2000 GS400
129k miles

6 of the 8 cylinders were at 160psi, 1 cylinder was at 175psi and 1 cylinder was at 155psi.

What do you guys think? Does the engine seem pretty healthy or worn? Not sure what the specs from the factory/new are supposed to be. Open to comments...

 

Typically as long as the numbers are close together then that shows you likely don't have a blown headgasket. If one was like 60psi, or 100psi or something drastically different you should have concern. It's hard tell just from a quick comp test the overall condition.

If the motor still feels strong, doesn't burn oil coming out the exhaust, you don't have gas or antifreeze in your oil pan, nor oil in your radiator I would be happy with the numbers, the spread isn't that bad.

You pulled the efi fuse when you did this right? So that the gas isn't going in the cylinders because that will affect the reading..

Are you experiencing issues, or did you just do it to know what it is?

The best trio of tests to get the best understanding of the motor internal sealing condition is a compression test, and radiator pressure test, and a leakdown test. The radiator test is further testing the headgasket seal, and the leakdown will tell you if your valves are still sealing properly, as well as the piston rings...

 

Engine feels strong. Just got this test done to see if everything is good before running FI.
not sure if they pulled the fuse or not.

 

I like where this is going.

Just boost it, as it's a great diagnostic tool to test the condition of the engine. If there are any problems you will find out pretty quick.

 

Manufacter specs:

142 psi is minimum
178 psi is normal
14 psi allowable difference per cylinder

 

14 psi allowable diff from new? So each cylinder could potentially be at ~164 psi when new? If so, that makes me feel better. But, does this also mean the cyclinders could have readings as high as 192psi when new? Thanks for that info!

 

Toyota is usually pretty consistent. their new engines are usually very close to that normal number. Your gauge could be reading wrong. The difference between cylinders is a reference for you. Usually if a motor is done for, you will have one or two cylinders reading way low. If all the cylinders are reading very close then the motor is ok

 

That spec is from manufacturer so i would follow it as a guide. The way you test the car or a gauge that is not accurate can play a role.

Make sure car is at normal operating condition. Take out all spark plugs. Throttle must be wide open throttle. Then crank it at least 4-6 times and write down the reading. Again, bad gauge can give false readings. GL

 

Also you should add a teaspoon of oil on the cylinder that you lower than others. If you see a big improvement in numbers, the piston got worn rings

 

Why does everyone think the test was done wrong or the guage was bad? Did I indicate anything of the sort?

 

Have you done a wet compression test yet?

 

No. should I still get that done? Given the test results and the car running fine? I just dont want to spend m any unnecessary money.

 

Thought you got your own compression gauge. Nvm then

 

Means the variation from the 175 cylinder to the 160 cylinders = 15 high, 155 to 160 = 5 low

Given that 6 of 8 cyl are 18 below regular but 18 above min, I'd say those are OK. 175 to 178 is 3 low, that's also fine, and the 155 cyl is 23 low but also 15 above min.

I think you'll be ok on a low boost setup, but anything beyond that you'd probably want to do internals anyway. Keep it cooled and ensure headgaskets are OK and you shouldn't have a problem.

 

Thanks for the clarification!