PITA noise from transmission (I think). Ideas?
Discussion
A bizarre noise has started to manifest itself in my car. Google hasn’t been helpful and the chap from the garage had a quick shufti and couldn’t see anything wrong. Emphasis should on the quickness of the shufti.
I think it’s transmission related, and possibly the torque converter, but it’s lacking the usual symptoms of a failing torque converter, eg: grinding noises, lack of lock up into top gear. I’ve had the trans fluid changed but it has had no effect.
Description:
•A cross between a fan belt type squeal and the pssssht noise that you get when a lorry’s air brakes release pressure.
•No loss of drive associated with it. It’s really quite loud with the windows open but the engine always still feels connected to the rear wheels
•Duration from 3-4 seconds to c. 0.5s.
•In my 1hr, 40 mile drive home, you might get 1 or 2 longer episodes and 2-3 short ones. Normally all within first 15-20 miles.
When occurs:
•Predominantly at start of journey, when drivetrain is cold. Frequency and duration reduces as distance goes up.
•When at constant load or just after changing upwards (especially when changing into top)
•Never when under load (eg: accelerating) – only happens when load released (eg: acceleration stops or under constant load / speed.
•75% of time in top gear, 25% in lower (3rd gear)
I know I could just leave it in the hands of the garage but I’d like to get an idea of possible causes beforehand, rather than just leave it with then for god knows how long for it to reoccur. Any test drive will need to be of reasonable distance for it to appear so if I can come up with a couple of theories first it would be helpful
Car is a Jag x300 btw, with the simple 4 speed autobox. No electronic sport modes etc lie therein.
I think it’s transmission related, and possibly the torque converter, but it’s lacking the usual symptoms of a failing torque converter, eg: grinding noises, lack of lock up into top gear. I’ve had the trans fluid changed but it has had no effect.
Description:
•A cross between a fan belt type squeal and the pssssht noise that you get when a lorry’s air brakes release pressure.
•No loss of drive associated with it. It’s really quite loud with the windows open but the engine always still feels connected to the rear wheels
•Duration from 3-4 seconds to c. 0.5s.
•In my 1hr, 40 mile drive home, you might get 1 or 2 longer episodes and 2-3 short ones. Normally all within first 15-20 miles.
When occurs:
•Predominantly at start of journey, when drivetrain is cold. Frequency and duration reduces as distance goes up.
•When at constant load or just after changing upwards (especially when changing into top)
•Never when under load (eg: accelerating) – only happens when load released (eg: acceleration stops or under constant load / speed.
•75% of time in top gear, 25% in lower (3rd gear)
I know I could just leave it in the hands of the garage but I’d like to get an idea of possible causes beforehand, rather than just leave it with then for god knows how long for it to reoccur. Any test drive will need to be of reasonable distance for it to appear so if I can come up with a couple of theories first it would be helpful
Car is a Jag x300 btw, with the simple 4 speed autobox. No electronic sport modes etc lie therein.
8Ace said:
Don't think so - steering angle doesn't seem to make any difference. A lot of my commute is motorway when steering input is minimal.
Thank for the suggestion though.
might not relate directly to steering angle.Thank for the suggestion though.
The PS pump maintains pressure all the time. You describe a noise that sounds like a release of pressure and a squeal - that could be PS.
Be worth just looking to check the fluid level hot and cold and to see if there are any bubbles in the fluid.
you could be getting cavitation.
TooLateForAName said:
might not relate directly to steering angle.
The PS pump maintains pressure all the time. You describe a noise that sounds like a release of pressure and a squeal - that could be PS.
Be worth just looking to check the fluid level hot and cold and to see if there are any bubbles in the fluid.
you could be getting cavitation.
Now that's a thought. I'll look into that, thank you.The PS pump maintains pressure all the time. You describe a noise that sounds like a release of pressure and a squeal - that could be PS.
Be worth just looking to check the fluid level hot and cold and to see if there are any bubbles in the fluid.
you could be getting cavitation.
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