Dick,
What do you mean about leaving the air space in tact? I just used some large reservoirs with out check valves. The caps have the diaphrams to keep some pressure in. Are the valves positioned to keep fluid in or out. School me here.

I gotta tell you, I am confused. I simply dont like the idea of only filling the drive to the upper plug, then adding some fluid to the bottle. That will leave a huge pocket of air in the upper. If it does eventually burp itself out, then the bottle will empty out, setting of the alarm. My practice has always been to fill the drive until there is a small amount of fluid in the bottle. That will allow the remainder of the bottle for room for expansion. UNTIL NOW !!!

The check valve in the bottle is the diaphram in the cap. In the Imco bottle, it is a seperate diaphram next to the cap.

The way I look at it. If you fill the drive to the vent hole.. plug it and then continue to add fluid.. the air in the upper case will compress and push the fluid up into the bottle.. The air space is above the fitting in the drive at about the same level as the vent plug. After you are done pumping fluid in, it should equalize and there will be very little pressue on the air in that space.
Now if you fill to the vent hole, and add to the bottle. There is the added air space afforded by the line to the bottle. Not a great deal more air space than when pushing the fluid up to the bottle. This is what I was referring to about the "air space staying intact". Either method traps air in the drive above the line to the bottle (which is level with the drain plug).
The check valve in the top of the bottle to let pressure build up, then the fluid will be pushed back in to the drive as it cools, and if it needs more, the valve will allow it to drain into the drive, equalizing the fluid level.
The air is trapped and while running will burp. In a Bravo the air space will stay intact, after the burping process.

In Racinfever's case it seems it isnt. It continues to let the air out and the fluid in, till it is pushed out the front of the drive.
Now in Vinny's case. He fills it the way the bravo is filled and he has not had any fluid in the bellows that he has told me about. Correct me if I am wrong, Vinny..

So why the difference? I have no good answer for that. Is RF running his harder than others? Could be. I know my friend had an issue with his SCX's and believes he solved the problem by installing thicker orings on the pinion bearing carrier. I am not sure of his symptons, other than he was pushing fluid into the bellows. After the oring change, he has not had a problem that I know of. He also states that he never sees the drive temp go over 160*. He has the sensors in the vent hole in the upper. I know he runs the boat hard.. and doesnt seem to have an issue with fluid leak, but I would have to talk to him about it again to verify that.
My thought is, if I fill it the way I have been and I dont have to keep adding fluid, then it should be staying in the drive. I am not sure if I will be able to run WOT for extended periods, like I used to. Ten or fifteen miles at close to WOT used to be common, but now I may have to hold back on the throttle to keep the speeds sane on Lake Michigan.
So I intend to try it the old fashion way an see if it reacts like RF's, drives. If it does, I will heed his advice and try it the other way. Just scares me to not know if the level is going down and no way to tell. The Imco bottle doesnt have an alarm switch added to it. Just one more thing to get used to and learn to live with, hopefully without a detrimental learning curve.
At least we have to thank RF for sharing his situation, so we all can keep an eye open for the same situation.
I guess the next question is, how many SCXer's are finding lube in the bellows?? And how do they fill it?
Just my .02.. :)

Dick

You are saying fill to the top plug and put a inch of oil in the reservoir. Lets say theres no air in the case already (burp)and you have the top plug out. Now the air gap in the case is not pressured up holding against the check valve in the reservoir. Here is where I think it gets tricky wouldn't the oil naturally drain down to the case till it pressures up against the check valve. Now lets say there is an air bubble also... it would leak down even more now you don't know how much oil is in your case. You open the top plug to see if its full...and the process starts over. If it is full the level should be above the plug with the oil in the reservoir. My thoughts are whats the difference if its air or oil pressuring up the drive, pressure is pressure. I understand they want to leave room for oil expansion but the pressured up air gap is not going to let it do that. It has to be able to relieve the pressure to expand... it will find a way (seal). This is why I don't use the check valve in the reservoir and let the oil flow freely. I have had no oil leaking at all. also Imco has my drive and says it look great internally

