Restoration Startup Transmission Whine (or not)

amcdonald

Active Member
Hello

After a long hiatus working on house renovations with zero fun factor, my second decade of NADA 3500S reno continues. Actually, in danger of completing it before the next pandemic. I went for a drive round the development for all money the transmission whine was horrendous. I thought that was a bummer as my warranty expired over 3 years ago when I had it reconditioned. Then I noticed the noise change a bit when I turned the steering wheel fast. I thought that is odd, so I disconnected the belt to the PAS pump and no "transmission whine". Result! Well, sort of.

Question - I presume this must be just something screwed up in the pump (that I reconditioned) and not elsewhere in the PAS system? I can't see what else could generate an RPM dependent whine?

Here is where I am even more glad that I binned my smaller leather covered and manky steering wheel as I much prefer the original ones. Crazy light with PAS but quite fine if you have disconnected it......

Adrian
 
Hi, It's cavitation whine, most likely just air in the fluid, keep turning the steering wheel from lock to lock and the air will eventually dissipate, the fluid in the reservoir will be pink and frothy but again will return to normal red.

Colin
 
Really? That is a thing? It was a pretty loud noise. Obviously would be pretty good news all round. What was odd is that it is hardly noticeable outside but inside its horrible. The magic of noise transmission through metal......I will cut the zip ties stashing the belt to one side and put the belt back on then and see if I can get away from the macho man manual steering again.
 
Hi, P6s are unusual in that noises from the steering, even normal operation, can be heard easily because they are right up against the bulkhead and brought into the cabin by the column, in front of the driver. More conventional cars have the steering box down by the feet in the engine bay.

Colin
 
Cavitation can get very noisy. Check that the hose from the tank to the pump is not kinked or restricted in any way. ATF - PAS fluid is very hard on the hoses, and they should be replaced as soon as there are signs of weeping, or fraying at the ends. I had a Disco once where the supply hose got trapped and restricted by the battery and the noise was horrendous.
 
Hi, When I was at the bus company we had a Leyland National that had the whine that resonated through the whole bus. After changing the pump and the power rack to no joy it turned out to be a bit of paper off the filter in the reservoir had laid across the outlet to the pump restricting the passage of the oil, causing the cavitation.

Colin
 
Cavitation on speed boat propellers - vacuum bubbles? - collapse so violently they actually erode the edges of the blades.
 
Hi, When I was at the bus company we had a Leyland National that had the whine that resonated through the whole bus. After changing the pump and the power rack to no joy it turned out to be a bit of paper off the filter in the reservoir had laid across the outlet to the pump restricting the passage of the oil, causing the cavitation.

Colin
Loved the old LN's MK 1 & 2. Did my apprenticeship on those. When the pumps went, the droning noise & vibration was horrendous accompanied by frothy strawberry milkshake pouring from the reservoir. Happy days!!
 
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