V8kilr

OK so as some of you know I got this 88 that runs real rough. I finally did a compression test today and the front rotor is excellent @ 100+ PSI. The rear rotor is like 30 PSI but even bounces on all 3 faces so I dont get it. The car has high miles but I was told it was a rebuilt. I dont know if I would say i believe that 100% but the motor is exceptionally clean and the front has much more compression than a car with 160k on it should have.

I decided to give the water trick a shot
http://mazdarx7.iougs.com/myfaq.shtml

What do i got to lose at this point anyway right. I was wondering if anyone has experience with this trick or any others that might help in regaining some compression on my rear rotor.

I know how to do the water method as far as which spot to use for vacuum and such but I dont know how much water to use, what RPM I should hold at, what to expect, etc...

Anything else that might help or that could have happened? Its an NA so the rear rotor just giving out when the front is @ 100+ PSI just seems so weird.

Thanks

freemanrx7

Flooded engines give false comp readings but you have this 7 running right? Have u tried using oil to get better comp #?

V8kilr

Yeah it runs but really rough @ idle and low power until about 3k rpm.
Its not flooded it starts right up. What do you mean try oil? Like dump it into the motor?
Im not interested in getting higher numbers just to say hay look at my compression, Im interested in finding out if the seals are stuck and if so how to fix it. I dont see how oil is going to help that because I cant constantly dump oil into my motor while im driving around, not to mention the people driving behind me probably wouldnt like that too much.

freemanrx7

Try all options. I'm not sure but maybe the injectors are flooding out the rear rotor causing false readings. Or maybe omp isn't working causing rear rotor to fail. Or maybe the seals are cooked or somebody messed up on the rebuild.

Try teaspoon of oil in the spark plug hole. Pull the efi and comp fuse, crank the engine a few times then wait a few min then install fuses crank and cross your fingers. Good luck

lastphaseofthis

iTrader: (8)

the last 13b with a half and half engine i got started, being 110+psi front 40 psi rear, it wouldn't hit on the last back half of the motor for anything. i tryed oil, i used water to try and break down the carbon and free the apex seals i thought were froze up. but...

It turns out there was nothing but water in the engine at one point and it cracked the middle iron on the rear side, after getting the car started and warmed up to do the water treatment method, compression dropped to 0, as the crack ate my side seals and rotor. the block held water, but i didnt have my coolant system pressurizer at my house were i was working on this one.

If i had just rebuilt the motor when was 110psi & 40 psi, i might have saved my rotor and not had to replace it. how much is it worth to you?

that being said, i've had another 10 rotaries just get flooded out in the rear and show 30-50 psi and later on recover to 90 to 110.

V8kilr

Attached front + rear rotors.
Front is @ 105 PSI
Rear is just under 30 PSI

V8kilr

K Ill try the oil, what do I have to lose

V8kilr

Car was free, I'll swap in a JDM turbo motor if I dont sell it. In other words not gonna rebuild it but might tear the motor down and sell the internals. Front parts seem to be like new lol

V8kilr

I took a squirt bottle and squirted in some oil while rotating the engine by hand.
Started it up and threw some hard rev's @ it all the way to 8k.

Put more oil in it and repeated a few times.

Checked compression and it looked slightly higher but not much. It was like dead on the 30 mark

Any other ideas?

V8kilr

I removed the exhaust manifold and loaded the motor up with ATF. Rotated it a bunch, flushed it with the water hose on jet stream while rotating it. I then rotated the motor more by hand and with the starter. I filled the motor again but this time with a grease / grime removing solvent that I have had great luck with in the past. After that I flushed it again with water while rotating it by hand. I then loaded the motor up with oil so the internals dont rust after the water was in it. I rotated it by hand while oiling and with the starter again.

Hooked everything back up and let it run, threw some hard revs to redline, shut it off and tested again. Still 30. Its done

freemanrx7

It's still good for one last burnout

2slow4stock

iTrader: (18)

^^+2

Gerald

iTrader: (1)

if it makes you feel better to hear my disgust, i have like 60 psi rear rotor, looks like maybe for $650 i could get a low mileage 13b, rebuild your talking over 1k i hear

V8kilr

Well over $1k to do a full rebuild. I could probably rebuilt this one for under $300 assuming the front is perfect and doesn't need to be touched.

Jimmy2222

iTrader: (3)

Yeah, you need a rebuild. 30 psi is junk and there's nothing you can do to fix this other than rebuilding. I blew a side seal on my rear myself. Rebuild kit from Rotary Aviation for $501 (no side seals included). Has apex seals/springs and more.

V8kilr

Nice I'll check them out

TrboSpdAnt

iTrader: (5)

Damn, bro. That blows. (No pun, intended). I say scrap a rebuild. Go with your initial plan od the Low-comp JDM engine swap (TII).

You can pick one up for fairly good cost. I'll pour some Guinness, in memory of the 7.