Howdy,

Got my compression done with Rotary Specific Compression Tool.

Rear Rotor Front Rotor
6.8 6.5
7.0 6.6
6.8 6.5

Would appreciate anykind of input on the numbers. Its my first compression test so be gentle. TIA

 

It seems low i think its supposed to be in the 8 or 9's? Not sure but what motor is this i think the 3mm motors have a little lower compression.

 

did you warm up the car?it is low

 

Assuming the results are valid, your engine is somewhat worn, but you don't have any blown seals or anything.

 

rynberg summed it up for my post.

 

Those numbers are normal for an engine with 20k+ miles, but they're not all that great...average really. When they approach low 6's all around then go on and rebuild it before it lets go.

 

mid 6s for engines with 20k+? I bought my last fd with 27 k on it and the readings were all 8.2-8.5.I almost bought two other 80k mi fds, original engines, and those readings were mid 6s. And they were on there way out.Get ready for a rebuild in the near future.

 

cool. at least i know whats in store. Thanks all.

 

Those numbers are a little weak but the engine still has life. Did you have the accelerator pedal on the floor when you did the test? Also porting drops the reading...

BTW: I have seen engines in the 50's last for a couple years.

 

8.5=Maximum compression
6.0=Minimum compression
Anything below 6.0 =bad

You be the judge!

 

Compression readings only tell half the storey. Due what you can to clean out as much carbon as you can from the engine then do another compression test. Too much carbon build-up will cause major compression problems due to some seals being stuck. There are many threads to search for more info.

 

FWIW~ my last motor scored almost exactly what yours is now and i drove with it like that for about a year of daily driving. the last month it was in, i drove it really hard to try to blow the thing. all the oil seals (front & rear cover, oil pan ect.) and even the rear oil feed line gave out before it did.

right now would be a good time to save up for a reman or rebuild and drive the thing like you stole it.

 

the compression tester we have here plugs into the front and rear sparkplugs. Compression is tested at 250RPM. Managed to get "engine steam cleaned" today. Routed total of 6 liters into both UIM nipples. Planning to get another reading on Monday. We'll see how much difference this makes.
Oh well. Will have a couple of mates help with the rebuild. will get Rotary Aviation seals.

 

I am curious as to how porting impacts on compression..?

 

My experience also. Low mileage like 20-40K gives high 7s and low 8s.

You motor could run a long time or it could be close to done. The compression test needs to be done with the motor warm and the other plug out. Cranking speed should be 250rpm IIRC.

 

It doesn't.

 

I'm in fact already in discussion with my rebuilders. Looking at getting the engine out close to year end, the holiday season will prove good distraction for my wife
Going with RA 2piece full rebuild kit. Whilst down there i hope to send the turbos for rebuilding and if...if all goes well i hope to port the motor. This is inline with my intentions of going single next year.