1987 Mercury 150 oil injection problems

[JP3623]

I was sent to these forums and was told the outboard guru's here would solve my problems. I just bought a boat with an 87 merc 150. I took it out for a spin, and the oil warning buzzer came on after a few minutes. I took the engine cowling off, and the upper oil reservoir was about an inch low. The lower reservoir had plenty of oil. I tryed unscrewing the cap on on the upper reservoir and starting the engine in order for the oil to purge up. This did not work. I topped it off with oil, and this made the buzzer go away. Does anyone know why the upper reservoir is not filling on its own?

 

[gss036]

Re: 1987 Mercury 150 oil injection problems

I will assume that you have a V-6 carbed engine since you gave very little information.
The lower(boat 3 gal) is pressurized by the hose that comes from the lower starboad side of the block. The hose has a check valve that is screwed into the block. If the lower tank is not holding pressure, then it will not force oil to the upper tank. Check the caps and fitting for air tightness.
If after filling the upper tank, is there oil being used by the motor? Does it go down? If so then I guess you can assume that the oil pump is working. You should see the color of the oil in the clear fuel lines going to the carbs.
Do a search and read some of the posts on oil problems, there are many, many of them and you should be able to get an idea of what to look for. You really need an OEM manual.

 

[JP3623]

Re: 1987 Mercury 150 oil injection problems

Yes, your assumption is correct. Sorry for the lack of info. The oil level in the upper reservoir is dropping, so the motor is getting oil. It just is not getting to the upper level on its own. I ran a search but found no problems like this. I was just hoping someone has seen this before.

 

[gss036]

Re: 1987 Mercury 150 oil injection problems

I was just about ready to turn this thing off for a couple of days, but decided to check back.
If you check the areas I pointed out earlier, you should be able to find the problem. Either the check valve is bad or the block is not putting out pressue or you have a leaking "O ring" at the lids on the 3 gal tank or leaks in the bayonet connects. There just isn't any more to the system.
Good luck, keep posting and someone will jump in tomorrow and help out. Weather permitting I am going fishing tomorrow.

 

[WillyBWright]

Re: 1987 Mercury 150 oil injection problems

The only things I can add are check for kinks in the oil/air line and check for leaks in the air line (oil would leak from the oil line and leave an obvious puddle).

The pressure comes from one section of the crankcase. If the cylinder of that section has low or no compression, it wouldn't pressurize the oil tank.

 

[JP3623]

Re: 1987 Mercury 150 oil injection problems

Would taking the air inlet/oil outlet quick disconnect off of the remote tank while the motor is running be a quick way to tell if the crankcase is supplying pressure to the tank?

 

[hkeiner]

Re: 1987 Mercury 150 oil injection problems

While I am no expert on the oil injection system, I have some experience with troubleshooting oil injection problems on my 1996 Mercury 150 V6 and know how the oil injection system works in great detail. If it is any help, this is what I would do to determine if the crankcase check valve is OK or not :

1) After shutting down the engine, immediately loosen the cap on the remote 3 gallon oil tank.

2) If you hear the pressure release, then you know that the crankcase check valve is sending pressure to the tank and that your problem is further downstream from the check valve.

3) If you don't hear any release of pressure, check that the cap on the tank is sealing correctly. If it is, then replace the crankcase check valve and repeat step 1) above. The check valve is fairly inexpensive and easy to replace so it is probably not worth the effort of figuring out how to properly test the check valve with a pressure gauge or other method.

4) If after replacing the check valve, you then hear the pressure release when loosening the cap immediately after engine shutdown, then you may have solved your problem.

5) If after replacing the check valve, you still don't hear the pressure release, then you may have a problem with the cylinder, as mentioned in an earlier post, or the cap on the 3 gallon remote tank is really not sealing. Check the cap again.

There are some other more unlikely causes but I would do the above troubleshooting first before considering the more unlikely causes.

Good luck and report back on how you resolved your problem, for the benefit of others reading this post that have a similar problem.

 

[LubeDude]

Re: 1987 Mercury 150 oil injection problems

Well, Welcome to Iboats, I guess the Iboats decals did some good.

This is my old boat and I have been working with Justin on this problem by phone and Emails. I had no Idea there was a problem with the boat at all, I even have offered to buy the boat back from him but he would like to keep it if he can get this problem figured out. The last compression test I did was 120#`s all the way accross and the engine runs very strong but it wouldn`t be a bad Idea to do one. I was going to one while they were looking at it but picked up my timing light case instead of the compression tester case. I think near everything has been covered, I can`t help but think that it`s something very simple.

Lets put our heads together and get this figured out.

Welcome aboard Justin.

 

[JP3623]

Re: 1987 Mercury 150 oil injection problems

I was actually sent here by a friend, but the iboats decals didnt hurt. Havent really had time to tinker with the problem, but can atleast rule the low compression theory out. I didnt really think it could be that in the first place, but had it done today as a precaution. It was a solid130# across all 6. I am glad to come across this board and appreciate Ray's (LubeDude) and everyone elses help. I will hopefully have an update soon.

 

[gss036]

Re: 1987 Mercury 150 oil injection problems

Have you cleaned the filter screen on the pick-up tube in the 3 gal oil tank? If not, unscrew the lid (cap) with the hoses (hoses will disconnect from the cap) and wash the screen off with gas in something you can dip it in. They do have a tendancy to clog over time.

 

[bhive]

Re: 1987 Mercury 150 oil injection problems

check ware the oil hose attaches To the resivior on the motor. It normaly is connected to a 90 degree brass fitting. This fitting has three barbs and if the hose is on the wrong barb it will not let the oil flow from the boat resivior to the motor. might not be the problem but have seen it happen

Chris

 

[bhive]

Re: 1987 Mercury 150 oil injection problems

I just got back from V6 efi school. If the 3 gal remote resivior is presurizing the check valve is ok. What I found out is that the brass piece wear the hose from the remote resivoir connects to the engine resivoir has a check valve in it, and since the motor is an 87 it is probably a 2 psi check valve. In 88 or 89 they changed this check valve to a 4 psi one. The reason for the check valve is if the screen in the tank becomes clogged or if the hose becoms pinched this check valve will alow air into the motor mounted resivoir. What they found isthe if the oil from the remote resivoir has to travel to high up to the motor(to high of a head) this valve would set off early and not allow oil to be tansfered and thus not keep the motor resivoir full. All you need to do is get a new check valve, It has been superseded to the new one.

 

[studlymandingo]

Re: 1987 Mercury 150 oil injection problems

JP, did you ever get this resolved?​