1979 Mercury 40 HP

[TheChad]

Re: 1979 Mercury 40 HP

Originally posted by Bro:<br /> serial number is sometimes punched on a welch plug on the side of the engine block: I think right hand side (looking from behind the engine) I think I can see it in your picture although my eyesight may be playing tricks on me

That's not a picture of my engine, just a picture of an engine just like mine, i found on ebay, i used it just to highlight that hose...<br /><br />I called back to the local dealer, and got a different person, who looked up the engine by year, and # of cylinders. They have the Diaphragm kits instock for $5, so i am going to pick one up today..<br /><br />Is there a difference in buying just the diaphragm kit, and buying a whole fuel pump?<br /><br />Thanks again for the help,<br /><br />-TheChad

 

[joblo33]

Re: 1979 Mercury 40 HP

You only need the diaphragm kit. I hope that solves it. Sounds like this is continuing to be a pretty cheap investment, unlike most of my engines

 

[TheChad]

Re: 1979 Mercury 40 HP

Well, I replaced the Diaphragm & gaskets.<br /><br />The old gaskets have been on for so long, they were stuck to the fuel pump housing, and I had to use a wire brush on my dremel tool to get off all the goo left from the old gaskets..<br /><br />I installed the new gaskets, and diaphragm... Still having the same problem, well sort of, it seams like it runs a little bit longer, and wants to stay running, so i'm wondering if maybe there was just some left over bad fuel in the carb, that is finally getting threw.. only now, the engine also stopped pumping water...<br /><br />It was pumping water strong before, so i have a hard time believing that it would just up and quit...<br /><br />I did notice though that the spitter is also connected to the fuel pump, so i am assuming this pump surves as a dual purpos...<br /><br />The check valves did not come in the diaphragm/gasket kit, so i polished those with the wire brush, and reused them with the new gaskets.<br /><br />I Think i have them installed correctly, it seams as though they would only fit in one direction, there is a little nub on one side, and nothing on the other, I assumed the side with the nub would have the basket side of the valve facing into the pump (Toward the diaphragm), and the side with nothing benith it would have the basket side down (Away from the diaphragm)<br /><br />But does any of that have to do with the water pump?<br /><br />Thanks for the help..<br /><br />-TheChad

 

[stan_deezy]

Re: 1979 Mercury 40 HP

Old engine and water pump failure is not uncommon and the water pump can fail without warning: to give you a "for instance" I recently sold a 25 Merc in spanking condition and took pictures of it running the night it left here (always do that: use date/time stamp and then people can't come back saying you sold them a dud!).<br />Anyway the engine goes off to its new owner who hooks it up after a few weeks and guess what? No water from the tell-tale. A strip down reveals the pump is shot but we have pictures and witnesses to show that the pump was working perfectly when it left here.<br /><br />If you are going to replace the water pump do it as a whole unit: don't just buy the impellor; it might be a few dollars more but it'll save you a whole world of heartache when you open up the pump and find that the base plate or housing is scored too <br /><br />The running problem is close to being fixed and I'm 99% certain that you had dirty/old fuel in there: may be worth blowing the carbs through to clear them. Cost zero but could make a heap of difference.<br /><br />This is still going to be a very cheap, good engine

 

[TheChad]

Re: 1979 Mercury 40 HP

Originally posted by Bro:<br /> Old engine and water pump failure is not uncommon and the water pump can fail without warning: to give you a "for instance" I recently sold a 25 Merc in spanking condition and took pictures of it running the night it left here (always do that: use date/time stamp and then people can't come back saying you sold them a dud!).<br />Anyway the engine goes off to its new owner who hooks it up after a few weeks and guess what? No water from the tell-tale. A strip down reveals the pump is shot but we have pictures and witnesses to show that the pump was working perfectly when it left here.<br /><br />If you are going to replace the water pump do it as a whole unit: don't just buy the impellor; it might be a few dollars more but it'll save you a whole world of heartache when you open up the pump and find that the base plate or housing is scored too <br /><br />The running problem is close to being fixed and I'm 99% certain that you had dirty/old fuel in there: may be worth blowing the carbs through to clear them. Cost zero but could make a heap of difference.<br /><br />This is still going to be a very cheap, good engine

How do you "blow the carbs through", I was going to take it off and clean it out, but you have to disasemble 1/2 the engine to get the carb out...<br /><br />I know nothing about the water pump system... How much does that cost to replace? and How do I replace that? (I know this is where you are going to tell me I have to take the whole lower unit apart, and I have no clue how to do that...)<br /><br />Am i correct about the check valves in the fuel pump, about the direction they go?<br /><br />Thanks again,<br /><br />-TheChad

 

[stan_deezy]

Re: 1979 Mercury 40 HP

Sounds right about the pump valves: Nos4r2 might know better: he's a bit of whizz on these engines.<br />Same with the carb(s)<br /><br />Water pump is a real easy job if you take your time. Check out this site: http://www.lot-o-nothin.com/lotonothin/article.cfm?id=1 <br />different engine but the basics are still the same and the great thing is you don't have to worry about disconnecting gear shift because you should have a splined drive there rather than a pesky bolt <br /><br />Cost: unknown because I'm sure it'll be a heck of a lot cheaper in the US than the UK but for a rough guide I did one recently and it cost me £33 or approx $58.<br /><br />You could try pumping water through on a hose first just in case you have a blockage in the system but it is more likely that the pump failed.<br /><br />And the other thing that most folks would recommend is getting a manual if you intend to keep the engine (which I reckon I would cos they are fairly great engines!)<br /><br />I'll dig out the manual later and look at the fuel pump valves to double check the position.<br />hope this helps?

