2007-07-26 10:40:34 · 3 answers · asked by Jason A 1 in Cars & Transportation ➔ Boats & Boating
Check your owners manual, or email mercury, that will give you the exact number.
2007-07-26 11:08:00 · answer #1 · answered by c2953lm 3 · 0⤊ 0⤋
The 120 is a Chevy 4 cylinder. You can buy an Auto Repair Manual at a Auto-Parts store for an idea. Buy a manual for a Chevy LUV Truck should be close.
The main thing you look for when doing Compression is how close all the cylinders are to each other. I not remember off hand but I think you want less than a 10% difference between cylinders.
Example; Say #1 has 100 PSI, #2 95 PSI, #3 108 PSI and #4 98 PSI. Then this is OK, but, if #4 has 78 PSI then something wrong in the cylinder.
What happens, you see normal wear and with normal wear all the cylinders should be close. If, one is off too much then it usually a broke ring or damaged valve/valve guide.
When a cylinder is off you put a little oil in the cylinder and check the compression again. If, it go up with the oil it the rings. If, it stay close to the old reading it the valves. BUT, when the compression on all cylinders is real low (like 60 PSI) then it most likely time for a overhaul in my opinion.
One last thing. IF, the compression is too low the engine will not run. If, it low and the engine runs, it may use oil and not have much power.
2007-07-26 11:38:20 · answer #2 · answered by Snaglefritz 7 · 0⤊ 2⤋
simply put, 100# at least on all 4 and not more than 10# difference between any 2.
2007-07-27 02:44:16 · answer #3 · answered by Anonymous · 0⤊ 0⤋