Kohler kt17 - in 1711

[bpientka]

Hello all,

Been running the 1711 I picked up late summer. The left cylinder had a stuck intake valve which I unstuck. While I have mowed the yard a few times and hauled leaves and firewood the compression on that cylinder is still running 90 psi while the other side is just over 100. Have been running marvin mystery oil in the gas. Maybe 3 tanks of gas through the machine. Having a little oil coming out the breather tube and a fair amount of air.

I know I have to update the breather system since it is the old umbra style.

With the blow by and lower compression think it may be time to pull the head. Does anyone have other suggestions?

Bernie

 

[jchamberlin]

Bernie,

I would keep running the Marvel Mystery Oil (MMO) and check the manual for the PERCENTAGE difference between cylinders before a rebuilt is required.

I would also suggest changing the oil and/or perhaps adding something to clean things --MMO or the additive of your choice. If the oil is OK, I would add the "cleaner" and then change the oil soon after.

You didn't mention pulling the plugs, I would be examining them for indications of blow-by.

The thing that seems to shorten the life of these engines is the state of the bearings, more than the valves or cylinders.

Just my two cents.

 

[bpientka]

Will take a picture of the plugs later today but they looked pretty good. Small cloud of black smoke at startup. Out of the breather tube. Looks like less air at higher rpms and more at low idle but maybe it is the pulsing of air that is making things more visable at slower speed.

 

[jdiederichs]

Bernie,

Updating the breather will be a big help. A good KT 17 will run lots of crankcase vacuum, (in the teens on a manometer) A weak one may even have + pressure. The vac is key to oil control.

You can use the old mechanic's trick to check. Fit a balloon over the oil filler and watch if it blows up or draws down when running briefly. Note, "other devices" may be used as well as a balloon.

Timing will factor in as well, so if you can get a timing light on that KT that would also help.

If I had a KT with that compression I would not be concerned. Have you tried doing a leak down check? Here's a low cost way: Take an old spark plug, break away the porcelain and install an air chuck male end. Seal it or weld in place. Now with both plugs removed and the oil fill cap off, spin the piston on that side to TDC. You generally can feel that sweet spot, if not the engine will rotate when air is applied, so retry.Once you have it at TDC with air on, listen by the oil filler, by the intake/carb and by the muffler. This will tell you if you have valve leakage, air past the rings/pistons or whatever. Note, you can use "line pressure" from the compressor or ~100 psi although less will work as well.

Expect to hear some valve leakage, as this was most common on the K series. Then pull the test spark plug and do the opposite side. Also that old breather will have lots of leakage, that's a given and needs to be updated asap.

Beats going into an engine "blind" for a rebuild. You may get by with a quick and simple valve lapping and resetting.

 

[bpientka]

In an early stop at the local cc dealer picked up head gaskets. Would it be worth just pulling the heads and look at things?

Ran out of time today will get the plug photo soon. I have the breather kit on order and should be hear soon.

 

[bpientka]

Well I did a little testing today with a home made leak down tester and I am not sure I have very good news. The homemade leak down tester was made with parts I had and borrowed the sparkplug connection from my compression tester.

One the left cylinder (90psi compression). With the leak detector I put 100 psi of into the left cylinder and it will only stay at 20psi. The air is flowing out the carborator. So this leads me to believe the intake valve that was stuck and I freed up is not sealing very well. I tried multiple times to make sure I wasn't in the wrong place.

The right cylinder - Compression test around 100psi. Leak down test. I put 100psi into the cylinder and it will stay around 75 psi with the air coming out the oil filler.

So what does this all tell me? For starts I have to get the intake valve on the left cylinder fixed. After that I then hope that the left cylinder leak down test will be closer to the right.

 

[bpientka]

Since the values were not good I tried it again. Now I am not sure of what exactly changed but with the engine cold and a slight adjustment of TDC I was able to get the left cylinder up some. This spot was found by slowly rotating the engine with 10 psi going in. At this point soudns like most of the air is coming out the oil filler. So I still think the intake valve may have problems but under this test the left cylinder is about half of what is going in.

Spark Plugs - left on left

Left Cylinder during test

Right Cylinder during test

 

[jdiederichs]

Well, It would appear then that quite a bit of leakage is happening at the rings, since the crankcase is getting pressure. I would still take a good look at the intake valve as long you have the head gaskets to replace anyway.
Even with a somewhat tired KT17, once you are sure of the left cylinder intake valve sealing properly, that old workhorse should still run relatively well.

Wouldn't it have been nice if that crankcase had a seperate sump that you could remove just like the single K series? Then doing an R&R of the pistons and rods would be so simple. Grrr!

I would still try to check crankcase vac next. If you can borrow a vac guage simply make a cap to screw on the oil fill tube that the guage will thread into. Just another indicator of engine health.

 

[bpientka]

Found a vacuum gauge in the tool box. Will try to rig something up tomorrow.
Thanks for all your help.

 

[bpientka]

Well I was able to get the vacuum gauge hook up to the dip stick and the engine is running a vacuum. Looks like just over 1 inch based on the gauge. The needle it dead on 0 with the engine is not running. Gauge was from a carb sync tool I got years ago for a honda motor cycle. Only used once or twice.

So here is the list.

Vacuum - just over 1 inch of vacuum (with old umbra breather - New one should be here next week).

