AlanG Posted November 20, 2017 Report Share Posted November 20, 2017 During our latest TR run my 4A suddenly starting making a noise that sounded like the fan catching something. It's an electric fan that wasn't running so that was ruled out. The noise was defo engine speed related and increased with an increase of revs. Took the rocker cover off, thinking a tappet problem but nothing appeared wrong. The noise then disappeared. Drove the car home, 25miles, with no noise or any problems. Oil and temp were fine. At home have removed the timing chain cover, the sump and the plate at the bottom of the bell housing. with nothing untoward found. Gearbox oil was also clear of any debris. Any ideas what the cause of the noise may have been and what to do next? Alan. Quote Link to post Share on other sites
BrianC Posted November 20, 2017 Report Share Posted November 20, 2017 I had a similar noise which turned out to be the water-pump pulley hitting one of the attachment bolts. The key had been chewed up and almost destroyed in the shaft allowing the pulley to gradually slide forward with resultant wobble. Noise increased with revs and then stabilised until the revs dropped again. Quote Link to post Share on other sites
RogerH Posted November 20, 2017 Report Share Posted November 20, 2017 Hi Alan, the spindle/bearing on the original heater fan can wear a smidge and every now and then it will vibrate within its rotation giving out quite a load painful noise. Switch off and then on will sort it until another day. Roger Quote Link to post Share on other sites
ctc77965o Posted November 21, 2017 Report Share Posted November 21, 2017 engine speed related? Rev counter cable or Rev counter itself...normally starts happening in the cold...sounds quite ominous from the drivers seat... Quote Link to post Share on other sites
stillp Posted November 21, 2017 Report Share Posted November 21, 2017 I had a similar noise when my dynamo bearings were packing up. Pete Quote Link to post Share on other sites
ChrisR-4A Posted November 21, 2017 Report Share Posted November 21, 2017 Hi Alan, you say it disappeared after removing and refitting the rocker cover. I had an alloy cover with a bit of excess casting on inside and one of the rockers was just clipping it. Reposition the cover and it did not touch. I sanded a bit of the alloy off the inside of the cover and it cannot hit in any position now. Chris Quote Link to post Share on other sites
AlanG Posted November 23, 2017 Author Report Share Posted November 23, 2017 Thanks for the replies folks. Water pump, heater fan, dynamo rev counter and rocker cover all appear ok. As there is no mystery noise at the moment I will continue to drive it. Hopefully it won't happen again but if it does maybe there will more clues to diagnose the problem. Alan. Quote Link to post Share on other sites
RogerH Posted November 23, 2017 Report Share Posted November 23, 2017 Hi Alan, if and when the heater fan makes its noise simply switch off to prove/isolate it. Easier than taking the water pump off when going down the motorway. Roger Quote Link to post Share on other sites
littlejim Posted November 23, 2017 Report Share Posted November 23, 2017 My best 'mystery noise' took several minutes to sort out. There was no correlation to engine speed, braking or gear selected. Turned out the radio switch had been bumped to just past 'on' and only the loud passages of music were audible as noise! Quote Link to post Share on other sites
Graham Harris Posted November 24, 2017 Report Share Posted November 24, 2017 Clutch release bearing? Graham Quote Link to post Share on other sites
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