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740 OD issues

mike66

mike66

Member
Joined
Jul 29, 2009
Location
Saint Louis Missouri
I just put a low milage m46 gearbox with a J Type OD on my 89 745T. I disassembled the OD and replaced all of the seals. everything looked OK inside. Now after I got it installed the speedo is not working (electric not cable driven) the little orange upshift light is stuck on and when I try to engage the OD the green OD light comes on but the OD does not engage. Any suggestions? I figure if the Green OD light comes on I am at least getting power to the relay. I am going to check for power at the solenoid today. Also the previous P type m46 had no issues going into overdrive, so the wiring should be ok? I also verified that both switches on the trans case are working. Thoughts?
 
What do you mean by check if the switches are working? Did you actually test to see if they?re getting power from relay? Inspect all the wiring and the connectors on the solenoid. Start at the relay and test for 12v, then the OD switch, then the 4th gear switch then the solenoid. The wiring is pretty simple
 
Had to fish this out of your description: Looks like maybe you replaced a P type (working) OD M46 with a J type (working?) OD M46?


It wasn't clear-- Just need to verify that before going any further.
 
Yes, replaced a P-type (loud but functional) with a J type.

I meant that I verified that the 4th gear lockout and reverse switch were functional. After further diagnosis today I am leaning toward something being bad inside the OD.

I have power and ground at the solenoid and I can hear the solenoid audibly click when I cycle the switch. Unless the solenoid can click and still not actuate the overdrive. In that case I might try to switch solenoids.
 
Could be a stuck solenoid? Give it a light tappy tap. Starter solenoids will click without engaging when it?s a bad starter or low battery. Have you confirmed full 12v at the solenoid? If it?s not getting the power it needs it won?t fully engage. Also did you use F type ATF?
 
I'll try the old starter tap method. Yes I used basic Type F from car quest. I used the same ATF for assembly. I plan to maybe go synthetic after a few hundred miles. But honestly I've always used regular type F like Volvo suggests with no issues. I did not use a voltmeter to verify a full 12 volts just my test light and some long leads. I noticed also when the vehicle is driving the orange shift reminder stays on constant. but when I'm KOEO it comes on and off with the overdrive light. gremlins I suppose
 
Tapping did nothing. I have 12.2 volts at the battery which is a little low form sitting. and I have 11.9 volts at the solenoid. So a slight voltage drop but that should be enough to engage the OD. The voltage will obviously increase with the engine running also. I'm gonna swap out the solenoid, I have a few laying around. If that doesn't work I guess she's coming back out. I can't understand what would be bad though, It looked great inside and came from a low milage car.
 
I could check the amp draw but its clicking pretty good, I also have all of the greenbooks for these models. I don't have a set up to check the pressure either. At this point I think its ether a plugged or stuck solenoid or something inside got jammed up. I followed the green book procedure for the OD rebuild checked all the parts for wear, etc.. this is my first time trying this project. And I had to make a few tools. In the past I just swapped the whole tranny out and moved on, now parts are harder to find. This somewhere around my 20th volvo and its been a very annoying one. lol
 
mike66 said:
At this point I think its ether a plugged or stuck solenoid or something inside got jammed up. I followed the green book procedure for the OD rebuild checked all the parts for wear, etc.. this is my first time trying this project. And I had to make a few tools. In the past I just swapped the whole tranny out and moved on, now parts are harder to find.
Click to expand...
As long as we are at the point of verifying proper solenoid function, here's one of the pearls that OD Guru Duane Hoberg shared with me: The solenoid should (internally) rattle freely when shaken in the hand. Somewhat like a rattle paint can. Guess that goes with your possible scenario of gummed up internals. There are also internal (in addition to the external) o-rings that can leak.

For me, the main cause of OD not wanting to engage is the ill-advised teflon piston seals. Might have been a good idea at the time, but they must be replaced with the larger rubber o-rings, which require matching pistons, as the teflon style pistons do not work properly with the rubber o-rings.
 
These were originally the big O-rings so I just replaced them. It was from an 85' 740 and the gearbox is now a iron case from who knows what year 240. I did make sure the solenoid was free when I had it apart. And when I shook it it rattled slightly, but more like a PCV valve than a spray paint can. It was almost 100 degrees here today so I didn't make any progress. tomorrow is supposed to be a little cooler. I'm going to rob the solenoid off of my P-type that I know works and see what it does.
 
