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View Full Version : 20 hp kohler trouble


buzzer12
06-02-2007, 06:11 AM
could someone please help me!! i'm asking again. i put new rings in, put it back together, new head gaskets. here's the problem i'm getting, one of the lifters is bending. plus when it does fire, i can see in coming out of one of the eshust port oil .plus i can actully see the fire inside the head, now when it does start, when i put the muffer back on, it won't start, take it off it will????????????? now when i put evrthing back i did it by the book . do i need a new head or should i just buy a new engin???? any help would be great thankssssssss

tomo
06-02-2007, 05:45 PM
hello,
1/a lifter bending very strange ,are u reffering to the pushrod ?????????

soak lifters over night in light weight oil
are the lifters worn on the base where the cam operates ,any depression in this area even minor replace lifter .Cam also becomes suspect when lifters r doing this [soft lobes ,very common in OEM cams]

were the heads serviced b4 reassembly [carbon etc can cause valves to stick and place greater than normal load on valve train ]

Camshaft to crankshaft timing ,marks aligned ??????????

Muffler causing engine not to run ,very unusal unless completely blocked u would think .

Engine bores measured properly taper and ovality ???????
Engine bores ,were they honed only or bored as well?????????
What was the cross hatch angle of the hone pattern ??????
Does the engine have nickle seal bores or cast iron ????
REASON 4 OVERHAULING ENGINE IN THE FIRST PLACE ??????????????

tomo ,any Q :waving: :waving:

khouse
06-04-2007, 02:07 AM
With the muffler off you will see fire in the exhaust port. You either have a binding valve or the mechanical timing is way out to bend a pushrod. How many times has it bent a pushrod? Once you get ll that fixed make sure the flywheel key is not sheered. Don't buy a new engine - I think we can help you.

buzzer12
06-04-2007, 04:33 PM
the push rod bends every time i will check the flywheel i made sure the timing marks lined up when i put it back together please i would like some kind of guidinance to get this running pleeeeeeeeeeeeease

khouse
06-04-2007, 04:47 PM
The flywheel key will not make the pushrods bend. I just wanted you to check it after you have the mechanical problems fixed. I think your cam timing is off and your valves are hitting the piston.

Restrorob
06-04-2007, 05:14 PM
Did you start the engine immediately after installing the push-rod ?

When the lifter is pumped up it's hard as a rock and when you torque the rockers down all your doing is opening the valve. If you start the engine in this state the piston will smack the valve bending the push-rod. Best to let the engine sit for 20/30 minutes to give the lifter a chance to bleed down before trying to start it up.

Also, Can you put your thumb on the end of the rocker and push the valve down ? This will tell if you have a stuck valve.

buzzer12
06-07-2007, 10:07 PM
i took the engine completly apart , stated all over again , the engine now starts , and does not bend the push rod . but as before when i attach the muffler it will not start take the muffler off and it starts . i do notice that there is alot off back pressure in the crankcase as i said before i put rings in this engine . aqnd a new carb and muffler. is the compression getting by the rings??? i put new gaskets in too!! while running if i take out the dipstick it almost pops out due to the pressure in the crank case . any idea whats causing this thanks for your help...........

Restrorob
06-07-2007, 10:32 PM
It's time to post both model and spec. numbers off this thing.

petez
06-08-2007, 03:04 AM
When you say the lifter bends, do you mean the valve? or the pushrod from the cam to the valve? Either way it should not bend and if it was bent it did not fix itself. If you see a flame coming out the exhaust port that valve is not closing, if it runs without a muffler but with muffler on it does not run. Elimination will tell you that you have a problem with the exhaust. It's not the muffler, that leaves the exhaust valve. The lifter you said bent wouldn't happen to be the exhaust one would it? Your problem lies in the exhaust valve. take the head off and see if the valve is seated, check that the spring for that valve is not broken. If you have a valve cover that you can take off and see the valves, turn the motor over by hand with no spark plug and watch the valve movement make sure the valve completly seats then do it with the muffler on and see if it still seats. If no problems seen then push on the valve with force and see if you can compress the spring it should be extremely difficult if you can even move them, if you can depress it, that valve spring is probably shot. It should take probably 60 lbs of pressure to depress one.

