Remove Thermactor Valve from Air Cleaner - '76 DeVille

[mgbeda]

Hi Folks,

I was tearing down my Air Cleaner Assembly for my '76 SDV, in preparation for getting it powder coated.  I got everything off in one piece, then got to the Thermactor Valve (vacuum motor) in the snorkel.  I looked up in the shop manual and it says to replace it one must drill out the two spot welds holding the bracket to the snorkel.  I'm kind of leary about that, especially because the thing still seems to work, and I'm only doing this for cosmetic reasons.

Has anyone removed this vacuum motor before, and if so did you follow the shop manual or find another way to get it out?

How rare is this part, in case i break it while taking it apart?

I could always leave it in place and hand sand and spray paint the whole assembly.  It'll take a lot longer and probably not look as good though...


Thanks,

-mB

[Scot Minesinger]

Jeff,

I removed these before in the past and it works fine to drill out rivets.  Only issue is this replacement part is sold with screws and the holes accept the sheet metal screws.  You can powder coat the housing with it removed and then install afterward.  It will not look factory original though.  Alternatively you could just use a real high quality paint over original.

["Cadillac Kid" Greg Surfas 15364]

Mike,
Just for conversations sake you can work the strap that holds the actuator to the air cleaner "snout" back and forth a few times and the spot welds will "yield" without any damage to anything.
In regards to finish of the air cleaner, it depends upon whether you are going for originality (paint by all means) or cosmetic enhancement in which case the sky is the limit. I have powder coated them, painted them, plated them(chrome or copper, phosphated them and pin striped them, depending upon both my moods and the desired purpose.
Greg Surfas

[mgbeda]

So once you work the spot welds and they break off, how do you reattach them?  JB Weld?  I'm afraid real welding on something this thin is not a possibility for me.

Thanks,

-mB

["Cadillac Kid" Greg Surfas 15364]

Pop rivets will work. 
Greg Surfas

[Scot Minesinger]

That is why I drill the welds and use the sheet metal screws as directed by replacement instructions if an authentic operation is demanded.

Another option for you is to leave in place and powder coat it essentially destroying the rubber inside, because you do not need it.  If you hired me to make your car run better, I would disconnect first thing.

Reason is that the no vacuum applied position allows air thru snorkel (warmed up mode) and the vacuum applied position draws are air across exhaust manifold to encourage the car to warm up faster.  The switch that controls vacuum or not is temperature sensitive and prone to fail open which forces the damper in snorkel to draw across exhaust manifold which is bad when car is already warmed up.  When I work on a Cadillac like this I remove the vacuum connection form switch and so you still have the vacuum hose going to snorkel damper (thermactor), and the car is in already warmed up mode all the time without the risk of overheating if switch failed on hot day.  I have seen a failed switch on 75% of the Cadillacs with this feature. 

Cook the thermactor and be done with it.  Only potential issue is if it catches fire - talk to your powder coater.

[35-709]

"When I work on a Cadillac like this I remove the vacuum connection form switch and so you still have the vacuum hose going to snorkel damper (thermactor), and the car is in already warmed up mode all the time without the risk of overheating if switch failed on hot day."

Same here.

["Cadillac Kid" Greg Surfas 15364]

Guys,
You seem to miss the point of having rapid warm up. First of all Mike lives In Colorado, and with few exceptions the weather is colder than in Florida, Virginia or southern Texas. IF all the rest of the emission features are in place, they count on the car warming up rapidly to bring it into range of performance.  Again, all this depends upon whether the car has all emission devices in place and operational.  Modifying one device without compensating by modifying the rest of the system leads to poor performance.
Greg Surfas

[Scot Minesinger]

The failure of that switch in air cleaner housing is so bad.  I have suffered a 100% failure rate on three new units (obviously made in China), and older originals are failing  too.  This little stupid switch fails in open position allowing vacuum into the snorkel damper actuator forcing intake air across exhaust manifold and limiting the engine ability to reject heat.  This causes overheating, rough running and poor performance when car is in warm weather and/or already well warmed up. 

