SCREECH WHEN HOT
Q
I have a 1971 Triumph Toledo which drives smoothly and runs without undue engine noise until I have been driving for around 50 minutes or longer. From that moment on, a whine begins to be emitted which seems to increase in volume until it gets to a moderate pitch. I have replaced the fan belt as I suspected that this may have been the cause, but this has made no difference. Although the noise does not sound as though it will be causing harm, it is something I would rather not have in the background when on a longer run. Are there any common faults that you know of which could possibly result in this kind of noise?
Ronnie Moss
AAs you have replaced the fan belt and as I suspect that this was the area where the noise was coming from, I would check the alternator bearings. This is very likely the source of the noise which is occurring after the bearing has warmed up. It may be due to them drying out over time, and it is possible that an overhaul of the alternator will cure it.
The easiest way to check would be if you can remove the alternator belt when the engine is hot and the noise is being emitted. If at this stage after removing the alternator belt and starting the engine you discover the noise has gone, this would confirm the diagnosis. You may also be able to feel any problem with the bearings by spinning the alternator up by hand, but as the noise is only present when the engine is hot and the alternator has run for a while, this may not be possible.