Vehicle is a 1984 F150, 351W, 4x4, C-6. I'm removing all the pollution control devices due to removing computer and changing carb./DS2 swap. My question has to do with the check valves (not the diverter or air bypass valves) in the Thermactor system. Are these check valves just one-way valves to prevent exhaust gases from backing up into the Thermactor system?

If so, then I presume that I can disconnect down to the check valves and leave things there for now, without problems. My system has two check valves, one on the pipe to the back of the heads and one to a pipe the connects to the exhaust behind the cat.

I would like to remove the pipes and plug everything properly, but age, a sore back and oncoming bad weather aren't cooperating. That will have to wait for spring if possible.

What say you gentlemen, is it a go or not?

 

Yes they are check valves and are there for what you guessed they are for. But don't be surprised if they leak, especially if the belt has been off the pump. The exhaust is very corrosive and makes them stick and eats them out.

 

Thanks for the reply. The belt has been on the pump until now, so I guess I'll just give it a try and see if they leak. If so, sore back or not, I'll just have to seal them some other way.

 

I just got through working on those things! I had installed a Cat a couple of years back so it would pass emissions; disabled the Thermactor system. However, one of those valves rusted away and broke off allowing exhaust gasses into the engine compartment and a heck of a noise as well. Found out that they were supposed to allow air into the exhaust system (I find that rather stupid for lowering emissions since once the exhaust is expelled there is a hell of a lot of air to mix with the exhaust!) so I had heat the part where they screwed in and removed them. Replaced with a 3/4 pipe thread plug. Engine happy again.