[scott_44113]

I hope someone can help me.

Here is a short video of my problem, in a nutshell:

The particulars are:

Cub Cadet GT 3185
Model 14A-665-100
Serial unknown
18.0 HP B&S Twin Vanguard, Hydro, Power Steering, Power LIft

Engine plate:
Model 350447
Type 1206-E1 4952
Code 98030911​

Thanks to SHELBYGT550, I was able to learn from the BRIGGS & STRATTON VANGUARD OHV V-TWIN CYLINDER ENGINE REPAIR MANUAL [https://docs.google.com/open?id=0B6NaqjIxWV1yZHlwUk9CWlNwYVE], especially pages 78-79, that the hose seen in the clip and in the top of the attached image is the fuel line! And the round, black plastic thing with "Mikuni" stamped on it is a fuel pump!!

What I don't understand is WHY the engine starts fine, idles as good as ever, just had an oil change, plugs, filters... Why does it have no power when there's a load on - like just the mower?

Here's a couple images of the items in question:

In the bottom half of the collage, the thick green arrow points to the tube [in upper half image] hose which is attached to the fuel pump. The red arrow is the fuel line. The other rubber hose (on the right side of the pump, just above the fuel line) is the vacuum which operates the pump.
I'll do a vacuum test on that line later today. It's supposed to be around 1.5psi if I read it right. Although...

I found this response here from SuperTurboDiesel [STD] that mentions a possible carburetor solenoid problem - but I don't think I have a solenoid. That's another thing I have to do. http://www.mytractorforum.com/showthread.php?p=699990

I should also mention that this started acting up as the fuel tank is nearly empty - which STD mentions as a symptom. Something to do with gravity from a more-filled gas tank assisting in fuel flow to the carb.

AND, last but not least, approximately 6 hours after an oil/filter change, cleaned & gapped plugs, new air filters. In changing the oil, I inadvertently added over a pint too much HD 30 oil. It ran fine for nearly 6 hours. Now as soon as I put a load on it, it smokes heavily (white smoke) and loses power dramatically.

Almost forgot, I did a compression test and after 4-5 revolutions the port cylinder steadily climbs to 150 and the starboard cylinder to 145, with no hesitation.
The engine manual says my compression should be about 1/2 of that, but says you're supposed to divide something in order to arrive at their figure. That part I didn't quite understand and will have to re-read. My math sucks as bad as my repair skills.

My compression tester isn't a "leak" tester, but it does have a pressure relief to reset to zero. If I don't press that, the needle doesn't drop. So, I'm guessing that's worth at least something as far as knowing I don't have a leak somewhere - maybe?

Sorry for all the verbiage, but that gets me to this mystifying conclusion so far.
EVEN if I have low vacuum, obviously there's enough to cause the pump to flood the air cleaner & carb. That puddle of fuel just isn't right. Is it??

And that logic precludes most of the rest of my problem theories. Blocked hose(s)? Obviously fuel is getting through enough to flood. Even if I blow them out or replace them - what good will that do to solve the problem?

Carb adjustment? It starts up great - never a problem. Throttles up & down smoothly. But if I put a load on the engine, it blows white smoke and loses power almost instantly.

What is the problem???

THANK YOU!

I see I need to update my signature! We've upgraded to a GT 3185

 

[38racing]

ground each cylinder alternately while running to make sure it's running on both cylinders. I just had an opposed twin that had a cylinder that would not run on 2 different plugs.

 

[WNYTractorTinkerer]

Coils are the usual suspect.. (that's why spark is the first thing you check in the troubleshooting section starting on page #28) It definately sounds ill to me.. almost like a knock.. How many hours on that thing?

The compression test looks good so that rules out any mechanical issues.

You say you changed the oil.. How did the old oil look/smell? OK?

You need to verify your fuel level in the carb bowl.. Close the choke and remove the air cleaner base. Set the throttle @ Idle (prevents any screws from dropping into the carb. bore) and carefully remove the top of the carburator and check the fuel level in the bowl. (You have to wiggle things a bit to remove and unhook the linkage but it can be done) If the level is too high you have a stuck/dirty needle or leaky float. **A failed solenoid usually fails closed and prevents fuel flow.. You have the opposite problem..

Fire back with any questions..

 

[scott_44113]

Sorry for the delay. Here's the update.
But first, as to your questions:
@38Racing, I didn't do the spark test as I am absolutely, most definitely certain that it is running strong on both cylinders. More on that to come.

