Compression testing

Nvy · March 2, 2021, 09:04

As title states I am about to do a compression test and want to know some details, this is what I found with the search:

1. WARM UP AND STOP ENGINE Allow the engine to warm up to normal operating temperature.
2. REMOVE IGNITION COILS (See page IG–4)
3. REMOVE SPARK PLUGS
4. INSPECT CYLINDER COMPRESSION PRESSURE
(a) Insert a compression gauge into the spark plug hole.
(b) Fully open the throttle.
(c) While cranking the engine, measure the compression pressure.
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 pos- sible.
Compression pressure: 1,270 kPa (13.0 kgf/cm2, 184 psi)
Minimum pressure: 1,000 kPa (10.2 kgf/cm2, 145 psi)
Difference between each cylinder: 100 kPa (1.0 kgf/cm2, 15 psi) or less

1. Fully open the throttle. - Means to press the pedal all the way in right?
2. Do I need to remove any fuse?
3. How much oil do I need to put in when doing the wet test? I will be using a syringe so need to know the mls to put in so I dont screw anything up.
4. After the test should I fire up the car to burn the oil or?

I have never done it and that's why the questions.. learning slowly. Nothing that could help me out on youtube.

gon · March 2, 2021, 09:22

1- yes ....
2 - no , I would remove the wiring to the ignition coils and disconnect the injector plugs to stop engine flooding (but ECU might do that when you have the fully open throttle anyway ... so maybe not required?)
3 - Oil ? no need to put any oil, unless you find a problem ... but I suggest trying it first without.

Nvy · March 2, 2021, 10:00

Quote from: gon on March 2, 2021, 09:221- yes ....
2 - no , I would remove the wiring to the ignition coils and disconnect the injector plugs to stop engine flooding (but ECU might do that when you have the fully open throttle anyway ... so maybe not required?)
3 - Oil ? no need to put any oil, unless you find a problem ... but I suggest trying it first without.

Yea, wont do the wet test if all the cylinders read within 10% of each other but in case two that are nearby read low will have to do the wet test to rule out the head gasket.

SV-3 · March 2, 2021, 10:50

You might find the attached link to compression and leakdown testing useful:

http://www.wcengineering.com/articles/leakdown.html

Nvy · March 2, 2021, 11:03

Quote from: SV-3 on March 2, 2021, 10:50You might find the attached link to compression and leakdown testing useful:

http://www.wcengineering.com/articles/leakdown.html

Thank you for that but shop around here are no good for changing a gasket let alone a leak down test. I will be doing the compression test myself and if I find anything that worries me I will look into that. Last time when I let a shop do the compression test they did it on a totally cold engine when the car was outside for the night and gave me some really dodgy results like 12.5/10.2/10.4/11.5. Not that it cant happen but they didnt do the wet test after that, they didnt read the manual and stuff, just my money on the wind.

Carolyn · March 2, 2021, 11:45

If it's more than 10 lbs difference, it really doesn't matter whether its the gasket, rings (most likely) or valves.

In all cases the head has to come off to fix it.

Nvy · March 2, 2021, 11:58

Quote from: Carolyn on March 2, 2021, 11:45If it's more than 10 lbs difference, it really doesn't matter whether its the gasket, rings (most likely) or valves.

In all cases the head has to come off to fix it.

True, I want to check if the engine is healthy, if not will be taking it off and will do tranny with it. Do I need to remove the injector plugs?

Carolyn · March 2, 2021, 12:02

Quote from: Nvy on March 2, 2021, 11:58
Quote from: Carolyn on March 2, 2021, 11:45If it's more than 10 lbs difference, it really doesn't matter whether its the gasket, rings (most likely) or valves.

In all cases the head has to come off to fix it.

True, I want to check if the engine is healthy, if not will be taking it off and will do tranny with it. Do I need to remove the injector plugs?

I'd just take out the EFI fuse. I think it's #11 in the box in the engine compartment.

Nvy · March 5, 2021, 14:16

So 1-2-4 are 12.5 bars and 3 is 11.5 bar. I ended up taking it to a "reputable" garage to try them out but they didnt do any wet test for the 3rd that is lower than the others. They will do it another time free of charge but not today and I have spent 2.5 hours there. Its just funny, I asked the guy to do it like its written in the manual but he didnt do it..

Will visit them next Friday again.

shnazzle · March 5, 2021, 14:41

That's a big difference in psi.

Nvy · March 5, 2021, 15:27

Quote from: shnazzle on March 5, 2021, 14:41That's a big difference in psi.

11.5 is quite high to be the ring lands I think so it could be a valve not sealing 100%. Will go down there again and try the wet test.

Maybe someone else could give their thoughts?

Nvy · March 9, 2021, 13:09

The wet testing was done today and the number for 3rd cylinder went above 15 bars. I guess its the rings and my engine that has less than 90k km and was replaced in 2008 with a brand new one from Toyota is shot. Silly thing that the car came with the pre cats still in, altho they were quite fine.

1979scotte · March 9, 2021, 15:15

Quote from: Nvy on March 9, 2021, 13:09The wet testing was done today and the number for 3rd cylinder went above 15 bars. I guess its the rings and my engine that has less than 90k km and was replaced in 2008 with a brand new one from Toyota is shot. Silly thing that the car came with the pre cats still in, altho they were quite fine.

If its not had regular oil changes anything is possible.