inuissus_cendi

Removed the exhaust system yesterday and found that my rear exhaust port on the engine is all white inside. I've figured this is from it running lean (correct me if I'm wrong).
How bad is this? Are there any serious problems I should watch out for? I won't be running lean on that rotor anymore as I'm going with a new carb and intake (the old one had a leak on the rear intake port... causing me to run lean) but is there going to be any long term damage to the engine? Have I fried my seals or anything?

Thanks.

Jeff20B

iTrader: (13)

If you have access to the exhaust ports, you should be able to reach a finger into the port and push on the apex seals to check for spring pressure. Compare the springs front to rear. That is the best way to determine whether the lean running has flattened them.

Lean running flattened the springs in my bro's RX-4 engine. It ran lean due to a manifold gasket that leaked around the secondary ports.

inuissus_cendi

I can't get to my car right now, I will on Wednesday though.

But say it has flattened the springs, I'm assuming a full rebuild is in order? I took the exhaust off because I'm working on a blow-thru setup.

81gen1

when i put headers on 2 of my FB's that white stuff was on both, and they both run great.

Kentetsu

Probable cause was a clogged jet leaning out the rear rotor. Hopefully your springs are still good....

Jeff20B

iTrader: (13)

My nice 12A had light colored exhaust ports.

locopr1

White can also be sue to antifreeze leaking through the rubber intake seals. Is there an antifreeze smell in the exhaust system? IF the springs are good that is your next check. But then I am not sure if one intake rubber seal gone bad would only affect one rotor?

Vashner

Could be some sulfer from whatever fuel your burning. Lot of refineries use different formulations.

Jeff20B

iTrader: (13)

The exhaust sleeves are stainless steel I think. They are thin and can get pretty hot which causes the carbon deposits to turn white and ashy.

trochoid

iTrader: (6)

Agreed, and the only way to get that kind of heat is to run very lean or have an exhaust leak on the rear only. I'd chase the carb first.

1983GSP

doesnt the shudder valve cut fuel off to the rear rotor? if that is so, wouldnt that cause an excessivly lean condition?

Jeff20B

iTrader: (13)

Sure.

81gen1

my 82 has had white ashy exhaust ports for over 158k miles. (258k total) and it still runs perfect i really wouldn't worry about it.

trochoid

iTrader: (6)

Rotarys are setup from the to run a bit rich fromds the factory to provide enough unburnt fuel so the cat can burn off pollutants and clean up the tailpipe emisiions. They can be run leaner than spec and often perform better. If concerned about running too lean, have the AFRs checked with a wideband.

Jaime Enriquez

Definately check with the wideband...my last engine blew a rear rotor (cracked seal) with white ports and white-ish plugs (running huge jets, but I think I had a float level prob in the IDA)....just be careful.

inuissus_cendi

Just got back from a long vacation, and will check the springs soon.
I removed the shutter valve so thats not the culprit but I'm afraid that I got a vacuum leak on that side of the intake manifold since my cap on the intake manifold was damaged.
Carb was not the culprit, it was a brand new Sterling unit never modified from spec. Now running on another car perfectly.
No exhaust leak.

old_skool

teardown
agressive streetport
rebuild.


problem solved

yetterben

BOth ports on my engine are whitesh too. car runs great. Stock carb for now. plugs are a nice mocha color as well. Got me on this one!