exhuast smoke question
 

I am looking at buying a 82 rex
but I have one question
the seller says that is smokes on start up
any input on what causes this

it has 200k on the motor
so worn seals would be fine as I plan on rebuilding the motor (wanna be familiar since i've never had a rotor)

smoke on start up is like comon termanology in the rx7 world,

its a pretty natural thing, doesnt mean anything bad at all,
it just what you tell someone who is new to rx7's when you are selling them one so they dont get scared away when they see a little smoke on the start up.

on the other hand 200k is some pretty damn high miles and i'd expect to do an overhaul real soon.

keep in mind with that many miles some main engine parts may need to be replaced as well, ie rotor housing, etc....

thxs alot
ill check things out
check the compression, etc.
but to even run at the many miles says something about the care it got

ill keep a 13b in mind as well

Color of the smoke is also an indicator.

Blue smoke = burning oil
Black smoke = burning fuel (rich air fuel mixture)
White smoke = burning coolant (white with no blue tint)

make sure you have a good rotary compression testor handy, or mod a piston compression testor,

also most rotary's will last to 200k,

no special attention required, doesnt mean that the engine will be in good condition though

I only have acces to a regular comp tester

woldnt i just hook it up and read 3 pulses for each rotor

The pulses occur too quickly for a regular compression tester to respond properly.

crap

I have always used a (modified) "regular" comp. tester. Because the pulses are so quick, and the needle is hard to see, I look at the "big end" of the needle. It is easier to see and note the position. Then just look straight across the dial to see where the small end was going. I'm guessing there are probably many differences in the various gauges that make some easier to read then others.

ill give it a shot
thx

BTW 90-120 is the range right

Yeah, but as was pointed out, if you use a "regular" the needle will be bouncing quickly. I don't think you get a reading "higher" than it really is, most likely a little lower. Of equal importance is the all 3 "pulses" are equal. 2 high and 1 low may mean a stuck side seal. 1 high and 2 low may mean a bad apex seal. Both rotors should read the same as well.

thx alot

Hey, what some people do is video tape the needle bouncing, the play it back in slow motion so you can see where it hits.

nahh im not going to do that
since i dont plan on running all that long before an overhual
just knowing its over 80 or so will do

Slo-mo replay,,,,That's an idea! No cam for me though.

bah, just use the finger over the hole method. :cool:

Will that be 1 whoosh or 2 sir?

at 200k i'd make no bets. lol

lol

the way i did my compression test is.... hooked the thing up in where the plugs go of course, then i was told to go full throttle (i dont know why) and turn the key until it cranked 8-10 times. to get an accurate reading you really should run the engine and get the temp up so the apex seals expand and all, then test it when its warm. When i tested mine cold, it was bad, i started thinking rebuild but when i tested it warm it really wasnt that bad.

--eric

thx
ill be alright once i get a little more familiar with rotaries

Ive rebuilt a few recipricating motors
and im really tired on haveing to get head work done :D

Concerning the smoking....try some Marvel Mystery Oil. 16 oz per full tank. It works REALLY good.

You want to go WOT, otherwise your engine sees a vacuum on the intake side and your readings will be considerably lower due to the negitive pressure

WOT?
it will always have a vacume on the intake side?

uh-oh :p


... the last few days the cars been a little hard-starting... I dismissed it as just the colder weather, but there is definately smoke when it does, white smoke at that... Doesn't smell like cat piss tho, smells like gas, definately white tho... *wonders*