Recently obtained a 1954 Pontiac Chieftain L8 with hydromatic transmission. It had been in a barn for ten years. First thing that was done was all the fluids were changed. Engine pan dropped, cleaned and refilled. Transmission pan dropped and fluids replaced. Rear axel housing drained and refilled. Radiator drained and refilled. No metal parts were found in any of the pans or rear end. Vehicle still a little hard to start but getting better. Problem!! After I get it going and the vehicle shifts into 2rd or 3rd when I let off the gas or apply the brake it makes an awful noise from the rear. Lower range is ok and no noise in reverse. Just when I let off the gas. As soon as I re-apply the gas the noise stops. It is really a loud rumble. Any Ideas?
The pros will be here shortly
In the mean time have some free coffee and donuts
Are you saying the noise is from the rear axle? Then it could be u-joint, brakes, bearings, or differential. Put the rear axle up on jack stands and check each of these out.
My best guess is either a bad u-joint in the drive shaft, or perhaps just the need to lube the splined shaft. However, it could also be the result of a bad differential.
Are you sure the noise is in the rear and not in the transmission? The transmission selector, as I remember, looks like this: N ’ D ’ L R. L allows the Hydramatic to go through the first two speeds. If you don’t get the noise here, move the selector to the D ’ position. This allows the transmission to go through the first three speeds. If you do not get the noise here, accelerate it up to 45 or 50 mph in the D ’ range and then move the selector to ’ D range. You should feel it shift into 4th or the highest range. If it doesn’t, and you get the noise, you have a problem in the transmission. If it does shift correctly into all 4 forward speeds, it could be a problem in the areas that the others suggest. At this point, I would suspect the carrier bearing in the differential.
To Triedaq: Good suggestions. Your right about the transmission selector. Thats what it looks like. I will try what you suggest. I have a feeling this may be the reason why the last owner parked it many years ago. I hear a transmission rebuild cost a fortune. We had it up on a lift and rotated the wheels and did not hear any noise in the differintial. No noise on reverse and or when moving slowely. Afraid to get it up to speed because of the noise and it causes the car to loose speed quickly. Not sure of the exact location of the noise because of the rumble is quite loud and hard to place. I’m inside the car of course which makes it more difficult. Rear U-joint is ok. we replaced the front differential seal. Looks like I may need to get into the differential and take a look see. Will keep you posted. Thanks for advice.
If the rumble is loud when you’re going straight, it’s likely not the spider gears in the differential, and if it’s a rumble and not a whine, it’s also less likely to be the main gears.
But you’re right not to get it up to speed, you need to find this first.
What about reverse? If the inner pinion bearing is failing there will be a noise on coast down and in reverse.
Mind you I am going slow in reverse but there is no noticable noise in reverse. The times I have noticed the noise is when I am up to speed in forward after the second shift. I have some other issues I must fix first before I can go into depth with this problem. The water pump is bad and must be replaced. I will order one tomorrow and take care of that problem as soon as new pump comes in. Also the car will idle for, “who knows how long” but if I try to drive it for to long it will stall and be reluctant to start again. I believe this problem to be in the carb, as I have already installed a rebuilt fuel pump and drained tank with filter between both. I will also rebuild the carburetor and see if that takes care of that problem. The car is really in good shape body and interior wise. The first thing I had to solve was the mice made nest in the car and the stench was terrible from their pee.
That has been 80% resolved. Thanks for the info you all. I’ll keep in touch as things progress.
You might also want to check the exhaust system to make sure that it is not touching the body when the engine moves within the confines of the engine mounts and takes the exhaust system along.
If the water pump bearing is bad, the water pump may be setting up a vibration that is transmitted through the driveshaft. Obviously, I can’t hear your car, but as your engine goes into a higher gear, this out of balance water pump may be causing the engine and transmission to vibrate and ultimately the entire drivetrain.
The 1953-54 Pontiacs were interesting cars. The 1954 was the last of the inline engines. Pontiac offered both an inline 6 and 8, although there weren’t that many inline 6 engines made that year. The Hydramatic transmission was first introduced on the 1940 Oldsmobile. The Hydramatic saw service in WW II on tanks. Pontiac began installing the Hydramatic in 1948 and 80% of the 8 cylinder models in 50% of the 6 cylinder models were equipped with Hydramatic. The Hydramatic was a rugged transmission although it did require periodic band adjustment. You’ll have to find a really old transmission man that knows that procedure or find an old service manual. There was a company that beefed up the Hydramatic for hot rodding applications–this beefed up transmission was the B & W Hydrostick. Under many conditions, it could beat a manual shift.
One thing I remember about these inline Pontiac engines was a tendency for blowby past the piston rings. There was no positive crankcase ventilation, so the smoke came out the road draft tube.
Since the body and interior on your car are in good shape, you have a car that should
be fun to own and drive. The 1954 Pontiac was one of the last hold-outs for the inline flathead engine.
I don’t know what the noise is but fuel problems and vapor lock is certainly a possibility on that vintage. I believe you need to add a thicker gasket under the carb and wrap the fuel lines to reduce the heat. Also you should be using the non-oxy gas.
Bing, I think you may have hit the nail on the head on the fuel problem. Pontiacs in those days did have a problem with vapor lock. I was never sure why, but they were worse about this than many other makes. I had a 1947 Pontiac and it would sometimes crank over awfully slowly when the engine was hot. All in all, however, these Pontiacs were rugged and reliable cars for this time period.
Have rebuilt the Carb and the car now starts every time on the first crank. Somewhere along the line someone added a heat shield under the carb which extends over the Exhaust manifold. Hopefully this will take care of the vapor lock problem. Still waiting for the water pump to be delivered. Other than that nothing new to report. When I get the water pump installed and the new brakes put on will drive the car again and let you all know what happens.
This has nothing to do with your problem, but in '54, GM put powerglide transmissions in some Pontiacs and Dynaflow in some Oldsmobiles because of a problem at the factory that produced Hydramatics
EllyEllis–I think you are off a year. The transmission fire occured in 1953. You are correct that smoe Pontiacs had the PowerGlide. My uncle had a 1953 Pontiac with the PowerGlide transmission. The PowerGlide did have a “Park” position while the Hydramatic did not. I think General Motors bought a plant at Willow Run from Kaiser and got production of the HydraMatic transmissions going before the end of 1953.
My town had Borg-Warner transmission plant that was actually helped by the GM Hydramatic plant fire. Hudson and I think another independent switched over to the Borg-Warner automatic. The GM HydraMatic was not only used by Pontiac, Oldsmobile, and Cadillac, but by Nash, Hudson, Kaiser, Frazer, and Lincoln.
Well, I worked at the BOP plant when that happened, I was thinking it was '54. It was the year that Buick came out with the V8,.
Buick came out with its “nail head” 322 cubic inch V-8 in 1953 in its Super and Roadmaster line in 1953. However, the 1953 Special kept the inline 8 overhead valve engine. In 1954, the Special got a its version of the “nail head” V-8 engine which displaced 264 cubic inches.
You are right. I bought one of the “Specials” that year. I put one of those 2 carbuerater, Split exhaust manifolds and duel pipes on it. It sounded like a V8.
Up date on 1954 Pontiac problems. Have located source of “rumbling” noise. The differential is the source and it appears the pinion bearing/s are the cause. Will have to drop drive shaft & pull rear axels to get at the “banjo” style rearend. Hope this is the only problem. So far have rebuilt Carb, rebuilt fuel pump, put on new water pump, completed front and rear brake job, and next I’m going to replace the Master Cylinder. Brakes were bled but still go to the floor. Looks like I have a winter project.