Oil injection system 98 Mercury 150 offshore carbed

[Gt30691stang]

I recently picked up a 98 Mercury 150 offshore carbed. I was told it came off a proline with a remote mounted oil tank and the lines were removed from the motor. My question is if I do not plan on using a remote mounted oil tank can I just run a line from the brass check valve to the crank case check valve to complete the circuit? I also have a vacuum tee on the starboard side valve cover w one of tees open the other line on tee goes to carb does any body know where that vacuum line is suppose to go?






Admin Edit: You were close - you copied the Thumbnail code, copy the Image code and you'll have the proper size for viewing.

[fitz73222]

So you intend to use the oil injection but only run off of the pony tank under the cowl? If so, there is not enough capacity in that tank to give you any kind of range without having to refill it often.

[Blue Agave]

The remote oil tank will have two hoses, one black and one black with a blue stripe.  Please refer to the photo below, i have added red circles to assist.  The black hose goes to the the bottom red circle and the black hose with the blue stripe goes to the upper red circle.  The remote oil tank supplies the pony tank under the cowling and the pony tank supplies the motor with oil.  I agree with Fitz, you'll need the remote tank unless you want to fill the pony tank every twenty minutes.

I imagine that you are asking because you intend to mix your own oil.  This is a popular thing to do with OMC motors but Mercury's oil delivery system is much more reliable.

[Capt. Bob]

This is a popular thing to do with OMC motors

Indeed but not just them.

From several years ago.
http://classicaquasport.com/smf/index.php?topic=6458.0

Again, I'm in the oil injection camp so I'm bias.

[Gt30691stang]

Yes I plan on utilizing the oil injection system. I'm w Capt Bob on using what the engineers designed, they do not always get it right the 1st time, but most of the time lol. I was not exactly sure how much was actually needed I do not not have much experience in 2 stroke engines extensive experience w 4 stroke engines. Currently I do not plan on going offshore or anything like that, but plan on using it on a decent size lake roughly 29 miles or so. As of right now I need to get it running so I can tune the carbs and ensure everything is running properly, once running i need to check my rpm and speed the prop is 14 1/2 dia and 19 pitch I'm not sure if this going to work well on the aquasport coming from a pro line weighing 3800lbs or so what I have read I will most likely have to up the prop somewhere around 21 pitch, the previous owner said the proline did 43 mph at 5300rpm which is exactly what is recommended. I'm going to search a local salvage boat yard for the remote mounted tank and lines. Does anybody know if the open vacuum tee is suppose to be open or does have a vacuum line and where it is suppose to be routed to?

[Gt30691stang]

Got lucky today found the tank and lines I need for 30$!! They also gave me extra set of lines and mounting bracket! This weekend I will finish hooking everything up and hopefully get it started this weekend.

[fitz73222]

Good job, nice find. Now after you get this all hooked up this is a must. You must start an run this engine on a separate 50:1 pre-mix 6 gallon  tank. You have to bleed the oil pump of air. Fill the main remote tank with a gallon of oil. Fill the pony tank with oil. Prime the line between the main tank and pony tank with the primer bulb to purge the air and connect to the pony tank. Hook up the line from the pony tank to the oil pump. Crack the bleeder screw on the oil pump and bleed any air from the pump then hook up the oil pump to the fuel line. Next, mark the oil level in the pony tank and the main oil tank. Disconnect the link arm that goes from the carbs to the the oil pump and let it rotate to full oil flow which would mimic full throttle operation or 50:1 oil flow. Start the engine and let it run on the pre-mix tank. This will take 20 minutes of running to observe the marks on the oil tanks that the engine is using oil from the oil injection system as the oil level goes down. If there is an issue with system, the engine is protected by running the pre-mix. After the engine starts using oil from the oil injection system, reconnect the throttle link arm to the pump and you're done. The engine runs at 80:1 at idle and the link arm reconnection will manage that. Hook your main fuel line back up and you're good to go. There is a test in the factory service manual if you want to measure the CC output of the oil pump with the outlet line dumping into a precision beaker while the engine is running on pre-mix to check pump flow. Example would be 30cc's of oil in 20 minutes with oil pump/throttle arm disconnected at idle if you want to check the pump output. Verfify those output numbers for the proper flow with factory manual since I may be giving you flow numbers from a 115 or whatever has popped in my head.

[Gt30691stang]

Thanks for the info! Good stuff there much better described than my selco repair manual!

[Blue Agave]

Regarding your question on the vacuum tee, no hose should go there. Confirm with your service manual.   Also, you may want to research the top RPMs for your motor I believe 5300 is low, I believe it may be 5800.

[Gt30691stang]

Thanks, I could not find it in the manual but found an article online describing it's function, it's a thermal air valve, The thermal valve shuts off air to idle mixture circuit to make it run rich at warm up. And only one hose is connected to the tee. The engine tag says 5600 max rpm, it's a 2.0l not the common 2.5l. Does anybody know much about these 2.0l I'm having a hard time finding much info on them it's all on the 2.5l I can't imagine there's too much difference?

[fitz73222]

The 2 Liter was Mercury's first V6 block dating back to 1976 specifically 122 cubic inches. A very good engine with a very loyal race following. It lacked a little bottom end on a heavier boat compared to others at the time. So the 2.4 and 2.5 were developed to improve overall performance. Basically, all the engines very similar to one another with the exception of normal upgrades and improvements through the years and of course bore and stroke changes for the larger displacement. 5600 max RPM is very tame for this engine and to get the most out of its smaller displacement I recommend propping it as close to the max RPM at full throttle, it will not hurt it. With some mild modifications we took the stock powerheads to 6800 rpm so mechanically it's bulletproof. Enjoy it, take care of it, prop it correctly and you'll get many years out of it.

[Blue Agave]

Fyi - those mounting brackets for the remote oil tank are very prone to rusting. I would recommend having one fabricated out of aluminum.   Regarding the prop, the 21 pitch may be to much prop and I don't believe you will reach the top RPMs of 5600.  Based on the figures you provided from the previous owner the motor was over prop-ed as it was not reaching top RPMs.  Once you get it running, run it with the 19 pitch to see what performance you are getting. 

[Aswaff400]

artec industrys makes a stainless steel bracket for the mer oil tanks http://www.artecindustries.com/Mercury-Oil-Tank-Bracket-_p_122.html

they also make them for yamahas http://www.artecindustries.com/Yamaha-Oil-Tank-Reservoir-Bracket_p_119.html