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View Full Version : 20hp Merc..... sounding like it's had a curry.



pipifin
08-09-2011, 03:50 PM
Long time reader/lurker, first time poster.
I've at long last made my first vessel purchase, but now I need some advice. I bought a 3.7 Stessl with a 87 20hp Merc sitting on the back for the price of the trailer, so naturally my hopes weren't high when it came to the condition of the motor. It starts 1st or second pull, even from cold, pumps loads of water etc. My problem arises once you give it some revs. 1st test run it started fine (maybe idling a bit high) go's into gear fine, but when you give it a bit more, it coughed, farted and spluttered like it was misfiring or just clogged up with crap, then would cut out. It would start again no problem. I took it into a boat shop to get serviced, gave them the run down and picked it up later that day. The mechanic said he played around a bit with the fuel mixture and got it running as well as he could and did the usual spark/impeller blah blah service. He said that it had a rattle and he was convinced it was a bearing (at the time I didn't think to ask which one) and there wasn't much life left in the old girl (300 bills later) I took it out for test run 2 on the weekend and the only change was it wouldn't cut out after coughing and carrying on. The motor, even at idle shakes around like Christchurch (I can say that, cos my wife is from there:P). I think I have found the manual and was gonna have a play with it myself, but I hate not being on the water. Do I bite the bullet and get a new/2nd hand motor? (the mechanic said they have a great one I could buy.... Hmmmmm) or persist and see what I can achieve with this one? Any advice/help would be greatly appreciated.

Goochi
08-09-2011, 04:09 PM
Sounds like its does not want to run under load. Thought the Mech could have offered a bit more insight than just air/fuel mixture. '87 is getting a bit long in the tooth, you could quickly find you spend just as many dollars on this, if you can't find a better mechanic, as you could on a decent newer secondhand motor. I'm don't know about your merc, I had a much larger old engine lose power and it was the electronic control unit dying.

cormorant
08-09-2011, 04:47 PM
Basic health of a 2 stroke is

Compresion test
Leakdown test
Seals in crankcase ( if it was apart on a bench a crankcase pressure and vac test)
Spark , timing
Fuel, pump, lines, filter , freshness.
Carb
Bearings
cooling
Gaskets

Any of the above can cause bad running.

Frankly depending on what you asked of the mechanic a good mechanic would have quickly heard the big end bearing noise , piston slap and spoken to you in regards to how bad it is and what you wanted to do - ie spend any more money or stop there. He may be very good and just heard the first hint or bearing noise so you need to speak with him or nother mechanic and determin just how terminal it is. I'd be carrying teh big set of oars from now on , a phone in waterproof and a radio

To be blunt a big end bearing noise won't generally stop a motor being tuned and running so not that impressed with the mechanic ( the motor may be well stuffed but that makes me wonder why he put parts into it?). Ok but will lead to it crapping itself sometime minutes or months or years in the future with no warning. Beraing could be from wear or neglect like no oil in fuel etc No one will tell you how long it may last.

The motor is possibly worth more in parts now or as a honestly described ( with a knock) sale that someone mechanical could rebuild. Once it is seized or thrown a rod it is worth the recoverable parts only.

Try and find out a bit more about why he couldn't tune it , talk to him as he may have thought he did and it ran OK in the tank or from his tote tank. Make sure your fuel is fresh and water free for a start and that your fuel lines ,bulb are all OK

You paid to have your existing motor fixed - he should have done that if it was possible. It may require a carby clean , flush or a full pull down of the carby and he may explain why he did/didn't do that and the cost etc. Don't go in on your high horse as there are decent blokes out there ( lots not) If you get a bad response you simply know wher enot to give your boating business.

Not sure where you are located but if you don't have any luck someone here may put you on to a mechanic locally who could look over it and 2nd opinion. I've seen lots of things that make nouses in motors over the years be it magnets in flywheels to other odd things.

Listing out exacty what the bloke invoiced you for will also tell people a bit about the mechanic whether he was having a lend or upfront.

Did he
grease all points, remove ,replace prop and grease it , check gearbox seal.
spark plugs
lower unit gearbox oil
Waterpump - impeller or full housinga nd impeller
Annodes
Tune
Thremostat
Compression test? What were the compression numbers hot ? cold? wet?

PADDLES
09-09-2011, 07:15 AM
Hi pipi, i'm with cormorant on this one, i wouldn't have been real happy with the techo's performance here. I guess it does depend on what you actually asked him to do.

Put it this way, if i had described my problem to a techo and he then spent $300 servicing my motor that's lucky to be worth $300, and didn't actually fix the problem i described in the first place, then i probably wouldn't be too pleased. For sure it'd be fair to pay him for labour to troubleshoot for you, but to throw new parts at a motor, that don't have anything to do with the problem, is insane. ie. if a techo had thrown a new impeller kit and spark plugs at my motor and then told me that it needed rebuilding i would have spat the dummy, and depending on what you asked him to do that's what this bloke has done.

finga
09-09-2011, 08:03 AM
Maybe it just needs a good fart?
That does me a lot of good after a curry.

Marlin_Mike
09-09-2011, 08:57 AM
Maybe it just needs a good fart?
That does me a lot of good after a curry.


ONLY from Finga :P do you get a comment like that ;D::):-[;D:o:o LMAO

PADDLES
09-09-2011, 09:06 AM
don't try too hard though finga, we don't want any gravy .............

finga
09-09-2011, 09:51 AM
Follow through......
The ill afforded side effects of curries in both outboards and myself (and the rest of you scumbags if your honest enough to admit it).

pipifin
02-11-2011, 12:16 PM
It's taken a while for me to get back to this post. But I'm happy to report there is still some life in the ol' girl yet. Thanks to all for their advice, especially cormorant, big help there mate. I was lucky enough to get to talking to an old timer (affectionately referred to as "old man emu" or for the sake of this post "OME") that lives across the road and fishes from his tinny regularly. He's one of those blokes that just has to help when something needs doing. He believed the mechanic was full of "Finga's follow through gravy" and offered to have a look at it for me. I spent a fair few hours over a few weekends with him making adjustments, and going through the list of potential problems kindly provided by fellow ausfishers. He was also impressed with manual I found on a link from this website too. Anyway I'll make a long story... less long, and let you know that after a few test runs on the water and compression tests, spark tests etc that old motor is pushing the tinny along nicely. OME said that he's been around motors for over 40 years and cant hear a rattle..... mind you, he is getting on and hearing can be one of the first things to go.
I learnt a huge amount from him and the info I got on this website and thank you all for your helpfulness.
As for the mechanic in question, I'm not one for confrontation, I'm more likely to vote with my feet, and hey, maybe I didn't give the mechanic enough info, I'll give him the benefit of the doubt. But they wont be getting my business again, and the Sunshine Coast has plentiful supply of other options should I need it. I say "should I need it" because I also now have the confidence to work through any problems I have with the motor.... I just needed a push, and someone to bounce ideas off.
Thanks again Ausfish.

pipifin

Screamin Semen
03-11-2011, 10:19 AM
Mate I would save the money and buy a new 20hp...you can get a new Yamaha 25hp CV for around $3k or a 20hp bit cheaper or price up a Mercury or Tohatsu for even less.

Cheers SS.