2005 Mercury 90hp 4 Stroke

[mav6759]

Question, I was thinking about buying a 2005 Mercury 90hp 4stroke. They found water in the oil. As I was reading, it was said, it's a headgasket issue. My question is, does the powerhead has to be removed to change out the headgasket. As I was reading, someone posted would take about 30 mins, is this true..

 

[ahicks]

As somebody that's changed quite a few Honda 4 stroke head gaskets, I'm going to stick my neck out here and say you'd have to be a magician to change one in 30 minutes. I think it might take 30 minutes (or most likely longer than 30 minutes) to just clean the head and block well enough (remove old stuck/burnt on gasket material) to install a new gasket.

Further, when it comes to repairing an engine that's mixing gas and oil, it's going to be a roll of the dice regarding the source of that water. An '05 is plenty old enough to have issues, other than the head gasket, that might allow the gas and water to mix. These issues might result in the need to replace the block or the head for instance - and in my experience, not all that unusual. If you can get away with just replacing the head gasket, that's the best possible outcome.

USUALLY, that head gasket that's causing the water and oil to mix has been overheated/burnt, and it's no longer able to seal. Point being, if the engine mixing water and oil has been overheated recently, there's a good chance the head gasket is the issue.

In the case where the engine has NOT been overheated, it's a total roll of the dice. You aren't going to know a thing until the head is removed.

 

[QBhoy]

Might not help you too much…and likely controversial…but unless your local boating area insists on a 4 stroke…I’d much rather have a 2 stroke over that age and technology of 4 stroke. I’ll sorely admit that the most recent of 4 strokes are just amazing things. Came on light years just in the last few years…but I’d stay clear of 4 strokes of that age for sure. Much better with a 2 stroke instead. Just my opinion.

 

[ahicks]

Might not help you too much…and likely controversial…but unless your local boating area insists on a 4 stroke…I’d much rather have a 2 stroke over that age and technology of 4 stroke. I’ll sorely admit that the most recent of 4 strokes are just amazing things. Came on light years just in the last few years…but I’d stay clear of 4 strokes of that age for sure. Much better with a 2 stroke instead. Just my opinion.

Right, controversial. I'll leave that be as well. ;^)

But making the case for older 4 stroke motors for use in freshwater MUCH MUCH easier. Pontoon boat owners are absolutely crazy over them.

 

[QBhoy]

Right, controversial. I'll leave that be as well. ;^)

But making the case for older 4 stroke motors for use in freshwater MUCH MUCH easier. Pontoon boat owners are absolutely crazy over them.

No doubt they have their fans. Suppose my
Thinking is just around the silly issues, design and just the bloody weight of the early ones. As for the idea of timing cam belts on a marine engine, especially an outboard…recipe for disaster to the unaware boater perhaps.
But as much as I hate to admit it. I now own a 2016 4 stroke merc engine. Literally blown away with how good it is. As light as the equivalent 2 stroke and even more powerful too. Just incredible how merc have brought things along with these.
I still own a collection of small Yamaha 2 strokes in the garage and run a lovely old merc 2.0 150 v6 on an old cvx16. Just to offset the planet saving 4 stroke a little. Haha.

 

[ahicks]

My work is mostly Honda, but I can share that I've never seen a timing belt related issue. Nothing. Not even the idler pulley, going back to even their earliest designs. Good thing too, as we both know what's going to happen with a failure there. Further, the engines I see most are generally 40-90 hp salties, that have spent all or most of their life operating in salt water.

I do agree Yamaha has a cult like following. That's why they're relatively expensive and hard to find. You probably know they made the power heads for the earlier Merc 4 stokes? Kinda like Merc was sharing lower units....

 

[Texasmark]

Might not help you too much…and likely controversial…but unless your local boating area insists on a 4 stroke…I’d much rather have a 2 stroke over that age and technology of 4 stroke. I’ll sorely admit that the most recent of 4 strokes are just amazing things. Came on light years just in the last few years…but I’d stay clear of 4 strokes of that age for sure. Much better with a 2 stroke instead. Just my opinion.

Amen brother. I have a 2002 115 2 stroker and my neighbor just bought a 2017 115 four stroker. Doesn't take but a heartbeat for you to realize you are getting in way over your head with all the gadgets that can break and cost you money on that 4. Don't rely on gas savings to push you in that direction. Light weight 2 strokers with Loop Charging give the 4s a run for their money in fuel consumption alone.......

