Petrovich

Hi everybody!
Long story short, a friend of mine bought a real cheap 86' NA with a blown motor. Blown as in it needs gas to keep idling, and I couldn't drive it much above 45mph on level road. Took us like 1/8th of a tank to drive it for 3 miles, too Smells awful, has the same power at 2k rpm as at 6k, previous owner has been told "low compression" by the dealership - the works.
Other than that, warmish A/C, and some minor paint imperfections, the car is in top shape. Came with a book full of records. So, here are my questions:

A) I'm 99% sure that it blew an apex seal, or even all three, on one of the rotors. The car has 186k miles on it, records go back to ~90k miles, and I see no indication of a rebuild, so I just figured that it was the time for it to die anyway. Now, assuming our currently non-existent budget, what should I do to verify that we don't have the miraculous 1% case here? I'm pretty sure that no spark on one of the rotors would cause the same symptoms, but it wouldn't be very likely that both the dealership (which, considering the records, shamelessly milked the guy for cash all these years), and the owner, missed it. Any other not-so-obvious thing to check? Could carbon build-up cause loss of compression that would be repairable without opening up the engine?

B) If the apex seals are blown, we plan on getting a shortblock from local u-pick-u-pull yard. Since there's no warranty on those, I'd like to know of any tricks that would let me pick the best engine without pulling it out, besides the usual turn-and-listen-for-3-thumps check. I found a nice yard in the middle of nowhere that constantly has ~10 1st and 2nd gens with engines in them.

C) When pulling junkyard engines, what are the years I should be looking for? Would later 160hp ones work with stock intake/exhaust/computer, at least as good as the older type engines? I'm trying to make this as straighforward as possible, but if I need a small (under 3 hrs and under 100$ cost) modification/part to widen my engine choices, I'll go for it.

D) What's the absolute SHORTEST, FASTEST, and EASIEST way to pull a 13b shortblock without damaging anything, and then putting the damn thing back in?

E) The old shortblock will be stashed, to be ported, and rebuilt this winter when we'll have better funds and tools. Any good, decently priced suppliers of master rebuild kits?

SimplyComplex

I'd just like to be the first to say "OH GOD NO." If you're planning on pulling an engine out of a junkyard, and actually paying for it, you better be damn well sure that thing runs. Rotary engines are prone to seizing when not started for a while. And the prices of parts at junkyards are insane today. Honestly, IMHO, I think you'd be better off having one built, or just working with what you have. Just my opinion.

Aaron Cake

iTrader: (1)

http://www.aaroncake.net/rx-7/blown.htm

That's about the only check you can do unless you have access to a boroscope (to look through the exhaust and intake ports) or the car is assembled enough so that you can spin the engine with the starter and do a compression check.

Even without a scope, you can examine a good portion of the engine internals if you can remove the exhaust and intake manifolds as well as spark plugs.

Stick with the same series. So you will want an '86-'88 engine.

It can be made to work but is likely more trouble then you want to go through.

If you want a short block, you must remove the intake manifolds and all accessories. However the fastest way to pull the engine is to cut the fuel lines, remove the harness from inside the car, unbolt the appropriate bolts (transmission, exhaust), cut heater/coolant hoses, disconnect whatever is left over and then pull the engine as a complete unit.

The old block will likely need a rotor and housing. Rebuild kits are covered in the Archives.

Petrovich

Well, unfortunately, 300$ is the current budget to get that sucker back on the road The local u-pick-u-pull sells engines for 100$ a pop, with no accessories. I guess we have 3 attempts to get a good one Naturally, I'll be looking for the "rear-ended" miracle cars first.

Otherwise, I have my questions answered I'll take a look at the car this week, and if all attempts to rescue the current motor fail, I'll start waiting for a good 86-88 engine. Thanks a bunch! I'll be back with updates in a couple of weeks.

Petrovich

OHHHH btw, it had mega-low oil pressure... I think it's a broken oil gauge, but would low pressure by itself cause the symptoms?

SimplyComplex

Holy god. $100 an engine? I'm going to MD for a week. The u-pick-u-pulls here are insane. Upwards of $1000 an engine. But hey, more power to ya. Good luck.

alexdimen

iTrader: (13)

ridiculous! i used to go and get 13b short blocks here for 60-80 bucks! ebay the parts and watch the cash roll in...

to check the engines i did an auditory test while rotating it by hand, then i took off the exhaust manifold and felt each apex with my finger. i didn't even bother with engines that had a blown rotor.

however, i would never stick a junk yard engine in a car without taking it apart, cleaning it, and rebuilding it unless it was well under 50k miles. it's really not worth the time because the junk engine will likely have low compression too.

Petrovich

Crazy Ray's junkyard. 100$ for shortblock, 150$ for longblock, any engine, be it a Geo 3-pot or a Jaguar V12 (they've got those, too!). There's a very bad one (read: over-picked) in Jessup, a much better one near Frederick (that's where I go), and two more near Baltimore. Never been to Baltimore ones but I heard one of them was pristine.

Thanks for the exhaust manifold tip, sounds like a nice and easy way to check the rotor and seals. If it works, then that's the way I'm gonna go about it

BTW, if pulling apart the engine, what should I change? Obviously I want to keep the apex and side seals cause currently it's cost-prohibitive to change them...

Aaron Cake

iTrader: (1)

Keep the side seals (they are generally not worn past tolerances and new rebuilders are more likely to screw up the clearancing procedure on new seals) but replace the apex seals as they are the wear item in the engine.

cdaleracer669

iTrader: (1)

junkyard engine is a bad route to go. but i cant really speak from experience cuz i got one from there from a wrecked car with really low miles and its treated me great and has awesome compression. for 100 bucks you can at least take it apart if it doesnt work and have a good conversation piece with the rotors and housings.

QUEST

Petrovich,

Sent you a pm.