Double oil fouled plugs?

[sutor623]

Hey guys, still breaking in my powerhead on my '95 Evinrude 130. Amazing how long it can take when you use your engine to fish inland lakes and small rivers . First 4-5 hours was done in 2 trips. Past 3-4 trips I put on about 2 hours.

Break-in is going well for the most part. I have the VRO removed so I am mixing oil 25:1. So far I have about 7 hours on the motor and have put 40-50 gallons of double oil mixed fuel through the engine.

Here are the issues that I am experiencing. First startup of the day, the engine is EXTREMELY thirsty. It helps to push the key in and have someone pump the bulb 1-2 times (with that solenoid valve open) just before I turn the key. The engine will start without doing this, but I have to advance the throttle to 1500-2000rpms or so and hold the key in for 4-5 seconds after she fires. Not a big deal there, just explaining what it takes to get it to fire cold. (Keep in mind quickstart is disengaged because it is acting up and nobody has been able to figure out why.)

If I let the engine warm up and then bump it into gear, it will "stumble" a bit here and there, and sometimes die. Almost seems like I have to get the rpms up real good to burn off the excess oil.

If I take a 5-10 minute run at 4k-5500rpms, then bring the throttle back to idle, she idles great for a few minutes, then will sometimes cut off. Other times if I bring the boat off plane and then knock it into neutral, the rpms will surge up to 1500-1800rpms and stay there for 10-15 seconds, then come down to 700-1000 rpms where it belongs. Not sure if this surge is related to this or something else.

Carbs have all been rebuilt, as well as fuel side of VRO, with all new filters, fuel lines, line fittings, and fuel tank fittings. Reeds all looked good when I put them onto the new powerhead. Everything was torqued down to a T, and factory manual was followed precisely.

After my last trip, I pulled the spark plugs to have a look and they were VERY oily. I had a 10 minute run to the boat ramp and only let the engine idle about 2 minutes before cutting it off for the last time. I went ahead and checked compression, and it was 148-150psi on all 4 cylinders. On the last powerhead 135psi was the best reading I got, so good news there. Also note, all of my ignition components are brand new and spark is strong. After jumping off plane, engine temp was 125-135 on both heads.

Does this sound like a double oil issue? I cant wait to get through break-in so I can have the proper amount of fuel in the tank again. I am also considering putting the VRO back on, because even 50:1 is a high mix for idle speeds.

 

[jimmbo]

I would check the floats, and the seats to see if they are tight

 

[ttankmoran]

40-50 gallons of double mix is plenty! thats 2 gallons of oil! Time to start weaning it off and see how it runs from there. By running double oil you are effectively leaning out the engine slightly (fuel) because oil is displacing the fuel which will certainly take its toll especially at idle.

 

[flyingscott]

Sounds normal enough, you are far enough into your break in to start doing wide open runs should help clear that out. Which plugs are you running is it the hotter ones. Do your carbs have adjustable idle circuits if they do richen them up a little and see what happens

 

[fhhuber]

While you probably don't need the 25:1 mix now... if all its doing is fouling plugs you don't have a bad issue. I run engines that have as high as 20:1 pre-mix for break-in. They tend to need the plugs cleaned often in break-in. Sometimes just running the plug at high rpm 5 min in another engine on the normal operation 40:1 or 50:1 will clean the plug...

Low rpm and high oil can give fouled plugs. Just not hot enough to burn off the oil.

OK... carry spare plugs and learn to clean them. Worst case is you spend a few min changing plugs on the lake.

More oil-rich fuel isn't going to help if the mix isn't causing issues in how it runs with fresh plugs. You'll still have excess oil and foul them running low rpm for an extended time.

 

[Chris1956]

25::1 gas oil mix should not foul plugs. That mixture and lower ones were used for years in older (pre-60s) outboards with point/coil ignition with no plug fouling issue. I suspect you have carb issues.

 

[sutor623]

Thanks for all the input fellas.

Jimmbo, the float heights are set perfectly with new seals, floats, needles and seats. I am about as sure as I can be on the carbs.

Scott, I am not running hotter plugs, but I do have a set of hotter plugs. Should I give them a whirl and see if it clears the issue up? Evinrude break-in says give 1-2min WOT runs on the 3rd hour I believe, so I have been doing some WOT runs.

Ttank, yea thats a lot of oil!!!

Fhhuber thanks for your experiences!

Chris, I have a hard time agreeing with this statement. I know that the older engines ran on a heavier mix, but there was also a lot of issues with long term idling, and most manufacturers offered a hotter plug for longer idling motors. Even mastertech at maxrules says to use 1 1/2 oil mix during break-in because double oil seems to foul the plugs. Here is his statement: " I recommend extra oil for the first 10 hours -- double oil seems to foul the plugs and 1? oil seems to work."

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And lastly, here is the engine at idle, in gear after a long run. Doesn't seem like a carb issue to me because I doubt it would run like this at all if it were.I have been through these carbs 3 times and unless the plastic is warped I just dont see how I could still be having carb issues.

