To test compression, do i need to intall pushrods?

[northernterritory]

I want to do a compression test to see if the cylinder head job fixed my compression issue. If I am going to to have to remove the cylinder head, if the compression is not there, I would prefer to not waste time with installing the rest of the head. So, do I have to reinstall the push rods, set the valve clearance, and etcetera.

 

[Scott Danforth]

Yes....otherwise how do you expect the valves to open or close

 

[northernterritory]

Yes....otherwise how do you expect the valves to open or close

Do they have to open though?

 

[Scott Danforth]

Yes, engine mechanics 101.

 

[Bondo]

If I am going to to have to remove the cylinder head, if the compression is not there, I would prefer to not waste time with installing the rest of the head.

Ayuh,.... Without completely assemblin' the heads, I guarantee it'll fail a compression test,.....

 

[Lou C]

Do you have a shop manual or access to the head installation process, including the hydraulic valve lifter adjustment? If not I'd suggest getting that information because this is something that must be done 100% according to the book. If you've never done it before, it is not just plug n play. Start with cleaning out the cyl head bolt threads in the block and making sure all your head bolts will thread all the way in.....Did you check the block deck for warpage with a straight edge and feeler gauges?

 

[jetmart]

Do they have to open though?

I don't think you do. Your wanting to check the compression and the valves need to be closed anyways. If you do it this way you won't be testing the operation of the valves and lifters though.

 

[hemi rt]

I don't think you do. Your wanting to check the compression and the valves need to be closed anyways. If you do it this way you won't be testing the operation of the valves and lifters though.

And how do you expect to get air into the cylinder to compress it. The valves have to be operational.

 

[Scott Danforth]

I don't think you do. Your wanting to check the compression and the valves need to be closed anyways. If you do it this way you won't be testing the operation of the valves and lifters though.

If valve does not open, engine can not bring in air to compress.

I suggest you sign up for an autos class at your local tech school and fully understand the otto cycle that is the internal combustion spark-ignited motor

 

[muc]

You can do a leakdown test.

 

[jetmart]

If valve does not open, engine can not bring in air to compress.

I suggest you sign up for an autos class at your local tech school and fully understand the otto cycle that is the internal combustion spark-ignited motor

By using a differential compression tester and bringing air in through the spark plug hole. It is done in aircraft engines all the time.

http://www.skygeek.com/eastern-e2a-...MIi6bftYXd1wIVVbjACh3cvwOAEAQYASABEgLH8PD_BwE

http://www.aviationpros.com/article/10386640/engine-compression-testing-back-to-basics

 

[Bondo]

[FONT=&quot] The type of compression test used for aircraft engines is a differential compression test. This is somewhat different from a direct compression test commonly used in testing automotive engines.[/FONT]

Ayuh,.... That's what's known to Us without an aircraft,..... as a Leak-down Test,......

That's how ya find the failure point after a bad Compression test,....

 

[Scott Danforth]

Jetmart, See post #9

You are confusing a leakdown test with a compression test. Internal combustion engines 101

Leakdown tests are used to determine what is broke when the compression test results are bad