What I Got for Christmas

[zedfoot]

What did Santa bring you? I got this.

[Dr.Diesel]

Zedfoot, that is a very useful diagnostic tool. I bought one of those 20 or so years ago & have used it many times. You will get a more clear idea of what's going on inside of any engine with one of those.

[colinc]

Looks like some kind of fancy compression, leak-down tester that uses compressed air. How does it work and what are the capabilities? Thanks

Oh, and i got welding stuff for Xmas. I have to start learning that skill in case i ever get the guts to tear the car apart.

[molstdZ]

This is what I got. Will soothe my muscles from working on z cars. Lol.

[zedfoot]

That looks like something Zguy made.

[Ont240]

Added a diagnostic tool and a tp gauge that i can read even in the dark!

[CustomZRoadster]

New 2022 Toyota 4Runner TRD OffRoad Premium - loaded with extra tint, ceramic protection and rust module. Will load some pictures soon.

[CustomZRoadster]

This one comes with Toyota KDSS which makes driving around town and over our terrible roads enjoyable for a 5000 lb + truck.

[molstdZ]

Man, I wished I was lucky as you. All I got was a wooden Datsun massager. Lol!. Congrats on your new ride. Looks fantastic! Enjoy the ride!!!

[72Dz]

Hi Eric, wondering if you used the compression tester on your 240z yet? Do you or anyone know what the acceptable compression range is for an L24 engine?
Thanks

[zedfoot]

Not yet. I was going to use it on my '54 Chevy truck, but I tore the engine apart before I got to it. When I get the Datsun in the shop I will use it and post the results.

[Ont240]

Having worked on many different 240's. I've found an acceptable range to be 150 psi or higher. Prefer to check with warmth in the engine, throttle all the way to the floor, and 10-12 compression cycles, plugs removed on all cylinders
The more important thing is ... are they even across all 6 cylinders within 10%
135 psi would indicate possible ring or valve leakage. Thats when you squirt oil into the cylinder (equal amounts, one at a time) and retest.

[Dr.Diesel]

Hey there 72DZ, Just in case you're not aware, the tool in the image that Zedfoot has at the beginning of post is not a compression tester. It is a "Leak Down Tester". Thats a different kind of diagnostic tool that will provide a lot of information as to the condition of an engine. The leak down tester works on compressed air which is applied to each piston at top dead centre. This is a great tool to use in conjunction with a compression gauge for a comprehensive idea of the condition of an engine.

With regards to compression, as Ont240 mentions, 135 psi on the compression gauge would indicate some further diagnosis should be done. I agree with him. You don't want to see less than 150 psi. It will run with less. But, the engine will have poor performance.

[zedfoot]

150 seems pretty high. Would you not need at least 10:1 compression ratio and no leakage whatsoever to get that?

[Six_Shooter]

There's no specific number that you "want to see" on a compression tester. Yes, higher numbers will indicate that sealing is good, however, what you need to be more concerned with is that all of the cylinders are very similar in numbers, say within about 5% of each other.

Things like static compression, head flow, intake and exhaust flow, cam, temperature (both of the engine and ambient), oil film in the cylinder and cranking speed all have an effect on the pressure produced in a cylinder as shown on a compression tester. It's because of the aforementioned things that there is also no rule for X amount of static compression will produce Y amount of cylinder pressure. Granted all things being equal, with the exception of static compression the higher static compression engine SHOULD produce more cylinder pressure during a compression test using a compression tester.

Again, look for the cylinder pressures being equal, more than a specific number.