Twin Disc transmision oil pressuer & shower drain

[Bill Root]

Hello. My name is Bill Root. I have a 1973 43 DCMY that had a complete mechanical/electrical/plumbing refit in 2003.

I've been following this site for several months, but this is my first post. I just retired, and am beginning the process of renovating the boat for the great loop in 2009. I've seen a lot of great advise from this group, so I'm sure I will be a very active participant as I work through the renovations. I have two immediate problems I'm hoping someone can help with.

Transmission Problem:

My boat has CAT 3126's with Twin Disc transmissions. Engines and transmissions have less than 200 hours on an OEM factory distributor rebuild. Several months ago, after a 5 day voyage from Fort Meyers to Sanford Florida, the starboard transmission began to lose oil pressure and slip in/out of gear at low RPM's. Fluid levels were OK, the filter screen was clean and the fluid was clear. I contacted Twin Disc who told me the oil pressure should never gio bleow 270lbs, even at idle, and should run 300-330lbs above 1,000 RPM's. They suggested it was the transmission pump. I replaced the pump. Pressure then came up to 270lbs at idle and 300lbs at 1200 RPM and 330lbs at 2400 RPM cruise speed, same as the port engine, although the needle on the starboard engine gauge did flutter a bit.

I thought I had the problem licked, but yesterday afternoon as I was returning from a 60 mile weekend trip, the transmission pressure in the starboard engine dropped to 90lbs at low RPM's again. It would come up to about 180lbs at 1200 RPM and 270lbs. at +2,000RPM, but woudn;t get to 300 at any speed. This time the transmission did not slip in/out of gear at idle.

I apologize for the lengthy post, but I thought the background would be important. I'm located in area that does not have good marine diesel mechanics near by. Before I pay one to drive 3 hours from Jacksonville, I was hoping someone on the forum would have some advice from a similar experience. By the way, recourse through the distributor who rebullt the engines is not an option for me.

Shower problem

Does anyone know how to remove the drain from the shower floor? The hose to the shower sump has become disconnected. I can reach the bottom of the drain from the sump access, but it feels like the collar that the hose attaches to has corroded away.

Any advice/insights would be much appreciated.

 

[Genesis]

First things first - stick a mechanical gauge on that transmission pump and make sure you're really seeing what you think you're seeing.

 

[Captned]

RE-Shower problem

Ha! The old corroded drain fitting problem. What I did was remove the screen from the drain, cut a hole in the bottom part of the drain or go through the existing hole, get a hose that is smaller than the orginal or remove the original all together, run the smaller hose through the existing hose (or not) to your sump. At the drain, 5200 the new hose into position. After its dry and sealed good, replace the shower screen... I could not physically get to the bottom of the shower to replace mine. This has worked for several years.

Hope you understand.

Capnted
78 46 CON

 

[SKYCHENEY]

There is a threaded ring that holds the elbow on the bottom of the shower drain. If you can't reach it to get it off, you may have to cut a hole in the floor as close as you can get to the drain for access.

 

[Bill Root]

First things first - stick a mechanical gauge on that transmission pump and make sure you're really seeing what you think you're seeing.

The gauge is mechanical. An oil line runs directly to the guage in the main bridge and the fly bridge Both gauges read the same, so I don't think it's the gauge. What would be the next step?

 

[Bill Root]

RE-Shower problem

Ha! The old corroded drain fitting problem. What I did was remove the screen from the drain, cut a hole in the bottom part of the drain or go through the existing hole, get a hose that is smaller than the orginal or remove the original all together, run the smaller hose through the existing hose (or not) to your sump. At the drain, 5200 the new hose into position. After its dry and sealed good, replace the shower screen... I could not physically get to the bottom of the shower to replace mine. This has worked for several years.

Hope you understand.

