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Difficult to identify noise from my '41

Started by rustytractor, June 26, 2014, 07:06:09 PM

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rustytractor

The '41 recently developed a noise whilst accelerating under load - it sounds exactly like the fan hitting the fan surround but it definitely isn't that. I may be paranoid but I think it seems to be getting worse so I need to find out what it is asap.

The problem is difficult to locate as it can only be heard whilst the car is moving and seems worse the more weight the car is carrying - I've had both front and rear passengers listen whilst I drive and everyone seems to think it comes from whichever window they happen to be hanging out of but the most common opinion is that it's coming from below the passenger side rear seat - right above the exhaust.

At first I thought it may be a heat shield but there aren't any, i've checked for exhaust vibrations but it seems solid as a rock. To me it sounds like it's coming from the front but I'm driving and everyone else says different. Possibly it's a baffle come loose in the muffler but that's really hard to check when not moving as it seems fine when tapping/banging/knocking it - no rattles whatsoever.

I can't be sure but it's possible that this started when I changed both exhaust manifold gaskets. This entailed having a tread tapped where the crossover pipe attaches but other than that there was no real disturbance to the exhaust itself and the repair worked fine, no more exhaust manifold blows.

Any ideas or suggestions would be much appreciated as I'm worried it may be transmission related and don't want to blow the hydramatic up. Last time I checked the fluid level it was fine, this was a few months and less than 1000 miles ago :(
Too many cars - too little time !!

joeceretti

Can you make a short video and post it on youtube for us to hear?

Bill Ingler #7799

I first would first jack up the rear of the car until both rear tires are off the ground, block the front wheels and then start the car. Put the car in gear and get someone to listen to see what noise is heard and where in the rear. I had a noise in my 41 which finally turned out to be the right rear hub cap medallion was loose on the cap. One of the areas that could be causing the noise is a failed axle bearing. Remember the axle bearing is a sealed bearing and if they are the original New Departure bearings then they are about 73 years old and means any grease left in that bearing is also 73 years old. Anyone driving these old Cadillac's should put on new axle bearings for piece of mind. Have been on two CCCA CARavans  where a 41-75 and a 47 both had fires due to failed axle bearings, fortunate the fires were put out.    Bill   

Jay Friedman

If the noise only occurs when accelerating under load, another possibility is that it is "pinging" due to the ignition spark timing being too advanced.  Check the initial timing with a timing light and adjust it if necessary according to the instructions in the shop manual.  This could also be due to the vacuum advance mechanism on the distributor being faulty.

Another cause of pinging is using fuel of too low an octane level.
1949 Cadillac 6107 Club Coupe
1932 Ford V8 Phaeton (restored, not a rod).  Sold
Decatur, Georgia
CLC # 3210, since 1984
"If it won't work, get a bigger hammer."

John Washburn CLC 1067 Sadly deceased.

Could it possibly be a motor mount or transmission mount?

The Johnny
John Washburn
CLC #1067
1937 LaSalle Coupe
1938 6519F Series Imperial Sedan
1949 62 Series 4 Door
1949 60 Special Fleetwood
1953 Coupe DeVille
1956 Coupe DeVille
1992 Eldorado Touring Coupe America Cup Series

joeceretti


sly37

I've heard some really strange noises from fan belts. Make sure yours are real tight.

D schroeder

John Washburn CLC 1067 Sadly deceased.

Quote from: sly37 on June 26, 2014, 09:46:46 PM
I've heard some really strange noises from fan belts. Make sure yours are real tight.

D schroeder
No, no... One does not want to tighten fan or generator belts "real tight", that will result in bearing failure in the generator and/or water pump. Follow the instructions in the shop manual and make sure you use the correct belts!!

Check out the article in the Self Starter last year on this issue.

The Johnny
John Washburn
CLC #1067
1937 LaSalle Coupe
1938 6519F Series Imperial Sedan
1949 62 Series 4 Door
1949 60 Special Fleetwood
1953 Coupe DeVille
1956 Coupe DeVille
1992 Eldorado Touring Coupe America Cup Series

sly37

Guess that was a bit misleading..I should have been more specific. But that said. Slightly loose belts can make more strange noises.....I recall a fella was going to remove his engine, it was running making all this clacking wheezing sounds. I poured some of a cocktail on the belts. Quiet as a mouse.  I thought he was gunna hit me. Haha.

