We own a 3 year old Sears Garden Tractor with a Kohler 25 HP twin V engine:

Family - 4KHXS.725ZGC
Displ (cc) - 725
Model No. - CV7305
Spec No. - CV730-0029
Serial No. - 3402901441
OEM Prod. No. - 190093

Recently it has been starting with a large puff of blue smoke, which after a few minutes of running lightens up quickly. After it fully warms up the blue smoke almost disappears. If you shut it off for a minute and start it it will only smoke lightly but if you let it sit for 30 min. it will blow a large amount of blue smoke again.

I don’t believe this would be rings because it appears as if the oil is seeping into the cylinders when it is turned off. Could this be some type of valve seal and can they be replaced easily. What would be causing this to go bad at such a young age (150 hours of run time)? What can I do to prevent this from happening again?

Is this typical of new Kohler engines? I thought they had a good rep.

Please help

Thanks,

Brian

 

There is a replaceable valve stem seal on the intake valves of your engine. This is very possibly the source of your aggravation. This is not an uncommon condition with overhead valve engines and since the smoking is not excessive it's up to you if you want to replace the seal.

The seal can be replaced without removing the head, but you have to be careful that the valve is not dropped into the cylinder when you have the retainer off or then the head will have to come off.

Kohler engines in my opinion (for what it's worth) are good, I see small amounts of smoke on many brands of overhead valve engines on start up, be it Kohler, Kawasaki, Honda etc...

 

If you have the oil even slightly overfilled and since this is a vertical shaft engine and since the number two cylinder bore is relatively close the oil sump oil level, you will get seepage past the rings on that cylinder and smoking such as you have. Also, if you have the mower on a slight decline (front of machine, therefore cylinders will be downhill) you may get the same effect as overfilled oil. Have you read the spark plugs and noticed one (versus the other) is noticeably darker and oil fouled? This will likely be the left cylinder (as viewed from the seat) as this is cylinder # 2 and the lower of the two cylinders.

 

I also am having a smoke problem with my 3 year old 25 hp kohler motor. I bought it, Craftsman Garden tractor toward the end of the season three years ago. Have used it less than two full seasons and do not use it in the winter. It is an oversized tractor for 1/2 acre of grass that I have. I change the oil and filter twice a year but engine still started smoking. Before you know it, I started fouling plugs at a rate of one every half hour. Took it to a mechanic who said that the right side valve stem was warn. He was suprised and said that he had only seen 1 other Kohler engine go bad like that in 29 years of work. Engine was not abused, it just went bad. Is there anyone else with this problem or does any one have an idea of how to fix it? Is it worth fixing?

 

You likely have a blown/leaky head gasket, Kohler has had
a lot of problems in this area. Compression leaks past the head gasket, and pressurizes the crankcase via the pushrod chamber, and pumps oil into the breather. Get the kit{update} for both sides, it has new bolts and instructions.


Fish

 

I am also having the identical smoking problem with my Craftsman garder tractor that 'cadman' and 'JohnMan' are having. This is more than a coincidence!

I called Sears and talked to a tech. He said he didn't see any reports of the problem we are having (hah!) I'll bet every person who bought this engine is having the same problem we are having!

Larry

 

Fish is on the money.

I have an '03 Kohler 25HP in a Craftsman GT5000 that went through the same thing at 130 hours. Kohler and Sears are fully aware of the problem. Kohler came out w/an upgraded head gasket kit w/new bolts/studs like Fish said. I bought the upgrade kit for both heads from OPEengines.com for about $35.00 including shipping. The Right side Head Gasket is usually the culprit, but I did both. No more smoke.

DSM

 

DSM - I believe I have a blown HG on my 25HP Kohler. On mine it appears as though there is oil leaking out from around where the exhaust bolts up to the engine. It's the cylinder on the same side as the oil fill..

I've not yet torn anythign apart. I found the service manual for my engine & have read the dis & reassembly instructions. I can't tell if you have to remove the rocker arms during this process (gasket replacement). If not I'm thinking about trying this myself as my dealer is 1.5 or more weeks behind in his shop work.

