75 Johnson Stinger...Overhaul needed??

[Ridiculous]

howdy folks,

i've got myself a 1975 75 Johnson Stinger on a 1975 Glasspar G-3...
bought it from my uncle for $500.

when i got the boat i tried to take all the precautions necessary in starting a motor that had been in storage, especially for this long (5 years since it's been in the water he said)...

so this is what i did...
first thing was soak the rings to free up any stuck rings and help loosen any carbon
then i did a compression test...140 psi on all 3 cylinders
did a spark test...passed...good strong spark on all 3 cylinders

now i'm thinking i'm ready to start it up! so i take the boat and put in 6 gal. of gas premixed with two stroke oil at 50:1.

now this boat is closed bow for those of you unfamiliar with this boat, and the gas tank is in the bow and you fill it from the outside. now this boat also has a gas guage but i was under the assumption it was not accurate...so without checking i just put the new gas in the tank with the guage showing 1/4 tank remainig...ok perfect

go back to the house...run it on the muffs and do a de-carbonize...shes purring like a kitten...time to hit the water

so i drop it in the lake with some friends and she runs good...almost too good it seems

well next week comes along...i decide to go to the lake again, only this time, she doesn't run so good...i get a lot of popping and farting and what not. so i thought to myself it's gotta be fuel/carb issues.

so i go home again and this time i decide to just drain gas, clean fuel filter, clean carbs.

the fuel was NASTY brown greenish crap and there was about 8 gal. that i got out total
so i got that drained and flushed the tank/lines with fresh

then i clean the filter, had a few chunkies but not like i expected

then i pull the carbs and disassemble and clean all the components (which were all very clean to my supprise!) and reinstall on engine.

now i hook it back on the muffs and the idle is a bit rough-ish but other than that she's running like a top

so off to the lake again...now this time...she's got zero balls! it takes what feels like forever to get up on plane, but once it does all seems ok.

so i cruise for awhile...hang out in a few coves...but i notice that it's not starting/idleing the best.

so homeward bound...i decide to do a compression test again and this time it reads...
top cyl. 130
middle cyl. 130
bottom cyl. 90

so to get to the point...is it time to pull the power head down???

sorry for the long story but i had to make sure i got all the details

thanks everyone!

 

[jtexas]

Re: 75 Johnson Stinger...Overhaul needed??

on that motor I would have been thrilled with 110 to 120 PSI, I wouldn't of believed 140 unless a recent overhaul. No matter.

Just pull the head & take a look, could be nothing worse than a head gasket, you'll be back on the water in no time.

Take the opportunity to test the temp switch.

 

[jjacobs007]

Re: 75 Johnson Stinger...Overhaul needed??

Always do compression check before you spend money on gas engine.But too late now,check the rings and gasket around cylinders and possibly do a leakdown test if you have one.Or pour little transmission fluid in carbs and see if smoke comes out gasket areas.

 

[Chinewalker]

Re: 75 Johnson Stinger...Overhaul needed??

Hate to say it, but if you had quit when you first noticed something was wrong, the motor might have been salvageable. BUT, your cruising around with the motor not running well may have been what killed the bottom cylinder - if it's a fuel issue. The cylinders feed from their respective carb and need the fuel/oil mix to maintain proper lubrication. If one carb leans out due to gunk in the system then that cylinder will suffer from no oil.

I'd start by pulling the cylinder head and see what's going on. Maybe you'll get lucky and find a blown head gasket instead of blown cylinder...

 

[Ridiculous]

Re: 75 Johnson Stinger...Overhaul needed??

thanks guys...hopefully i'll get a chance tonight if not later this week to pull the head and take a look inside...

i'll keep ya'll posted

thanks again

 

[Ridiculous]

Re: 75 Johnson Stinger...Overhaul needed??

well folks,
i was able to get the head off today and saw that in the bottom cylinder the piston started to melt/boil. also did quite a number on the cylinder head too. so it looks like now i get to pull the power head and do an overhaul.

i've got pics but my phone is being a huge POS so i can't get em transfered over as of now but it's pretty ugly.

i think that i quit running it just in time b/c the cylinder wall still appears ok. maybe some slight scoring but not like i expected to see. but i'll know more when i get it all pulled down...

so my next question is...what's the best place for parts???

is it my local marina or can i get better/cheaper online?

thanks

 

[Chinewalker]

Re: 75 Johnson Stinger...Overhaul needed??

Generally I try to support my local guy first. You may pay a bit more up front, but often if you buy from the local guy it also buys you a bit of free advice if you're doing the rebuild yourself. They'll be more likely to help you if you're in a bind if you bought the stuff their, rather than somewhere else. If the price differential is way out of whack, though, don't be afraid to tell them that you can buy X parts online for less and see if they'll deal a bit...

