Mercury 40hp 2 stroke

mwb.wright · 13 November 2016, 09:19

Hi chaps,

I have a 1998 mercury 40hp, 2 stroke which I believe is the 2 cylinder with a single carb.

I'm wanting to give it a service myself so could anyone help me out with what exactly needs doing?

I have the new plugs ready to go in and the impeller is very strong so both those items are sorted.

Do I take the carb off and just clean/strip or what?
Do I replace the gear oil on the bottom section or leave that alone?

I can't find the relevant PDF file on this specific engine so slightly unsure.

Thanks.

beerbelly · 13 November 2016, 11:35

change the gear oil yes but as your asking this question I'm assuming you haven't done this before so I would leave the carb well alone. fwiw that engine has never missed a beat so doubt you'll find much in there anyway

69cmw · 13 November 2016, 12:25

Quote:

Originally Posted by beerbelly

change the gear oil yes but as your asking this question I'm assuming you haven't done this before so I would leave the carb well alone. fwiw that engine has never missed a beat so doubt you'll find much in there anyway

And if it's your old 40hp beerbelly, the carb was bran spanking new about 2 years ago [emoji106]

jeffstevens763@g · 13 November 2016, 15:07

If it's running ok don't mend it, change gear oil, if it's pumping water ok leave impeller until it doesn't,leave carb alone, change fuel filter, good grease round, and a good clean inside and out.

mwb.wright · 13 November 2016, 16:06

Thanks guys.

Yea Paul, I've never messed with a boat carb before so I'm glad your all advising not to haha.

Gear oil is just the bottom two plugs I understand so I just need the mercury fitting and some oil.

Also where would I get a fuel filter from?

Good to know the carb is only a few years old!

I've had the boat stripped and once back together it fired up on the first turn of the key! - didn't bleep on the ignition but it didn't when you fired it up so I'm not to fussed about that.

paintman · 13 November 2016, 17:09

Change the gear oil on mine - 135 Black Max - using an old style oil can like this:
Neilson Oil Can With Flexible Spout1/4 Pint Lubricant Thumb Pump Spout 11B | eBay
Put the tip of the can against the bottom hole & pump until the oil flows out of the top hole. Refill can as necessary. Drain off the specified amount & refit the plugs. Dead easy.
The smell of the oil is something else.......Mrs P thought there was a gas leak!

jeffstevens763@g · 13 November 2016, 19:04

Pacer marine for spares quick & reliable service

mwb.wright · 13 November 2016, 20:58

Thanks guys!

beerbelly · 14 November 2016, 05:57

you can get the oil on ebay with the correct screw in attachment that's what I did when I changed the oil in it

uncle al · 14 November 2016, 12:39

if you get the gear oil in a tube you can refill the gear housing using the nozzle on the tube, you don't need to buy any fittings. don't forget fill the gear housing from the bottom and until it starts to come out of the level hole, put the top plug in first, then quickly the bottom one.

denisbreizh · 15 November 2016, 08:08

Hi,
I have the same motor, but only with 30HP.
You can find the relevant information there:
Boatinfo - Mercury Service Manual for 30-40hp 2 cylinder

watersidemat · 16 November 2016, 14:42

https://www.youtube.com/watch?v=tih4o9-VJ2g

general servicing video on two strokes, i learned lots from it, just do the bits that seem relevant to you!

Mextli · 26 November 2016, 07:28

Quote:

Originally Posted by jeffstevens763@g

If it's running ok don't mend it, change gear oil, if it's pumping water ok leave impeller until it doesn't,leave carb alone, change fuel filter, good grease round, and a good clean inside and out.

I wouldnt wait with the impeller until it breaks down. That could ruin your engine or distribute small rubber bits into the cooling passages of the power head.
Impellers are cheap and straightforeward to change.

Tim M · 26 November 2016, 08:47

Quote:

Originally Posted by Mextli

I wouldnt wait with the impeller until it breaks down. That could ruin your engine or distribute small rubber bits into the cooling passages of the power head.
Impellers are cheap and straightforeward to change.

Impeller should be done at least once a year regardless of usage or how good the tell tale flow is

Xk59D · 26 November 2016, 10:35

Change an impellor at least once a year? How many hours are you expecting to be done?

I've never ever changed them every season, every 2-3 yes. My current engines are about to be changed which is end of their 2nd season.

jeffstevens763@g · 26 November 2016, 16:09

Quote:

Originally Posted by Mextli

I wouldnt wait with the impeller until it breaks down. That could ruin your engine or distribute small rubber bits into the cooling passages of the power head.
Impellers are cheap and straightforeward to change.

He says his impeller is strong and sorted no need to change I see no point in changing every service if it's not hard with memory or damaged.

Mextli · 26 November 2016, 16:35

Quote:

Originally Posted by jeffstevens763@g

He says his impeller is strong and sorted no need to change I see no point in changing every service if it's not hard with memory or damaged.

Im doing my impeller once every two years, no matter how it looks. s
So far never had one blow on me.