2001 C70 107k Trans problems, Flashing arrow, Hard Shifts.

[theCman]

To everyone who reads this and can help me, thank you in advance!

107k
55-50SN
Ser #00EV710400

My buddy started having problems with his C70 a few years ago. The car was banging into gears so I told him to go get it checked out and in the meantime don't drive it. It sat for a while and he ended up getting a brand new car about a year ago and told me that if I want to work on it, I can have it. I have been doing all the work on my vehicles for about fifteen years now which is why he made the offer instead of having it junked. I have never really done anything major such as an engine rebuild or trans rebuild (or take them out of the car even), but I have kept up with the routine maintenance and any problems that have come up. I feel that I am a competent back yard mechanic than can handle many tasks as long as I have some sort of direction.

So now to the meat of it. Here is the problem in a nut shell. The trans is shifting very harsh. What that means to me is that as I am driving along, when it goes to up-shift or down-shift, it will go out of the gear that it is in, the engine will rev almost as if it is in neutral, then bang into the gear that it is going into. It usually seems OK at first, then as it warms up the problems start. The check engine light will turn on, then the flashing arrow. I have read the codes and the two that seem relevant are P0785 and P1618.

After reading many many posts on different forums I started to get to work. I have flushed a case of Mobile 3309 through her, replaced the B4 servo cover, and added transtune. The flush had little results as well as the B4, but the transtune helped a little. On a short drive from my old apt to my new, I only didn't really have any issues. But when I took it out for a test drive around the block it acted up again. I am really leaning towards the solenoids being gunked up since it will act normal then go all monster on me.

I have not checked if the S/N is disabled, the software update, cleared the adapts, or the oil counter.

My plan right now is to flush another case through her to get the fluid to perfect trans fluid red (it didn't get all the way last time) and get the transtune out as well. Then to replace/repair the linear solenoids. After that, if she seems better, do the rest of the above.

Any advice, comments, or critique are appreciated.

Craig.

[theCman]

So I wanted to give a quick update for anyone who is checking this post. The problem was with the valve body solenoids. It was a PITA to get the pan off and the back covers off the solenoids. Shifts much better now. Highly recommend this as a fix to similar problems.

[polskamafia mjl]

Was it similar to this: https://www.matthewsvolvosite.com/forums ... =1&t=65527 ?

[theCman]

Same idea, different transmission.