Onan KY broken valve spring

Look in the parts manual at the rocker arm stud make sure the bottom nut is tight against the wall if its loose it will throw the spring and rocker arm off don't ask me how I know.i would set the valves to spec and try another spring. Do you need the service manual.

When you pull the stem up what is the valve lash? If the lash is close to what it should be spring replacement may be an option. If the lash is loose the valve is bent or the rocker stud is loose. If the lash is tight the valve head may be gone or hammered in to the seat. Both of these scenarios mean the head(s) are coming off. Good luck in finding any one who will slap springs on it for you. Liability would have kept me from doing it in my shop. Small claims court will always find against the repair shop and the judge will always state, "You should have known better" when he finds in favor of the plaintiff. Trust me, you will sue when the generator fails in 1 week or 6 months from the date of repair and the shop refuses to give you any sort of credit for the previous repair.
If the lash is good and you are capable of replacing the springs your self then by all means go for it.
Randy

This story could have a happy ending. The responses above gave me a few ideas of things to check out. After inspecting what I was able to without pulling the head, including seeing a little bit of the valve and piston through the spark plug hole and pressurizing the cylinder with compressed air, it looked like there is a chance that nothing was seriously damaged. I ordered 2 new valve springs ($30 each!) and popped them on. Lo and behold, the other original spring was also broken. Ran the air conditioner from the generator for an hour today and it all went well. Only time will tell, but there's a chance that the thing is ok now.

The generator was built in 2008 in the middle of a period where there was an epidemic of broken valve springs in the Microquiets. Did Onan maybe try out a new Chinese supplier and get burned? A lot of these units were fixed under warranty. I paid the penalty for not running up a lot of hours before the warranty was out.

Glad you got it fixed without an expensive repair bill.

Wayne Dohnal wrote:
This story could have a happy ending. The responses above gave me a few ideas of things to check out. After inspecting what I was able to without pulling the head, including seeing a little bit of the valve and piston through the spark plug hole and pressurizing the cylinder with compressed air, it looked like there is a chance that nothing was seriously damaged. I ordered 2 new valve springs ($30 each!) and popped them on. Lo and behold, the other original spring was also broken. Ran the air conditioner from the generator for an hour today and it all went well. Only time will tell, but there's a chance that the thing is ok now.

The generator was built in 2008 in the middle of a period where there was an epidemic of broken valve springs in the Microquiets. Did Onan maybe try out a new Chinese supplier and get burned? A lot of these units were fixed under warranty. I paid the penalty for not running up a lot of hours before the warranty was out.

Here is a good link to have. Service Manual for KY Microlite 4000 series

The below comes from page 1-2 (page 7) of this PDF: http://www.cumminsonan.com/www/pdf/manuals/981-0503.pdf

3.6 = 3600 watts
KY = Product family
F = remote startable
A = voltage and Freq. (120V, 60Hz)
261120 = Specification number
L = Specification letter



C = build month: March
08 = build year: 2008
0 = MFG'd in Fridley, MN
167118 = Active Serial #

Great news.