 

[ahicks]

Realizing full well the 2 vs. 4 stoke controversy is not going to end any time soon - but - comments like this generally come only from somebody that's never owned a 4 stroke "Doesn't take but a heartbeat for you to realize you are getting in way over your head with all the gadgets that can break and cost you money on that 4"

In FACT, Honda's have been built since the mid 90's, and they have NOT proven this to be true at all. Pretty much just the opposite actually. Others may be similar, but my experience is primarily Honda.

Further, I find it darn funny that the engine manf's have all gone 4 stroke and are selling all they can build. I can't help but believe that would NOT be the case if that comment had any truth to it..... My opinion, FWIW.

 

[Texasmark]

Realizing full well the 2 vs. 4 stoke controversy is not going to end any time soon - but - comments like this generally come only from somebody that's never owned a 4 stroke "Doesn't take but a heartbeat for you to realize you are getting in way over your head with all the gadgets that can break and cost you money on that 4"

In FACT, Honda's have been built since the mid 90's, and they have NOT proven this to be true at all. Pretty much just the opposite actually. Others may be similar, but my experience is primarily Honda.

Further, I find it darn funny that the engine manf's have all gone 4 stroke and are selling all they can build. I can't help but believe that would NOT be the case if that comment had any truth to it..... My opinion, FWIW.

So 4 strokers don't have more parts to break than 2 strokers........really???????

 

[ahicks]

So 4 strokers don't have more parts to break than 2 strokers........really???????

The better question from where I'm sitting, is "do they break parts?"

In my own experience, and from what I've read, they don't. Worst case is they're no worse than the 2 strokes....

really......

 

[QBhoy]

Amen brother. I have a 2002 115 2 stroker and my neighbor just bought a 2017 115 four stroker. Doesn't take but a heartbeat for you to realize you are getting in way over your head with all the gadgets that can break and cost you money on that 4. Don't rely on gas savings to push you in that direction. Light weight 2 strokers with Loop Charging give the 4s a run for their money in fuel consumption alone.......

Hi Texas,
It takes the better of me to say this, having always been a 2 stroke man (still am at heart, having a collection of small 2 strokes and the wonderful bomb proof old black max 2.0 150 v6 merc on the old classic cvx16), but the boat I use all the time these days, I bought for the attributes of the boat itself. This particular UK fletcher 19 cuddy is a model renowned here for their rough water ability and general all round function for a 19 footer. For a number of years I have had a notion for one, just to use as an all rounder. So when I got onto one that had been just re powered with a 2016 mercury 4 stroke 115 CT at a price less than the engine cost alone, I couldn't refuse. at the time, even when towing her back home on the day of buying her, I didn't have much expectations around the idea of having a 4 stroke on the back. knew nothing about these engines at the time.
So the first day I get her on the water...my goodness, I was just blown away with it. Being the CT model, she was propped with a tempest plus prop. I was amazed to see her run all the way up to around 45 mph gps at just on the limiter. The power from these things is unreal. Instantly thought that they must have more power than the claimed 115hp. since then, I've been made aware of the fact that they are now renowned to have way more power than claimed. they have tested them like for like on the same boat with a 125hp optimax.. both propped well. The 115 simply embarrassed the optimal in every department. top end, acceleration and fuel economy. Mercury were present for these early tests. Even they were lost for words. they put it down to the larger displacement. The fact that they are no heavier than the 2 stroke engine too, is just remarkable.
As for any 2 stroke being as efficient. not a chance. this set up of mine will cruise at around 20/21 mph and manage around 1.5-1.7 miles per litre of fuel. Incredible. There was 18 hours on her when I got her. now just over 900 hours and she's still as new. What an engine. Honestly. Suppose the only down side is the cost to buy one new. Thankfully I didn't have to suffer that.
Just finally, id add that the 115 pro XS version, is just a level above again. These things must be putting out near 140hp. Just recently a uk event called the conniston records week, saw a 17ft monohull with a 115 pro XS record a two way timed run at close to 70 mph. winning its class. says it all really. anyway, bored you enough by now...long live the 2 stroke, but the usual thoughts around 4 strokes should not be applied to these new merc 115's for sure.

 

[Texasmark]

Interesting comments, glad you are happy. Interesting on the weight equalization comment, and the MPLiter efficiency. On what I said, if the part isn't in the engine it can't possibly fail, regardless of the impeccable reliablity of the 4 strokers and the 2 stroke Optimax.

 

[ahicks]

Interesting comments, glad you are happy. Interesting on the weight equalization comment, and the MPLiter efficiency. On what I said, if the part isn't in the engine it can't possibly fail, regardless of the impeccable reliablity of the 4 strokers and the 2 stroke Optimax.