Can you advise on the arm removal & just how hard this really is?

Thanks
Twin

 

The rocker arms do not have to be removed since you are not doing a valve job. The head and valve train can come off as one.

 

I have a CV730 on my Deere G100 which blows smoke on startup and I am planning to replace the head gaskets this spring.

I've worked on cars for 30+ years but have never taken a mower engine apart. Anything tricky about it?

Is P/N 2484103 the "updated" head gasket kit?

What else do I need? Valve cover gaskets?


Debating whether to replace the valve seals while in there - your thoughts?


IIRC the engine has ~200 hours on it, and the previous owner probably did not maintain it properly.


I have the service manual for the engine - just asking for any beyond-the-manual knowledge you might have from experience.

TIA.

 

There's nothing tricky about it...pretty straight forward. The only thing I might give you a heads up about is that some of the shroud bolts may be stuck in the aluminum. If they don't turn, or begin to back out and then get stiff...don't force them or they'll likely break. Get some PBlaster and spray it, turn it in, then back out, then back in, etc... until you are able to work it out. For some reason this seems to be a common problem on kohlers. It's no fun when a steel bolt breaks off in aluminum.

 

I too am having the same problem with the same engine.
It seems to be getting worse, or at least it's taking longer to clear out. It's also consuming a fair amount of oil in the process. At first I suspected the valve seals going bad but I have been on another forum asking what's wrong with it.
Most people have been saying that it's most likely the head gaskets going bad and pressureizing the crank case.
What do you guys think??

 

Head gaskets.

For some reason that reply wasn't long enough, so I am typing this to meet minimum character requirements for a reply and avoid the error message that my reply was too short and not allowed.... That should do it.

 

Thanks! I'll be careful.

 

Well, I ordered the head gasket kits and decided to go tear her apart while I'm waiting. Sure enough, the head gasket on the right side is blown and there is about a half a teaspoon of oil lying in the cylinder.

I cant believe how close the cylinder wall is to the oil galley.

 

Yup, something like 1/4" between them on the gasket if I recall correctly. Let us know how it turns out, or if you run into trouble along the way!

 

Sure will. I may need help putting it back together, I can't believe how much crap you have to take off just to pull the heads. Tearing apart a bran-new engine,

 

I just replaced both head gaskets on my kohler CV730 and I had to remove the rocker arms to remove the heads. Does anyone know what to torque the rocker arms back to? I don't believe they can be adjusted so I must not torqued them down properly, I can start the engine but it is not firing correctly and running poorly. Any suggestions?

 

You need to torque the rocker arms down so that they have the proper spacing between the valves. Like the other post i replied to I am not sure what the correct spacing is but I am sure one of the tech guys knows. You can adjust the spacing with a feeler gauge.

 

I found the torque spec for the rocker arms; 100in lbs. I re-torqued them and still not running correct. I don't think you can adjust the valves on hydrolic valves, am I right? Currently it's only running on the #1 cylinder. Which leads me to believe that the valves on #2 are not closing.seating and no compressing/firing is happening.
Thanks for any replies.

Mike

 

That is why you have to adjust the spacing between the valve stem and the rocker arm. I know on most small engines it is around .01 for the exhaust and .008 for the intake.. I might be wrong Techs correct me if I am.

 

I understand and agree 100%. However, these rocker arms are bolted to the head. I don't see where you could adjust the spacing like on a car with a feeler guage. These simply bolt down and get torqued to 100 in lbs. But obviously the valves are not seating correctly. Would installing the intake and exhaust rocker arms on the wrong valve steams cause the problems I'm having? I tried to assemble the back the way they came off, but I could have mixed them up.
Thanks again for your help.
Mike

 

I am not all the familiar with Kohler engines but there should be two nuts on each rocker arm. One is smaller than the other and is on top of the bigger nut. You loosen the smaller nut then adjust your spacing with the bigger nut once the spacing is right tighten down the smaller nut making sure that the bigger nut doesnt move. Hope this helps
-Will

 

These hydrolic rocker arms are not like that. I am familiar with the type you discribed but these just bolt to the head. No place to adjust them. I will try switching the intake and exhaust rocker arms. That could be my problem, I hope.