 

[ezeke]

Re: 75 Johnson Stinger...Overhaul needed??

No matter where you buy, you want to talk in terms of a rebuild kit, not individual parts. That goes to gasket kit, etc.

 

[Ridiculous]

Re: 75 Johnson Stinger...Overhaul needed??

so i'm lookin around for parts and johnson's website is telling me that pistons and cylinder heads are discontinued...not good news for me.

so then i think to myself that i need a used powerhead...so i look on ebay and i find one. the guys says it's a 1979 70 75 HP. also claiming compression is good or he'll buy it back. he also said he did a leakdown test and it was all under 12% (i think i'm going off memory here) and he's asking $295

so that's what i know...is this the way to go???

 

[jtexas]

Re: 75 Johnson Stinger...Overhaul needed??

I have one a those and I like it a lot. Gear ratio is 29:12 (about 2.4167 to 1).

Doesn't he know whether it's a 70 or 75? Different block, cylinder head, reeds & carbs.

 

[Ridiculous]

Re: 75 Johnson Stinger...Overhaul needed??

I have one a those and I like it a lot. Gear ratio is 29:12 (about 2.4167 to 1).

Doesn't he know whether it's a 70 or 75? Different block, cylinder head, reeds & carbs.

No clue...its advertised as 70 75...so will this powerhead even work should I decide to buy it?

 

[jtexas]

Re: 75 Johnson Stinger...Overhaul needed??

block, cylinder head, reeds & carbs are the only differences between the 70 & 75hp.

www.shop.evinrude.com click on "electronic parts catalogues" then drill down to year/hp/model. johnson and evinrude are identical, part for part.

find out what your lower unit gear ratio is, and if different whether you can make up the difference in prop pitch.

drive shaft splines I think are primary concern. I may have a pic around here somewhere.

I don't know what the "going rate" for a 31 year old powerhead is, but my gut tells me that if mine were blown, I'd be willing to pay $300 for one in good condition.

 

[coolguy147]

Re: 75 Johnson Stinger...Overhaul needed??

i havent seen an impeller replacement in here???????


change the gear oil too

 

[Ridiculous]

Re: 75 Johnson Stinger...Overhaul needed??

gear oil has been changed and the water pump (assuming that's what your talking about) will be changed as well...

 

[jjacobs007]

Re: 75 Johnson Stinger...Overhaul needed??

I find it hard to believe that those parts are no longer available? Find someone to bore her out and keep looking for the pistons and parts there out there.

 

[ezeke]

Re: 75 Johnson Stinger...Overhaul needed??

Here is one of many places to find the parts: http://www.powerheadkit.com/3cylOmc.htm

 

[Ridiculous]

Re: 75 Johnson Stinger...Overhaul needed??

ok so i found the exact outboard i have for sale in WI. he's selling the powerhead which has a broken connecting rod for 125 or the whole outboard for 200...i'm thinking the whole outboard sounds like a good deal!!

what ya think bout that? is it worth the road trip? i live in NE and he lives in WI. about an 8 hr drive one way.

ezeke, i'll check that site out...

 

[Ridiculous]

Re: 75 Johnson Stinger...Overhaul needed??

nice site man...i don't know why i can't find stuff like that...must not be looking hard enough.

so what the heck would you guys do?
$200 for a whole outboard (that's what i understood anyway)
$425 for a rebuild kit with all the parts i need all brand new

keep in mind for the outboard i'll have to drive at least 16 hrs to pick it up...

 

[ezeke]

Re: 75 Johnson Stinger...Overhaul needed??

If the motor that you are looking at has a broken rod then it is good for parts which I guess is what you are interested in.

Regardless of what you can salvage you would still need a gasket kit and some new rod screws. I am fairly certain that you would at least want to put new rings on the pistons. You would also need various sealers and gel seal.

In the end, I don't think that you would save much if anything over the rebuild kit with the parts motor but you would have lots of other spare parts.

 

[Ridiculous]

Re: 75 Johnson Stinger...Overhaul needed??

that's just it man. it would be nice to have all the spare parts but like you said. i'll still need gaskets, sealers, rings, etc.

so i would probably end up spending more than what the rebuild kit is worth in the end...

i think i know what side i'm leaning towards...
it would just be nice to have all new parts, wouldn't it? you never know what your gonna get with a used engine.

so now i've got another question...
when it boiled the piston it did some damage to the cylinder head...quite a bit of pitting. do i need to replace the cylinder head or can i run it? not sure if i'd lose compression or what.