Carb. Cleaning on 1977 Merc. 115 question.

[jrichardson88]

I bought a 1977 Merc. 115. the shop gave me a 30 day written mechanical warranty. Good compression, good lower unit. However, he told me that I need to clean carbs before running due to not running in a while. Question is this something that is easily done. And is there instructions somewhere here that I can go by? Shop told me this needs to be dine frequently, and I should learn how myself......Any comments..

 

[ifixf18s]

Re: Carb. Cleaning on 1977 Merc. 115 question.

I just got done cleaning my carb but it was on a 25HP. However my boat was not run for a few years. I purchased a carborator rebuild kit and some regular carb cleaner i picked up from an auto parts store. The place were i bought my carb kit was nice enough to print the diagram of the carb for me. I also took my digital camera and took photos of the tear down process, including taking the carb off the engine. So if there were any questions i could look at the pics on my computer. If you are mechanicly inclined i dont think it should be that hard. Not really sure if theres something specific you need to know, except the floats may need to be checked for proper adjustment, kinda like on the old car carborators. Maybe you dont have to go as far as i did but thats your call. If the carb has never been rebuilt maybe its time. Good luck and let us know how it went.

 

[Chris1956]

Re: Carb. Cleaning on 1977 Merc. 115 question.

Cleaning the carb on that old inline six is pretty easy. The real question is how can he give a 30 day warantee, and then ask you to rebuild the carbs? If you were to mess them up and fry a cylinder, will he honor the warantee?

Get a service manual and three carb gasket kits. Remove the cowling, cowling support (disconnect electrical), remove starter. Remove all three carb bowl covers. Remove top carb, disassemble it and soak it in carb cleaner. Inspect the floats and the springs on top of the floats. Replace floats if they are disolving(foam floats) or have cracks(hard plastic floats) or the springs are gone. Blow out high speed jet and idle restrictor jet, as well as the small holes in the side of the carb throats. Replace the brass plugs, and seal with auto silicone. Install new gaskets, and set float height, with cover inverted, making sure the top float lever is level. Turn cover over, the float levers should drop to be 1/4" apart at their tips. Reassemble carb, with new inlet needle and seat, if it needs it. Repeat with other carbs.

Set idle mixture screw 1-1/2 turns out form lightly seated. Now you need to adjust idle mixture screws to a compromise between rich and lean, to allow nice idle (lean) and allow acceleration (rich). Post back on results.

 

[Jeff_G]

Re: Carb. Cleaning on 1977 Merc. 115 question.

If I can interject here.
It is recommended not to soak the carb in a carb cleaner unless totally disassembled. You have a plastic venturi, small round deal in the center of the carb, that can be distorted in some solvents. On the top carb linkage is also a rubber/plastic piece that can be damaged. Best to use a spray carb cleaner instead of soaking.

 

[jrichardson88]

Re: Carb. Cleaning on 1977 Merc. 115 question.

So, As far as the warranty.....yes he would stand behind everything with the exception of the electrical....stator, distributor, and etc.. Yes, I am really wanting to start motor. Mechanic stated just to "clean" carbs, not rebuild entire system. Basically, clean with spray put back together. Question - Can I start engine with Muffs to test then tear into carbs? Also....If it runs smooth is there a reason to rebuild or clean carbs....?

 

[Chris1956]

Re: Carb. Cleaning on 1977 Merc. 115 question.

The motor could very well run smoothly with partially clogged carbs. The risk is that one or more cylinders could run lean, and scoring and/or overheating could occur.

What Jeff says about the plastic parts is true, however, I have nver had that problem. I also remove the carb linkage piece as a matter of course. A gasket set for those carbs is like $5 each. It is cheap enough to install it if you are taking the time to clean the carbs. The floats and needles are more expensive, but it they are bad, you really have no choice.

 

[daveswaves]

Re: Carb. Cleaning on 1977 Merc. 115 question.

I bought a 1977 Merc. 115. the shop gave me a 30 day written mechanical warranty. Good compression, good lower unit. However, he told me that I need to clean carbs before running due to not running in a while. Question is this something that is easily done. And is there instructions somewhere here that I can go by? Shop told me this needs to be dine frequently, and I should learn how myself......Any comments..

Chis and Jeff have given you what to do with the carbs, I just have a comment on the shop you bought the engine from. It is absolutely irresponsible to sell an engine and tell the customer he has to clean the carbs. It is either an as is engine with a price to match, or it is a working engine with or without a warranty. This guy obviously does not want to work on the inline 6 mercs. He probably does not know how. One can only hope he did not "tune it up" for you.

 

[jrichardson88]

Re: Carb. Cleaning on 1977 Merc. 115 question.

First of all thanks for all the replies, I took my "muffs" and turned on the Water and she fired right up. Ran very smooth for about 30 seconds. Really hate to tear down carbs. when its running this smooth. But I guess its best. Thanks again,
jr

 

[Jeff_G]

Re: Carb. Cleaning on 1977 Merc. 115 question.

There are two very important passages than must be checked. First is the main jet in the bottom front of the carb. If it is partially blocked you will blow the engine yet it will idle fine all day. The second is an idle tube that goes from the top right of the carb, looking at it, to the bottom. It too must be clean or the engine will bog terribly on take off yet may idle. You may also be idling on two carbs, and not know it. Easy rebuild, just follow the manual, and set the initial idle mixture at two turns out from lightly seated.