Compression reading for 2,4?

[guy_geo]

Can someone give the range of compression acceptable that I should get on an engine with 93 000 miles on it?

Whait is the compression for a new engine?

Merci!

[2ManyZs]

I'm just taking this off the top of my head, but I think it should be in the 170-180psi range. I can't seem to find it in my pile of books right now, but I think I'm pretty close.

Hard to say about one with 93,00 miles. Could be in the 140's or 150's. I think if it would be much lower you would be looking at a ring job.

Anyone else that can find what I can't seem to??

[Royce]

I think the exact number would depend on you specific head/valve/piston combination. Typically you are just looking for consistent readings across all 6 cylinders. If there is a problem it will be obvious! Is there a particular reason you want a specific number or are you just trying to get a base line.

[guy_geo]

Just trying to get a base line for my future inspection.

I'm building my file for the spring inspection.

The engine is all stock, no mods made on it.

Thanks for your help!

Guy;)

[guy_geo]

So nobody elses got numbers for a stock engine, smog pump removed?

Thanks guys!

[Royce]

Sorry, I have Nissan, Haynes & Chilton's manuals and could not find any such number listed. If the compression test provides consistent number then the only other thing I can think to do would be to do a leak down test. If all cylinders hold air without leaking then that's as good as it gets! But remember these tests don't tell you everything about an engine. For example they don't tell you if the crank bearings are worn. But unless someone rebuilt the engine and reused the old crank bearing they are "probably" okay. Look for good oil pressure readings, ex. above the half way marker on the oil gauge at 2000 RPM.

Have fun!

[2ManyZs]

I don't have it any manuals and can't seem to find it anywhere else. I'm thinking I may have guessed a little high, it's probably closer to the 150 psi range.

If you have more than 10 pounds variance between cylinders it's time to start taking it apart to find the cause. If there are all within 10 pounds you can safely say the rings are in pretty good shape.

If you do a leak down test and prssurize the cylinders with 100-120 psi of air pressure and can hear air leaking out of the intake manifold or carbs the problem is most likely worn valves or seats.

If you open the oil fill on the valve cover and hear air the problem is in the rings, or cylinder walls or both.

No, like Royce said you still won't know how the main and rod bearings are but to be safe you should hook up a mechanical oil pressure gauge to the stock sending unit location and check the pressure, better to do it wiht a mechanicla gauge and get an accurate reading than to trust the electric stock gauge.If you are going to pull the pan to check the mains you are half way to a rebuild so it might pay to check the pressure correctly and get a good reading.

[guy_geo]

Obe Wan Kenobe taught you well young Skywalker!

message received!!

One more thing to add to my list!