No fluid has leaked ino the bellows through my SCX. :drink:

I know years ago, I was told there has to be an air space in the drive or it will cause problems on a bravo. How you get that air space and keep it is the issue here. Filling it either way should do that. Once the drive is run it will take on a bit more fluid (from what I have seen over the years). It burps, but there is still an air space in the top of the drive. With the plug out, it will drain the bottle, but shouldnt fill the drive because there is air above the vent hole (when the drive is in the upright position).
George, you are saying you have no check valve in your bottle. Are you referring to the diaphram air valve on top of the bottle or something inline with the hose to the drive?

Imco said to fill to the vent and put the plug in.. now you have an air space. Put some in the reservior and maintain a level you can watch. If you pull the vent plug, there should still be air above it. The bottle will drain, but it would flow out of the vent hole. Unless the drive is on it's side the air pocket should stay intact..
Now the check valve on the helmet may be a restriction to oil flow when it expands, but I dont see it as a major problem, but I may be wrong. It would be interesting to know how fast it starts to expand and what air space is needed to keep up with things so it doesnt get forced out of the drive somewhere it shouldnt.

I guess we could tell if there was a pressure gauge on the bottle and a temp gauge on the drive to determine the forces involved.

Its my understanding there is a one way valve in the bottles plus the diaphragm cap you guys are using am I wrong, you need something to trap the air? Mine has the diaphragm in the cap only my fluid moves up and down constantly. Now knowing what the pressure is in the drive would be interesting but my thoughts are it would still push the air out of the drive into the bottle if there is no one way valve inline. What keeps the cap diaphragm from opening up and letting oil into the dive a little at time till its full when the pressure drop in the drive?

I dont think there is a one way valve in that bottle.. pretty sure, I will check. But the air should stay above the bottle line.. not sure if the air in the drive lube (when it is mixed at 6000rpm) would go to the bottle or stay in the drive. That is the big question.

I guess we make a hard pass or two and go home and let it settle and then pull the top cap. See if there an air space. If not, I am wrong, if there is, then make more hard passes till you see more burping and fluid keeps going down, etc.

I dont know what happens to the air and oil. I am just speculating, until I can play with it and see what actually happens. Soon as the water gets soft in the spring! Can't wait to go WOT with it!!

I guess we could beat this to death. :lolhit: Hear is another thought the ones that are blowing seal what gear oil and weight?
I am running Amsoil sever gear 75-90w

You're right.. :lolhit:
It is going to be along winter!!

THINGS I KNOW:
First guys, I appreciate all of the input in trying to sort this out. I think Dick has a great insight on what's happening inside the drive. You must have an air space. It's not going to starve the drive it's going to allow for room for the oil to expand inside the drive and room for the oil to move. This is due to the straight cut gears. All drives can benefit from adequate air space even Bravo's could really use more. I use the Torco RTF fluid as recommended. I do turn mine up to 6200 rpm which could attribute to my symptoms. But one thing for sure, you do not want to continue to fill the drive past the vent hole while filling from the bottom. It's probably to late for most of us to offer much more input until Spring but at least we all have the necessary information to watch our drives for potential problems.
Participation and discussion is what keeps this forum interesting. Any other thoughts along the way would be appreciated.

I turn my motor 64-6600 RPMs

Glad to see you're one of my kind.

I fill mine to the top vent plug then added to my non imco reservoirs. Use the Torco RTF. No oil in the bellows. I ran hard this fall. Noted drop in level, but after the initial drop no more. Since air volume expands more than fluid, the more air in the drive the more movement of fluid to the reservoir you will have. Personally I don't know what difference any of this makes other than it may be an excuse for imco as to why their pinion seal has leaked.....

Drives filled incorrectly will probably run inefficiently and rob speed. The oil has to move into the air space or you will hydraulic the gearcase and cause unwanted pressure. Just my thoughts.

