psha8224

My 98 Boxster has been making a "rumbling" noise from the right rear wheel area when turning sharply to the left, gets louder if power is applied. This isn't tire noise and apparently not bearings as my shop just replaced them thinking that they were the source.
The shop (independent Porsche) seems to be stumped. Any help would be appreciated.

insite

motor mount without a doubt. when the motor mount goes, the motor can move side to side a bit. on hard corners, it contacts the frame. the sound is identical to a front wheel drive car with a bad CV joint.

psha8224

Thanks for the suggestion. Motor mounts, and pretty much everything else, have been checked. Right now the noise remains a mystery. New bearings were installed and this weekend I'll put in some driving time to better evaluate if there is any improvement.

Turboflyer

Seems to be a major division on what will and will not work. Of course the dealers say only Porsche coolant will work. Something about it gelling up with the wrong stuff. Could be true. Has anyone used something other than factory with good results? Somewhat along the same lines, when is a good time to do preventative maintenance with regards to hose replacement. There are quite a few. I have an 01 with 64K. I am doing the tip filter service now. I could not wait till 90K so doing things early does not bother me. Everything looked good and will button her up tomorrow.

Tennessee Turbo

I know this is 6 years ago, but I am having the rumbling noise when turning left and accelerating. Motor mounts have been checked. new struts. any other thoughts?

Ray S

Did you check the wheel bearings?

Tennessee Turbo

Wheel bearings done at the same time as shocks.
Half shaft, maybe?
clutches in the limited slip (I am totally ignorant of the design/construction of the ltd slip)

flyingpenguin

Unless you complete remove the motor mount (the one up front by the pulleys), it is impossible to get a good view of the rubber bushing that deteriorates over time and causes the lateral movement of the engine block.

Tennessee Turbo

Thank you. I'll have to do a more thorough check of the motor mounts. Other people's descriptions of the sounds from a bad motor mount exactly describe what I am hearing. I'll post when I know. thank you, again.

gfl

wheel bearings are the common cause

tires

unlikely but possible - CV joints/driveshafts

unlikely but possible - differential (you dont want this to be the case)

Its not simple rotor noise - rust etc wearing off an occasionally driven car is it? If so ---> ignore

Grant