1985 magic chef stove and oven thermostat overhaul

[GM Airstream]

My oven didn't work... it would light but not turn on the main burner...

(NOTE: IF YOUR NOT MECHANICALLY INCLINE... DO NOT ATTEMPT TO REMOVE OR WORK ON THE OVEN/STOVE AND/OR THERMOSTAT ... THIS IS FOR ENTERTAINMENT ONLY... DO SO AT YOUR OWN RISK)

Some also say that the oven burner will lights up and won't shut off in temp control... both conditions are symptomatic... Mine would work after it got hot.. but not when it was cold...

Having made sure the gas lines are open and clear.. and the jets are not plugged...After many hours of searching for help on getting the oven back to working... and putting up with " REPLACE THERMOSTAT" when parts are NO LONGER AVAILABLE.... and the parts guy saying... you need to buy a new stove/oven for $600 bux... AND...

I like the advantage of having the 4 burners. The stove and oven being in good condition... I am not about to throw it away.... and back then they made them to last.. after all its 30+ years old and made out of good metal...

I, being a engineer, decided that the problem with the oven part is in the thermostat... but try and find a line drawing of one... nada...

Ok... so lets get to it... the pilot flame would light.. but the pilot would not grow to heat the gas valve thermocouple on mine when cold...(ah ha clue here) but would work when hot just fine.... This then leads one to suspect the Thermostat valve... failure when cold...

After removing and taking the thermostat apart... to come to a understanding of how the parts work....

(you want to be very careful here as them gaskets and all are 'NOT AVAILABLE' and your dealing with 30+year old parts.. )

I now have a understanding of how the thermostat works... and once apart.. found out why it fails... (Which in fact it is not a defective part but instead the lubricant grease that they used 30 years ago.)
After cleaning and lub'n it back up with new tech materials... its working just fine and saved the unit from the trash bin.

What the major problem is ...

Its the adjustment screw slipping inside the temp shaft... that is not allowing the operation spring to stay set.

Why does it slip... well the main screw that is located under the larger spring was coated with grease back when it was built. Through the years it has hardened up.. and gotten sticky... thus it almost could be considered glue... and thus cause the adjustment screw inside the temp control shaft to slip which then causes the assembly to fail to operate correctly even though you are turning the control knob.. its not changing the compression on the temp spring due to the lock up of the control screw.

Solution:
(You do this at your own risk... as your playing with pressured gas... that can leak and cause damage)

Shut off the gas at the tank... and lock it so that on one else can turn it back on while your have the thermostat off
Remove the gas lines... remove the two hold down screws... (don't lose the silicone O ring that is the seal)

Try not to bend or damage the thermocouple tubing
Remove the 3 screws that hold the thermocouple plate on the back of the thermostat...

Being careful you take the temp bulb back plate off... (three screws) do not damage the old gasket... (again their are no parts for these units that are over 30 years old) so if you damage it you need to have someone make you another gasket identical to the existing....

being careful not to lose the Temp control device inside the housing and/or damage it.

Work only over a table with a clean non lint piece on the table... remove the temp device from the inside of the housing.. it almost will fall out the back
Set the housing aside... and work with the Temp device.. that looks like a shaft with a spring on one end in the middle... (mine also has a small spring over the shaft... with a C clip keeper...that I removed by compressing the spring and carefully removing the C clip setting it aside for later)
Un screw the shaft... (it is a reverse thread) being careful to note that the spring is under pressure and at the end will want to jump... (before doing this you may want to take a pic of the unit so that you don't forget how to put it back the same way they made it...)
Once you unscrew the shaft.. you will see the threads of the screw... and if like mine.. the old grease that they used will be sticky and hard like goo...
Clean the old grease off all the parts... ( I used isopropyl alcohol to help clean mine)
Make sure the threads on the screw are clean and the threads in the shaft are also...
Re lube with silicone gel or other anti siezse material.

Re assemble the unit.. (again note that the temp assembly screw is reverse thread.. and should be compressing the large spring...before placing it back in the housing... and reverse order the installation... and ensure that the two ears of the shaft are seated into the temp control shaft inside.

When done check for gas leaks... if none found proceed to lighting the oven...

Put the temp control knob back on... and turn it to about 300 deg ... this opens up the supply valve in the thermostat and start the gas flowing...you should find that the pilot flame will probably be enlarged (which it does to heat the thermocouple for the main burner... )

Have a small 3/32 blade screwdrive... to work the temp adjustment screw located inside the temp control shaft... You will need to adjust this for oven temp to match the control knob...