I will admit I know nothing about these drives but...

It would make sense to me that a pinion seal would be much stronger then a check valve or reservoir cap, so if the fluid was going to push out anywhere it would follow the least path of resistance. If the pinion seal is the fluids first choice then thats one really strong check valve and reservoir cap!

I agree, definitely need an air space..

And then there is the one issue of orings on the pinion bearing unit.. My friend replaced the orings with thicker ones and no more oil in the bellows.. Something to look at.
I will only be turning my motor to 5600-5800.. liquid rollers..

Where is summer when you need it??

Is anyone but me surprised that IMCO has not posted anything on this thread? I would think that a lot of their business for the SCX comes from people that are a part of this website, whether a lurker or an active poster. Seems to me that in a way, you are doing a fair amount of R&D for these guys, the least they could do is add some guidance. I think that these are the drives I will use on my boat, but stuff like this makes me question them.

x2

i'll keep you posted on how IMCO handles my leak issue and shifting issue. All i know is I bought two drives, one doesn't leak and shifts great. The other leaks through the casting and shifts like you need a leverage bar. Which is fun when your trying to dock and need the starboard drive. They stated shift cables are the problem, so I switched the drives around. Now i need the leverage bar on the port side.

My drive is on the way back from IMCO I threw a blade into my case. I ask them to check it all out while they had it I also ask about my shifting and was told it was the cable??? I was told they did change the shift cam. BUT I must say... I do think they were very reasonable and fast on replacing the case and prop shaft (Great Customer Service).

Thats good to know. I'm not expecting any problems.

yes it has the new style cable

Are you still considering the new SCX? Are yours still for sale? Will be interesting to see what IMCO does about your issues.

Got my drive back today looks great. Got a new Manuel with it. The only thing different I could find is this cable warning sheet was in with the Warning... Please read carefully . Now my question is…is there a different cable for left and right hand rotation??? If not... I am taking it that the RH rotation is ok with the shoulder on the cable. I will check my cable tomorrow to see if mine has a shoulder on not on it. My drive is RH (confused agene).

Rh rotation still could be a problem in reverse.

Got the drive back in ...my cable does have the shoulder on it. Fire it up on the hose and it shift so smooth and easy now (WOW). Not sure if it's the Torco oil or what work IMCO did to it or both. I am a happy camper.

I'm considering buying an SCX/SCX. So I read this thread with great interest. Whats up with the porous lower cases? Has anyone figured out the proper recommended fill procedure?

Per IMCO, how I did it, and it is working great.
Fill drive from the bottom to the vent screw. Fill reservoir to mark. Run it and recheck reservoir level.

Ok, sounds great. What about the porous lower cases and leaking seals? Since this drive costs 15k I would think that they would have sorted that out before hitting the market

I have had drive for 15 hrs, no problems, sent back for hard shifting and delayed engagement sometimes, Dave at Imco was a pleasure to deal with and is even painting drives again. I guess mine where few serial #'s of the new cam change. So far very happy with drive.
I am running a sc lower, have some metal on magnet, may upgrade to imco lowers.I don't know about porous but if it was, I am sure it was in the beginning and has been adressed

The porous problem was in the casting on the outside by the trim pin area. Not porous to the inside causing any leaks. And Imco took care of the problem to the customer's satisfaction, I was told.
Hope that helps.
Dick

Thanks Dick, Still thrashing around between the SCX and Arneson.

I had to make the same adjustment when I installed new style cables for my BMax drives. On left hand rotation the cable pulls in to shift into forward gear and it needs a little bit more throw. If you don't cut the shoulder off you don't get enough throw.

I wonder if IMCO ran into the same issues the BMax had in years past. The clutch pack heights for the bigger upper gears would be off slightly and it would cause hard shifting or delayed shifts. The good thing is it was an easy fix and they could send the drive back the next day.

The new owner of BMax has figured out how to make it a permanent fix.