Hey everyone, excited to find this forum - I just purchased a 1989 volvo 240 about 2 weeks ago for 300 bucks with an overdrive issue. Been driving the car anyway and I must say it does pretty decent on fuel even with O/D not working all the time.

I am trying to track down this issue - after about 30 minutes of driving the O/D will suddenly start working and be fine the rest of the trip. Usually even if you shut the car off and come back to it pretty quickly it will keep working. I suspect its the relay, however I was trying to see if anyone has been successful at bypassing the relay and switch?

I have no desire to turn O/D off for any reason, so loss of control of it doesn't matter to me.

 

Most likely its the relay or the OD solenoid itself. You can use this to permanently enable OD:
http://www.ipdusa.com/Volvo-200/Tran...9-266-672-1891

 

Will it hurt the car to drive on the Interstate before the O/D starts working. I know my gas mileage will probley be less, but is 70mph to fast without O/D?

 

It should be OK. My car survived having to do this for a little while.

 

I would drain & refill tranny fluid several times for starters. Fluid is probably low and old. I wouldn't flush just drain & refill. Flushing can stir up crap, safer to drain. Don't over tighten drain/fill plugs.

 

I was really wondering if that might be my problem. This transmission has a drain plug in the pan I hope. I haven't looked yet.

Does the fluid have to warm up before O/D starts working, or should it be immediate?

 

It is better to change fluids when they are hot. Although, I suspect not much more flows out when hot than otherwise. Probably more of a winter consideration when it can get really cold.
Since you bought the car with high mileage it might not be a bad idea to change all the fluids even brake fluid & power steering. I'm not familiar with the Volvo automatic. I have dropped the pan, cleaned it and and changed the filter on my wife's Jeep auto. It is good for the long term health of the tranny. I do know low fluid is definitely a problem for autos. Not all the fluid will drain out at once so it is necessary to do it several times over time to swap out the old with new fluid. Some people do it at every oil change. I made a rig with a hose and funnel to fill my 5 spd overdrive. I can see the fill plug looking down into the engine compartment.

 

Also, check the wire running from the switch to the OD, as it is easily broken/damaged. Especially if the switch is on the shifter, where the wire is flexed every time you switch between gears. This was a significant wiring design flaw on the 240. If you can find a dashboard switch, the conversion is very easy. Even without moving the switch, it's an easy fix. The wire runs from the switch (on dash or stick) down through the floor to the OD, so you don't have to get into the wider electrical system. Also, because of the exposed run of wire under the car to the OD, the wire can be damaged by road debris or the rubber/plastic coating can become brittle and cracked with age, or dissolved by leaking fluids.

Other than poor mileage the only real problem with highway driving w/o OD in an old 240 is the higher amount of crankcase blowby this will generate. This will eventually clog the PCV system and start forcing oil out of every seal on the motor.

 

My 240 never had an overdrive on its four-speed to start with, and I've been up to 115 in that 35-year-old station wagon. I've been regularly driving 80 miles per hour for half an hour at a time on the motorway and its never complained at me.

EDIT

Fortunately my crankcase has been venting into the open air since I bought it. I'm guessing the previous owner removed the hose as soon as the car was too old for emissions testing, and not a moment too soon I say.