@WNYTractor, I agree that the audio on my clip above sounds suspect. I think that's an anomaly with the way my camera records in stereo. It actually sounds more like solid lifters, up close. Not a knock.
The hours is questionable. The guy we bought from, presumably, disconnected the clock. I estimate that it has at least 800 hours. At least.
The condition of oil prior to my changing it last month was the same as when we bought it; BLACK and thin - almost watery. The guy told me it was synthetic, and never having seen synthetic oil before, I believed him. When I changed the oil & filter (last month), I got the impression that it had the original oil filter. It was practically welded on, and was painted solid black with no markings. I had to shove a screwdriver through to get it off - my wrench wouldn't work.
I drained well over 1 qt of old, black oil that didn't smell like anything but oil as I recall. Nothing to make me suspect a problem. And at the time, the engine was running fine.
This current problem didn't occur until approx 6 hrs after the oil change and cleaning/gapping the plugs. And new air filters.

Thank you for the info on the solenoid.
I've since determined that I most definitely do not have a fuel problem, either.

And now for update. I still have a problem.
Last week I spoke with a trusted Cub vendor whom I met via eBay. He doesn't do email, or forums, but from my paraphrased description of my initial post, he made a diagnosis.
He keyed in on my oil level. As mentioned in my original:

In changing the oil, I inadvertently added over a pint too much HD 30 oil. It ran fine for nearly 6 hours. Now as soon as I put a load on it, it smokes heavily (white smoke) and loses power dramatically.

His theory was that in overfilling the oil - even though it was just over a pint - I had saturated the engine with oil and that along with fuel was spewing from that (small green arrow) tube in my image above. The tube, he confirmed, is a breather. I thought it was a breather, but I misread the manual and thought it was some weird way of fueling the carb - what an idiot....
His advice was to toss my air filters and run the tractor for as long as possible with a load on it - believing that the filters were also saturated with oil and the engine was suffocating.

I took his advice, after first making certain that I had a full dipstick. It was RIGHT on the FULL mark.
He was right about the filters. Although they looked like new - which they were - on closer inspection they were indeed soaked with clean oil. [I'm wondering if I can salvage them by soaking in gas or something?]

I started the engine - which always starts perfectly, even when it was blowing smoke - and it ran flawlessly. Not a puff of smoke, and virtually no smell of exhaust. Before, it would cloud the barn in less than a minute.

I mowed for almost exactly 2.5 hours. Heavy grass over 8" tall, and thick. Not a puff of smoke or a hiccup. It actually ran better than ever; we've only owned it for a year. On shutoff, no backfire or strange noises. Perfect. I shot this with my old phone so the sound kinda sucks, but I think you can tell it's a steady sound, even while cutting very thick material.

http://youtu.be/0tGKJ20Li2w​

But, as you can see at the end of the clip, I still have a serious problem - I think. After 2.5 hours, I had less than 1/8" of oil showing on the dipstick. And there's probably 1/2 pint of it around the air cleaner and sprayed about the engine compartment.
But WHERE did the rest of it go?? Over a quart of oil, that certainly wasn't detectable if it burned through the exhaust.

If I have a sticking valve, why is my compression so good?
Why don't I have a misfire? I can't emphasize enough how WELL this engine runs right now. From the day we bought it until just last Friday it wouldn't idle smoothly unless the choke was 1/2 closed. But now, it idles perfectly with the no choke at all. Perfectly.

I hate to tinker with the carb when it's running so well. What diff would it make?
How can there be any sort of ignition problem?
And if there isn't one, Why?

The tractor has been sitting over newspaper for 3 days now. I just checked, and there's not a drop of oil leaking from it.

I'll call the eBay fellow ["cubcadetmaster Dave] tomorrow and hopefully he'll have suggestions as well. In the meantime, any hypothesis as to where my oil went is appreciated.

 

[38racing]

you may have a blown head gasket or bad breather. You can make a simple manometer to test for crankcase pressure.
http://www.perr.com/tip3.html
It should be negative. I had a briggs opposed twin that used oil without major smoking but with oil in the air filter and it was a bad breather. Disc had broke off.

 

[scott_44113]

hmm. Definitely food for thought - thank you 38.

I do have a vacuum gauge, but haven't gotten around to figuring how/where to measure the breather at. I presume right at the air cleaner opening is a good start. I don't know or understand the construction/plumbing of this particular breather, yet. But it's beginning to look like the problem.

