Mazda Rotary Club

Cars by Model Type => 3rd generation RX-7's => Topic started by: davyv on August 23, 2007, 06:33:46 PM

Title: Is it a rebuild.
Post by: davyv on August 23, 2007, 06:33:46 PM
Did a compression test today, i followed these instructions.
With both spark plugs out, fully depress the accelerator pedal to the floor, and motor the engine for 5-10 seconds. You should watch for 3 bounces of the needle (once for each rotor face).
  I am only getting two bounces of the needle, is it knackerd, thanks.

 I should say the car is missfiring. I took out the two front leads and it didnt change , still missing, so I took out the back two and it wont start. I checked the plugs and they all fire ok.  There there is no water loss or white smoke
Title: Is it a rebuild.
Post by: shaunwil on August 23, 2007, 06:47:07 PM
I thought you only took one of the plugs out for each chamber. Did you make sure the engine was warm too ?

2 bounces isn\'t good, could mean you\'ve damaged a tip and lost compression on one chamber.

Shaun
Title: Is it a rebuild.
Post by: Hayward North on August 23, 2007, 07:06:31 PM
Can you loose compresion to one chamber ? though when a tip went you lost 2 of the chambers.

Anyway you need a proper compresion tester to test a rotary as a standard one with the valve taken out isnt reliable enugh.

You only take out 1 spark plug at a time from my understanding.

Im on a learning curve here :)
Title: Is it a rebuild.
Post by: pete sparrow on August 23, 2007, 07:11:27 PM
Where are you located mate? Don\'t get too depressed too soon! Go and have a proper test done by one of the vendors,and then you\'ll know for sure and they can advise you on what action to take.:)
Title: Is it a rebuild.
Post by: arrouk on August 23, 2007, 07:15:00 PM
correct procedure but you only remove the bottom plug and yes if a side seal or corner seal is damaged you would lose one chamber.
but to echo above best bet is to take it to a specialist.

matt
Title: Is it a rebuild.
Post by: Hayward North on August 23, 2007, 07:18:45 PM
My appologies read it to be tips insted of side seals :)
Title: Is it a rebuild.
Post by: arrouk on August 23, 2007, 07:45:26 PM
thats the problem in that a comp test is only an indication, davy have you tryed the deflooding, replacing the plugs and reving a bit.

when i had low comp and i flooded the car it would sometimes require that i rev the engine a bit (or a lot) to clear as the extra gasses force the seals into place.

also what happened immediatley befor it started running rough. ie were you driving hard, driving off boost just started like that one day?

it all gives more of an impression as to what has happened/is wrong.

matt
Title: Is it a rebuild.
Post by: davyv on August 23, 2007, 08:01:50 PM
I was going about 30 mph changing from 3rd th 4th gear on a slow road.
Changed plugs and leads.
 I have had the car about 4 years. Its a 97 type RSR , its done about 34000 miles and it is only a 1 day a week car. Its never been raced. I was the first uk owner and by its condition it had been very well looked after.
Title: Is it a rebuild.
Post by: Carl on August 24, 2007, 07:38:19 AM
Compression test is doone with the TOP(Trailing ) plug removed from both chambers at the same time,then insert the compression tester into each trailing plug hole and do the test,having the chambers plug out that is not having the test done helps the rpm a bit.
Each test must be done with EGI fuse out and at wide open throttle while cranking.
Regards
Carl
Title: Is it a rebuild.
Post by: RobbieRX-7 on August 24, 2007, 09:07:01 AM
Quote from: davyvIts never been raced.

This could be the problem. Not good for this sports car:confused: Have you ever noticed how much sh1t these cars throw out when you drive like a granny for ever, then wot on a nice road. I always take mine over 6000rpm every drive as it clears the throttle so to speak. By doing this, my car throws out virtually no carbon black smoke from the exhaust