Compression Results and Implications for Long-term Engine Health

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So I just had the mechanic run a compression test. Results are below:

Cyl 1: 138
Cyl 2: 141
Cyl 3: 140
Cyl 4: 132
Cyl 5: 125
Cyl 6: 130


He said they did the test cold; does anyone know how much that would skew the numbers in these motors?

I was a little concerned at the max variation being 16 psi, 2 over the factory spec, as well as the cylinders at the back of the block being lower, where the HG usually degrades. The mechanic told me the piston rings are probably a little worn and it's nothing to worry about, but I wanted to put this here in case anyone with a lot of experience with the 1fz thinks its a sign of deeper issues. Thanks.
 

SmokingRocks

I bought a Cruiser to keep miles off my Cruiser
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Where are you at? Elevation?
Mileage?
Engine condition ?
Has it ever been overheated?
 
Last edited:
Joined
Aug 20, 2021
Messages
220
Location
Northwest Arkansas
Where are you at? Elevation?
Mileage?
Engine condition ?
Has it ever been overheated?
I’m in northwest Arkansas so the elevation is roughly 1400 feet.

226k on the engine. I just got it 500 miles ago so no idea if it's been overheated. The PO replaced the radiator shortly before I got it at the advice of their mechanic.

It runs pretty well, just a slight rough idle; possibly related to the 0401 code.
 

SmokingRocks

I bought a Cruiser to keep miles off my Cruiser
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It’s fine. Your mechanic is probably right. Piston rings are worn but your numbers aren’t so off that I’d tear her down.
 
Joined
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It’s fine. Your mechanic is probably right. Piston rings are worn but your numbers aren’t so off that I’d tear her down.
Yea I thought so too but I'd just been reading how the FSM technically calls for a tear down at 300k km (186k miles) for optimum operation.

But I gather basically nobody does this since the 1fz just keeps groaning along like a tractor.
 

flintknapper

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Yea I thought so too but I'd just been reading how the FSM technically calls for a tear down at 300k km (186k miles) for optimum operation.

But I gather basically nobody does this since the 1fz just keeps groaning along like a tractor.

^^^^^

Yes, no need for a tear down....based solely on a mileage figure being hit. I have 327K (MILES) on mine and it runs fine.

But my compression is higher than your figure. May be due to elevation differences (I'm at 320 ft.)

Slightly lower compression on cylinders 5&6 might not mean anything since generally, they start on cylinder 1 and by the time they've cranked the engine 6 or 7 revolutions per cylinder, the battery is feeling it. I never do a compression test without a battery charger on the battery (and starting with a fully charged battery).

Compression 316K.jpg
 
Last edited:
Joined
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Messages
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Location
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^^^^^

Yes, no need for a tear down....based solely on a mileage figure being hit. I have 327K (MILES) on mine and it runs fine.

But my compression is higher than your figure. May be due to elevation differences (I'm at 320 ft.)

Slightly lower compression on cylinders 5&6 might not mean anything since generally, they start on cylinder 1 and by the time they've cranked the engine 6 or 7 revolutions per cylinder, the battery is feeling it. I never do a compression test without a battery charger on the battery (and starting with a fully charged battery).

View attachment 2818380
The engine was also cold when they did it, so I imagine it'd be closer to 170 if they had warmed it up first.
 

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