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a.dumont

Kohler 18 HP Lacks Power

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1973 Kohler 18 HP twin K482S. Carb cleaned, new fuel pump, fresh fuel, changed oil, gapped plugs and points... Starts and runs just fine, but lacks power; most noticeable when mower is engaged and moving. The engine slows down considerably and takes a while to catch up. Does anyone know the cranking compression spec for this engine? Can it be a timing or valve adjustment issue?

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I am not sure if this will help, but on My c81, when i engage the pto by pushing the lever forwards, my motor slows and my pto doesnt spin. It could be a problem with the pto or it could be your timing for compression is off. 

I am not sure about the cranking compression stats, I am a newb- i just really got my first tractor a few weeks ago and am trying to make it as close to restored as i can get it. 

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Get the Kohler manual , either the pdf version here for older K series twin opposed engines or the paper versions but look for an original manual , not a copy as the photographs aren't very good at all . Sounds like you need to set the valves - it's pretty simple but it's a good idea to order the valve cover gaskets first as they tear easily during disassembly . Over time , as the seat and valve wear they can hold the valve open slightly which will severely drop it's power output and can burn an exhaust valve . Mine were down to nearly zero clearance , starts and runs perfectly now . Also , on the K482 - check the breather vent located on top of the governor - it has two long bolts holding it on . I ran a bit of brake cleaner through mine (non-chlorinated type) and got quite a bit of carbon out of it . I cannot find a replacement but would like to put a new one as mine is starting to develop several small leaks at the seals . If the breather can't function as it should - you lose the vacuum on the crankcase which helps keep the rings seated properly and can start causing seal leakage . It basically works just like a pcv valve from what I can see of it , just a spring loaded valve although it doesn't fully seal as there is a bleeder hole .

 

That K482 is one of the best engines ever built - monster torque levels , decent oiling system and built like a tank , not to mention the weight of it's rotating mass . There are also settings for the timing - easy to check and set once you find/highlight the marks on the flywheel - settings are done through the governor housing slots .

 

Sarge

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My mistake in searching for a manual was including the "s" at the end of the model number. Searching for just K482 I found a very clean version. (See attachment) I ordered a timing light, and will set the valve clearance today and retest. I'll also check the static timing while waiting for the timing light to show up. Thanks sarge!

Kohler-K662-Engine-Manual.pdf

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Checked the valve adjustment and only found #2 intake out of spec. Verified static ignition timing. Ran engine until at operating temperature and checked compression. Book says 90 PSI minimum, no more that 15% difference between cylinders. Measured both at 65 PSI... Engine is not burning oil. Carbon cleaned cylinders and retested at 75 PSI. Will do a cylinder leakage test next. This "free gift" from the father in law is turning into a real project. Just need this thing to run strong enough to mow, snowblow, and drag a york rake. So far it's not promising. Timing light will be here on Tuesday to adjust the dynamic timing.

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Something to keep in  mind. An engine can run real nice but lack power if the exhaust is restricted.

Had one that I thought was carburetor icing. Same symptom. Let it sit a minute, restart and good for a while. What happened was an internal baffle disintegrated inside the muffler and it would move around until it covered the exhaust outlet. Exhaust pressure would hold it there reducing performance. Shut it off and the baffle would fall away from the outlet. Power restored after a restart. Tapping the muffler with a rubber mallet one could hear the loose baffle.

 

Garry

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The compression should have actually gone down after the carbon is removed, don't know why you would have had a increase.  Can you see if the throttle is fully opening under maximum load?

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Yes , those mufflers on the D's can be a real problem when they rust and collapse internally - both of mine barely flowed anything . It seemed to have almost too much torque at low to mid rpm , but at full revs lost power - that's why I built the new stacks/mufflers for mine . Pulls like an idiot now .

 

Go through those governor settings closely as well as the the throttle limits and adjustments . Make certain that choke is opening all the way as well as the throttle valve with no slop in the shaft . If it can't breathe it can't pull right . The timing was off a bit when I first got mine - I chalk it up to wear over time but overall mine is in excellent condition . Also , look very closely behind the main engine cover tins and hope a rodent hasn't been busy packing it full of nesting material - mine had a 5-gallon bucket full as well as deep into the fins . The engine is pretty easy to pull and inspect - 4 bolts for the nose , a few wires and the 4 main bolts on the frame as well as the stator wiring . More work if it has the front pto , of course .

 

You'll also want do download the parts list here -

https://www.kohler-engine-parts.opeengines.com/index.php?main_page=document_general_info&products_id=12023

 

Very helpful knowing those original part numbers when trying to locate replacement parts . Without it , the shops have to look it up and that takes a lot of their time .

 

Sarge

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First thing I did was to pull the engine and pressure wash thoroughly. Removed all covers to find a lot of mud wasp nests.

 

So the timing light showed up, flashed once, and then died... sent back for a replacement. Getting one with a tach feature so I can properly set idle and max rpm. Will then set timing. Once all is complete, will recheck compression and cylinder leakage if necessary. Like a fool, I forgot to remove the air filter and leave the throttle and choke wide open. May have skewed my compression numbers.

 

The muffler issue is something I will definitely check. Sounds healthy, but by adding load to the engine, I am demanding more airflow, hence if they are restricted I will have issues. Just concerned with getting them apart without getting broken bolts stuck in the heads. Are the heads cast iron or aluminum?

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11 hours ago, a.dumont said:

First thing I did was to pull the engine and pressure wash thoroughly. Removed all covers to find a lot of mud wasp nests.