Update: I swapped in a known good solenoid and still no OD. I've got good power and ground and could still hear the same sound from the other solenoid, I would say both that I tried are working. I guess it's coming back off to see what went wrong. Unless anybody has any other suggestions before I do this. At least I don't have to pull the whole transmission.
 
Do you have a gauge or way to spin the pump cam on the bench & power/pressure it up?

Pressure filter gummed up or unloader valve scratched or o-rings on that shrunken/leaking?

The pump seems to last forever.

Sometimes if the bores are egged out in the raw aluminum after 500,000 miles or so, they?ll leak same as the raw aluminum directional valve housing on the (ZF) otherwise quality hydraulic-assist PS rack & updated pistons from the Teflon pistons w/fresh o-rings won?t fix it :raincloud:
Swap the valve body or Teflon coated steel insert sleeve it. bTDT.

At least that *is* fixable unlike a shattered cast aluminum cone clutch hub, blown overrunning clutch or shattered hollow gun-drilled main shaft (plugged pressurized oil passage on the main shaft between the valve body & overrunning clutch is a good riddle to diagnose).
Cone clutch or its thrust bearing it won?t decelerate or reverse/slips in reverse, usually?

Lots of parts NLA, gear vendors (who bought GKN & all their tooling/inventory & that was Leycock before that iirc?) wants the whole unit with their tag on it most times to do anything/won?t sell individual parts & wants $4K+ to do anything for a whole new or reconditioned unit & has made most parts proprietary/incompatible with the Volvo-application OD?

You used to be able to buy a new OD (or new guts / reconditioned tested unit complete, anyway?) from Volvo in their exchange for $800-$1000 (whatever that is now, inflation-adjusted in 2022 dollars instead of early 2000s dollars?) or so?& still can iirc??outta most Volvo guys budget or they?d run an M47, T5, UK takeoff low mile M90 or M51 getrag, instead, at that price?

This said, direct drive or planetary gear set for OD worked good for towing and no thrust load in 4th & OD to wear out the transmission bearings/other parts, so I do like the direct drive in final gear (4th in most cases or 1:1 5th with the M51) w/OD as a configuration, if not the POS British OD unit in execution/quality control, so much? :lol:

If it engages in torque multiplied slow reverse up a hill or speshl thrust-rated ball- bearing or cone clutch is marginal, it?s often game over / full of hardened metal paste? not much worth saving/can be reused except the alum housings.
 
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^on a lift or Jack stands with a pressure gauge & long hose is fine, ya.

Gauge is nothing special, just needs to be for some kind of oil & 600psi capable?I used one that Chevy guys used that I found on a junkyard Chevy to setup their hydroboost compatible pump or ford truck guys use with the econoline bracket to install F450 hydroboost in their F250s & F350s with a quiet Saginaw Chevy style pump. ~600-1000psi real common for most ?low? pressure hydraulic & steering or their control circuits?

Drill some sort of adapter/bolt thru from the 3/8?? Course straight threads on the pressure port or use a banjo bolt & crush washers?
I think I drilled a brass bolt or something after okie sanding it flat with the copper washer on the original pressure port bolt/plug thing?
I *think* a 1/8? or 1/16? grease zerk is what I drilled into one bolt to energize the solenoid & pump the thing up with the grease gun to un-bind the splines on a J-type & earlier.
(Not an issue with a p / 1pc)

Jack stands under the axle with the suspension loaded works good?
Just make sure the front is well supported/nothing?s tippy?

But if you need to observe the leaks/faults/noises etc up close spinning an old main shaft with a drill?

If there are no leaks/clutch bites good, the OD should engage down to 25-30mph solidly / with a no slip ?ga-bang? such that you don?t forget to use the clutch if the pressure is to the higher side or spec/ 240Turbo or 260 spec on a J-type (shim unloader valve accordingly) ..
 
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well.... I bought a cheap pressure gauge off of ebay, made an adapter to fit and the result is: I have zero pressure at the port under any condition? Might be the cheap gauge? or a bad pump? Thoughts
 
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