Hey guys i need some help i just bought a 1991 volvo 740 and is not going in to over drive is only using 3 gears but the light gos on en off wen i press the over drive button and the relay clicks need some help by reading on the forum foun out it coul be the over drive solenoide undet the trany any advise

 

So far you have ruled out the switch and the relay. It could be the solenoid or the wiring going to the solenoid. IPD sells a plate that replaces the solenoid and bypasses the system.

 

if ya wish to bypass the OD system ya can also get a plate from these guys Volvo Overdrive Solenoid Bypass Replaces 1239928 1239679 in Stock | eBay ....or do this yourself (scroll down to see the pic posted by pierce) https://volvoforums.com/forum/volvo-...h-79482/page2/

 

Personally i would not bypass the OD on a 3+OD tranny, why not just clean out the od unit? get on turbo bricks and you can read about people who were able to accomplish that task with the tranny still mounted... Much easier with it removed though..


Thread on non-working OD units..
http://forums.turbobricks.com/showthread.php?t=301252

Full write up for OD rebuild...
https://www.brickboard.com/FAQ/700-9...iveRebuild.htm

 

Thaks guy's i ordered The OD bypass plate let's see what happens i ordered it from ebay

 

Its not really a 3 speed with overdrive, its a 4 speed and the solenoid drops 4th mainly for towing. I don't know why they call it overdrive it always seems to be confusing.

 

it is a sort of overdrive, its a separate reduction gear in the transmission, not part of the main 3 planetary gears controlled by 2 bands.

 

Thanks for clearing this out. I had read somewhere that the transmission was a 4 speed and not a 3 speed with overdrive. Just proves that you cannot believe everything you read.

 

well, both are true, depending on how you look at it. its not an EXTERNAL overdrive. and, the classic definition of an overdrive was a greater than 1:1 ratio, when in fact, most overdrives including the ones used with the British sports cars and volvo M46 were really underdrives, and OD was 1:1.

 

Got it.

 

Im going to take the car to have the bypass installed tomorrow lets see what happens ill keep you guys posted

 

um, installing that bypass plate takes about 10 minutes with a small wrench. ok, 15 tops if you properly clean the area before removing the solenoid.

 

Just finished installing the OD bypass now it works great have my OD back

 

Just changed the OD solenoid for the bypass and it work awesome now i have a problem the car feels like a small loss of power and in low rpms sometimes feels like it wants to shut down im thinking the in fuel punp or something like that or maybe a tune up of sparkplugs and wires and distribution cap what do you guys think

 

power loss from fuel starvation would normally show up at high throttle upper middle range RPMs, especially in a taller gear, like accelerating uphill in 3rd.

low RPM power stumbling could be from air leaks in the intake path (anywhere between the MAF and the head), or from ignition problems. bosch cap and rotor, volvo brand or bosch spark plugs, and bougicord sparkplug wires would get you to a baseline, ignition wise. other potential sources of ignition problems would be a tired/old coil, or a flakey ignition power module (if bosch... regina ignition integrated the power module into their square coil)

 

Maybe some one can help on this my 1991 volvo 740 wen I turn the key off the car keeps running what can be causing that thanks

 

if it keeps running normally, it sounds like a broken ignition switch.

if it 'diesels' (chugs along roughly for a few or few dozen seconds), that can be caused by excessive carbon buildup, but when the fuel pumps shut off with the ignition, the engine should die quickly.