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Sloppy Jalopy
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Discussion Starter · #23 ·
what did the leak down and compression test tell you?
Leak down and compression went strangely. I definitely wasn’t expecting this but oil looks brand new, atleast there’s still some translucent golden colour to it, maybe a little darker than something fresh out the bottle but definitely not something due for an oil change in my opinion. Compression is what stumped me. When I had first had this engine in the car it was running upwards of 200psi on all four cylinders. Now they’re all more or less at 150psi. Me being a noob at this I’m fairly confused, I’d expect it to have decent compression through three and one be faulty for example. For all four to be 60+ Psi down… what the hell is that supposed to mean? My best guess is a headgasket failure somewhere… any advice?

supposed to have that in all Honda’s. I talked to someone with a 94 hatch said he had overheating problems without it too.
 

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93 4d lx, z6,ported, port matched, compression bumped, balanced, manual swap
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Did you disconnect the fuel injectors and block throttle open for the test? In the case of cylinder wash down you may need to squirt some oil in each cylinder and crank it for a minute with no plugs to get oil back in the rings as well. Additionally any change in cranking speed will skew the results, so be sure the battery is fully charged and your starter is not drawing excessive amperage to verify its good.
 

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Discussion Starter · #25 ·
Did you disconnect the fuel injectors and block throttle open for the test? In the case of cylinder wash down you may need to squirt some oil in each cylinder and crank it for a minute with no plugs to get oil back in the rings as well. Additionally any change in cranking speed will skew the results, so be sure the battery is fully charged and your starter is not drawing excessive amperage to verify its good.
See here’s the thing joe. I didn’t know what a leak down test is and I’m not sure if I can get a tester at the moment. I’m assuming what it does is tell u the compression and whether it leaks away right? What would that have to do with the injectors and propping the throttle body open, out of curiosity. I was going to just try a test by pulling the rail and injectors out and fire it up, to see if the fuel spray patterns are out of whack.
 

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Discussion Starter · #27 ·
So if it is leaking what should I do…? Replace piston rings? The engine was remachined writhing 50k kms so I’m assuming the valves and guides are sealing properly. Although there is some pulses of air coming from the oil filler cap, not sure if that is just the air from the oil pressure or some kind of moving parts making some air pressure.
 

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When you had 200, was the engine slightly warm or fully warm, then cold when you had 160?

Or were conditions the same?
 

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Discussion Starter · #29 ·
When you had 200, was the engine slightly warm or fully warm, then cold when you had 160?

Or were conditions the same?
I’m assuming by 200 and 160 you mean oil temps? If so no the coolant temp was hotter at 200 and it wouldve been slightly below ideal temp at 160
 

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I’m assuming by 200 and 160 you mean oil temps? If so no the coolant temp was hotter at 200 and it wouldve been slightly below ideal temp at 160
Just coolant temp. Didnt know if you did comp test at different engine temps. Readings change based on temp.
 

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Discussion Starter · #31 ·
Pull spark plugs out and check their condition.

Just because it ran rich, doesnt mean an injector or two isnt being super finicky.

Do you have a thermal gun that can read upwards of 1200 degrees? Next time the car is cold, fire it up, let it idle, and take a temp reading on the exhaust runners every few minutes. See if they are somewhat close together, or if you have one or two runners going at a wildly different temp.


SMell the exhaust and see if the fuel smell sorta matches what the O2 is saying.


It is pretty rare, but a super rich condition can actually show as running lean to the sensors, but you would still know if its actually rich via exhaust color and smell.

Checking the plugs will let you know if its running rich because its not BURNING. Weak ignition control module is common enough, along with crappy distributor caps.
It definitely fires on all four cylinders, all four headers got toasty after about a minute of running. The spark plugs were all wet with fuel and nicely charred.

Just coolant temp. Didnt know if you did comp test at different engine temps. Readings change based on temp.
That’s a good point it may have been warm when I did the compression test first. Which would obviously make a lot of sense. The thing is with forged internals they expand more under heat. That being said these engines hate the cold and sound like a diesel when they are cold started. I had read that the pistons are slightly too small for the sleeves so they kind of bounce around before it’s up to temp, meaning there would be a pretty big leak in compression . I would test that right now but I have a full aluminum rad on the way, and wasn’t planning on using the oem one again… means I can’t really test it properly without the new rad… I don’t have extra coolant.
 

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BATSLOMAN GIVES NO FUCKS.
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So if it is leaking what should I do…? Replace piston rings? The engine was remachined writhing 50k kms so I’m assuming the valves and guides are sealing properly. Although there is some pulses of air coming from the oil filler cap, not sure if that is just the air from the oil pressure or some kind of moving parts making some air pressure.
where is it leaking from? rings? head gasket? cylinder wall? crack in the head?

also, you dont have any extra /water/ to test it? lol,

Im going to go with head lift
 
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BATSLOMAN GIVES NO FUCKS.
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I meant leaking as in compression leak. Is there some way to know how to figure out where it is instead of taking it apart?
yes. that is what a leak down tester is for. do you not click on any of the links provided?
 

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Discussion Starter · #35 ·
I meant leaking as in compression leak. Is there some way to know how to figure out where it is instead of taking it apart?
Yea I did but I don’t have access to one at the moment

I’m assuming by 200 and 160 you mean oil temps? If so no the coolant temp was hotter at 200 and it wouldve been slightly below ideal temp at 160
It’s still 150 psi cold and hot…
 

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Here is a very simple test. Go under the hood, remove the fuse for the fuel pump relay and injection. Heck, yank the fuse for the ecu.

Turn the engine over with the key until you know for sure it is not trying to fire.

remove spark plugs.
remove intake tubing, stick half a rag inside the throttle body to keep the flapper open.

Now do a compression test on all four cylinders. Crank for the same amount of time each one. I think 10 seconds is okay. Have a battery charger hooked up if you have one.


Now, find some oil. Pour a cap full of oil down each spark plug hole as you test them again. Pour oil, check compression. Pour, test.


Compare numbers. If you have a significantly higher pressure after adding oil (example, 120 psi after 10 seconds of cranking dry, 200 with oil), the pistons or piston rings are the reason for lack of compression.

If the numebrs are only marginally better, say 120 to 140 psi, then the compression loss is in the cylinder head. Head gasket, valves, cracks near spark plug holes, etc...

Slo gave you good links to read. But a poor mans leak test is adding oil and rechecking compression.

Harbor Freight has a halfway decent compression tester for cheap.

Do not focus too much on the actual PSI you get. Focus more on whether they are comparable to each of the other cylinders. Even if the numbers decide to show as low as 100 psi, if all 4 match up quite closely, likely you do not have any issues.

If you find 1 or 2 cylinders wildly different, you need to check valve lash adjustment, as that too tight will hold valves open, leaking compression, and if too loose, will wait too long to open valves, increasing compression and making other cylinders look bad.


Valve lash adjustment can effect what is known as elastic compression.
 
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