Borg Warner/Velvet Drive 72 - Question about pressure sender port

Where exactly am I supposed to connect the pressure sender? On the diagram in the service manual, there are three ports, and I have attached the mentioned diagram here. One port for the oil to the cooler outlet, one for the mainline pressure tap and one for reverse clutch pressure tap. So I have attached the hose to oil to the cooler outlet, I have attached mechanical pressure gauge to the reverse clutch pressure tap, and I have attached the electrical pressure sender to the mainline pressure tap. Mechanically, everything runs perfect (gearbox is new). When in reverse I do read the pressure on mechanical gauge, but in forward there is no pressure on electrical sender (no reading at the gauge). Sender, gauge and the wiring are OK (checked twice). Am I reading this diagram wrong, should I connect the sender to the cooler outlet? Where am I mistaking?

I think you're reading it right. Try putting the mechanical gauge in the mainline port

Ken

Greetings,
Welcome aboard Mr. N.

Thank you very much for the welcome and for the response. I will try putting mechanical one in mainline port, I would have done that already, but fittings are different, so I have to find or build the adapter first or find the mechanical gauge that fits for test purposes.

I must say that I have just joined this forum, but I am reading this forum for quite some time and I have found many useful information, especially during my boat renovation/restoration process.

Pressure Guage fitting to Velvet Drive

What is the thread requirement to fit a pressure guage directly to a Velvet Drive...

I'm a little lost. Why is this important?

pete

Fitting Oil Pressure Gauge to Velvet Drive

I am new at trying to fix my own transmission but following on from the post above there seamed to be some question about the thread to fit an oil pressure gauge to check pressure on a Velvet Drive...
My Velvet Drive decided to stop selecting either F or R gears two days ago. So before I pull the box of the back of my Perkins Ranger 200 engine I thought I would try and do some fault finding, The manual seamed to indicate it would be prudent to check old pressure.... hence my question so I can source a guge with the correct thread

Could be a failed drive plate (torsional coupling). Oil level ok?

I think that on these if the drive plate is intact, if you take dipstick out with engine idling there will be oil splashing around in there. No splash means guts are not spinning, so drive plate is suspect.

Here’s the link for the manual that’s in the Forum Library that may help.

https://www.trawlerforum.com/forums/downloads.php?do=file&id=11

tedt_2778 said:

What is the thread requirement to fit a pressure guage directly to a Velvet Drive...

Click to expand...

I believe a 3/8" x 18 NPT for the oil pump pressure (line pressure in the manual). My manual shows this port to be the same size as the Oil cooler return line port. There is also a 1/8" NPT nearby for the reverse clutch pressure.

tedt_2778 said:

My Velvet Drive decided to stop selecting either F or R gears two days ago. So before I pull the box of the back of my Perkins Ranger 200 engine I thought I would try and do some fault finding, The manual seamed to indicate it would be prudent to check old pressure

Click to expand...

First try shifting via lever on side of transmission to make sure it's not a simple linkage problem.
Then remove one of the set screws. Start engine with stop solenoid engaged. Cover set screw hole with rag. Oil should flow out of hole when engine turns. Failure to do so would indicate bad oil pump or clogged control valve.
Control valve is easy to check. one nut on linkage side, 3 bolts on the other. Pretty obvious if it's clogged with sludge. If not, transmission needs to be removed.
Oil pump is not that expensive. Simple replacement. 4 bolts. If I removed the transmission I would replace the clutch plates and install a new damper plate. Hardest task is removing/reinstalling transmission. Once you pull it, overhaul it.

Thanks to all for your feedback and advise - very encouraging.

Last night I fired up the Starboard Perkins Ranger 200 and looked down the Velvet Drive Dipstick hole - there was no movements or oil slopping around in N, F or R. I did not open one of the set screws. I think it is a safe assumption that the Transmission of not engaged with the flywheel and I need to replace the Damper?? As I look at this job and other posts I note my rear engine mounts are attached to the bell housing. What does the team think/know about being able to change the Damper without removing the bell housing, just taking out the transmission?

If I get the Transmission off I think I will also take your advise and have the gearbox rebuilt by a professional while it is out - even if this is not the issue.

Check for splashing in your good port gearbox, just as a sanity check.

Yes, with mounts on engine that simplifies pulling the tranny. Need to back prop shaft back a few inches. A zinc in front of a strut can prevent that, or a prop real close to a rudder.

I used Transmission Marine in Fort Lauderdale for my rebuild. Highly recommend FYI.