 

[Chris1956]

Sutor, I never had a plug foul on my '58 Fat-fifty or my '61 Big Twin, even though both ran 24::1 gas-oil mix, and had magneto ignitions. Heck I used to run last years fuel mix on the first outing of the season. That fuel was likely 20::1 or lower.

Also, fuel stabilizer hadn't been invented, and I was mixing the gas with the cheapest SAE 30 ND oil I could find.


I only did a "normal" amount of idle time, but never had the motors load up on me. JMO.....

 

[ondarvr]

Check the thermostat, if it's stuck open it will run too cold at idle. It will warm up at high RPMs and then run ok for a minute or two when it idles back down until it cools off again.

 

[sutor623]

Sutor, I never had a plug foul on my '58 Fat-fifty or my '61 Big Twin, even though both ran 24::1 gas-oil mix, and had magneto ignitions. Heck I used to run last years fuel mix on the first outing of the season. That fuel was likely 20::1 or lower.

Also, fuel stabilizer hadn't been invented, and I was mixing the gas with the cheapest SAE 30 ND oil I could find.


I only did a "normal" amount of idle time, but never had the motors load up on me. JMO.....

Fair enough. What exactly does the term "load up" mean?

This motor failed with a scorched #1 cylinder if that means anything.

 

[sutor623]

Check the thermostat, if it's stuck open it will run too cold at idle. It will warm up at high RPMs and then run ok for a minute or two when it idles back down until it cools off again.

Thanks ondarvr. The motor seems to be reaching operating temp. The stats and springs are also brand new. This motor definitely does not like very cold water though. I have some 82s that I may try. Theotor calls for champ 78s which are in there now.

 

[ondarvr]

What exactly does the term load up mean?

Loading up is when too much fuel collects in the crankcase and it starts to run very rich.

 

[ondarvr]

It should be running at 140+ at idle, then drop down when a run at higher RPMs, so you need to check it after it's been at idle and acting up.

 

[AlTn]

the video of the motor at idle....I don't see how you could expect it to be better than that...that's smooth for a 2 stroke

 

[sutor623]

the video of the motor at idle....I don't see how you could expect it to be better than that...that's smooth for a 2 stroke

Thanks Aitn, good to hear from you. The issue isn't that beautiful idle, it is that when I try to start her up I feel like I have to "burn" off excess oil to get her to idle well. And them sometimes when I come off plane and knock her into neutral the motor will surge up to 2000rpms for about 10 seconds and then come back down to normal idle. I am just trying to figure out if it is the double oil that is causing these issues.

Another thing it will do is if it has been a few weeks since I started her up, she will back fire out of the exhaust and run crummy unless I hold the key switch in for 10-15 seconds after I crank her up. Just seems really thirsty at start up.

 

[sutor623]

Loading up is when too much fuel collects in the crankcase and it starts to run very rich.

Thanks, I assume the biggest reason for this would be bad needle seats or floats set too high? I am sure I set the float heights perfectly so I just cant see how it would be loading up.............

 

[sutor623]

Alright guys, so I did some more testing. Had the motor running in a bucket in the driveway. Put an infrared thermometer on it, and sure enough, port side head is reaching 140degrees at idle, and starboard is only reaching 80 degrees!!!! I swapped out the thermostat, the cup, springs and rubber grommets and could not get the temp up any higher. Then I put a freeze plug into the where the thermostat cup goes and blocked off the water flow in that head completely. Motor heated up to 130 degrees within 30-45 seconds so I shut her down. I don't understand how it won't reach OT with the stat in but with it out it gets hot quickly. Ignition system is all new so that's not the issue. Compression is great. Any ideas?!

 

[sutor623]

I double-checked and my cup/gromme/stat are all seated properly, but why in the world is the engine only getting to 80 degrees on the STBD side? Motor passed cylinder drop test, compression test etc. At least it is getting up to temp when I blocked off water flow completely with the freeze plug.............

 

[sutor623]

Ok, so I swapped stats and it seemed both heads were only reaching 80 degrees or so. This was running on the lake in 65 degree water.

I went ahead and finished my last two hours if breakin at 25:1 oil ratio. I brought a 5 gallon tank pre-mixed at 50:1. Pulled the fuel line and hooked it into the tank. Started her up and after 2-3 minutes, head temps were at 120 degrees. Idle was still sputtery so I tuned the low speed jets on the carbs. Motor ran best with them tightened up another 1/2-3/4 turn. Once I got them tuned to nearly perfection, I check head temps, 140 degrees on each head!!!! I ran her to full throttle for a few minutes, then back down to idle and checked temps, 120 degrees on both sides, and within a minute they were back up to 140-150 degrees. I let that motor idle in gear at 650rpms for 10 minutes and not a single hiccup.

The jury is in. The double oil had my head temps way lower than they are supposed to be at idle, and motor running pretty rough at idle. This caused for hard starts and nearly impossible warmup times in the morning. Thanks guy, finally got this figured out. I am very pleased!!!

 

[Chris1956]

I do not think your conclusion is sound. Most 2 cycle OBs are run with double oil for break-in. They do not have the issue you did.