Oil injection check valve 1992 200hp Mercury

[jdupree]

After a long diagnosis process, it appears my motor is still getting oil after shut off. By the looks of my racor filter, oil is being pushed into the fuel system after the motor is cut off and sits for a long period of time.

Isn't there a check valve or something to prevent this? If so, was wondering if someone could tell me where it is. Thanks.

 

[jdupree]

Re: Oil injection check valve 1992 200hp Mercury

Anyone?

 

[hkeiner]

Re: Oil injection check valve 1992 200hp Mercury

In short, the most likely culprit is the crankcase 2psi check valve, which provides pressure to the remote oil tank when the motor is running and relieves pressure from the remote oil tank when the motor is shut down. If this valve is defective (i.e., provides too much pressure when the motor is running or does not quickly relieve pressure when the motor is turned off) too much oil can be pushed into the fuel lines after the motor is shut down, causing the symptoms you describe. The below link contains a much much longer discussion on the oil injection system and possible causes for too much oil in the fuel line and too much smoke.

http://forums.iboats.com/showthread.php?t=182406&highlight=faulty

 

[jdupree]

Re: Oil injection check valve 1992 200hp Mercury

hkeiner,

Thanks for the response. In reading that thread, it sounds like my motor has the same problem that yours did. Where can I find the valve you are talking about and how hard is it to replace? I did look at the diagram but am confused as to where this valve is at? Thanks for the help!

 

[hkeiner]

Re: Oil injection check valve 1992 200hp Mercury

Follow the two tubes going from the remote oil tank to the motor. One tube connects to the reservoir oil tank and the other tube connects to the crankcase 2psi check valve your want to replace. I believe that it is near the starter on your motor. Remove the tube from the old check valve, unscrew the old check valve, screw in the new check valve, and then reconnect the tube to the new check valve. That is it. A pretty simple job.

Note that the new check valve will be a little smaller in size than the original check valve (they redesigned it since 1992) and that the new check valve will already have dry thread sealer on the threads and you do not need/want to add any more sealer.

 

[89Champion]

Re: Oil injection check valve 1992 200hp Mercury

I have a feeling that this is the same delima that i have been fighting. I have a 88 Mariner 150 Magnum II that starts fine with a little help of the throttle. I idle though a no wake zone and have such a build up that it takes forever to clean out to get up on plane. I though maybe i was having a oil pump putting out to much oil into the system. I am now going to check my check valves and go from there.I have cleaned all carbs and checked needle seats. At idle it smokes alot and above 2300 rpm it big up in rpm and runs awsome.

 

[hkeiner]

Re: Oil injection check valve 1992 200hp Mercury

One way to test for a bad crankcase check valve is to unscrew the cap from the remote oil tank a few minutes after shutting the motor down. If you hear some air pressure escape, the check valve may not be releasing the pressure in a timely manner.

I have not found any published spec on how quickly the check valve should release the pressure and I have not played around with my motor to time it, but I think that the pressure should most certainly be released within 15-30 minutes at the longest. I have read some posts where some guys with smoke problems found that the air pressure stayed in their remote tank for over 1-2 days, which was most certainly too long. Considering the minor cost of a new check valve, the ease of replacing it, and the lack of specs for bench testing it, it is probably best to just go ahead and replace the check valve and see what happens.

 

[89Champion]

Re: Oil injection check valve 1992 200hp Mercury

I check out the motor yesterday. I have had it for the past week with the motor tillted up. So I looked into the carbs and there is just oil sitting there in the throat of them. I am pretty sure it is the check valves now.

 

[jdupree]

Re: Oil injection check valve 1992 200hp Mercury

hkeiner,

Thanks for the help! I will replace that valve and let you know how it goes.

 

[jdupree]

Re: Oil injection check valve 1992 200hp Mercury

Update: Sorry to say I have not replaced the 2psi valve yet. In reading the entire thread, would the 2psi valve cause too much oil to be pumped into the motor?

My basic problem is that the motor appears to be getting too much oil while running. Startup is especially bad! Motor smokes like I have never seen and runs rougher until it warms up good and burns some of the oil off. Appears to smoke excessive at idle as well. Would this sound like the 2psi valve?

I have even tried lately to unplug the oil injection hose from the main tank and leave it unplugged till I start it up again to relieve the pressure. Even when I crank it up the next time it smokes like a freight train! Any further suggestions would be greatly appreciated!

 

[Faztbullet]

Re: Oil injection check valve 1992 200hp Mercury

The problem with your motors are is the crankcase pulse valve thats bad. It is what pressurizes the oil tank, as it is a plastic disc that has .012 hole drilled in center. When engine is shut down oil tank pressure is bled back into crankcase, to repair either replace the valve or drill hole out to .018 with pin vise . Also check your bleed/recirculation valves as they can cause loading up and smoking at idle if defective or clogged...

 

[hkeiner]

Re: Oil injection check valve 1992 200hp Mercury

Sorry to say I have not replaced the 2psi valve yet. In reading the entire thread, would the 2psi valve cause too much oil to be pumped into the motor?

The answer is yes, but this valve is not the only possible culprit for excessive smoke. As the previous poster has indicated, defective bleed valves can also cause some excessive smoke. However, the 2psi check valve is a common culprit and I would suggest replacing it to eliminate it as a possible cause.

Another thing to check is that the linkage that syncs the oil pump and the carbs is correctly adjusted. Your shop manual will describe how to adjust this linkage.

 

[j_martin]

Re: Oil injection check valve 1992 200hp Mercury

The answer is yes, but this valve is not the only possible culprit for excessive smoke. As the previous poster has indicated, defective bleed valves can also cause some excessive smoke. However, the 2psi check valve is a common culprit and I would suggest replacing it to eliminate it as a possible cause.

Another thing to check is that the linkage that syncs the oil pump and the carbs is correctly adjusted. Your shop manual will describe how to adjust this linkage.

You were told about 8 posts ago to change the crankcase check valve. Of course if the valve is failing, and it loads a bunch of oil into your fuel system it will start hard, smoke like a demon, and load up during the idle period/no wake zone.

After that, and probably after a set of new spark plugs, start to worry about adjustments. It's a pretty simple stable system. Just fix the obviously bad part.

hope it helps
John