 

Well are the springs in good shape??

 

I guess so. How do you check to see if they are still good? I bought the mower 20 Feb 2005 and I put about 100-200 hours on it. The head gaskets failed once under warrantee and again last weekend. I changed both head gaskets, re-assembled the engine and it runs rough. I unplugged the #2 cylinder spark plug wire and it runs the same. So, I think the valves are not closing correctly on that side. I'm going to swap the rockers and see if that helps. Thanks again.

Mike

 

They should be generally no less than 90% of a new spring, but i doubt you dont have any new springs so I really dont know.

 

I just switched the rocker arms and it is still running on the other cylinder.

 

Ah just wait till one of the techs get on. They can probably more helpful.

 

You may have a bad lifter. The hydraulic lifters, as you know, do not require adjustment of the valve clearances. They are self adjusting. When you tighten the rocker arms down, if the valve opens and the engine is on TDC, then the lifter is still pumped up and may need some time to compress. Leave the valve cover off and come back to it later. See if the valve is still open. If not, put the cover on and crank it up...you should be fine. If the valve is still open after letting it sit for a while, then the lifter is stuck and will need to be replaced or at least cleaned out.

 

I let the mower sit last night with the #2 piston at TDC between the exhaust and intake stroke. Hoping this would let the lifters bleed. I just tried to start the mower and I was unable to. I can visually see both valves opening and closing as I turn the engine over. Would they do this if a lifter was stuck?

 

I'm not saying the lifter itself is stuck in the engine, but the hydraulic components inside the lifter are possibly stuck. The lifter itself will move, but the lifter is not a solid piece of metal. It has moving parts of it's own, and sometimes they get stuck. Commonly after doing engine work that could introduce a piece of carbon or gasket material into the workings.

 

I think I understand what you are saying. If I have a bad lifter, would that prevent the valve from closing completly? If so than I think that is what I'm experiencing. Looks like I have to pull that head off and service/replac the lifters. Thanks again.

Mike

 

Yep...if the lifter hydraulic components inside it are stuck or clogged, it will not bleed down. This keeps the lifter from adjusting itself. It stays pumped up too far, holding the valve open. The lifters on these seldom give problems, so I'd just replace the one in question, not all of them, if it were me.

 

After following the blead down procedure again, I let the mower sit for a day. It will start but still will only run on one cylinder (#1). I opened the valve cover on #2 and watched carefully to both sides of the rocker arm as I loosened the hex flange bolt (that holds the rocker down) and the valve spring remained still as the push rod backed out. This indicates that the lifters are indeed bleading down correctly and the valves should be seating properly. If the valve spring back out then I would suspect a bad lifter keeping the valve from seating.
So, I am still only running on one cylinder. Both head gaskets were replaced, both cylinder heads were reassembled the same way, to specifications. I get spark on both cylinders, and the fuel pump pulses fuel when the engine is turned over/started. When I can get the engine to start on the one cylinder I can see a small back fire (a puff of compressed air and fuel) out the carb. As if the valves are not operating correctly on the dead side (#2).
So what does anyone think I should do next. Any imput is appeciated.

Mike

 

Mike,
I have been working on Kohler CV23S with very similar problems you are having. I can unplug the wire on cylinder 2 and it sounds hardly no different than when both wires are pluged. When I unplug wire 1 with 2 plugged the engine stalls. So I was convinced that cylinder 2 is not firing. I then took the valve covers and heads off on oboth cylinders and compared. I saw no differeneces. Both cylinders, valves appear to be working and seating and the head gaskets looked good. I reinstalled with new head gasket kits to specs in the service manual. I tightened the rocker arm bolts to 100 in/lbs and made sure the rods and arms went back in the same positions. I even swapped coils between cylinders. Nothing I did has changed the sympton. What is interesting is I have a 17 HP Kawisaki
Twin Cylinder engine on another comercial mower that is working good. When I unplug cylinder 2 at medium idle on this mower it hardly makes a difference, just a slight shift in firing. When I unplug cylinder 1 with cylinder 2 pluged the engine stalls emediately, exactly like my Kohler does. I am by no means a small engine expert, but either I have 2 engines with the same problem although the Kawisaki works or I have the wrong idea on how a twin cylinder works. Is it possible you can not unplug individual cylinders on a twin v to diagnose problems. I am all ears for any suggestions.

