• Hello Guest, welcome to the initial stages of our new platform!
    You can find some additional information about where we are in the process of migrating the board and setting up our new software here

    Thank you for being a part of our community!

740 OD issues

I removed the OD pan and took out the center plug under the pump and made sure the ball was seated properly and the spring seemed ok. Still no pressure at any speed and no OD still won't engage. any suggestions out there? at this point I'm about to just pull the whole OD back off and dismantle it. Maybe a clogged passage?
 
There is a tiny orifice between the bores for the solenoid and the relief valve. Make sure it isn't plugged.

When you had the pump apart did you rotate the driveshaft and verify that the pump piston was moving? The eccentric for the pump is indexed to the main shaft with a small woodruff key that may have sheared.

If the pump was working at all you should see ~20 psi on the gauge with the OD off.
 
I'm about to re-test the pressure today. last test I had zero pressure all around. I did not rotate the crankshaft while it was apart I considered it but I was working alone and I don't have a remote starter wire. I did verify that the cam lobe on the output shaft was solid before installing it, and as expected it was slightly hard to mate the OD to the gearbox flange. Everything was free prior to installation but maybe something got fudged up on install?
 
hiperfauto said:
There is a tiny orifice between the bores for the solenoid and the relief valve. Make sure it isn't plugged.

When you had the pump apart did you rotate the driveshaft and verify that the pump piston was moving? The eccentric for the pump is indexed to the main shaft with a small woodruff key that may have sheared.

If the pump was working at all you should see ~20 psi on the gauge with the OD off.
Click to expand...
^at least....20-40psi is normal IIRC with the pump plunging along on 'bypass' before the solenoid is energized?

I've so seldom seen pump problems (other than pieces missing/omitted on re-assembly from some idiot being in there previously :lol:) but eccentric cam removed or someone forgot the woodruff key, yes!

Blocked pressure filter or unloader valve passage is a good suggestion if seals and the rest are all in there and working & piston bores in the raw aluminum aren't egged out...
 
I Just tested it again with the same results. Zero pressure running on jackstands up to 55mph. I cannot rule out the cheap gauge I bought from eBay but I did blow shop air into it and it read pretty close. I?m thinking maybe something went wrong on re-assembly. Not too hard to just take the OD back off. I?ll start with the previous suggestion and turn the crankshaft to observe the pump operation or lack of operation.
 
My understanding of the o/d is that the oil pump is always working off that input shaft cam. it's just whether the bypass channel or the solenoid is engaged to allow the pressure through.
So if you measure no pressure I'd make sure the solenoid moves when engaged. I've had them click but not move when I had a bad one on the D type in the 123gt long ago.
 
tintintin said:
Don't the 7xx have a remote starter connector dangling along the left inner fender bulge under the hood? Mine does. Pink wire, connect to +12VDC to energize starter solenoid.
Click to expand...
240s have that as well by the firewall connector for the engine harness; female spade & blue-yellow wire most years...

I forget where they move it to on late '92+ models when they eliminated the firewall connector / oil, heat & corrosion exposed sealed bullet connection in the engine bay in that location....
 
I've tried 3 solenoids, one that I know worked a couple of moths ago on my P-type. How much of a voltage drop is too much at the solenoid? My battery reads 12.18 (Low) Volts and I've got 10.6 at the solenoid KOEO. Seems to me like it would be enough, especially when the engine is running and spinning the alternator. Maybe tonight I'll make a new harness and see if it changes anything. I think even if the solenoid is bad I would still get the 21 psi at idle? Looks like I may have multiple issues.
 
FYI, the O/D pump is driven by the mainshaft which has to been turning to make the pump work which means the driveshaft has to be turning.

So you don't get any pressure inside the O/D while idling at a stop.
 
yes, I realized I said that after I hit the button. It was driving on jack stands at 45-50 mph. with zero pressure. I realize no pressure at "idle" my bad.
 
You must log in or register to reply here.
Back
Top