Was Damage Done ?

[ehenry]

My 25 hp 2000 model Merecury leaned out and quit on me yesterday. When it quit, I immediately grabbed the cord and pulled. It was harder than normal to pull. I paddled over and tied up to a tree and pulled again. This time it pulled easier like it nomally does. I did get it to crank and run but only on one cylinder. It got me the last couple miles back to the landing sloooowly.

When I got home I pulled the spark plugs. They were dry, not the normal wet looking and no aluminum deposits. I will do a compression test this evening or tomorrow evening to see if there is any significant difference in the two cylinders.

I guess my question is this . . . with it being hard to pull that one time then pulled normally less than 5 minutes later. . . in yall's oppinion. . . has my engine been damaged ?

 

[Boss Hawg]

Re: Was Damage Done ?

I know it won't do any good to say it but i would'nt worry till you do a compression check
Let us know what you find--

 

[hdodt]

Re: Was Damage Done ?

I dont know how your motor is built, but I had an old boat motor once that over heated and died. I tried to start it but the pull was so hard I could barely get it to turn over. I started to paddle back to shore and like you when I got there I tried again, and this time it was back to normal. It started normal and had no problems running it. My thought was that with the aluminum pistons and the cast block the aluminum expands faster than the block and thus causes the rings to be pressed tight against the cylinder walls making it hard to crank. Once they cool, which with aluminum happens fast, it returns to normal, and cranks easy again. I dont know if you did damage, just something to think about.

 

[northernmerc]

Re: Was Damage Done ?

Have you discovered why it only runs on one cylinder? If it has spark and gas, then you may have a problem inside the cylinder. The compression test should give you a good idea whether you need to remove the head or not.

 

[ehenry]

Re: Was Damage Done ?

Did a compression test yesterday. Had 110 lbs on the top cylinder and zero on the bottom cylinder. All I did was a compression test, nothing else. This weekend I will probably pull the head off and have a peek in cylinder and see what it looks like.

 

[will941s]

Re: Was Damage Done ?

If it's a two stroke, the head does not come off. All thats there is a water jacket. The pistons are installed through the inside of the cylinders. If you take the water jacket off all you have is the spark plug hole to look through.

 

[northernmerc]

Re: Was Damage Done ?

Hmmh, 0 compression sounds a little low. It may be time for a new piston?

 

[Faztbullet]

Re: Was Damage Done ?

Pull it down and repair it, that engine has the Mercosil block and can be repaired and bored....

"In the mid-1980?s, Mercury Marine started its largest and most systematic field study in its die cast Merc 25 block to evaluate a family of copper-free hypereutectic aluminum-silicon alloys called Mercosil technology. Mercosil is anacronym for Materials Engineered for Resistance: Corrosion(copper free) and Wear (silicon). After accumulating 1,000,000 field hours with test fleet of engines with no failures attributed to the alloy, the decision was made to gointo full production in 1994 with Mercosil for the Merc 25 block.The Mercosil Merc 25 engine replaced a very successful engine block that had chrome plated bores, and was in production for over 20 years. The only flaw inherent in the previous Merc 25 with chrome plate bores (besides cost of manufacture) was its susceptibility to fatal damage when large debris was ingested by the engine. The Mercosil Merc 25 ist olerant of ingested debris"

 

[ehenry]

Re: Was Damage Done ?

How can this engine be bored if there is no head like Will941s says??

 

[will941s]

Re: Was Damage Done ?

If it is the two stroke with no head and just a water jacket, the engine will have to taken apart, either way this would have to happen. Instead of boring it from the outside (through the top of the cylinder) they will bore it from the inside (through the crankcase). Exact same process, just from a different angle. It's a very good engine, I have a 89' and a 98' and I love both of them, find a reasonable dealer with a reasonable price and go for it.

 

[sschefer]

Re: Was Damage Done ?

How can this engine be bored if there is no head like Will941s says??

The engine can be bored like Will951s says, by tearing it down. It is what's known as a "Blind Hole" bore. Most automotive shops do not have the right boring bar and hardened tipped hones to do the job. There are tricks to using a standard boring bar and a shop that does this on a regular basis will be practiced at it and can probably do a decent job.

Blind holes usually have a relief cut at the very bottom of the hole. If you have it bored make sure you have the releif re-cut or you risk having exposed aluminum in line with the sleeve which will expand when heated and could potentially squeeze the piston. Piston, rod and crank damage could occur if that happens, so ask.

In some cases, the sleeve seats fully to the bottom of the casting. In that case you are better off finding someone that has the correct boring bar to do "Blind Hole" boring.

The best solution is to replace the sleeve but boring can be done and is a good solution.

 

[Faztbullet]

Re: Was Damage Done ?

If you need it bored send it to me, I can bore it for you. There are only 2 persons besides myself in Nashville are that will bore blind hole engines(Merc inlines)and I have the diamond stone hones to crosshatch cylinder.

 

[sschefer]

Re: Was Damage Done ?

If you need it bored send it to me, I can bore it for you. There are only 2 persons besides myself in Nashville are that will bore blind hole engines(Merc inlines)and I have the diamond stone hones to crosshatch cylinder.

And that's the truth! Faztbullet is one of the few that do know how to do this right.

 

[ehenry]

Re: Was Damage Done ?

Been talking with a guy that is in the outboard repair business. He was telling me that parts for small outboards are getting hard to come by. I noticed on Mercurys web site that they dont offer a small 2 stroke any more.

Is this something i need to worry about?

 

[sschefer]

Re: Was Damage Done ?

If it is the two stroke with no head and just a water jacket, the engine will have to taken apart, either way this would have to happen. Instead of boring it from the outside (through the top of the cylinder) they will bore it from the inside (through the crankcase). Exact same process, just from a different angle. It's a very good engine, I have a 89' and a 98' and I love both of them, find a reasonable dealer with a reasonable price and go for it.

It's easy to think of it as the same process but it's not so don't just take it to any machine shop and expect them to know how to bore and hone a blind hole.

I have a feeling the Merc dealer will tell him to just get a reman powerhead because it will be cheaper in the long run. That would be my advice also.