Capnted
78 46 CON

Thanks. I can reach the bottom of the drain from the shower sump access hatch. It sounds from your message like there should be a collar or elbow that holds the drain to the shower floor. If so, mine must have corroded. If I can get the old pieces off, maybe I can pull the drain through the shower floor to 5replace. If not I will try your method.

Bill
73 43 DCMY

 

[Brian Degulis]

There is a relief/regulating vavle in the valve body it may be dirty or scored and getting stuck partialy open. If not there then your pressure pack seals do you see any diffrence in forward or reverse?

Brian

 

[Bill Root]

Brian:

I wasn't looking at the gauges when I was backing into the slip yesterday. I'll go to the boat tomorrow, check it out and get back to you.

Bill

 

[Genesis]

Yep - what Brian said.

 

[captddis]

On most twin discs the selector valve is held in place by a flat bracket with two 5/16 bolts. If the bolts loosen the valve will rise up and at that point the clutches will not get full pressure. I have seen this a few times. If you have a trolling valve that can do the same thing. If you have the valve make sure it is against the stop. Disconnect the cable and confirm it is all the way off.

 

[Bill Root]

OK. I went to the boat today to gather more info.

The transmissions are twin Disc 506's. There is no trolling valve that I can see. When started, the starboard transmission oil pressure immediately jumps up to 270-300lbs, then quickly drops to 90lbs. It then fluctuates between 90 and 270 at idle. Increasing RPM's causes it to go up to 270, then drop back to 180 and eventually back down to 90 as the engine warms. It does the same thing in reverse. The port transmission goes to 330lbs immediately after starting and stays there.

Any thoughts before I call out tghe mechanic?

Bill

 

[Boatsb]

Get a hold of Kirk here.

http://www.thermacomarine.com/index.htm

If he cant get you fixed he will find the guy who can. he is honest, experianced and a great guy to meet.

He helped me out on a Velvet drive problem and sent me to the Volvo specialist on another transmission issue.

 

[mtadamek]

Just to be sure I would disconnect the tubing from the gear and put a gauge directly on it. You never know, you could have some tubing problems or some trash in the line, or a faulty gauge. Just a thought since you don't have a mechanic near by.

 

[sgharford]

I recently had this problem with tranny pressure gauges - Port engine was reading a little low since I bought the boat (180 psi, should have been 200 psi). I was going to flush with Marvel Mystery Oil until one day both upper and lower gauges dropped to 95 psi. Futzed around with sender and wiring a while hoping it was that. Found a 400 psi manual gauge prevoius owner has stashed in drawer and hooked it up. Turns out it was making 210 PSI. I tested it on other tranny to make sure this manual gauge was OK and it checked out with electronic gauges. The pressure sender had gone bad. As always, start with the simplest things first.

Maybe getting ahead of myself here, but if it is the sender the only one I could find for dual stations was VDO which SAMs carries. You will probably have to replace the gauges too to match sender (Stewart Warner, also carried by SAMs, work). If and when you get the sender, it has two identical looking electrical connections and no instructions. It would appear you would have to run a seperate wire to the 2nd gauge by looking at it. This is not the case, you ground one terminal and connect the existing single sending wire which goes to both gauges, (no need to modify existing sending wire). If you don't ground one connection both gauges peg to 400 psi as soon as you turn the ignition switch.

 

[Bill Root]

Thanks for the advice. I'll try it this week and report back.

 

[Bill Root]

Re: Update - Twin Disc transmision oil pressuer & shower drain

Ken Ruse, diesel mechanic, visited the boat today. Confirmed that starboard transmission low, fluctuating oil pressure and slipping in/out of gear is caused by the gear that drives the oil pump being loose and rotating freely on it's shaft. This gear is pressed onto the shaft. There is no key or mechanical fastener. The transmission will need to be removed in order to repair. That will happen tomorrow. Mechanic's recommendation is to have the gear re-pressd onto the shaft, then spot welded to avoid a recurrance of the problem. Any thoughts?

Bill