compression?? odd readings

[vex]

95psi on an NA isn't all that great. You may want to do a few things to try to increase your compression numbers. (You're only 5psi off from my rebuild limit--where I would tear it apart and rebuild.) Do the water trick or sea foam treatment. This "should" remove excess carbon. Do an oil change and replace the filter and oil with quality products. Make sure that your oil is the right thickness and has the right visc. for the temperatures you're seeing.

[Jeff4764]

sorry to ask, but what is the water trick? and also ive heard you can put about a teaspoon of oil in each cpark plug hole and that will increase compression

[Whizbang]

if you are using a normal compression tester for piston engines, the the value that you get can be skewed heavily. take it to a dealership and use a rotary engine compression tester and get numbers.

its cheaper than a rebuild!

[WE3RX7]

My two cents on this....

The piston tester is ok for "general" assumptions. What it proves is that you haven't lossed a seal or one isnt stuck.

50psi is low, even for a cold engine so vex's suggestion of letting it pump up to the overall psi is a better assumption. for the s4 NA 100psi would be better, but 95 isn't the end of the world (but I would start saving for that rebuild).

I would not do the ATF/MMO/Water trick. In certain cases, this is acceptable such as a motor that has been sitting in storage or got completely locked. Its a last ditch effort for freeing an engine, but not something you should do on a running one primarily because what it can "free up" can also cause MORE damage to the seals/springs in the engine than good.

Start running premix 100:1 at least on the ratio, do regular oil changes and start saving.

This is all speaking from experience on two separate NA engines - so I'm sure some people have had different experiences...

[NoDOHC]

Is your battery fully charged and was the clutch down? The engine has to be cranking at about 200 rpm to get good compression readings.

[vex]

Originally Posted by WE3RX7

My two cents on this....

The piston tester is ok for "general" assumptions. What it proves is that you haven't lossed a seal or one isnt stuck.

50psi is low, even for a cold engine so vex's suggestion of letting it pump up to the overall psi is a better assumption. for the s4 NA 100psi would be better, but 95 isn't the end of the world (but I would start saving for that rebuild).

I would not do the ATF/MMO/Water trick. In certain cases, this is acceptable such as a motor that has been sitting in storage or got completely locked. Its a last ditch effort for freeing an engine, but not something you should do on a running one primarily because what it can "free up" can also cause MORE damage to the seals/springs in the engine than good.

Start running premix 100:1 at least on the ratio, do regular oil changes and start saving.

This is all speaking from experience on two separate NA engines - so I'm sure some people have had different experiences...

I'd love to hear those experiences some time (not calling you out just curious). I used to get really low compression on my engine--around 90-95psi but that was probably from the 6 months to the year it wasn't run. I ended up doing the seafoam treatment and I gained back alot of compression. I don't do it as much as I used to anymore because it fouls the plugs, but the positive benifits have happened more than not to me. Then again I only have 50k on my engine so it might just be night and day.

OP, i'd listen to WE3RX7. He has much more experience with engines on the way out--where I haven't experienced my first one yet. You don't necessarily have to take it to a dealership. There are units out there that can tell you the full compression readings and conditions of the seals I believe full units sell for around 200-300 bucks while you can pick them up for 150 at the cheapest end.