Compression gauge test
 

1984 auto

Hi,

At last I bought a compression gauge tool.

Today I made my first diagnostic then please help me to know if I did something wrong.

I took out the spark plugs and I disconnected the coil.

I connect the tool to piston 1 then to the others, then I repeat,
later I insert 9 ml of oil to piston 1 and I connect again the tool, the to the other.

Obvious I did the test at wide open body throttle

Ok, I have this readings

1.- 165
2.- 167
3.- 150
4.- 160

with oil

1.- 210
2.- 205
3.- 200
4.- 205

I supose that this are bad news !

I recently replaced the head gasket and valves then I need first overbore rings ?

Let me know

regards

what is the correct compression presure ?

what is the cr of the engine ?, I believe 10.25 1

if a healthy engine should produce compression that is 18-19 times the compression ratio

then 10.25 x 19 = 194.75 ?

let me know

Compression on a NA should fall between 171 and 180 PSI on a good engine.

Your numbers are looking a little on the low side for #3. Based on your with\without oil numbers, it looks like #3 has some rings that are on the way out.

THe other numbers are consistant with a 19 year old engine.

AFJuvat

Thanks afjuvat

reading another compression posts, I saw that I did some things the wrong way.

1. I did not disconnected the fuel relay
2.- I did not take out the air filter
3.- I did the test in a cold engine

Do I need to do it again ?

I don't recall where, but in the last couple of days I ran across a web site that said the minimum COLD compression was 145 psi. This would put your #3 cylinder close to the lower limit.

I was using a compress checker and it said for my car it should be around 145 or within 10% of that. Mine came up as between 150-152.