Compression testing

[Segun]

i own a nissan pulsar 2004 which is the sentra or the Almera in america, i got a compression reading at around 150PSI for each cylinder, to nissan standards the compression should be: 192 PSI / 1324 kPa / 13.5 kg/cm^2
Minimum compression: 168 PSI / 1157 kPa / 11.5 kg/cm^2 and i haven’t not done the wet test as of yet need the time to get a around to it, but if its the same reading with a wet test what faults could it be

Topic

[richiepearce]

What are the actual figures?
How many mile has it done?
Post the wet test results.
If the compression for all cylinders are the same but a bit low this is usually due to a high mileage vehicle, could be letting by on piston rings hence need for wet test or valves/seats due to carbon build up.

[college man]

If oil is added and compression increases rings are at fault.
If pressure stays low. a valve may be sticking or not seating
properly.

[Segun]

with out oil

1 2 3 4
130 149 149 151

with oil
1 2 3 4
150 170 151 160

my car has done 108xxx km which is 67,108 miles

let me know hat you think

[richiepearce]

As you will see from your results some compression is being lost past the piston rings on cylinders 1,2 and 4.
I would say number 1 cylinder also has a valve/s not seating due to carbon build up or starting to burn.
I have seen a number of nissans which burn valves due to low quality material used in production.

[Segun]

so how to fix this problem….?

[richiepearce]

Remove head, check valves and seats best way is to get it pressure tested. Personally I would replace and lap new valves in all cylinders. As for the rings it is a sump off and remove piston and replace rings job. Depends how much time and money you want to spend. If the valve seats look good then you can save on the pressure testing and just replace and lap valves.
I say do all valves as they are not too expensive and you don’t want to be doing the job again on other valves a thousand miles down the road.

[college man]

Try this test.

[Author]

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