buzzer12
06-08-2007, 06:16 AM
here are the spec's skh624u1g2ra mod. ch20s. spec, 64554, dis 624
ser# 2922306151 like i said the push rod does not bend any more . it does start right up without the muffler . i will check the valves today, and it was the exhust valve that was bending. there is a whole lot of back pressure in the crankcase thanks everyone for ur replies, it seems the back pressure is my only promblem now!!

tomo
06-08-2007, 06:40 AM
here are the spec's skh624u1g2ra mod. ch20s. spec, 64554, dis 624
ser# 2922306151 like i said the push rod does not bend any more . it does start right up without the muffler . i will check the valves today, and it was the exhust valve that was bending. there is a whole lot of back pressure in the crankcase thanks everyone for ur replies, it seems the back pressure is my only promblem now!!

hello, compression in to crank case !!!!!!!!
If i remember correctly u can measure at the breather outlet 4 either a positive pressure [sounds like your situation] Bad!! or as per manual have a vacuum present .
Either way a process in the engine build has been missed if there is a positive pressure in the crankcase.

tomo:waving:

Bill Kapaun
06-08-2007, 01:30 PM
Sounds like a head gasket(s) leaking.

buzzer12
06-09-2007, 06:29 PM
there are new head gaskets in this can anyone tell me what the compression numbers should be ( 20HP KOHLER CH )

Restrorob
06-09-2007, 09:13 PM
Well buzzer,

There is no set compression reading for this engine due to the compression release. But 120 lbs. is a good number to be around and make sure the throttle is set at wide open with no choke.

I'll bet my plug nickle you have a baffle broke loose in the muffler restricting exhaust flow backing it back into the crankcase. Have seen this quite a few times.
If I happen to loose that plug nickle it could be a broken breather reed also.

buzzer12
06-12-2007, 06:09 AM
as i said i put a brand new muffler on , replaced the reed valve and new head gaskets. and it still has back pressure in the crankcase. it starts up but the back pressure is to much to the point if i take the dipstick of a little bit and let go, it will raise a least an inch . does anyone think that the compression is get by the rings ( compression is at 120 full throttle open choke) please any helppppppppppppp!!!!!!!!!

Restrorob
06-12-2007, 07:15 AM
What numbers did you get for ring end gap on both top and second rings (top, center and bottom) of the cylinder bore ?

Did you de-glaze the cylinders and re-cross hatch ?

Did you install the top and second rings in the proper ring lance ?

Did you install the second ring proper side up ?

Did you stagger the ring end gaps before installing the pistons ?

buzzer12
06-12-2007, 09:51 PM
is there anyone who has had this problem, and what did u do to correct it

khouse
06-12-2007, 10:22 PM
Restrorobs questions are valid.
I have changed my mind from my 1st post.
I think you need to buy a new engine.

randy448
06-12-2007, 11:08 PM
how about a leakdown test on both cylinders and in different spots ie. top, middle and bottom of stroke. Seehow well those rings are sealing.By the way ,you cant take the dipstick out of any small engine with it running.

Restrorob
06-13-2007, 07:05 AM
There have been quite a few good suggestions as to what may cause this engine to have too much crankcase pressure and you have eliminated all.

The only things left are the questions I asked and I was being lenient by only asking for ring end gap measurements and not cylinder bore measurements using a telescopic gage and micrometer.

I believe the problem lays with the ring install and if you can't/don't want to answer my questions that's fine.

I'm now with khouse, I believe you need to purchase a new engine;

http://www.smallenginewarehouse.com/ProductList.asp?Category=Engine&Supplier=Kohler

heritage
06-13-2007, 11:09 AM
as i said i put a brand new muffler on , replaced the reed valve and new head gaskets. and it still has back pressure in the crankcase. it starts up but the back pressure is to much to the point if i take the dipstick of a little bit and let go, it will raise a least an inch . does anyone think that the compression is get by the rings ( compression is at 120 full throttle open choke) please any helppppppppppppp!!!!!!!!!

Replace the Exhaust valves. Be sure to lap/seat the new ones w/lapping coumpound. Make sure too that you have enough lash between valve stem and pushrod. Restrob could tell you this # off top of his head.

You have a bent valve.

Pete D.

buzzer12
06-26-2007, 10:58 PM
i put new pushrods and lifters and the engine runs great!!!! thanks everybody for your heip!!!!!

VegetiveSteam
07-03-2007, 12:13 AM
Plugged muffler??? Oooops sorry. I missed your last post.