You said yours didn't have any major smoking, though. Ours has NO smoking. None - not even minor. I paid very close attention to the exhaust throughout the day. I assumed since it wasn't burning, it couldn't be using oil as there are no leaks. But it's definitely blowing out through the breather.

Thank you - very much!

One more thing - what is the "disc" that you said was broken off? Where exactly is that located?

 

[TobyU]

The breather is at the other end of the rubber hose that is blowing all the oil into your air cleaner area.

Two screws hold in on. Has a little metal spring loaded disc in it. You can take it off and clean it wil carb spray cleaner. Air should only move one way through it. A check valve.

Have you pulled dipstick or that blue plug you have in valve cover to see if it has blowby when running?

 

[scott_44113]

The breather is at the other end of the rubber hose that is blowing all the oil into your air cleaner area.

Two screws hold in on. Has a little metal spring loaded disc in it. You can take it off and clean it wil carb spray cleaner. Air should only move one way through it. A check valve.

Have you pulled dipstick or that blue plug you have in valve cover to see if it has blowby when running?

Thank you, and no - I did not check for blow-by from either the valve cover or dipstick. I'll do that this evening when I get back from class.

This thing you are describing as the breather - Is it by any chance the round black object with Mikuni stamped on it, visible in the bottom half of the image in my original post with the red & green arrows? That thing, in either my owner's or shop manual is labeled as the "fuel pump".

Is there any chance that blowing compressed air through the breather tube opening - at the air cleaner - will fix my problem? Or just make it worse?

Thank you!

 

[TobyU]

The plastic Mikuni thing is the fuel pump. The breather is a metal rectangular thing about 1.25 inches by 3.5 inches. Under the carb on mine..but I have a horizontal one. The hose from the air cleaner goes right to the port on the breather.

 

[38racing]

careful with that breather. You are not to press on the disc. blowing air back to it may damage that disc. Testing is done by inserting a feeler gauge. Your vacuum guage is likely the wrong calibration range for the crankcase pressure if it's used for automobiles.
The homemade one needs some sort of tapered plug with a hole through it for the hose and pushes in top of dipstick tube. Put a shut off valve in the other end of the hose and have it closed when starting the engine. Then gradually open it. This prevents the water from either being sucked into the engine or blown out of the tube. A good engine will pull the water up toward the engine.

 

[tomw0]

If you put air pressure into the crankcase, be sure to plug the hose leading to the fuel pump or you might just have to buy a new one. It has a spring loaded diaphragm that gets sucked into one position, and is spring loaded to push back to the other. Add too much air, and it will pop.
The oil was misted out over the grass, or was fed to the engine. I was told by an aircraft powerplant engineer - my dad - that if you saw blue smoke, it was burning a LOT of oil.
I think I would inspect the check valve/vent assembly that feeds the tube leading to the intake manifold or carburetor to see that it is not gummed up by the apparent lack of oil changes, and check the labyrinthine maze used to get the oil to drop out of the airflow for being clogged.
I think you can continue to use it as long as you keep the oil level up. See how much volume it uses for the 1/8" you noted. It may not be that much oil. It may also improve as the new oil works its way into the rings, and may free up the rings to control oil more.
From what I've read, the head gasket thing causes a lot of oil to be consumed, but is definitely worth checking.
tom

 

[scott_44113]

OH-kay... here's what happened.
Thank you, all, by the way, for all the advice & suggestions. Especially about using the compressed air, which I decided not to do.

To reiterate, there was and is no oil leaking from anywhere around the engine. Not a drop.
After removing the oil-saturated air filters and mowing for 2.5 hrs I had oil blown inside the air cleaner and on the inside of the hood - presumably from the air cleaner since there were no other leaks around the engine. And there was less than 1/8" of dark oil on the dipstick. I made sure the crankcase was filled with clean oil before starting

The engine continued to start flawlessly, idle fine, and run strong. Without the filters, no detectable smoke. I even held my hand over the exhaust to see what kind of residue I could get; none.

The last thing I did was to drain the crankcase and oil filter. I didn't replace the filter - just drained it. I was able to get almost 1/2 quart of very dirty, heavy gas-fumed oil out. Here's what it looked like:

That was SAE 30 with less than 8 hours of use, installed with a new filter, and air filters.

