Weird symptoms runs great no codes

File under “Doctor, this anything?”

1st time driving my 2016 XJ8 without a radio and heard slight “moan” from engine only on startup and low speed/idle. Checked gauges - heat starts mid-range, idle high then both settle to normal after a short warmup. No problems driving no codes changed all fluids just ‘cause, no obvious if any leaks. Hoses look fine though tough for me to gauge serpentine/belting. They “eyeball fine and tight.”

Read all I can read and concluded “don’t throw good money after bad” as it appears a “cat quirk” but if anyone recognizes these symptoms please post. I’ll do same as/if progresses to anything worthy of passing on.

Hi David, I have moved your post to what I think is the more appropriate forum the X300 forum stops prior to your model.
Unfortunately I haven’t any experience with your series engines, hopefully some one will be along to help, what will help is if you identify the actual engine we are discussing.

Thank you for your help Robin. FYI in case anyone stumbles over it, further inspection and I think it’s my idler pulley so I’m replacing it and what appears an old alternator, easy enough and may be time. Thanks again.

If it is the idler pulley depending on the style, some you can drift the bearing out and replace it without the cost of purchasing a complete unit, however if the idler pulley is plastic (I don’t think they are) then replacement would be a better path to go.

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Thanks - inspection seemed like it’s tight, all is well there. I changed all the fluids, oil, transmission, power steering, brake…

Took it on 100 plus mile drive to open it up. So far all well. Will probably change seals (thinking they are original so at 60,00 plus worth a switch if still plastic) but the “moan” gone - for now. May check the alternator as well, but frankly don’t know what the “test” is.

Purchase a mechanics stethoscope and check for bearing ‘moan’ just be carful with the probe as it accentuates the noises very much.

A little late but changed all fluids, detected zero moans after, drove round trip about 340 miles like a charm. Likely just needed one of its various fluids changed.

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