Wondering what exactly a compression leakdown test does and if I should have one done to my newly purchased Gsr with 89k miles on it.

 

It tells you how much compression you have in each cylinder which will give you an indication of how much wear there is on your piston rings and such. If your car is running strong now, there is really no reason to check it, but if it's luggish and you have smoke coming from your tail pipe under acceleration then I would have it checked. Also, If you plan on running boost you should have it checked as well. Good luck.

 

click here for more info on compression tests.

 

Compression and Leakdown are COMPLETELY diffrent tests.

Compression tests measure static cranking compression on a motor with tp wide open and with a gauge it will tell where you stand interms of STATIC COMPRESSION readings. Most hondas are in the 200-250 range.

Leakdown tests are when you put 100 lbs of air pressure in the cylinder when the piston is at the top of the compression stroke with all the valves closed. If the 100 lbs bleeds off somewhere (wheather its past the piston rings, or the valves, or headgasket) it will give you a percentage of leak. you listen for the air bleeding off in the exaust (bent exaust valves), from the intake (at wide open throttle) (bent intake valves), through the oil valleys in the head, (worn rings), or bubbling in the coolant system (headgasket).

edit: holy crap this is an old thread. oops.

-s


Modified by sander at 6:43 PM 1/25/2005