This time I decided to use SAE 5-30. I was careful to put exactly 1.5 quarts. What I did NOT do was pay close attention to the level on the dipstick after putting in the fresh oil. I just assumed it would take forever for the stuff to get down to the bottom of the engine, and I wanted to test it out.

So, I ran it again for nearly 2 hours, mowing average height grass. No air filters, again. No smoke, no fumes. Tractor ran perfectly. As good as or better than ever.

When I shut it down and checked the oil, there was less than 1/4" of clear oil showing on the dipstick. :fing20:
And this time, almost no oil in the air cleaner. In fact, only a slight film of clean, clear oil.
Exasperated, I walked away to let it and me cool down. Several hours later I checked the dipstick and there was no detectable change.
Not leaking, not burning, but yet not in the engine.

Family matters kept me away from it for 3-4 days.
Then, on a whim I checked the dipstick and lo' & behold.... the oil level was AT the Full Mark, and it was clean & clear - just like when I put it in. And no gas fumes.
And, of course, the engine starts on the first crank, idles perfectly smooth, and runs strong as usual.

Now, I know that many people think it's foolish to look a gift horse in the mouth, but I would really like to know just what the **** happened here. :dunno:

tomw0 has a good theory to,

inspect the check valve/vent assembly that feeds the tube leading to the intake manifold or carburetor to see that it is not gummed up by the apparent lack of oil changes, and check the labyrinthine maze used to get the oil to drop out of the airflow for being clogged.

I agree with everyone who has said that the lack of oil change(s) caused this mess. Especially since nothing seems to be broken. But obviously something was seriously wrong. Going on the theory that intake was gummed up, would carburetor cleaner have alleviated the problem?
And along the line of cleaners, would one of those crankcase cleaners that you add when changing oil have done any good to clean out some of the engine sludge?

Something else that really bothers me is the lack of diagrams/pictures and/or descriptions in all of the Cub literature I have. Including the Engine Manual, two "Operator's Manual"s, and the 133 page Service Manual. Especially with respect to the breather plumbing.

Thanks again!

 

[scott_44113]

Family matters kept me away from it for 3-4 days.
Then, on a whim I checked the dipstick and lo' & behold.... the oil level was AT the Full Mark, and it was clean & clear - just like when I put it in.

I forgot to ask, along with the other stuff: Is it typical for the oil level to take 3-4-5 days to register accurately on the dipstick?
OR, is this engine still "gummed up" somewhere?

 

[WNYTractorTinkerer]

For your oil to be that thin in just 8 hours tells me your rings are blowing by.. JMO.. You did a compression test cold? Warm the engine up and retest it.. I'll wager it's a lot lower.. Those engines do not like to be overfilled.. It could be a head gasket but I don't think it could leak or burn that much oil so quickly.. It's gotta go somewhere unless you got ahold of some super-secret formula 'disappearing oil' Here is a link to a Vangard Service manual and you can use it to find many helpful tips with that engine: HERE :goodl:

 

[scott_44113]

For your oil to be that thin in just 8 hours tells me your rings are blowing by.. JMO.. You did a compression test cold? Warm the engine up and retest it.. I'll wager it's a lot lower.. Those engines do not like to be overfilled.. It could be a head gasket but I don't think it could leak or burn that much oil so quickly.. It's gotta go somewhere unless you got ahold of some super-secret formula 'disappearing oil' Here is a link to a Vangard Service manual and you can use it to find many helpful tips with that engine: HERE :goodl:

Thank you, WNYTT. A sound opinion, IMO.
I did idle the engine for 5-10 min's before doing the compression test - but it wasn't hot hot, I'm sure. And I know I didn't do a fast idle. I'll do another compression test with a hot engine and post my numbers.

You've also reminded me that when I last checked the oil level, and verified that it was full and clean - I didn't smell it. So, I don't know if it smells like gas or not. I'll do that, too and let you know my findings.

At the risk of being redundant, when I did the initial oil change, at most I overfilled the oil by a pint. I know this because I used two 1 qt bottles and when I became aware of my overfill sin, I still had one bottle that was just under 1/2 full. I thought I'd put in 1.5 quarts - as called for - and replaced the filter with a new/empty one, but, well.... I don't know what happened there. I still can't figure it out, and believe me, I've gone to sleep thinking about it and wakened thinking about it more... Of all the things I have to think about, this thing is tormenting me...
The "super-secret formula oil" is starting to make more sense.