Fast warm up is not an issue for me.  (BTW it is 28'F and just finished snowing in VA with salt on road so not driving) I have a temp gauge on my car, and most of the time when I'm leaving my driveway it is already at 150'F, and within a mile up to proper temperature.  The warm up time for my driving is fine.

The pros and cons of thermactor (snorkel damper) activation:

Con:  Car can overheat and run poorly
Pro:  Car will take another minute less to warm up.

Poor performance is only when car is not fully warmed up, which is not long for me.  Plus that first five minutes I'm driving gently to let trans warm up too.

Given that the overwhelming majority of Cadillac enthusiasts reading this do not drive their car in severe cold weather due to salt, I think this is a perfect solution - deactivate it.  If I lived in cold climate and drove the car regularly in winter, OK, might look into making this thermactor active, but that is a unlikely.

Greg,  On this rare occasion we will agree to disagree.  Usually you convince me.  Wish it was like South TX here.

[mgbeda]

True, I will not be driving this car when there's snow on the ground.  But still I am at least going to try to put everything back to the way it was originally.  For one thing I want to find out what it was like to drive this car when it was new (by the time I inherited it, it was 11 years old with 78,000 miles.)  If I go for any modifications or upgrades I will add them later.

Of course if I can't get that thermal switch working right or replaced I will disconnect the system, because i don't want that constant manifold hot air thing going on.

I'm still torn on whether to remove the valve and powder coat (much easier, a bit expensive, will never look QUITE the same because of rivets or screws now needed, might break something now working) or to leave it in place and sand and paint (much more work, probably won't look as good).  But now I have more information about everything so I can make my choice.  Thanks guys.

-mB

["Cadillac Kid" Greg Surfas 15364]

Scott,
What are we disagreeing on? First of all ALL the components fail in the "open" position, so any malfunction just leaves the damper open.  Second I don't think I have ever run into anyone that has has as bad a run on new parts.  The "switch" is a simple $15.00 bimetallic warranted for 3 years.  I personally have never seen one that  (unless damaged by physical trauma) that did not function, but that is just me.
You may note that the temperature in Colorado and many other locations is much colder than Northern Virginia, and this device was intended for just those areas.  Will the car function without it? Sure.  Will the Cat. plug up sooner running the richer mixtures a cold engine requires? Sure.
The point made is that these devices were all made to operate in concert with each other and deleting any one would require a good mechanic to make considerations for such.
Greg Surfas

["Cadillac Kid" Greg Surfas 15364]

Mike,
If you really want originality just clean and paint the air cleaner as it was originally.
Greg Surfas

[Scot Minesinger]

Greg,

The switch fails open allowing vacuum to flow to the thermactor placing it in the position of drawing air across intake manifold during all operations warm, hot and cold.  So unfortunately the common mode of failure is warm up which overheats the car in summer.  You say make the thermator active, I say disconnect source of vacuum so it stays in already warmed up (normal) position.  Better to run cold a little longer than to operate in warm mode 100% of the time.  Every switch I bought (reproductions) has leaked and been bad.  I have seen original switches still operational after 40 years, but many failures too.

I do agree, just paint the assembly without removing thermactor and reinstall.



 

[mgbeda]

Yeah, I'm leaning towards the hand sanding and painting myself.  I don't mind unbolted or unplugging things, but removing this just violates the "If it ain't broke..." rule a bit too much for me to feel comfortable.

And rest assured i will test everything before it is put back in service.

Thanks again,

-mB

[Scot Minesinger]

When the car is warmed up look into the snorkel (after disconnecting plastic duct into it) and see if damper is open-you will see thin edge of sheet metal damper blade so that from your view with flash light you can see air filter.  If it is closed and drawing air over exhaust manifold, then you have the problem discussed.  Check this from time to time especially if your car seems like it is running hot in warm weather.