1980 20hp Merc probs.

[Rudderman]

Hi, I've just acquired a 1980 Mercury 20hp blue-band, short shaft, manual start, serial no. 5412401. I want to fix it up for use on my Glen-L Squirt, a 10 foot speedboat.<br /><br />I do not know any history of the engine, but<br />it runs (smokily) in a test tank and shifts gear ok<br /><br />The concerns I have are:<br /><br />1. There was no lube in the lower unit when I got it and the original "fill plug" had been replaced with a piece of threaded rod with a nut screwed on! Should I strip down the lower unit and check the condition of the gearbox?<br />2. The plastic "flush screw" is so mangled up that I can't open it. Any ideas how I can get it out?<br />3. When the engine is swiveled left to right, the clamp hits off the bottom of the steering arm (where the tiller handle fits on). Am I just swivelling too far or is there something bent?<br />4. The wrap-around cowl is pretty dented and scratched and the front cowl with the sound cushioning is missing. Is there any other way to quieten this engine? ...and any tips for getting out the dinges would be appreciated.<br /><br />Thanks<br /><br />David McAdam<br />Ireland

 

[WillyBWright]

Re: 1980 20hp Merc probs.

Sounds like that poor thing was thoroughly abused. I'd look for another like it. That way you can swap parts around to make one good one. Around here, they're common as dirt. Overall, I feel they were the best motor Mercury ever made. But even the best of motors won't provide reliable service if they're not taken care of.

 

[merc20]

Re: 1980 20hp Merc probs.

I have an '81 Model 20hp that I absolutely love. Good luck with quieting that thing down, mine is pretty loud even with all of the cowling on. Have you checked with any used parts dealer for the plugs you need? Try drilling the plastic plug out. You could at least drill enough to get an "easy out" in it to get it out. Good luck.

 

[Rudderman]

Re: 1980 20hp Merc probs.

I think I'm gonna have to just strip the whole thing down and see whats what.....I have a seloc manual so maybe I should just "go at it"<br />I've tried to get another engine for parts but there don't seem to be many around..but maybe I should wait til I do the stripdown and then decide whether to buy individual parts or a parts engine.

 

[Chinewalker]

Re: 1980 20hp Merc probs.

Hi RM,<br /> Those motors were never what you would call quiet from day one. However, a face plate does help. Does your motor have two notches in the front of the top cowling and a slide lever release in the front of the bottom cowling? If so, I have an extra face plate.<br /> As for the flush screw, why do you need to remove it? Has the motor been used in salt? If so, simply running it in fresh will accomplish the same thing.<br /> As for the tiller hitting the transom bracket - is the tilt pin in place? If not, it may allow the motor to tilt too far inwards and then the tiller will hit the bracket.<br /> Replace the oddball drain screw with a proper stainless one (hardware store standard issue - just match up the threads) and refill the unit. Run it a bit, then drain the oil and check the condition. If it's not milky (water intrusion), not metal flaky (grinding bearings/gears), and not blackened with a burned smell, then you should be alright.<br /> You should be able to tap out most of the dents with a small hammer and some deft pinging. Lay the cowling on a thick towel so that you don't mess up the outer surface.<br /> Good luck!<br />- Scott

 

[Rudderman]

Re: 1980 20hp Merc probs.

Thanks for all the replies. I found even more things wrong with the engine when I started to dismantle the lower unit. I found a big crack on the lower unit casing where someone had tried to pry the lower unit free with a screwdriver or something. The anti-cavitation plate had been filed away and repainted (because it hit rocks probably) and I found a big split in the exhaust housing, probably from rock damage also.<br />So the upshot of it all is that the guy I bought it from is taking it back because he told me the engine was complete and in good condition....but it has obviously been mistreated over the years!<br /><br />I should have familiarised myself with outboards before I went to buy one....at least now I know what to look for and what to avoid in a used engine.

 

[mellowyellow]

Re: 1980 20hp Merc probs.

you are more fortunate than most in this situation.<br />better luck next time,<br />M.Y.

 

[Rudderman]

Re: 1980 20hp Merc probs.

I know this is an old post but I just wanted to add an update. When I brought the engine back to the dealer, he said he'd take it and give me the money for it when he sold it....its now 6 months later and he hasn't sold it yet and refuses to give my money back. <br />I'm now considering that my best option is to keep the engine and refurbish it as a winter project.

 

[Rudderman]

Re: 1980 20hp Merc probs.

Heres a photo of what I am dealing with.. http://homepage.eircom.net/~aerocam/Squirt/EngineOld.jpg

 

[andrewkafp]

Re: 1980 20hp Merc probs.

Your motor is a 1979 with a 1980-81 cowling wrap. You can tell by the serial number 541* and also that small blue band around the top of the leg. The 1980 had 2 tone blue bands an no horsepower on the leg. A bit trivial.. I know, but just in case you're looking for part no's etc<br />The appropriate cowling looks like this for your motor.<br /> http://www.myfishingpictures.com/watermark.php?file=527/141379-20merc.jpg <br />This is the 1980.<br /> http://www.myfishingpictures.com/watermark.php?file=527/1413merc50b-med.jpg <br />MAKE SURE that the L/U will come off.. as there have been a few 20HP Mercs on here that had the drive shafts seized the the crankshaft. Yours is stainless and has a better chance of removal.<br />For part no's and diagrams go here.<br /> http://www.dougrussell.com/partscatalog/collections/index.cfm?fuseaction=collectdetails&colid=01

 

[Rudderman]

Re: 1980 20hp Merc probs.

Unicorn, thanks for the info. I get the feeling this is gonna be a long term project!