 

[TheChad]

Re: 1979 Mercury 40 HP

Originally posted by Bro:<br /> Sounds right about the pump valves: Nos4r2 might know better: he's a bit of whizz on these engines.<br />Same with the carb(s)<br /><br />Water pump is a real easy job if you take your time. Check out this site: http://www.lot-o-nothin.com/lotonothin/article.cfm?id=1 <br />different engine but the basics are still the same and the great thing is you don't have to worry about disconnecting gear shift because you should have a splined drive there rather than a pesky bolt <br /><br />Cost: unknown because I'm sure it'll be a heck of a lot cheaper in the US than the UK but for a rough guide I did one recently and it cost me £33 or approx $58.<br /><br />You could try pumping water through on a hose first just in case you have a blockage in the system but it is more likely that the pump failed.<br /><br />And the other thing that most folks would recommend is getting a manual if you intend to keep the engine (which I reckon I would cos they are fairly great engines!)<br /><br />I'll dig out the manual later and look at the fuel pump valves to double check the position.<br />hope this helps?

Yes, Helps alot, Thank you very much for all your help!<br /><br />Which water pump kit do you suggest?<br /> http://www.oldmercs.com/lowerunit.html <br /><br />#47-89983K - Aftermarket Water Pump Impeller Kit (includes impeller, gaskets, wear plate, etc.) <br /><br />#46-60366T1 - Mercury Water Pump Kit includes pump housing<br /><br />Or neither?<br /><br />.. It seams most parts for thease engines are actually pretty inexpensive (I don't know if its the same for newer ones or not), but it seams like the reason people say boat engine repairs are very expensive, is mainly because of labor ($65/hr)..<br /><br />I was hoping to get this engine up before the weekend, but it doesn't look like that will happen, so I will order a repair manual and get started on the water pump..<br /><br />Thanks again,<br /><br />-TheChad

 

[Nos4r2]

Re: 1979 Mercury 40 HP

Cheers Bro, not sure I can take up that honour though-it's the 50hp 4cyl's that seem to come my way a lot.<br /><br />Not sure on the fuel pump check valves.<br /><br />Personally if it's going to be cheapish anyway I'd buy the mercury kit-if nothing if you don't need the pump housing this time you might need one in the future when parts might be harder to get.<br /><br />You MIGHT just have a clogged telltale-Laddies suggested backflushing through the telltale with water if thats the case-it worked a treat for me. Try blowing down it-there shouldn't be much resistance.Water should come out of the prop if it's just a blocked telltale-but replace the pump anyway.<br /><br />Water pump replacement is really easy-drop the lower unit with the engine in neutral (don't forget the bolt under the trim tab/anode) and the pump housing is visible. Remove it and renew whatever looks worn. Use new gaskets. While the water pump is off blow down the hole with something and make sure your intakes aren't clogged.DONT lose the impeller key-remove the old impeller somewhere you won't lose the key if/when it drops off. Grease the inside of the pump housing and the impeller with a light coating something (KY works well-or LM grease) and turn it the normal engine direction to fit the housing down onto the impeller.<br /><br />Carbs aren't actually that hard to remove and clean once you get used to it. As long as you take a methodical approach to it then you'll be finished a load quicker than you're expecting-and you'll trust your motor a load more.That's half the reason I do stuff to mine-just so I KNOW I'm not going to have to call the lifeboat...<br />Don't use anything corrosive to clean them with. Blow everything through with carb cleaner.<br />Possibly the most important-make sure you've made a note/marked up any settings you disturb so you can set them all back.

 

[stan_deezy]

Re: 1979 Mercury 40 HP

I agree Nos: the pump kit with the housing is definitely the way to go: chances are you may find the housing scored anyway. Better to do the job right once than have to rip it back down again <br /><br />Fuel pump valves: may be easier if I try and scan the picture in from the workshop manual (I'll need a bit of time on that) but from what I can see the plastic check valve goes so that it is facing the diaphragm: the rubber valve disc should be mounted towards the pump body.

 

[TheChad]

Re: 1979 Mercury 40 HP

Originally posted by Bro:<br /> I agree Nos: the pump kit with the housing is definitely the way to go: chances are you may find the housing scored anyway. Better to do the job right once than have to rip it back down again <br /><br />Fuel pump valves: may be easier if I try and scan the picture in from the workshop manual (I'll need a bit of time on that) but from what I can see the plastic check valve goes so that it is facing the diaphragm: the rubber valve disc should be mounted towards the pump body.

