing, and all the above procedures were done/checked and the noise is still there. To an experienced mechanic, the noise is clearly not main or rod knock, so we are gonna just drive the cars and have the fun we usually have.

A side benefit of checking the valve lash on one of the cars is that one of the valves had no lash at all cold, so you know it was hanging open when hot, and the owner dodged a bullet in the form of not burning that valve. Luckily the engine only had 1000 miles on it.

Before you begin any work be sure to document a compression test so you know your starting point. Be sure to do the test with ALL the plugs out

good luck
 
Ok this is what we found out, I have a manifold leak:o I always thought it had a leak from day one but it has got worse and I convinced myself that it was something more. Having said all that I'm still thinking there is still a much more expensive under lying problem and I hope its my paranoia shining through:rolleyes:

The mechanic friend rode along with me and he is certain he can hear nothing that would indicate a main or cylinder bearing. So I have removed the manifold and this is what I found...(don't know what that red stuff is.)

This is the gasket:
9781834733_544cc3ddf0_c.jpg


And the manifold

9781765234_9f766db07a_c.jpg



I should have the gasket in hand from Snyder's by the late afternoon, I'm not sure if the manifold should be milled or not(opinons?) I am taking it down to mechanic friend to see what he thinks. Depending if I can find a place here to do it it will be a couple of days before I get it back together. If I can't found someone to mill it here I may bite the bullet and order a new one.

Mechanic says this will take care of all the bugaboos rattling around in my engine....will see:)

dusty
 
Hi Dusty,

Thanks for update -- it helps everyone to see Model A problem areas.

Some mechanics can look, listen, & diagnose problems instantly; others cannot & have to try several remedies before the main problem is found -- sounds like you have a good one thus far to locate this one (1) gasket leak problem.

If you have high humidity, please go with copper metal on manifold gaskets -- steel ones always rust out over time in humid areas.

Let us know what happens next.
 
Thanks Dusty,
Glad to hear this is a non-issue for you. Keep that Mechanic on your Christmas Card list! Sounds like he has a good head on his shoulders.
 
Your manifold has drooped at the rear.Very common.Look at your pictures and you can see the offset in the leakage.Also,the lineup of the ears is way off.Age and heat will droop these old manifolds.I have one that should be replaced,but I just put on a new $12.gasket every five years or so.It looks like you can't use the gland rings with the droop you have,but if you can,and you did,they could very well be clinking around in the muffler by now.You really need a new manifold at this point.
 
New manifold will arrive in the PM tomorrow, the manifold was warped by about 7000 on one end and about 6000 on the other. Figure the cost of a new one at 91.00 bucks just made more sense instead of investing money in the old one.




Running low on cash in WV

dusty
 
Well this fablasko continues to get worse, ahh sort of. New exhaust manifold arrived and I got everything back together and guess what I can't keep the car running:mad: It won't idle but I can keep it running if I half cover the carb intake. So I'm thinking what could I have done to the carberator:eek: I called the not so local Model A guru and he chuckles and says its sucking air, I asked why. He says did you put a new intake on as well, I said no, he says still chuckling that's your problem:(

He said to pull it back off and to use a straight edge to see if there is a gap between where the exhaust seats and the intake seats. Hell yes there's a gap:eek: I'm surprised it ran at all and it now makes sense to me that the new manifold would have more metal then the probably already several times milled intake. Also surprised no here caught my error in the making.

So my options are take the new manifold with the old intake and have it mill, I really don't want to be cutting on the new manifold. Order a new intake:( Stick the old manifold back on with the new gaskets and see how long it holds. I chose number three:rolleyes: Well it sounds and runs great, did not have a chance to take it out to see if I can hear any other bugaboos but I will tomorrow. I hope it holds the rest of the fall as winter is fast approaching anyway and I will order a new intake in the spring along with cast iron drums for the front...that's another problem. I will report back tomorrow if I hear anything else, I still don't have a warm fuzzy feeling that this is the end to this saga.

dusty
 
You must log in or register to reply here.
Back
Top