Left cylinder
Compression - 90 psi
Leak down - 100 psi in - 55 psi out - 45% loss
Air comming out oil filler
Intake valve questionable - Stuck when purchased

Right Cylinder
Compression - 100 psi
Leak down - 100 psi in - 70 psi out - 30% loss
Air comming out oil filler

Should have new style breather first part of next week will replace and check vacuum again.

Also forgot to mention needle very stable at fast idle to full throttle. At low idle really bounces around.
Bernie

 

[jchamberlin]

Bernie, I still think you're about borderline on this motor. Rule-of-thumb on twin cylinders is 20% difference between cylinders: You're on the edge. I still think it will respond positively to working it carefully with good lube and and a watchful eye.

But if "wait and see" doesn't appeal to you, when you tear into it, don't stop half-way, go through it all.

My $0.02.

Edit: What am I thinking? We're talking about one of the most notoriously unreliable engines Kohler ever built!

On second thought; Bernie, if you need this engine to run the tractor --Rebuild it. If you can afford to lose it for the sake of science, try to run it enough to work out any kinks and see if the reading improve or degrade further. If you keep running it, you risk losing it; on the other hand fixing it is no guarantee that it will run a good long time either. If it is a Series I it can fail without warning at any time --at least from what I've heard from people who've run them.

 

[mgonitzke]

You know, everybody knocks the Series I because of the inferior lubrication system, but in the end, it comes down to maintenance. I have heard of quite a few Series I engines that were maintained well and are still going strong. I have had three blown KT-17 engines. One was a Series II, and two were Series Is. The Series II threw a rod because whoever rebuilt it got really carried away with the RTV on the case halves, and a glob clogged the oil passage in the crank. Both of the Series I engines were...you guessed it...run out of oil.

The engine in question here appears to be a Series II, judging by the plastic oil filler neck.

 

[bpientka]

Yes it is a series II but based on model number 24302 and serial number 15007003 i think it was an early series II. Not sure. I am right now just looking for a backup machine to my 1512. I didnt pay a lot for the machine but have put money into it. Outside of the lower compression and leak down test results the engine is not making any strange noises. I truly wonder if I can do a partial rebuild: piston, ring, valves and light cylinder honing just to get by for a while. My greatest concern is things will go bad fast if I keep using it.

 

[bpientka]

Swapped the breather assembly to the new style and checked the engine. Still running same vacuum levels.

 

[jchamberlin]

Bernie, If the 782 is a backup, then I would use it as long as it works and worry about fixing it when it breaks or when you get ready to fully rebuild it completely. I still think the engine is working well enough to use. The data you've gathered doesn't conclusively prove the motor is bad (yet). But you've established a baseline, so you will be able to monitor motor degradation or perhaps even improvement.

I know it is hard to resist the temptation to "fix it" until it is perfect, but engine work costs money. More, its work that must be done right to last. So unless you have experience and are confident that the motor will run better for your working on it, I would hold off until you decide to do a restoration on the 782.

Those are my thoughts, but its your machine; I can't even be sure I would follow my own advice.

 

[bpientka]

Thanks Jeremiah,

I tend to jump into things. I used the tractor today to clean up the yard. To be honest it runs pretty well. Even after sitting days it starts right up. A small cloud of black smoke at start up. I just replaced the triunion seals on the pump and have tto swap things back. My spare pump which is currently on
the 1711 is little whiny. There appeared to be little if any wear in the pump. Which seemed to match the hydro linkage
(little wear). I really have no plans to rebuild the 1711 just want to keep it running. I have a engineless 782 with cast iron rear end that I hope to restore. If I was smart I work focus on that since the 1711 is up and running.

 

[jdiederichs]

As JC said in his post, after all that data you have a great base line established. At this point I would simply run it also. I owned a 4000+ hour KT-17 that still ran great and was untouched! Not saying all are like that extreme one but they are not any more prone to grenade than other engines. Except for ignition, so much of the KT series 2 was carried over to the next gen engines, the Magnum 18 etc. Nobody ever viewed them as weak, so I would rest knowing yours will keep on going.

 

[bpientka]

Well the work continues. The starter has been engaging 40% of the time (starter spinning but not engaging the flywheel) and I remembered all the crud I cleaned off the engine. I figured it need a cleaning. Since I about to swap the transmission and I have new flex couplers to replace, thought it might be easier to pull the motor. Last night I pulled the motor and took off the sheet metal to gain access to the starter. Cleaned starter and it looks good. Cleaned out more mouse material and still need to clean the engine a little more. Couldn't resist pulling the heads and looking at the pistons and cleaning out carbon.

There was a fair amount of carbon on the head.

Here is the right side after a little cleaning.

Right side cylinder wall close up.

So all the all the right side look so so. It seems like a little corroision on the bottom but no major damage. Pistons have STD stamped on the face.

 

[bpientka]

Left side

Left side cylinder picture

There is a similar corrision on the bottom as the right side. Also a few small issues on the top but I couldn't get a good photo. This side also has STD stamped on the piston head.

Intake valve is looking marginal. Compares to the right side the cleaned machined area is only half as wide as the right side.

Will spend some more time today cleaning the engine while things are apart. Hopefully can get a friend over soon (much more engine rebuild experience than me) to get his impression.

If anyone had some suggestions I would enjoy hearing. Either way the carbon had to be cleaned.

 

[jchamberlin]

Bernie, Everything looks pretty good to me. In my experience, a little more usage will remove the oxidation, or it can be honed. What is more important is the shape of the cylinder from top to bottom: you need at least a 3" micrometer and a T-Gauge. I would be interested to see what you find.