I thought both the check valves were the same.... I will have to take it apart and check on that...<br /><br />The next question is which does does each go on..<br /><br />It looks like that water pump kit only comes with 1 side of the pump houseing?! The local dealer stocks the pump kit, but they want $80 USD for it, so i'll probably just order it online..<br /><br />Thanks again,<br /><br />-TheChad

 

[stan_deezy]

Re: 1979 Mercury 40 HP

Woah!!! Don't rip the pump apart again!<br /><br />The manual shows two discs (valves) but each valve is in two parts: each has a clear plastic disc and then a rubber disc.<br /><br />There was quite a debate on here a while ago about the fact that the clear plastic discs often don't come with the kit: some people reused the old ones, some didn't and some went and got a different kit to make sure they got the clear plastic discs......most people came to the conclusion that they didn't seem to make a lot of difference whether fitted or not.

 

[TheChad]

Re: 1979 Mercury 40 HP

I guess I didn't look that close. I thought they were both the same, I didn't notice any plastic disc, Just a rubber disc, but that doesn't mean it wasn't there, i just didn't notice it.. <br /><br />-TheChad

 

[stan_deezy]

Re: 1979 Mercury 40 HP

cool: no harm done. I had visions of you rushing out and ripping the carb apart then cursing me black and blue because you couldn't find anything wrong <br /><br />Let us know how you get on with the water pump.

 

[TheChad]

Re: 1979 Mercury 40 HP

I'm still curious though if i have the check valves in the right direction.. I know 1 goes up, and 1 goes down... But i'm not 100% which side is suppose to be up, and which side is suppose to be down... I *think* i have it right, just want to verify... I am going to order a repair manual when i order the water pump.<br /><br />(To my suprise the fuel pump was very simple to remove/repair/replace.. Only took about 15 minutes!)<br /><br />I'm not too overly excited about having to drop the lower unit, but I am learning alot about this motor already, and the more I take apart, the easier i will understand it if/when something goes wrong (After i get it running correctly in the first place).<br /><br />Assuming this is probably the first time any of thease parts have ever been replaced, having been 26 years, I have a feeling once I get it running correctly, I may not have to fix it for a long long time.<br /><br />Thanks again for the help..<br /><br />-TheChad

 

[TheChad]

Re: 1979 Mercury 40 HP

I see there are 2 different Service Manual's for this engine... Clymer & Seloc<br /><br />Is one better than the other?<br /><br />Thanks,<br /><br />-TheChad

 

[andy6374]

Re: 1979 Mercury 40 HP

I like Seloc. However, it is best when combined with a Mercury factory manual for your engine. As where Seloc covers many years and horsepowers, the merc manual will be more geared towards you engine.<br /><br />There are a whole bunch of merc factory manuals on ebay right now. Search "mercury outboards" then sort from lowest to highest price. They should be on the first couple of pages.<br /><br />-andy

 

[TheChad]

Re: 1979 Mercury 40 HP

I broke down and bought the water pump at the local shop. Also bought some gear lube, since i have no clue when the gear case was last lubed..<br /><br />When building the new water pump, do I need to lube any of the orings or any parts? or do i build it dry? If i do need to lube it, what do you lube it with?<br /><br />Thanks again for all the help,<br /><br />-TheChad

 

[Nos4r2]

Re: 1979 Mercury 40 HP

see my last post for lube ^^^^

 

[TheChad]

Re: 1979 Mercury 40 HP

Originally posted by Nos4r2:<br /> see my last post for lube ^^^^

Awesome, I read your post at work, but must have missed that part...<br /><br />It helped alot!<br /><br /><br />As you guys can probably suspect, the impeller had sheared off all its fins, which were all in the pump, Its good it happened now, rather than when I was out on the water..<br /><br />It was actually rather easy to do the water pump. I'm finding this engine is VERY easy to work on, and its saving me a ton of money from having it done at the shop.<br /><br />The housing of the water pump was actually in great shape, but as noted above the impeller was in pieces, and the gaskets were aged.<br /><br />But now i know its all new and can trust it when i go out on the water.<br /><br /><br />** Update **<br /><br />The engine has finally burned threw whatever junk was in the carb and old gas, and is purring like a kitten.. It seams to be running good now. And pumping plenty of water!<br /><br />Thanks again everyone for all your help, It has been EXTREMELY helpfull.<br /><br />-TheChad

 

[TheChad]

Re: 1979 Mercury 40 HP

Please forgive me in advance for this question...<br /><br />How does the throttle system work on this engine? There is the throttle lever, but when you shift the boat into drive and begin to pull back on the shifter, it increases the throttle as well...<br /><br />So basically my question is: What is the proper way to operate thease controlls?<br /><br />When I start the engine do i put the side throttle all the way up, once started bring it all the way back down then begin to use the shifter as the throttle? or do i leave the side throttle all the way up, then use the shifter for the rest of the throttle range?<br /><br />My fauthers boat just had 2 controlls, Shifter (R-N-F), then had a throttle lever... So the controlls are a little different.<br /><br />I just want to make sure i'm operating it correctly!<br /><br />Thanks again for the help,<br /><br />-TheChad