DIY : Compression and Leakdown Check

[Mister_Perkins]

Tools you will need:

1. Compression Gauge ($19.00 from Harbor Freight)
---- http://www.harborfreight.com/compres...kit-66216.html

2. Leakdown Tool ($39.99 from Harbor Freight)
---- http://www.harborfreight.com/cylinde...ter-94190.html

3. Spark Plug Wrench / Extension / Ratchet

4. Air Compressor


Safety Note:

Make sure to remove the EFI Fuse before turning the motor over. If you do not, you will spray fuel in your cylinders and you can risk washing the rings out

Thanks for that addition Chris



Compression Test


First remove all spark plug wires and spark plugs


After all plugs and wires are remove, we will start with a compression test.
Grab your compression gauge, and spin it into your #1 spark plug tube making sure its tight. After your gauge is installed, crank the motor over 3 or 4 turns. Wahh Wahh Wahh Wahh. Get out, check the gauge.






HINT: Always use a fully charged battery to obtain
engine speed of 250 rpm or more.
(d) Repeat steps
(a) through
(c) for each cylinder.

NOTICE: This measurement must be done in as short a
time as possible. ( 3 or 4 cranks is sufficient)

Compression pressure:
1,226 kPa (12.5 kgf/cm. 178 psi) or more

Minimum pressure:
981 kPa (10.0 kgf/cm, 143 psi)
Difference between each cylinder:
98 kPa (1.0 kgf/cm. 14 psi) or less




If you are reading below 143psi, you will need to perform a leakdown test to determine whether your valves are bad or not. (May need re-seated)

Note: 143psi is for the 92-96 camry 5sfe. Pressures may be different for newer or older model 5sfe. (Especially 98+ Because the cylinders have a 1mm increased bore diameter)


Leak Down Test


To do that We grab the Leak-Down tool and spin it into the spark plug tubes, just the same as the compression gauge. The only difference here is you will be using air pressure to determine if anything is bad.

For me, I made my own just because I could. Its the same concept as the ones you buy at the store, but on my air compressor I have an in-line air pressure regulator so I just adjust the one side of the T to 15 psi of pressure. It does the exact same thing as it would with a store bought.

Hook your compressor air cable up to your tool and run 15psi of air through it. While the air is running through, you should be checking the intake tube or manifold and the exhaust (Back of car) For a sound like a leaking tire. pffffffffffffffffffffffffffffffff








If you hear air, that means that air is escaping past the valve seats on whatever side you hear the air on is the side your low compression could be related to.

Example:
I hear air coming out of the intake manifold on cylinder 1 only
( Your problem would be on the intake side on cylinder 1 . Repair the problem and re-check with leak-down tool )

Preform this test on each cylinder.

HINT:

----- Make sure to have the motor at TOP DEAD CENTER before preforming the leak-down test!!!! If your valves are partially open, your test will NOT BE ACCURATE!




A leakdown test is more like a static test of a specific cylinder. It will indicate whether the leakage is due to intake- or exhaust-valves or piston rings.
An engine in great condition should generally show only 5 to 10% leakage. An engine that’s still in pretty good condition may show up to 20% leakage. But more than 30% leakage indicates trouble

-If you hear air coming out of the tailpipe, it indicates a leaky exhaust valve.

-Air coming out of the throttle body would point to a leaky intake valve.

-Air coming out of the breather vent or PCV valve fitting would tell you the rings and/or cylinders are worn.

-A cylinder that has poor compression, but minimal leakage, usually has a valvetrain problem such as a worn cam lobe, broken valve spring, collapsed lifter, bent push rod, etc.

-If all the cylinders have low compression, but show minimal leakage, the most likely cause is incorrect valve timing. The timing belt or chain may be off a notch or two.

-If compression is good and leakage is minimal, but a cylinder is misfiring or shows up weak in a power balance test, it indicates a fuel delivery (bad injector) or ignition problem (fouled spark plug or bad plug wire).

[Chris Crash]

Just adding, before you do the compression test with the starter, remove the EFI fuse so you're not spraying fuel in your cylinders!

[Mister_Perkins]

Originally Posted by Chris Crash

Just adding, before you do the compression test with the starter, remove the EFI fuse so you're not spraying fuel in your cylinders!

good point

[BMR]

Nice job; good DIY post.

I've heard it's possible to have good compression, but fail a leak down test. Is that true?

[Mister_Perkins]

Originally Posted by BMR

Nice job; good DIY post.

I've heard it's possible to have good compression, but fail a leak down test. Is that true?

Theoretically, you could pass a compression test, but fail the leakdown.

The compression test is a good indication though... tells you whether there is a serious leak in one of the cylinders with all valves closed.

[lemegacool]

great write up but i think you forgot to mention that the compression test must be done with the engine hot... at least i think you have to do it with the engine hot

[reluctantmechanic]

thanks mr. perkins, another great write up

[Stillrunning]

Without a pressure gauge on the leak tester you won't know what the leakage rate is. Leak down tests should also be done with engine hot and piston at TDCC. The leak down tester I made has a gauge. I set my compressor to 100psi and watch the gauge, a pressure at the gauge of 95psi would indicate a leak down rate of 5%.

[lemegacool]

i really need to build a leakdown tester! didnt even knew there was a tool for that lol

[LynchburgCSI]

Mister_Perkins, you've done it again. You gotta post these links in the "add this to the sticky" thread. I'm tired.

[Mister_Perkins]

Originally Posted by LynchburgCSI

Mister_Perkins, you've done it again. You gotta post these links in the "add this to the sticky" thread. I'm tired.

haha, Alright Lynch... i will

Originally Posted by lemegacool

i really need to build a leakdown tester! didnt even knew there was a tool for that lol

lol, it comes in handy.. Especially if you are doing your own valve work, just to make sure you did your stuff right

[OldElPaseo]

HI

My 5sfe overheated and is useless. but i have a spare 5sfe lyin around. i know its workin good. but before i put it back in i was wondering if i should rebuild it.. can i do this test with the engine out of the car ?
I guess i would install the starter for the compression test ( i have a spare 5sp tranny too) and for the leakdown would be the same ? or would the missing exaust and intake false up the readings ?

[mail2_jb]

Very helpful (even though I don't have to do this now) in understanding how to perform this test when needed.

Any way to put a DIY on EVAP leak detection (not sure it is even possible by DIYers without expensive tool). I have been battling an evap leak and is now kind of replacing random parts (from junkyard).

[88 LE]

Originally Posted by OldElPaseo

can i do this test with the engine out of the car ?

I guess i would install the starter for the compression test ( i have a spare 5sp tranny too) and for the leakdown would be the same ? or would the missing exaust and intake false up the readings ?

Leakdown test can be done with engine out of the car. No starter needed, but you do need to turn the crank with a socket and wrench so that the cylinder your testing is at TDC compression.

Missing intake and exhaust manifold does not matter for a leakdown test. Listen for air escaping at the intake and exhaust ports of the cylinder head.



P.S. One thing not mentioned in the OP is air escaping at radiator or adjacent cylinders which would indicate a blown head gasket, cracked head, or cracked block.

[Stillrunning]

Originally Posted by 88 LE

but you do need to turn the crank with a socket and wrench so that the cylinder your testing is at TDC compression.

Air pressure in cylinder will turn engine over so that testing cylinder will go to BDC. Best to lock engine in TDCC position. Also, engine out of car will not be hot so test will show worse than actual results. There will always be some leakage past piston rings which will result in air escaping into engine block and through vacuum system which you may assume is leaking past intake valve.