checking out an 86 mk3 tomorrow

oregonjoe · 01-15-2010, 12:45 AM

Good luck!

Everyone has their own opinion on this.

I started mine, ran for 30 sec to 1 minute then shut off to check for leaks

Then restart and run to check timing avout 5 minutes. Really can't get a good timing check till the engine is fully warmed up and the thermostat opens up at which time the ECM has backed off the idle control motor and engine pulling max vacuum. At this point you listen for vacuum leaks (hissing sound) which will also cause the engine to loop at idel (if ait can hold idle)

Only after the engine will idle smooth after full warm up do I rev anything or drive it.

When thermostat opens up the engine RPM will drop from 1500 to about 1000

Turn off and check OIl to be sure no water is getting in from head job.

NOW is the time to actually drive it. I use short burst to 3000 from dead stop and coast to let engine cool down between busts (30 sec each) Its a fun time because a rebuilt engine will have some pep. The graddluy increase time getting to 3000 in burst with cool down inbetween. I only ran for 5 minutes at atime for first few runs with cool down so cylinders did not get too hot before rings got a chance to seat (thrich is to keep oil from glazing to walls)

Then take it on short drives with lots of dead stop to 4000 as fast as it can. You are trying to load the crank, valves and rings so they get through full travel during bearkin.

Thats how I do it - worked for me several times. Others baby it for 5000 miles. - To each his own.

01-15-2010, 12:45 AM	#197
oregonjoe 3" Exhaust Join Date: Aug 2009 Location: Southern Oregon Coast Posts: 83	Start up Good luck! Everyone has their own opinion on this. I started mine, ran for 30 sec to 1 minute then shut off to check for leaks Then restart and run to check timing avout 5 minutes. Really can't get a good timing check till the engine is fully warmed up and the thermostat opens up at which time the ECM has backed off the idle control motor and engine pulling max vacuum. At this point you listen for vacuum leaks (hissing sound) which will also cause the engine to loop at idel (if ait can hold idle) Only after the engine will idle smooth after full warm up do I rev anything or drive it. When thermostat opens up the engine RPM will drop from 1500 to about 1000 Turn off and check OIl to be sure no water is getting in from head job. NOW is the time to actually drive it. I use short burst to 3000 from dead stop and coast to let engine cool down between busts (30 sec each) Its a fun time because a rebuilt engine will have some pep. The graddluy increase time getting to 3000 in burst with cool down inbetween. I only ran for 5 minutes at atime for first few runs with cool down so cylinders did not get too hot before rings got a chance to seat (thrich is to keep oil from glazing to walls) Then take it on short drives with lots of dead stop to 4000 as fast as it can. You are trying to load the crank, valves and rings so they get through full travel during bearkin. Thats how I do it - worked for me several times. Others baby it for 5000 miles. - To each his own.