I have a Whirlpool model #LGB6300PW0 gas dryer that has suddenly stopped drying properly. The ignitor works and the burner lights, the drum tumbles and there appears to be plenty of air flow out of the exhaust vent. That exhaust flow doesn't feel very warm however. There just seems to be a lot less heat being generated than is needed to do the job, but it doesn't make sense since I can see the burner lighting up, apparently normally. Do I have a bad thermostat or is there some other explanation? Thanks in advance.

-Jeff

Take a look further into the drying cycle. See if the burner is shutting down. Set timer for 40 minutes and check at 20.

Thanks for the fast reply. I went right down and tried what you said. The dryer starts and the burner ignites but then shuts off about 5 minutes later. There is a distinct solenoid click when the flame shuts off. I left it running and it came on again in about another 5 minutes (maybe less). It's continuing to go on and off at about those 4-5 minute intervals. The burner seems to spend about as much time lit as it does off. Laying my hand on the outside of the vent pipe there seems to be a lot of heat when the flame is lit. How often should it be going on and off?

I should add that my wife was using the heavy and permanent press cycles, not the timed drying cycle when she noticed the problem. Don't know if that makes any difference or not.

Whoops, correction: she tried all three cycles, heavy, Permapress and timed with no luck.

I also just noticed, about 20 minutes in now, it trying to relight and failing! The igniter probe glowed red hot and then went out and the burner didn't light. I wonder if that's the problem?

It's not the ignitor.

3 possibilities

1. The overtemp sensor is shutting the system down. Usually a capilary tube on the gas valve. Follow it. Remove any lint around it.
2. The fan extracting the heat has belt or bearing problems. Inspect.
3. The burner tube (looks like a cobra head) is fatiqued and is bending and not putting enough flame across the flame sensor to keep the gas valve open. Check to see if it's solid. Turn of dryer after the burner shuts down and see if bends really easy.

There is a diagram here at Parts & Accessories | Shop & Find Lawn & Garden, Appliance Parts at Sears Parts Direct | SearsPartsDirect.com from Sears

Thanks again 'simple. I've dissembled the thing and inspected the "cobra head". It seems to be fine. It's nice and solid and seems to be in the right position relative to the diagrams. It's even a bit shiny still. All the bearings seems smooth and the unit was running nice and quietly before anyway.

That leaves me suspecting the sensors. I don't see anything that looks like a capillary tube but there are three sensors I suspect.

The thermal cut off P/N AP3176214 (#17 on the diagram)
The T-Stat, high limit P/N AP3084674 (#15)
And the Dryer cycle t-stat P/N AP313939 (#9)

The latter rattles when I shake it. Is it supposed to do that? Someone mentioned that the solenoid coils on the burner valve could be bad. Is that something that's common?

Just to close the loop on this one, the repair guy at the appliance parts store was convinced I needed to replace the gas valve coils when I described my problem. I bought and installed a set ($30) and sure enough, that did the trick. The dryer is now back in service. Thanks for all the replies!