International mobile home furnace issues

Kirwinjd

customer has an old International mobile home furnace.
About a year ago I replaced the gas valve and pilot assembly. Ever since then I've had to relight the pilot several times. I've replaced the thermocouple twice. Checked gas pressure, any condition that would blow the pilot out and it still goes out after about a week. I don't what else to do but replace the valve again.
Any ideas out there? Thanks alot!!

jb8103

Is this a propane unit?

Kirwinjd

Thanks for responding.
No. Natural gas.
I relit the pilot about a week ago and so far it's still lit but I'm sure I'll get the call within the next 3-5 days that once again it's out again.
I'm hoping she'll go with replacing the furnace but since she's about 85 years old she doesn't want to invest alot of money into something she won't be around to enjoy very long. I hate giving up on this though. Really wish I knew what the heck is going on with this piece of poop.

jb8103

If this has been happening consistently since replacing the valve and pilot assembly I'd suspect a faulty valve.

Kirwinjd

Yep. That's my final diagnosis. Already picked up a new valve. Will install it next week if it gets cold again. Really bites cause I'll probably have to eat the faulty valve. Those slow opening valves are not cheap.
Thanks for your input.

Residentialtech

Have you checked for cracked het exchanger or back draft through flue pipe?

Kirwinjd

Thanks for the good suggestion but I made a thorough inspection of the heat exchanger. No visual cracks and no change in the pilot flame while the fan motor is running. Also checked the roof cap. I can't really check anything else without removing the furnace. If the valve is bad, I really wish I could understand how the valve can open and close dozens of times and then kill the pilot. Is it internally shorting out or snuffing out the pilot?
What's your opinion on using either the 25% or 40% slow operating valve?