DallasFC1

iTrader: (2)

OK,
So I got angry that my Vert STILL would not start last night... I pulled out my compression tester, pulled the EGI fuse, pulled the bottom two plugs, and started my testing. I started on the rear iron first. 3 very even bounces of 35psi, and a total rotor reading of 110psi. So I rule that rotor out and move on to the front rotor. This is where I got stumped. Absolutly no movment of the needle on the tester while cranking on the front rotor. SO, I thought I had a dead rotor. Pulled the tester out of the spark plug hole and did the poor man's compression test. This confused me more, I got 3 even hard puffing chugs from the front rotor with my hand in front of the hole... So I figured I must not have had a good seal on the tester the first time and hooked it back up. Much to my dismay, I got the same results, no movement at all on the tester.

This is an 88 Vert, N/a, no mods.
Compression tester is BRAND NEW OUT OF THE BOX as of last night. Literally the first time I have used it.

So I'm just sittin here scratchin my head wondering WTF?!

Any ideas?

hanman

Well, a couple of things.
1. did you pull the schrader valve out of the compression tester, or hold the button down to release the pressure as you took the test? (i am assuming you are using a conventional tester and not a mazda rotary tester)

2. Did you have the throttle wide open?

3. When you say you had 110 psi on the rear, it looks like you are adding all three scores together. That's not how it works. You need a score for each face of the rotor. 35 psi is NOT good.

Well, I guess that was more than two things.

DallasFC1

iTrader: (2)

Had the GF in the car doing the cranking and peddle holding. Thats odd, the tech printout I have from (dont slap me yet, but ill verify the source,) either bonzai racing or rotary performance website... On how to compression test with a non-mazda tester.

1: Yes, I held the release valve down to watch the bounces... Left the valve shut to get a total compression value.

2: Yes the throttle was held wide open HOWEVER, my battery started to run low while testing, I had to charge it to do the test in the first place.

3: I'm still stumped and it's ok that it was more than 2 points, I can't count either

Need some more info guys! Anything is good, keep it coming.

NotTTT

With the valve removed or depressed the comp gauge will generally NOT move to the higest reading. When you're cranking the engine with the valve removed or depressed, you're looking for eveness in the bouncing. 35PSI dead even bounces is ok. With the valve replaced or released, you'll be recording the peak pressure achieved. This is the fault of doing a comp test in this manner - the valve limits the airflow to the gauge itself which is why it's best to REMOVE it.

If you're feeling air pressure against your hand, then there is some compression. It may not be enough to register on the gauge. I would make sure that the comp gauge is seated securely, leave the valve operational, and see what the highest reading is. It sounds like the motor is dead though.

DallasFC1

iTrader: (2)

This is the write up I used for my compression test:
http://www.rotaryresurrection.com/2n...ion_check.html

(my bad Bonzi and Rotary Performance.. lol )

So my question now is:
Could the upper plug hole be used for compression test???? If so, may I ask why (braces for flames)....
Thank you very much for the quick replies. As of right now I am rebuilding my 86 13b so if this one turns out to be toast I will just simply swap them when the rebuild is complete.

THANKS in advance!