So I've owned my 2nd S40 for almost a week now, I have some normal problems as with any neglected S40.

Today I started my car and let her warm up for about 5 minuets. It's the coldest temperature the car has seen since I got it. It's been about 60 degrees throughout the week but today it was a little above freezing 34 degrees.

The car started and idled normally but once I put the car in drive it started to shake very bad and would not go forward, it would hesitate and shake its way a few feet. I pulled it to the side of the road after only making it 2 blocks turned it off and scanned the car to see if it threw any tranny codes but noting.

Frustrated I was I decided to walk back home and do some research but found nothing of this issue, after about 25 minuets I went back started her up and she ran fine. Only have the normal hard shifting sometimes like I had in my previous S40 but noting that really concerns me.

Any suggestions would be greatly appreciated.

 

Might be down to transmission fluid being dirty and well overdue for changing.
That along with very cold temperatures would account for hard shifting until the engine and transmission have warmed up sufficiently.
Drain and fill only for the transmission, not a power flush if the fluid if dirty brown or black.

 

The fluid is a darker brown/red color and after being heated up for awhile I checked the stick and it registered up to the first line below "hot" a lot of people recommend not replacing the trans fluid so do you really think that could be the culprit?

 

There is replacing the trans fluid and then there is flushing the trans. Replacing the trans fluid involves several drain and refills until you have a higher percentage of new fluid versus old fluid. This is generally accepted as safe and will definitely be an improvement over old worn out trans fluid.

Flushing is a different animal that involves specialized equipment. Flushing of an old trans may do harm in that all that sludge that has gathered in the corners is suddenly being moved where it could get into places it doesn't belong. I have read the horror stories but do not have any personal experience.

 

Your 2001 presumably has the 5 speed auto as opposed to the 4 speed.
Some earlier 2001's apparently still did have the 4 speed however, so you need to select the appropriate transmission fluid accordingly.
Dex III is correct for a 4 speed but the 5 speeds need a JWS3309 spec'd fluid.

I have done the drain and fill on my 2002 V40 (5 speed) with no problems and the improvements in shifting were immediately noticeable.

 

just a note on checking levels - the levels do change with engine/transmission temperature so check the owners manual or google for proper level check instructions. If you do the drain/fill, the easy way is to have two identical buckets. drain into one mark the level then put the new fluid into the other to that same level, then fill from that bucket.

 

+1 That is exactly how I did it. Probably got the idea from you too!