My 1990 240 has 245K miles. I regularly clead the flame trap. I wasd thinking about removing my intake manifold and cleaning out the breather box. Do I need to do this, how cruddy could it be with a well maintained car with high milage?
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1990 240- 245K- Original Owner-M-47, VX cam, IPD sprt springs, bilstiens, spt exh, euro lamps-turbo whls,- still slow but handles well- Near Houston

Yes. My engine had been serviced properly from new. I bought it at 180,000 miles and found the flame trap clogged. Having later read about the breather box I tested it, at about 200,000. It was virtually solid. I think even on a well-maintained engine it clogs up, like the flame trap.
Apart from the actual restriction of breathing, it also becomes a source of old built-up oil crud which dribbles back into the engine and contaminates new oil.
You don't need to remove the inlet manifold to remove it. Mine had a plastic lug on top for fixing the wiring harness. If you cut this off and fix the wiring to something else, it gives half an inch more clearance.
Now I'd say its a 20,000 mile maintainance job.

On my 81 K-Jet the box was totally clogged. I replaced it and cut the old one in half to see what was inside. I found a buch of gunk inside the box and an old-style metal flame trap stuffed in the spout of the breather box sideways. It was lodged about two inches down the spout blocking all air flow. The job got bigger and bigger. I ended up doing heater hoses, throttle body cleaning, injector seals, breather box, flame trap relocation, gauge sender, some other stuff, and cleaned everything along the way. Later, I had to take the manifold off again to do a wiring harness, at which time I replaced the thermal time switch and the coolant temp sensor. It would have been easier to do it all at once. Do like the others say. Put a two foot hose over the spout, take the oil filler cap off, and try to blow through the hose by mouth. It might be fine. With a new box you can blow through really easily. Let it breathe. Good luck.
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Thanks to everyone for the help, Doug C. 81 242 Brick Off Blocks, stock, M46; 86 244, 140k , auto.

As other have implied I also feel that the oil breather/oil separator rarely clogs up except when an engine has been severely neglected. If the flame trap is left plugged up over a long period of time lack of air flow through the oil separator may be a cause of it clogging up.

I do not consider cleaning it a preventive maintenance item. I hear of so many Bricksters wanting to rip it out when they have not even checked to see if it is clogged. This is done by simply blowing through it.
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David Hunter

Also on a 1990 fresh from the PO, I did the test Randy describes: connecting a long hose where the flame trap goes on it and blowing. It was blocked solid. I took my new spare off the shelf and removed the old one expecting it to weigh 5 pounds, but it was as light as the new one. There was just a small plug of oily crud right at the top, when removed allowed me to blow easily through the oil trap. I put my spare back on the shelf.
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Art Benstein near Baltimore

My "well maintained" '88 had 182K on it and severly started blowing oil out of the breather cap. Took it apart and was very surprised how cruddy the system in a car that has oil changes every 3k could be.

Oh Uh- I hope that I am not breeding paranoia with my question, But it looks like I had better clean it out. Thanks for the response.
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1990 240- 245K- Original Owner-M-47, VX cam, IPD sprt springs, bilstiens, spt exh, euro lamps-turbo whls,- still slow but handles well- Near Houston

Let me know what crud you find. I have an '89 with your mileage. and I actually was hoping never to venture under the Intake Manifold after the breather box.
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'75 Jeep CJ5 345Hp ChevyPwr and two motorcycles: it wasn't Volvos safety , it was Longevity that sold me

Actually that's not a bad job, if you first pull the throttle body. Combine the jobs, get a clean throttle body, new breather box, and new engine coolant temp sender. They are each a PITA, so suffer only one PITA!! And that way it's not necessary to unhook the intake manifold.

Regards,

Bob

:>)

Could be cruddy enough to create enough back pressure to blow out the rear main seal (or any on the front). Had a well maintained 88 240 with 220K that pushed out the rear main 180 miles from home.

Remove the hose from the box and attach a length of 3/8 or 1/2" hose. Remove the oil filler cap and blow into the hose. Do you feel resistance? Could be a restricted box.

Randy