Steve Passmore

If its under acceleration sounds like a classic UJ joint failing. They will work fine on the flat but under load the rear suspension drops changing the angle on the UJ making the rollers operate at a much more extreme angle. A worn UJ will always complain under load.
Steve

Present
1937 60 convertible coupe
1941 62 convertible coupe
1941 62 coupe

Previous
1936 70 Sport coupe
1937 85 series V12 sedan
1938 60 coupe
1938 50 coupe
1939 60S
1940 62 coupe
1941 62 convertible coupe x2
1941 61 coupe
1941 61 sedan x2
1941 62 sedan x2
1947 62 sedan
1959 62 coupe

Doug Houston

For wot it's worth, here's a true story.

A friend living near by me had a '41-75, that he drove a lot to meets, and all that.He too, had a strange, unidentifiable intermittent noise, possibly in the drive line. He drove the car thousands of miles with this mysteroious noise.

He moved to Florida, took the car with him but had a sale for it almost immediately. Trailered the car back to Detroit, and got here with a broken rear housing on the (Manual) transmission. Now, wot?

The car was originally built with a bolted-on front U-joint, and a slip-jointed drive shaft. Somewhere along the way. some birdhead replaced it with a n on-jointed drive shaft.that left no slip joint in the drive line and the transmission With the jouncing from Florida here, the trans finally broke.

He was able to find a later model trans, that had a slip joint in the tail housing. I have he old transmisison.
38-6019S
38-9039
39-9057B
41-6227D
41-6019SF
41-6229D
41-6267D
56-6267
70-DeV Conv
41-Chev 41-1167
41 Olds 41-3929

Smedly

Just another idea, Have you lubricated your water pump and generator  lately ? I know my gen was starting to make some awful noises before I removed it. and it was intermittent but if you wacked it with a hammer it would stop for a while >:D 
Sheldon Hay
When a Doctor "saves a Life" it does not necessarily mean that that life will ever be the same as it was, but he still saved it. My 46 may not be as it was but it is still alive.
Sheldon Hay

rustytractor

Thanks for all the suggestions - I'm now more confused than I was before I posted about the problem !

I've done a little digging and there appears to be a bit of play in the prop UJ's (nothing major) and one of the rear shocks is definitely weak so either/both of these may contribute.

The car is auto so it rules out some the manual gearbox suggestions but recently I've noticed that the car doesn't always pull away in 1st when cold unless low is selected (I assume it say's low, the little letter legend in the gear selector quadrant is missing - if anyone has one spare would you please let me know ??). This seems to recify itself when warm but I'm also puzzled about the whole gear selection process.

I'd swear that when I first got the car moving the lever from Hi to Low dropped it down a gear but now it doesn't. It sort of seems that Low or Hi both give access to all gears but only Low lets it pull away in first when cold. I checked the gearbox oil level when I first got the car and it was fine and I've probably done a thousand or so miles in that time - can anyone tell me what should happen when changing from Hi to Low (at moderate speeds of course) and if you think I have a gearbox problem or low fluid issue.

The gearbox changes up/down fine at all other times and makes no strange noises - except possibly the one raised in this post in the first place.

Re a possible generator noise, if I could identify where on the car it's coming from it would help but it's definitely worse when there's more weight in the car.

Re generator belt needing tightening - these belts seem to be fairly thick and were relatively loose when I got the car (by loose I mean not following the 1" total  up/down movement I usually follow when adjusting drive belts. The generator works fine so I've left it adjusted as when I got the car - how tight it should actually be ?

Too many cars - too little time !!

rustytractor

#13
Well the noise appears to be gettting worse. I've narrowed it down and am 99% sure it's coming from the rear end of my '41. I've attached links below to a couple of small sound clips in the hope that someone can identify what it is. These are uploaded to my own ftp site so are safe to download and will play with most Media players.

www.romar.co.uk/Cadillac/1941/41CadiRearEndNoise-1.m4a
www.romar.co.uk/Cadillac/1941/41CadiRearEndNoise-2.m4a

I recorded these while driving with the window open so there's a lot of wind noise but hopefully someone may be able to identify the source of the problem - as mentioned before it sound just like a fan hitting a fan surrond. The noise starts when accelerating and all but stops when backing off the gas - what you'll hear in the clips is me accelerating then backing off the gas. If driving with a steady throttle the noise isn't there and the car drives and stops perfectly.