 

So the timing light showed up, flashed once, and then died... sent back for a replacement. Getting one with a tach feature so I can properly set idle and max rpm. Will then set timing. Once all is complete, will recheck compression and cylinder leakage if necessary. Like a fool, I forgot to remove the air filter and leave the throttle and choke wide open. May have skewed my compression numbers.

 

The muffler issue is something I will definitely check. Sounds healthy, but by adding load to the engine, I am demanding more airflow, hence if they are restricted I will have issues. Just concerned with getting them apart without getting broken bolts stuck in the heads. Are the heads cast iron or aluminum?

The exhaust is bolted to the block not the head and it is cast iron...also brittle with heat and age.  Be very cautious use penetrant and work;slowly you can easily break off a piece of the block...don't ask me how i know this

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:text-yeahthat:

 

The cast iron Kohler twin opposed engine's and their exhaust outlet is a very brittle area from heat/age - I have one outer bolt hole that ended up getting a heli-coil in it and it is cracked already . When I built the stacks I went ahead and installed studs to prevent further problems later . I've seen two of these blocks welded and once you go that route re-drilling and tapping for threads is pretty tough due to the carbon content being concentrated from the weld - no fun to try to re-tap those holes . The very front holes seem to be the worst - both bolts broke off , one came out with heat/wax and the other refused to budge so it got drilled and also snapped a tap off in the hole . Removed that with a Dremel and a carbide burr , installed the heli-coil and it was good enough to work . Trying to use pipe wrenches to break the pipe connections loose on the 90* adapter may put enough leverage on the engine block to snap off at least half of the port outlet - so I'd avoid that at all cost . If nothing else , have a welding shop remove those bolts - those guys are specialized in getting steel out of old cast iron and can deal with it better than the average Joe...

 

Sarge

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So new, quality, timing light came in this week. This afternoon I adjusted the timing, set the idle and max RPMs (light has a digital tach). I verified the governor spring is in the correct holes. After bringing up to operating temperature, noticed that there was still a lack of power. Retested compression and found 110 PSI on both cylinders. (Better than last time. Remembered to keep the throttle wide open while cranking.) Removed the mufflers and ran again (boy did that sound awesome, almost like a v-twin Harley at idle)... but no change. It has Champion H10C plugs gapped at 0.035". Depending on which manual I read, I seem to get different gaps and plug numbers. What should I be running? Is this thing supposed to have glass-pack style mufflers (wife said it's too loud even with them on)?

 

Moving next week and need this rig to be running it's best.

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13 minutes ago, a.dumont said:

Champion H10C plugs gapped at 0.035"

That would be fine for a single cylinder Kohler with a battery ignition.

What you need is Champion RBL15Y gaped at .025"

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11 hours ago, 953 nut said:

That would be fine for a single cylinder Kohler with a battery ignition.

What you need is Champion RBL15Y gaped at .025"

My engine is battery ignition, but just a 2 cylinder. Does it make that much difference?

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51 minutes ago, a.dumont said:

My engine is battery ignition, but just a 2 cylinder. Does it make that much difference?

Yes, same plug, but gap would be .035.

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There are baffles in those mufflers - or at least at one time there were baffles , lol . Most rot out on these the way they can hold moisture if you don't run it long enough to get them fully heated . Correct plug gap is critical to the head/valve design in these engines and it does make a big difference .

 

I do have one key question - how are you determining the lack of power/performance ?? Is it not pulling a deck very well , or a blower or some attachment ? Or , is it just slow...?

 

Sarge

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Everyone I've talked to says this thing should mow fairly well. With a 48" deck, full throttle, and only 1/3 forward speed... the engine slows down as soon as it needs to cut only an inch off the top of my grass. I'll try the plugs today and see what happens. Going to Fleet Farm to find new mufflers too.

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If Champion RBL15Y's even existed, they don't anymore. Searched their catalog and came up empty handed. The 2016 Champion catalog surprisingly had a listing for a Kohler K482: standard plug H10C, premium plug RH10C, both to be gapped at 0.025".

 

I replaced both plugs, air filter, and warmed up to operating temp. Adjusted idle to 1,350 and max to 3,300. Readjusted main and idle jets. Took it out and it seems to be running better. Hard to tell, as I mowed all the grass already... maybe my neighbor needs a cut.

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37 minutes ago, a.dumont said:

If Champion RBL15Y's even existed

Check page 4 of the manual, I didn't make it up.

On page 41 of this Champion booklet it calls for a RV17YC for the Kohler Twins.

 

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I'll be. Fleet Farm had two 2016 catalogs. Both skipped over "B" as a possibility for the second letter.

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Just a suggestion - have you checked the spindles and pulleys on the deck and mule drive ? A 48" deck to the K series twin shouldn't be any issue - that engine should hardly notice it .

 

Sarge

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Strange ..... with all you've ckd would've thought it would act right! I have 2 D's with 48 decks and I'm sometimes still amazed at what that thing will do, in heavy grass the governor will kick in and that thing will just roar and keep on cutting!

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Yeah - there is no reason that engine shouldn't just grunt and keep pulling - it has so much torque it's crazy for it's hp rating . Any time that governor kicks the throttle - either something is going to move , or something is going to break - it doesn't care which , either . Mine barely grunted when I caught the cement with it last year , peeled up the cement pad and promptly destroyed the hydro pump coupling all in one snort of that engine .

 

Sarge

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23 hours ago, a.dumont said:

I'll be. Fleet Farm had two 2016 catalogs. Both skipped over "B" as a possibility for the second letter.

On page 41 of this Champion booklet it calls for a RV17YC for the Kohler Twins.

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