 

I'm all ears, too. I started another thread and I posted all of my info there. Check out Kohler VC730S problems. I can't fix mine so I hope some else can help.

 

Unplugging either cylinder should have an equal effect as the other. Not sure what's the problem without performing a leakdown test.

 

This engine has proven to be flawed in many tractors. For those of us who cannot tear an engine apart, we are out of luck. Service from folks like Home Depot, Sears is hit and miss - and for me I have found genuine dealer will not service what they didn't sell you.

True customer service is dead or on life support.

Old but accurate:

My '04 Husqvarna GTH2548 with 60 hours on it started blowing bluish smoke and ran thru a quart of oil in 10 mins. Called Warranty Repairs, as soon as the Tech came out he went right for the right side of the engine (right side looking from driver's seat)and pulled the plug out. Badly fouled. Head gasket blown. He replaced it and the 4 bolts. He told me this is a KNOWN issue with these particular engines. Told me Kohler used the wrong bolts and after heating and cooling the bolts on the right-hand side "stretch" and cause the gasket to fail. Also said Kohler had redesigned the head and eliminated 2 bolts, making the head almost impossible to torque down evenly onto the gasket.
I am livid. I know this engine had to reach unacceptable temperatures when it blew a quart of oil out, yet the Tech tried to reassure me by telling me there wouldn't be any other damage to the engine from the failed gasket and low/overheated oil.
Needless to say, I am now on the warpath and Kohler, Lowes and Husqvarna WILL make this right, even if I have to resort to "extreme measures" to get their attention. When I went to Lowe's and gave them $2400.00, AFTER they talked me out of buying a competitor's tractor, I TRUSTED them, and believed them when they told me if I had ANY problems with the tractor they would "stand behind it all the way."
And, for those of you still reading, this issue is in addition to the ongoing problem I have had since day one with the tractor lurching foreward or backward and taking off when the shift lever is in neutral. They have been out 3 times to fix THAT problem and haven't FIXED it yet.
If you have an '03-'04 25hp Kohler... you might want to get ready for a bumpy ride.

 

Hi,
I have been searching the Internet for solutions to my problem and it looks like there are A LOT of people with the GT5000 (I have a late 2004 25hp model) Kohler engine that have the same issue.

Here is what I did, which did NOT solve the giant plumes of blue smoke: Based on Internet research, changed the head gaskets, they both looked fine (old ones). Guess what, still blowing blue smoke after about 30 minutes of mowing.

Further research:
Determined through jerry rigging that the culprit is the breather going from the right side valve cover to the carb. When the mower gets hot it shoots a LARGE amount of oil into the carb (loosing almost an entire quart after 1 hour of mowing). Easy to verify, I put a hose from the breather into a temp bottle on the side of the mower. After a short bit of mowing, can see oil spewing out the hose from the breather.

My shadetree analysis:
It appears that the mower is overheating for some reason causing the blow through. Any ideas on why this thing would be overheating? Or is there some seal (other than the head gaskets that would allow blowby when hot)?

Another test:
I tried mowing without the engine cover on, guess what, didn't smoke for quite a while (100+ temps here in AZ). It smoked a small bit after another 30 minutes but no where near what is was. That is why I am leaning towards either overheating or some seal is leading at a certain temp.

My situation:
2004 Craftsman GT5000
Head gaskets replaced (old ones looked perfect)
Oil level good
Deck cleaned before each use
Zerks greased

Thanks for any assistance.

BTW, had Sears service techs out twice and the have "no clue" can't believe Kohler doesn't know about this.