You will also have to make sure that the oven control temp shaft doesn't move when you make your adjustment...

with the oven door closed... give it time to stabilize... and you should find that the Magic Chef oven now works as advertised 30 years ago... correctly again... and should last another 30 years.

I don't know why their hasn't been someone that has found out how to overhaul these units years ago when the problem started to show up...

Its a shame that a lot of people were forced into buying a new stove and oven.. when for a little labor could have repaired their existing one... its not rocket science...
I can see how the old company (whirlpool) wanted to make money... back when they bought out Magic Chef... but now... that they are gone.. what options do the user have ?...
True new is current supply... but wait 30 year.. and they too will be history... The old engineers did a good job designing the old Magic Chef... and it could contenue if parts were made again... but, at what cost...

Lucky that we have the forum here to help maintain the good old units...

[rmkrum]

GM, you are true well-rounded engineer/technician after my own heart, sir!!! Well done!

[mayco]

Nice work and worthy save! I totally agree with your motive to make it work rather than trash it. We use our '82 model a good deal on the road and luckily it still works great. Gotta save this post for eventual failure. Good write up, thank you!

[PaulnGina]

Nice work! Thank you for taking the time to do it. Our stove in our 1987 Avion is probably identical, so this is great information to have

Part of our throw-away society.... pitch it and get a new one rather than repairing a better-to-begin-with stove.

[High-pockets]

I realize your post regarding the Magic Chef disassemble is dated but I have a similar issue on my "new to me" 87 Excella 32 oven.( I previously have owned a 71 & a 73 Excella) I am going through system by system, my MC stove looks basically new, all burners light but cannot push in oven knob nor turn it so I can light. I was thinking your cure might work. thank you, I have scoured airforums, Google and cannot find replacement part.

[Maggieoknapp]

My problem is that the pilot light sputters, but it will light the thermocouple thingy I think no problem, but gas will not disperse to the rest of the oven to fully light. Any ideas?

[Maggieoknapp]

I am totally amazed. What do you mean though when you say "Remove the 3 screws that hold the thermocouple plate on the back of the thermostat...?"
I am attempting to undertake your process!

[richard5933]

Without seeing photos to know for sure, my first thought is that the pilot light needs a good cleaning - just a little carbon buildup on the end will prevent the flame from spreading out.

Same for the oven burner - if the burner is not clean then it will be difficult to light and may not have a good flame.

When is the last time the oven was in use? Is the gas orifice that supplies gas to the oven burner clean?

[Maggieoknapp]

Thanks very much. I'm soaking it in alcohol and will try carb cleaner too. I confirmed that it is the constant pilot that is sputtering, heater pilot starts up no problem. I took out the long tube that would fill with gas to fan out under the bottom plate and tried to clean the little orifice that would fill it; it did indeed have carbon all over it. I last used the oven a year ago and it was annoying then - it would turn off randomly, I assume now because the pilot light would go out. Then I rented my tiny house out to someone for a few months and just turned gas off to the oven so it wouldn't leak propane.

I'm still unclear exactly what a thermocouple is since I can't find any part that matches my stove online. The model number is t727 which I think means it's from the sixties!

Alas in reassembling it I bent the smaller of the aluminum hoses and it snapped but I will try to solder it!

[Maggieoknapp]

The pilot light not staying lit is one problem, but it seems the gas not dispersing to the big tube may be another, since the heater pilot does ignite. I'm curious about this mercury leaking out problem that other people have had, or if it the gas not dispersing indicates that the thermostat has gone bad.

[High-pockets]

Originally Posted by High-pockets

I realize your post regarding the Magic Chef disassemble is dated but I have a similar issue on my "new to me" 87 Excella 32 oven.( I previously have owned a 71 & a 73 Excella) I am going through system by system, my MC stove looks basically new, all burners light but cannot push in oven knob nor turn it so I can light. I was thinking your cure might work. thank you, I have scoured airforums, Google and cannot find replacement part.

Update, I after a period of time had passed I decided to use a spray used for nuts that are frozen up with rust etc. I think it’s called P & B or something like that. I lined area with paper toes to catch any drips. Carefully sprayed and let it sit fir an hour, used pliers to wiggle, push and pull till it freed up. Works perfect now.