22RE: Dry Compression Test #'s

[meatloaf]

These are from a 92 truck. Truck runs but cant get it over 20mph. i think I also have a vacuum leak somewhere... Opinions??

cyl#1 = 125
cyl#2 = 90
cyl#3 = 140
cyl#4 = 150

Thanks,
ML

 

[snobdds]

Sure looks like a HG to me, however didn't you just replace your entire head with a new one...? I would assume you replaced your HG while in there.

I know numbers can be affected if the cam timing is off. It makes the valves not seat fully, thus letting air excape. How is your cam timing?

 

[KLF]

A compression test will tell you that something is not right, but a leakdown test will tell you what's wrong.

 

[meatloaf]

Sure looks like a HG to me, however didn't you just replace your entire head with a new one...? I would assume you replaced your HG while in there.

I know numbers can be affected if the cam timing is off. It makes the valves not seat fully, thus letting air excape. How is your cam timing?

Snobdds,

Yes, the HG is new. the head itself is not new. i found a used one that supposedly had 20k miles since rebuilt. It sounded like a diesel engine. I need to check valve adjustment. can you expand on the cam timing? not sure I understand.

Thanks,
ML

 

[snobdds]

Cam timing simply means your cam and pistons are in proper time. For a 22re that means your timing chain is properly aligned on both the bottom sprocket (crank) and the top sprocket (cam). If there not in proper time, then your cam is opening and closing valves when there not suppose to be open or closed. If it's off by a link or two, then the valve will be partially open when it needs to be completely shut...thus allowing air to escape and showing a low compression reading.

The bad thing is, once the timing cover is on, it's hard to make sure everything is lined up. One can be "pretty" sure by just looking at the cam sprocket and having the engine at TDC on the compression stroke...there should be the odd color link at about 11:45. If it's off, then it's impossible to have correct compression.

I would confirm CAM timing and then a leakdown test will tell you if the rings are worn...

 

[meatloaf]

Cam timing simply means your cam and pistons are in proper time. For a 22re that means your timing chain is properly aligned on both the bottom sprocket (crank) and the top sprocket (cam). If there not in proper time, then your cam is opening and closing valves when there not suppose to be open or closed. If it's off by a link or two, then the valve will be partially open when it needs to be completely shut...thus allowing air to escape and showing a low compression reading.

The bad thing is, once the timing cover is on, it's hard to make sure everything is lined up. One can be "pretty" sure by just looking at the cam sprocket and having the engine at TDC on the compression stroke...there should be the odd color link at about 11:45. If it's off, then it's impossible to have correct compression.

I would confirm CAM timing and then a leakdown test will tell you if the rings are worn...

Ok, we did align the 'shiny' marks on the chain to the notches on the crank/cam gears but not at 11:45 as you mention. crank was at tdc, gear notches were at 6 o'clock on the crankshaft (woodruff key at 12 o'clock) and 12 o'clock on the cam.

I may have to pull everything again

 

[KLF]

This where the "dimple" should be in the top sprocket, when the bottom pulley is exactly at TDC:

Just slightly left of center.

 

[toy4x4runner]

If it were timing wouldn't the problem be consistent in all 4 cylinders? Have you looked at ignition? What does it do under load? You said it cant get past 20 mph?

 

[snobdds]

If it were timing wouldn't the problem be consistent in all 4 cylinders? Have you looked at ignition? What does it do under load? You said it cant get past 20 mph?

Since the HG is new, I don't think compression would escape through that. Valves or worn rings would be the only place it can go. Even being off by a 1/2 link can replicate those numbers.

Before you tear things down again, do what KLF said and do a leak down test...