I tried to remove the rear drums yesterday but didn't have a puller man enough for the job so this will be the first area to be investigated as soon as I can locate a decent puller (I've read the posts and know that this has been a problem for many people before me). It appears to me that the noise is coming from the drivers side rear but it could be being transmitted from the diff or prop and it's difficult to identify while driving.

Hopefully it's something fairly simple like the prop - I thought I'd get some opinions on the noise itself before ripping bits off the old girl as someone out there has probably had exactly the same problem.

I've checked the diff oil and the level seems ok although the oil appeared a bit light and "foamy" - is this normal ?

Grateful for any advice from the big wide world ASAP please.
Too many cars - too little time !!

harry s

I'm with Steve, it sure sounds like a U joint. Check for any movement in either joint. Even if it doesn't move it can still be bad. Good Luck,    Harry
Harry Scott 4195
1941 6733
1948 6267X
2011 DTS Platinum

sly37


To check u joints I've always removed shaft and feel them. They don't have to be loose to be bad. They can be froze or very stiff and make some very strange sounds. Been there done that.
d schroeder

Steve Passmore

Russel, you say theres only a little play in the UJ. No amount of play is good in a UJ. Those tiny needle rollers are a tight fit and when you have play the lubricant is gone and the needles are shot.  As sly37 and Harry said, they don't even have to be loose to be bad, the looseness comes usually after they have run dry and worn out.  As its something that needs doing why not just renew them anyway and see if that cures the noise.  Elimination is the name of the game. 
Steve

Present
1937 60 convertible coupe
1941 62 convertible coupe
1941 62 coupe

Previous
1936 70 Sport coupe
1937 85 series V12 sedan
1938 60 coupe
1938 50 coupe
1939 60S
1940 62 coupe
1941 62 convertible coupe x2
1941 61 coupe
1941 61 sedan x2
1941 62 sedan x2
1947 62 sedan
1959 62 coupe

Jay Friedman

I listened to your recordings of the noises and can't identify what sounds like crackling noises, added to which are the all the wind noises you mentioned.

Several years ago my '49 (has similar drive train to '41) started making strange noises underneath, which differed at different times and different road speeds.  After talking to lots of fellow CLC members at the 2008 Grand National and inspecting the drive train myself and having it inspected by amateur and professional experts, I finally took the car to a shop which specialized in drive lines and springs, mostly for large trucks.  They immediately diagnosed the problem as being partially worn universal joints compounded by my drive shaft (prop shaft) being out of balance due to dents in the shaft.  They fixed it completely by replacing the drive shaft and both universal joints.  Since they had the special equipment, they were able to make a new driveshaft with parts they had in stock.  The u-joints they obtained from a parts company.
1949 Cadillac 6107 Club Coupe
1932 Ford V8 Phaeton (restored, not a rod).  Sold
Decatur, Georgia
CLC # 3210, since 1984
"If it won't work, get a bigger hammer."

Steve Passmore

Just to let you guys know my fellow countryman Rustytractor has found his problem, the UJ's are shot, and he's presently trying to track down some replacements.
Steve

Present
1937 60 convertible coupe
1941 62 convertible coupe
1941 62 coupe

Previous
1936 70 Sport coupe
1937 85 series V12 sedan
1938 60 coupe
1938 50 coupe
1939 60S
1940 62 coupe
1941 62 convertible coupe x2
1941 61 coupe
1941 61 sedan x2
1941 62 sedan x2
1947 62 sedan
1959 62 coupe

rustytractor

The problem is 100% the UJ's.

I pulled the prop today and the rear UJ is partially seized, dry as a bone and badly worn hence is total toast, the front has some play so also needs replacing.

Hard to get these in the UK, does anyone have a pair to sell or know of a reliable supplier I can order them from ?

I'm glad it's nothing to serious but p****d off that I can't use the car until replacements are sourced.

Is it as difficult to get parts for older British cars in the states as it is for 40's cars over here ? 50's cars are no problem but anything earlier is a real PITA !
Too many cars - too little time !!