I do have that manual, thank you. BUT, I see on the list you linked me to that there's a manual for twin-cylinder head repair. This may be a[nother] winter project.

Why do you suppose it takes sooooo long for the oil to drain to the pan so I can see it on the stick?? That makes no sense to me whatsoever. I'll tinker with it this evening do the compression test and oil check. Anything in particular I can look for without taking it apart?

 

[rscurtis]

A compression test is useless on an engine with a compression release. If you want to really test the engine's condition, use a leakdown tester. Also, remove the valve covers and make sure the drain holes in the heads are clear.

 

[scott_44113]

I did the compression test on a hot engine, 3x on each cylinder. The readings on each side did not vary by more than a few PSI.
Port side = 135 to 140
Starboard = 145 to almost 150

The oil on the dipstick had not odor of gas; just smelled like motor oil.

I did make some new discoveries, though.
The spark plugs, which have less than 10 hrs on them, had carbon. Not thick or crusted, but required a wire brush to get it off. It wouldn't just wipe off.

Next, the air cleaner had a shallow pool of clean oil laying in the bottom around the carb throat.
I probably didn't mention this before, but I tried to salvage my oil-soaked air filters that had less than 8 hrs use. Soaked them in gasoline a few times and let them dry out. I could see light through them, so figured it was safe to use. Maybe not

So, while the engine did not smoke, or run rough, apparently it was still spewing oil through the breather hose in the air cleaner.

Last observation: Before I started the engine the dipstick showed almost full. The engine ran at medium idle for almost 30 minutes before the compression test. I checked the oil level 3x over the next hour, but there was never more than a 1/4" of oil showing on the stick. And it didn't burn out because I ran it inside a building and the air was fine after 30 minutes and just the overhead door open for ventilation. No smoke.

My theory, based on very little knowledge of how this engine works: When the engine is starving for air and sucking hard through an oil-soaked filter, it builds up vacuum to the crankcase which causes oil to somehow get pulled up through the breather and into the air cleaner.

The Problem with my theory is that if you look at the video at the top of this thread, you can see oil spraying on the air cleaner pan while the engine is running and there's obviously no obstruction (filters) for the carburetor to breathe through and cause excess vacuum.
But that's the best I can think of.

Can someone explain to me the route that the oil in the crankcase/pan takes through or around the block? Maybe the sludge that appeared after the first oil change was blocking, and is still partially blocking, that route. Ports? Channels?

Perhaps the oil gets to the top end and for some time after the engine is shut down, it takes time to drain back down to the bottom so it can register on the stick??

All I have now are guesses. I don't have time to try and Google up how small engines lubricate. I always thought it was a splash method. But maybe this twin-cylinder B&S has something more elaborate?

I soooo want this thread to end.... :/

 

[tomw0]

I would toss the oiled filters. I doubt you can make them functional, and they will always have a bit of extra hydrocarbons on the filter elements. You cannot clean the oil off, IMO.
Did you ever disassemble the crankcase breather I and others have mentioned? One stated there is a disc in there that must not be messed with. I don't know the details of each engine, but there is generally two things behind the little cover. A check valve, and a spongy-type material, possibly metal shavings or hog bristle, that is a labyrinth for the crankcase vapor to pass through. If you had too much oil at one time {you mentioned you might have}, it is possible the breather check valve is damaged and/or the labyrinth is soaked with liquid oil. There should be a pinhole {actually larger} in the bottom of the chamber that allows liquid to drain back to the crankcase. I suppose crud could plug it up, causing the oil level to rise, impeding ventilation of the crankcase.
Did you take that part apart for inspection & cleaning? I would. I would also replace the filters. I would also stop being obsessive about the 1/4" or so change in crankcase level. It is allowed to run the engine anywhere in the marked range. You will not get an absolute {relative?} reading without waiting for all the oil to drain down the sidewalls and moving bits inside the crankcase. I crawled under cars as a teen, and was dripped on by the cam/lifters/??? for up to a week{possibly longer} after taking things apart. Oil takes its own time in collecting and forming drops.
In short, check the level before first operation. If it needs some oil, add it. Keep a general track of consumption to see if it is excessive. Do not worry until the next time you use it. Replace the filter element{s}, and check the crankcase breather/ventilation system. It can cause oil droplets to get into the intake via various problems. Crud, blowby, overfill to name a few.
tom