I can see the logic in that minimum parts count thinking. There's little doubt the 4 strokes are more complex. Beyond that though, it's pretty clear they are holding their own when it comes to reliability. Consider the automotive motors that now routinely go 2-300k without having their heads removed....

And there's one last thought - I've never seen a 4 stoke outboard owner replace his motor with a 2 stoke.

Point being, just keep an open mind regarding them. If you get a chance to go for a ride, pay attention...

 

[QBhoy]

I can see the logic in that minimum parts count thinking. There's little doubt the 4 strokes are more complex. Beyond that though, it's pretty clear they are holding their own when it comes to reliability. Consider the automotive motors that now routinely go 2-300k without having their heads removed....

And there's one last thought - I've never seen a 4 stoke outboard owner replace his motor with a 2 stoke.

Point being, just keep an open mind regarding them. If you get a chance to go for a ride, pay attention...

Agree. I have totally had my eyes opened. The boat I have with this merc 115 on it came almost exclusively with a yamaha 115 4 stroke on them. The inboard version of them came with mostly a 3.0 or rarely a 4.3.
I know that the 115 Yammy original spec manages about 36/37 mph gps with a well suited k series prop. The Merc 115 CT mine now has will manage an easy 43/44 mph GPs with fuel and canopy up on any given day. 45 mph with canopy down a few times and one or two touching 46 mph. The 3.0 inboard version won’t see past 37/38 mph and the 4.3 will be about 45 mph most often. Shows you how good these new mercs are. Like I say…the 2.1l 115 CT comes in at only 163kgs…amazing. That’s less than the 125 optimax 2 stroke that’s as far as I m know…a 1.5l. Fair play.

 

[ahicks]

Agree. I have totally had my eyes opened. The boat I have with this merc 115 on it came almost exclusively with a yamaha 115 4 stroke on them. The inboard version of them came with mostly a 3.0 or rarely a 4.3.
I know that the 115 Yammy original spec manages about 36/37 mph gps with a well suited k series prop. The Merc 115 CT mine now has will manage an easy 43/44 mph GPs with fuel and canopy up on any given day. 45 mph with canopy down a few times and one or two touching 46 mph. The 3.0 inboard version won’t see past 37/38 mph and the 4.3 will be about 45 mph most often. Shows you how good these new mercs are. Like I say…the 2.1l 115 CT comes in at only 163kgs…amazing. That’s less than the 125 optimax 2 stroke that’s as far as I m know…a 1.5l. Fair play.

I would add that for every person I know happy with the wide open throttle 4 stroke performance there are a hundred more who are just nuts about they way these motors can just putt nearly silently for hours and hours without complaint. And the big one among women especially, is there is no foul smell following you when traveling down wind.....

Oh heck yes, I was a huge fan of 2 stroke performance in ALL of my toys since I was a kid. Bikes converted me first, then came the ATV's, then the snowmobiles, so when it came to outboards I was a sitting duck, converting nearly immediately after becoming familiar.....

Admit too I was a little intimidated when it came to working on 4 stoke outboards. Now, with several years on them under my belt, it's something I don't even think about. It IS something you get used to doing. If anything, carbs are easier to work on as they don't seem to be as buried. There is NO difference working on the lowers. Yes, changing oil and filters can be a pain. That's a price I'll pay any day when it comes to any 4 stroke downside, with only a minimum amount of gripping..... -Al

 

[QBhoy]

I would add that for every person I know happy with the wide open throttle 4 stroke performance there are a hundred more who are just nuts about they way these motors can just putt nearly silently for hours and hours without complaint. And the big one among women especially, is there is no foul smell following you when traveling down wind.....

Oh heck yes, I was a huge fan of 2 stroke performance in ALL of my toys since I was a kid. Bikes converted me first, then came the ATV's, then the snowmobiles, so when it came to outboards I was a sitting duck, converting nearly immediately after becoming familiar.....

Admit too I was a little intimidated when it came to working on 4 stoke outboards. Now, with several years on them under my belt, it's something I don't even think about. It IS something you get used to doing. If anything, carbs are easier to work on as they don't seem to be as buried. There is NO difference working on the lowers. Yes, changing oil and filters can be a pain. That's a price I'll pay any day when it comes to any 4 stroke downside, with only a minimum amount of gripping..... -Al

Agree for sure. I’d also add that on the particular engine I have…mercury should be commended for actually encouraging self/owner servicing. One of their build and design scopes was to enable this. The quick connect oil drain and drip tray under the oil filter are just some of the lovely wee touches that make these things all the better.