Trying to get her going, spring is around the corner.

I had posted previous to running problems, I cleaned the carb, new fuel filter, drained and cleaned the tank, new plug, fresh gas, she runs like a champ.

Sorta......

She will start great, run around great, idles smooth, sorta.......

When at idle, (I sat and watched it for about 15 minutes at full power idling), she will bog down every so often, no pattern to it, and right as she bogs and almost dies, she puffs out a plume of blue-white smoke that stinks of oil, then idle right back up and purr til the next bog, a minute, or two, whenever.

Do I have a oil leak into the cylinder?

The front valve cover leaks bad, I need to address that, but wanted to see if that would get into the combustion or not.

It leaks out the front on the bottom of the valve cover.

Craftsman mower, 18.5hp OHV Intek Plus engine.

What could I be looking at?

Thanks, let me know of anything else needed for diagnosis.

Blair

 

Well if the engine revs up to high oil will come out of the crankcase breather wich is conected to the intake, this could cause what you described.
Does it idle real high?

 

No sir.

With the throttle in the highest position, it idles no higher and smooth, until the stumble where it will belch the smoke.

Then it idles back up to normal high position.

 

What do you mean by idling in the high position? Do you mean 1200RPM or 3600 RPM (3600 RPM being the highest speed for most lawnmower engines)

If I idle my old Kohler K341 for a while on oil with ~12 or so hours on it, as I rev it back up, it bogs down and chugs blue - whit smoke for a few seconds until it burns all the oil out of the cylinder (cylinder bore has oval-ised a bit over the year)

 

drop a ford 302 in it and hit the lawn full throttle!!!!

 

How old is the unit (year made)?

What kind of ignition system does it have - solid state, or does it have points?

 

The problem is (1)crankcase breather which is connected to the intake via little rubber hose, usually under the airfilter. It is usually not bad and wont cause problems unless you have put too much oil in it. (2) Valve seals are leaking. They are just like a little OHV car or truck and are repaired the same way. I vote #1. You can remove the tube from the intake to rule it out, but be sure to crack the oil fill/dipstick to relieve pressure. Also, be sure you have the propper ammt. of oil in it. Good luck.

 

Sticky governor ???

I've never worked on an Entek, but have seen this on my blower w/ an 11hp B&S.

 

We'll start here.

Typical lawn tractor, throttle has rabbit/turtle markings. Lever in rabbit position, but instead of driving around, I've got the tractor in nuetral, parking brake on.

Just sitting there idling, with the throttle up like your getting ready to mow.

It's a 05'. Good question on the ignition. Has a magneato (?) that feeds off the flywheel, and runs to the spark plug. After that I need a book to look at. New plug and magneato.

Good oil and level.

Could the intake be getting the oil in it from the tube directly? The oil level looked good, but I suppose there could be a bit much. I can just drain it and refill for good measure. Got lots of good oil to use up.

I was leaning towards valve seals after doing some reading.

Never done a valve seal. I consider myself a decent backyard mechanic, just haven't done those yet.

Could I tell if I took the hood off, took the cover off the valve cover, and simply looked at them?

Any special tools needed to change the valve seals?

Oil level is good right now.

Many thanks for the replys.

 

When the oil level is too high, the vacuum from the motor will suck the oil into the tube and cause the puff of smoke thar you refer to. The crankcase breather acts like a PCV valve on a vehicle. It will suck out the pressure before it has a chance to build up. Being an '05 model 18hp, it probaly has full pressure lubrication with a spin-on oil filter. It is very easy to overfill one of these type motors. If the oil registers on the stick above add and below full, it is ok. IMHO I think that the full mark is too full so I keep mine and all that I work on 4oz above the add mark. (It usually takes 8oz between add and full) The crankcase breather has a foamy filter in it that I have cleaned in the past with some brake cleaner and let sit and dry overnite. As far as the valve seals go, They are simple to replace with the right tools. You usually can't see them with the springs still in place and definately could not tell if they were bad without removing them. You will need to remove the head, it will come off as an assembly with the valve train. You can leave the pushrods in place or remove them, they are the same length. You will need an automotive OHV type valve spring remover/installer. You will need a new head gasket and valve cover gasket and two valve seals. The valve seals are metal and are pressed into place over the valve guides. You can remove them with a pair of needle nose or similar. give them a gentle twist and they will come off. To reinstall, I have used a 9 or 10 mm socket to press them back into place. Be careful not to damage the spring in the top of it. Then just reverse the process. As I stated before, I think that it is a breather problem and not valve seals. Just my .02. Good luck.

 

Thanks Kevin.

I'll give her a once over and check that breather.

It does have the spin on filter and full pressure lubrication. Even says so on the engine cover with a sticker.

Thanks,

I'll look at it tonight.

Blair

 

Blair,

I'm really 'old school' when it comes to small engines.
First. . . idling is idling.
Full power idling is not 'idling'. That is running full speed without a 'load' on the engine. I don't recommend that, at all.
Does the engine 'lag' or 'stall' or 'stutter' when you have a load on it?


As for the oil leaks at the front cover, absolutely, replace the gasket(s). I don't like leaks, at all, whether it be car, truck, mower. . . any of 'em!

I'm also of the opinion that if you are only getting a brief 'puff' of burning oil that this is 'o.k.'. That is, only if it is a brief occasional occurance.

I've got a 16 hp B&S I/C twin engine that is 16+ years old, and has never had anything done to it, other than a 'magnetron' and oil changes.
It does 'puff' burnt oil when starting up, when hot, after running for 45 minutes or so.
I have to add 2 to 4 ounces of oil every other time I cut grass.
(And NO leaks!!!)
That 'puff' of oil shows me that everything is getting lubricated and I haven't worried about it.

 

It sounds to me like you have a peice of dirt in the fuel bowl, which is shutting off the gas for a split sec. As she is bogging down the choke starts to close and richens the mixture. Hence the smoke. Try putting a little Sea foam in the gas and run it with a load on it.(drive it around) This Should solve your problem.

 

It doesn't puff at all on startup. I hear you on the full throttle without load, won't do it anymore.

Under load, it has no lag or stutter or stall, except when it does this bog down with the plume of oily smoke directly thereafter.

But it's often enough (every couple of minutes), that it's highly aggitating. We're talking while a small plume to me, it's enough to cloud the yard for a minute or two.

Thanks for the idea on seafoam, I used some when I first bought it and the carb was real dirty.

I can try some again and check back to the thread.

Lots of good ideas I need to address. I'll post up, supposed to rain tonight though.

One thing I noticed, I used the wrong plug. The last one as I stated was different too.

The new one is a CJ12YJ or something, I grabbed a CJ14YJ and didn't know it.

I'm going to get another, but wondered what difference it could hae on things if any?

Many thanks,

Blair

 

Crankcase breather hose has oily residue in it. Enough to coat my finger.

Didn't do anything else with it. Just felt the hose.