orinoco

Becuase my engine is a non starter, a few of you asked me what the compression is with the engine, well today i did the test and all the results for trailing and leading on both 1 and 2 were about the same, i am showing between 60 and 64 psi for all 4, this normal or am i to start looking for a new engine?

lovintha7

new engine. that's a bit low from what I understand.

Kentetsu

Well, it depends on how flooded it is. With a compression like that you should at least be able to get it started. I wouldn't worry about looking for a new motor yet...

orinoco

how do u drain a flooded motor? when i took the plugs out to do the compression test, none of them were fouled and they all had a good spark, both leading and trailing.

orinoco

i jsut came accross what haynes manual has to say, it says the compression limit is 85lb/in with a permissible difference of 21lb/in. This is at 250rpm. Sincei cant get the engine started and i dont think craking would cause it to turn at 250rpm, does this mean my copression is normal? (still need to know how to drail the engine tho, if flooded)

orinoco

oh and yeah, the fuel pump is disconnected right now because i took it out to check that it was flowing correctly, its back in and the lines hooked back up, but no power to uit, so there still might be gas in the engine right that needs to be drained soemhow? i dont know how it all works, hence why i am askign so much advice. Also its low on coolant in the radiator, does the rx7 have to have coolant in just to start the engine? (i will put some in btw, i dont want it to overheat). It has not been run at all snce coolant was taken out lol

Rx7carl

Ive never gotten a motor to start wiht that low a compression. Below 70, its toast in my experience. Having said that, compression test results are VERY dependent on having a really good cranking speed. Rotaries have very low compression at low RPM's. Make sure your battery, starter etc are in tip top shape and you have a good fast cranking speed before you trust those numbers your getting. If the low number persist, put a tablespoon of oil or atf in each primary barrel of the carb (throttle open, engine off) and see if the numbers get better.

orinoco

will try that, will any old atf do? Does the engine on crank really produce 250 rpm which the haynes manual says is what should be needed to produce the 85psi of compression needed. If my compression numbers are low, isnt that just proportionate to my cranking rpm being lower than 250rpm?

BMS2004

orinco, don't fret just yet. I tested mine today and got 60 psi on front and ~55 on rear. My numbers suck so much b/c I just realized today I "prepped" the comp tester wrong. I was just holding down the bleed valve. What you need to do is remove the schrader valve (tire type valve) so that it can pulse back into the motor. If you were just holding down the bleed button then it's prolly fine. If you had prepped it the right way then yes thats really low. Yes any ATF would work.

Ron

orinoco

the compression tester i used was a friends and not top quality may i add. Basically i think i was losing a lot of the pressure because it was just a push in tester with a rubber boot that just pushed int othe plug hole, not screwed in. It reset by pushing in the valve which released the pressure. So i am thinking i lost a lot of compression pressure cos it wasnt a screw in unit. Hence i think my compression is normal. Now what else do i try to get this tub working? Got spark, got startying fluid, got air.....got gas when fuel pump is connected. Now i al lost, will redo the timing tomorrow. fingers crossed.

matt_rally

clutch the car, if still no good tow it in 3rd or 4th gear it will start when the rotors start to spin fast enough.
But i would say that the motor is in need of replacment.
Also you will find that once its started and warmed up it should start easily.

orinoco

its a funny thing tho, u dont need to press in the clutch pedal to get it to crank, never had that in a car before.

PT Ray

Same here! Actually, I think on my first FB the switch on the clutch pedal did work for a short period when I first got it. My other two FBs, the switch never worked.