Is this part normal looking?

[Tripp Halbert]

1996 Johnson 70hp j70TLEDA. Just purchased this engine, wouldnt stay running (was gunked full of oil in carbs) when i first bought it. Bypassed VRO and drained carb bowls and the engine fired right up and continue to run (now premixing). Water tested it and would not go WOT but ran fine at idle and low speeds. cranks everytime. so i Rebuilt all carbs and only bottom carb with a kit.

Ran great but i noticed it seems more hot than it should be, it pees steady and the pee is warm enough i can hold my hand under it. Compression is T-122 M-122 B-121.

My main concern though is that the bottom spark plug is always pretty clean. I have good blue spark on all 3 wires and bought new plugs. Bottom cylinder is firing but weaker than the others. Went to change thermostat yesterday and found some sand and salt residue, i figured it was time to remove the exhaust plate and look inside. This is what i found; is this normal looking or are these corroded holes possible leaking steam into my bottom cylinder, causing the motor to run hotter as well? Are there any signs of overheating? Can i weld this if these are in fact leaks into my cylinder?:blue:

 

[Bosunsmate]

Re: Is this part normal looking?

Hard to tell from that photo.
Hows the piston on that cylinder look?

 

[Tripp Halbert]

Re: Is this part normal looking?

Bottom piston looks similar to the other two. Its not super clean or pitted or anything odd.Wat should I be looking for?

 

[Bosunsmate]

Re: Is this part normal looking?

Steam cleaned.
Remove sparkplug lead for that cylinder, ground it to engine somewhere, run engine and then check that plug is wet from unburnt fuel

 

[Tripp Halbert]

Re: Is this part normal looking?

Okay i will try this and let you know the results. I have to get all those broken bolts off first which may be a week or so before i have it up and running again:facepalm:

 

[Tripp Halbert]

Re: Is this part normal looking?

update: I got everything back together and ran motor for an hour or so on the river the other day, ran amazingly with so much power and no problems at all! Swapped it to new boat and cranked it up on hose yesterday, ran fine. I then noticed later black oil seeped out of the bottom spark plug so i made sure it was tightened up. Runs fine on the hose but when i sat it in the river and cranked it up (motor now running with back pressure), it began to pop out the exhaust (not the prop exhaust but the mid-section one) every 20-40 seconds or so. put it into gear and it will stall almost immediately.

I am going to run some tests again today; new fuel, new compression test, check for vacuum leaks. @ Bosunsmate: i will also do the ground test today but im almost positive this cylinder is burning the fuel because i pulled the bottom plug while it was running and its loses alot of power. I need help, any thoughts on this????????????

 

[phillnjack2]

Re: Is this part normal looking?

while you had the exhaust cover off and thought there was holes you should of cleaned it up real good and put some jb weld on it.

is the idle speed high enough ? about 900 in nutral and 750 -800 in gear ?
is the timing right ?
and what spark plugs have you got in there ????????


phill

 

[Tripp Halbert]

Re: Is this part normal looking?

I indeed cleaned the crap out of this, along with the therm housing, using CLR and brushes. I dont have a timing light but will get one. No RPM gauge yet, sorry!! Brand new plugs from boat store, will list the exact kind later though.

It pees fine and runs at an optimal 143 degrees so im good in terms of cooling now. Concerning this opening in the pic: turns out an old man mechanic (79 and still boring out engines haha!) informed me that these parts were formed by OMC with some type of styrofoam molds, which gives it the rough weird look, completely normal per him.

During the swap, I had to disconnect the linkage, and on an embarrassing note i might add, accidentally swapped the throttle and gear cables the first crank but quickly shut it down and swapped them back. Could this have screwed some sync up? Could my link and sync really cause it to run like this?

BTW Phil i read your whole post about link and sync, i have the manual file for the 1990-2001 johnson/evinrudes all hps if your interested still...

 

[Tripp Halbert]

Re: Is this part normal looking?

later, i will upload a video of the engine doing its pop/cough thing as well.

 

[Bosunsmate]

Re: Is this part normal looking?

pop is normally from lean running, blockage has got into carb etc

 

[Tripp Halbert]

Re: Is this part normal looking?

i just rebuilt all the carbs!!!??? (which did fixed my WOT problem earlier on) How do i test if its running too lean?

 

[Bosunsmate]

Re: Is this part normal looking?

A you running a filter?
Did you put soft wires down the small idle channels and blow carb cleaner/compressed air down them? i almost always find the blockages in those channels not the jets
Have you pulled the other plugs and seen how that affects the running of it?
Is bottom cylinder doing most of the work?

 

[Bosunsmate]

Re: Is this part normal looking?

Have you swapped the coil to see if weak spark follows it?

 

[Tripp Halbert]

Re: Is this part normal looking?

Yea I am running an inline filter. I have not tried anything on carbs since the rebuild, and are you referring to the inlets at the top plastic cover? Bottom cyl has always seemed the weaker one but i have not pulled any of the others, i will check this. My spark gapped the 7/8" mark on all 3 cylinders so i know all coils, power pack, and ignition are good. i am now wondering if its indeed running lean, why doesnt it pop/cough on the muffs( in theory: lean is lean even without back pressure, correct??)

 

[Tripp Halbert]

Re: Is this part normal looking?

I really appreciate all the brainstorming here too guys!

 

[Bosunsmate]

Re: Is this part normal looking?

Yes up the top, all those channels that go into the carb body.
Have you tried backing out the needle valve a bit

 

[Bosunsmate]

Re: Is this part normal looking?

yep thats right it should on muffs too

 

[Tripp Halbert]

Re: Is this part normal looking?

okay that eliminates the lean issue then, it runs flawlessly on muffs. I did toy with the carb needle valve yesterday (in the water) but to no success i could not get it to stop making the pop noise.

The pop is definitely coming out the mid exhaust with one big puff, the bubbles rise to the surface and simultaneously during every "pop" blue smoke blows out the top exhaust holes (nothing out the prop exhaust i believe). This also slows the motors rpms considerably.

 

[Bosunsmate]

Re: Is this part normal looking?

Ok will look at video when you post it to see if i can make anymore out of it
Have you checked timing?

 

[Tripp Halbert]

Re: Is this part normal looking?

no i have not checked the timing, i need a timing light for that right?