As title says how easy is it to a compression test, I'm told you can do it yourself ?

Dead simple, same as any other car. Just a bit of a pain getting to cylinders 5 & 6.

 

Warm the engine, pull the fuel pump fuse, remove all plugs. Turn over several times with the throttle open until the gauge settles. I usually take readings when the engine is cold to see how everything is sealing before thermal expansion. Published figures are taken from a warm engine.

 

The minimum is 128psi, factory is 171 psi, no more than 14psi difference between cylinders. If one cyl is low, drop some oil down the bore and retake. If compression increases, it's usually worn rings. If the result is the same, issue is in the head or head gasket. 2 adjacent cylinders low can point to the head gasket. All cylinders low can be a incorrect timing (eg a tooth out) or an engine that badly needs a rebuild.

 

Generally-speaking, if you've got all 6 cylinders at 150+psi, you're looking at a healthy engine.

if its low on cylinder 5/6 its more likely to be melted piston

its not common for the head gaskets to fail on these cars

what makes you think you need this?

 

and Nos is spot on... (and you can test first cold but remember your battery may not hold out)

 

this is a little more step by step (from a previous post):

 

 

 

Prerequisites:

 

A good time to change spark plugs so get a new set (HGK’s PFR6B-11C).

Also a good time to check and clean coil pack connectors, so emery board & contact cleaner.

You may need some silicone gasket sealant or new O rings for the balance bar.

Make sure the batter is up to it (i.e. well charged).

Obviously the right tools to remove the balance bar coil pack brackets and spark plugs.

And again obvious, a pressure tester with 14mm thread, ensure it either has an extension of will fit down the cavity.

 

Compression test:

 

1 - warn the car up to normal running temp (should take about 10 min).

2 - remove, fuel pump fuse (and or disconnect CAS connector) RHD cars - on drivers side near firewall.

3 - remove, balance bar, ensure you do not loose the three rubber O rings/seals,

4 - undo coil pack connectors then remove coil packs and spark plugs (so as to allow as least resistance as possible, battery will last longer).

5 - connect pressure gauge up to one of the cylinders, hand tight.

6 – press fully down on the accelerator and turn engine over, 6 times should get a good reading (this is to open the throttle bodies to allow as much air in as possible).

7 - repeat point 5 & 6 for all cylinders and write down the results.

 

Info and checks:

 

NA - Min 142 psi, max 186 psi

TT - Min 128 psi, max 171 psi

(no more than 14 psi deference between any cylinders).

 

If any of the cylinders are showing lower pressure (obviously check it a few time first and check the pressure tester connection) put a bit of oil in the cylinder (method – one at a time get a small piece of vacuum line or fuel line about 12 inches long. I use a syringe type turkey flavouring injector but anyway you can measure and insert about 1 tablespoon of oil into the cylinder, do the test again and if the pressure looks better after this it would indicate the rings are leaking.

 

If the pressure is still low it would indicate:

 

1 - head gasket (should have other symptoms for this as well, i.e. bubbles/CO2 in the water or possibly if bad enough mayo in water or oil)

2 - valve stem seals (again other symptoms with this, i.e. burnt oil).

3 - valve seats not closed flush (reduces performance and/or un-burnt fuel/ black smoke/backfiring if it’s the exhaust ones).

 

 

Finish:

 

Put your old/new spark plugs in, coil packs, reconnect coil packs (check and clean connectors if needed), balance bar (check O rings) and reinstall fuel pump fuse (and/or CAS connector, check and clean).

if its low on cylinder 5/6 its more likely to be melted piston

its not common for the head gaskets to fail on these cars

 

Head gasket issues across adjacent bores being 1&3, 3&5 or 2&4, 4&6.

i know how it could be the head gasket and where... all i said was its not common for them not to fail

thanks for your input guys, 2 reasons I wanna ckeck, 1. Peace of mind 2. Learning