SkiDoc

iTrader: (4)

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.

Vinny P

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 !!!

Mr Gadgets

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

goebel1

iTrader: (2)

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

Vinny P

No fluid has leaked ino the bellows through my SCX.

Mr Gadgets

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.

goebel1

iTrader: (2)

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?

Mr Gadgets

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!!

goebel1

iTrader: (2)

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

Mr Gadgets

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