Thread: NEED AN EXPERT ON 2002 150 HP 2 STROKE OIL INJECTION SYSTEM--PLEASE

PM Sliderman, bet he has the answer to your problem.

Originally Posted by cray

PM Sliderman, bet he has the answer to your problem.

I will do that first thing in the morning.
Thanks

Be absolutely sure that the remote tank caps are tight. Your engine side tank is mounted on the side of the engine, it will have a small fill cap. The cap has a male thread that screws down into the tank. Place an o-ring under the cap. Don't use teflon tape and don't over tighten the cap. Just snug it down.

There is no check valve on the oil line to prevent the oils return to the remote tank. It's held in place by the low pressure it creates as it tries to return to the tank. (like placing your finger over a straw that is placed in a beverage and lifting up) When the cap begins to loose it's ability to seal off, the tank will no longer hold a low pressure and the oil will siphon back into the remote tank. Since the engine side tank is several feet above the remote tank, the oil in the line creates a good amount of low pressure in the engine side tank.

Originally Posted by sliderman

Be absolutely sure that the remote tank caps are tight. Your engine side tank is mounted on the side of the engine, it will have a small fill cap. The cap has a male thread that screws down into the tank. Place an o-ring under the cap. Don't use teflon tape and don't over tighten the cap. Just snug it down.

There is no check valve on the oil line to prevent the oils return to the remote tank. It's held in place by the low pressure it creates as it tries to return to the tank. (like placing your finger over a straw that is placed in a beverage and lifting up) When the cap begins to loose it's ability to seal off, the tank will no longer hold a low pressure and the oil will siphon back into the remote tank. Since the engine side tank is several feet above the remote tank, the oil in the line creates a good amount of low pressure in the engine side tank.

I actually replaced the tank with a new one and had the same results as far as the alarm going off. I did not know at that time that the oil was bleeding out of the tank. Does it seem reasonable that if the oil bleeds out of the on board tank that there is air entering the system somewhere or is that not an issue?

Air entering the system is the problem IF the oil is draining back to the remote tank. It relieves the low pressure and allows the oil to return to the remote tank. The remote tank is pressurized during operation by a check valve that is located on the starboard side of the engine (#5 cyl). The pressure from that cylinder applies pressure to the remote tank. Which forces oil up the line into the engine mounted tank. If someone has been messing with the system, check that the two hoses that attach to the remote tank are correctly attached. If they are backwards, no oil will flow to the engine. If a pin hole is present in the oil feed line, you should notice a leak. And if the cap is not sealed off on the remote tank, no pressure will form to move the oil upward.


One of two things are happening.
1) The remote tank is not feeding the engine tank and you are getting the buzzer chime every few minutes as the oil level drops from normal oil consumption.
or
2) The cap is not sealing off low pressure and is allowing the oil to back feed into the remote tank.

The plastic cap that I'm referring to has to seal in two ways. It has to hold pressure in the tank as it increases above atmospheric (during operation). And it has to seal in the reverse direction as the pressure in the tank drops below atmospheric. (storage time)

The check valve in the side of the block that I mentioned earlier is designed to hold pulses of high pressure during operation. If it's operating correctly the pressure will release a short time after shutdown. Which allows air to escape the remote tank as oil back feeds back into the tank.

Does all that make sense? Remove the little fill cap on the engine tank and put a suitable size o-ring on it. Top the tank off and tilt the engine to test. That should resolve your issue.

Tilting the engine does two things. It raises the entire tank higher above that of the remote tank which creates a stronger low pressure in the tank. And it reorients the inlet where the oil enters the engine tank to a lower position. Which in turn adds additional weight of oil in the tank on the feed line. The two together compound the amount of force exerted on the oil in the line to want to drain back into the tank...... Which increases the low pressure (more vacuum) on the tank... = More stress on the small cap to remain sealed.
(Boats with low bilge areas and taller jack plates will experience this issue more often)

As mentioned earlier. If the lines on the remote tank have been reversed, the engine side tank will be feed a supply of air and not oil. A static test of the tank's oil level over a period of time with no motor operation will confirm that oil is back feeding. Also, when filling the small tank. It's best to disconnect the pressure line coming off the starboard side of the block and apply a small pressure to it with the oil cap off the small tank. This will purge the oil line of air and fill the tank from the remote location. Otherwise, just to simply fill the small tank with a funnel will leave the 'fill' line void of oil. Which will lead to a continued drop in the oil level on the small tank during operation while the feed line primes with oil.

(As complicated as all this sounds in print, it's really pretty simple and straight forward.)

sliderman,

Thanks so very much for taking your time to help me trouble shoot my problem. The great thing with having someone of your caliber to help is that you obviously know what you are talking about but also have the knowledge to explain theory behind how it should function. That is really helpful to an old Geezer like me.
I am going to go through your methodology step by step, and with all due diligence. I have already covered most of the areas that you have mentioned but apparently I have missed something. I feel confident that I will find the problem and I will post the results once I have fixed the problem.

One final question if I may,
If I were to disconnect the oil supply line at the 4psi check valve with the engine tilted, and everything is working properly, am I correct in stating that there should be no oil flow back to the main supply tank?

Thanks Again for sharing you knowledge. I truly appreciate it.

If I were to disconnect the oil supply line at the 4psi check valve with the engine tilted, and everything is working properly, am I correct in stating that there should be no oil flow back to the main supply tank?

Oil supply or air supply? I'm not aware of a check valve on the oil side. Only on the air side. Mounted to the block as stated earlier. It will not prevent back flow of oil. That is dependent on how well the small tank holds low pressure. (Think of this system like placing your finger over a straw in a tall glass of water and lifting. The water will remain in the straw as long as you keep a tight seal on the top of the straw. Once air is allowed to enter, the low pressure is relieved and water will drain.)
If the new tank was installed and merely filled by way of a funnel, I think the air in the fill line would vent into the small tank and allow oil to return to the remote tank. This process would continue an unknown number of times before it finally purged. Filling by pressurizing the remote tank with the cap off the small tank to allow venting is the only way I fill them when low.
(As unusual as your problem is, I went through this not long ago. The corrective action was an o-ring and proper filling technique.)

As for the compliment, it's much appreciated but keep in mind that I see issues on a near daily basis that are new to me. Some are easier than others to figure out. I hope yours is not one that I've not seen.
Did the old and new tank have any sort of sealing ring on the small cap?