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H2o no flow, 40hp 4cyl 2stroke ser. # OG 186 166

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dumbcountryboy

New member
hello to all, I have just bought this 40hp merc ser OG 186 166 when I look it up im finding 95 with jet foot the best I can tell, maybe someone swapped the foot out who knows, it sat sopossedley 10 or so years , the guy had upper carb bowl off when I got it, I stuck it back on and mixed some premix and got it started, sorry about all this bold under lined stuff I put it on the hose with muffs and get nothing from telltale at all, if the ser number on the transom bracket is correct and Im, searching the correct engine diagram I cant find a thermostat but did find a temp switch that sells for 200 bucks, that wouldn't stop water flow would it?, Im a pretty good shade tree mechanic and but awent to vocational collage 30 years ago for marine mechanics and remember a little but discouraged after seeing what looks like approximately 25 different variations of a 95' modle merc 40 hp, they must have made bunch of dealer exclusive engines for many different boat manufactures, I was hopping to hop it up into a 50 or 60 with larger carbs, on the plus side it sounds very tight and percission with any rattle and slap that common for a 2 cycle, if I can get some water out the telltale I can run it enough to know if I need to vat the carbs and so on, when I suck on the telltale hose it taste like exaust but if its dry I guess it would be gassy in there? any body already learned this 4 cylinder 40 hp 2 cycle mercury out there that can give me a heads up, looks as though mercury has discontinued many parts , thanks in advace and sorry for typos and punkuation
 
Could be as simple as a blocked tell-tale.Poke a bit of fine wire or weedeater line into the tell-tale.'95 is the correct year for that number.If that doesn't work,drop the lower unit and have a look at the impeller,in fact,change the impeller as it has sat for so long.
 
It will few days before I can get my hands on an impeller, anyone know if it has a themostat or electric temp switch that could block water flow????? when on the hose turned up high it seems that the garden hose pressure would be getting a very small amount or water to telltale, I don't think I got any water to reach the powerhead, I drained the foot oil this morning and it was only oil and wasn't milky, I was expecting some water from the garden water hose water pressure being above normal operating pressure,
 
I droped the foot, impeller had, no veins blades or flaps whatever the correct term is when dealing with pumps, left on it, the foot had an 8 and a 9 marked beside the studs looked like what I call junk yard marker, would that be for 1989 since th mote serial number shows this as a jet engine, how many year models could this foot be? any tips ordering an impeller, and when im looking down on top of the foot does it turn clockwise or counter clockwise?
 
I think this is your motor here. http://www.crowleymarine.com/mercury-outboard/543.cfm I usually use the link to the parts dept. on this site but I can't find your motor here so I used www.crowley,but if you need parts it keeps this forum going if you buy from here.Part # for impeller 89983T. http://www.marineengine.com/newparts/part_search.php?part_num=89983T+&x=18&y=15
I can't see any thermostat on the parts schematic but I do see a sender.If the impeller vanes broke and went up the water passages they will block them,so you will need to flush the block. The lower unit could come from a number of different years.I use an '84 unit on my '69 Merc800
 
I forgot,always turn the drive shaft clockwise or the vanes may turn in the wrong direction.Lube the impeller with liquid soap,it helps with the fitting.
 
Thanks for the helpful replies, 10-4 on ordering from the site, I was expecting a nylon shim below and above the impeller, and the keyway was strange compared to what I had mentally pictured, impeller housing looks great,but should I change it due to fact its old plastic, however it doesnt seem brittle and wanted to atleast test run it before putting a lot of money in it, and really thanks again
 
No need to change housing unless the metal cup is scored.Not that old,I still have the original housing on the '84 lower unit.No shims and the key is usually a flat piece with a ridge that mates with a flat face on the driveshaft and groove in the impeller.Just make sure that it stays in place when fitting the housing,otherwise the impeller won't move
 
When I did have it ru nnin g I had to keep priming the blub, so can I just take it for granted that the fuel pump surely needs a diaphragm kit being that this engine sat for 10 years ?
 
Thanks for helping, Im hopping there is a big mercury fan of this 4 cylinder 40hp on here because I don't ever remember seeing one myself, hopping for a club like old Honda 4 cylinder street bikes because when I ran it the one minute that I did ,it really sounded tighter and smoother than an 06 3 cyl 50hp mec that I had bought brand new, it was really like a sewing machine, the seller gave me the original 20 yr old title and claimed it had only been in the water 15-20 times in twenty years and sat for the last 10 of those years, it hanging on a 1648 aluminum boat without a single scratch or dint or dig on bottom, Im just as excited about this rig as any brand new one that I've ever owned, I love nice nostalgic stuff and From what I've read so far the carbs are only difference between the 40 and 50 or carbs and exhaust tube and it's a 60hp, I haven't checked all the facts yet but a lot of people swear by it, claiming its the cheapest horse pwr that you can get, I know check valve in the bulb was sticking a little and I never thought about excess fuel being returned back to supply line and thereby loosing prime, that would be very good if that's the case, my plan has been to hopfully get it pumping water and take it out and run some seafoam through it, mercury catalog says "1995 40 HP 30jet" I wander what the 30jet stands for, And really Thanks again
 
I've search on the web, reading old post on this engine, words like "legendary" and "undestructable" (like the engine I've never even here'd the word "undestructable") keep popping up, not a single negative thing, couple people said an old merc brouchure claimed it was the best running 40 hp outboard ever made. prior the the 4 stroke, Now question is why have myself and so many others seemingly never notice and somehow overlooked this outboard until now, it seems if such a great motor everyone would know of it and the easyHP increase to 60 HP
 
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