usmarinedelta

Hello,

So there is a local guy here and I was doing a compression test on his car. The results are as follows.

Starting with the cylinder closest to the front bumper (Cylinder 1?)

180
180
210
240 (then it starts dropping in psi slowly as I stop cranking, If I keep cranking it goes higher and higher)

I assume there is a leak? We've put a cap full of Lucas thick oil stabilizer in the cylinder and it still does the same thing.


Questions:
Would a valve adjustment solve this issues? I drove the car and drove it hard, no issues what so-ever.

Also what does it mean when the numbers go up as the cylinder # is going up?

He is using 10w-30 oil. Maybe he should switch to 10w-40?

Thank you.

Habitforming

It sounds like the check valve in your tester is bad. I'd address that first.

Habitforming

Either I'm not understanding your problem, or you have bad luck with gauges. A compression tester should have a one way check valve in it, such that the pressure developed on each stroke is added into the chamber. No matter what the engine does, it can't remove pressure from the gauge. That's why it has the relief valve on the side.

If your gauges aren't holding pressure, there must be an issue with them. I don't see any alternative.

Habitforming

Also, is the engine warm when performing the test?

The next step will be a leak down test, to determine where the cylinder is losing pressure.

A valve adjustment is never a bad idea, so long as you know what you're doing. But there's no way to know if that will resolve your problem without doing the leak down test first.

And if you're a Marine - Thank You for your service!

shind3

are you doing it with the fuel injectors unplugged? maybe fuel is getting to the seal by the 4th cylinder and ruining the gauge?

Car Analogy

...and to prove if its gauge or cylinder, you should have tried one of the 'working' cylinders again. Do those still hold pressure, but cyl 4 still does not?

If now none of the cyl will hold pressure, then gas broke gauge theory sounds right.

Sent from my SM-G920P using IB AutoGroup

Habitforming

Honestly this is all a distraction anyway. Wether cylinder 4 is 220 or 240 is irrelevant- it's clearly healthy. Time to focus on 1 & 2. Either do a leak down test, or a valve adjustment, but stop worrying about #4 for now.

windhund116

Agree. Do a leak-down test on all four cylinders & report back with results.

Habitforming

Again, nothing the cylinder does should have any impact on the gauge losing pressure. That is 100% the function of the check valve on the gauge. If it is losing pressure, perhaps it isn't designed to hold 240psi, thus why both gauges did the same (were they the same brand/model?).

Your focus should be on the cylinders with 180 psi.

THE REAL DEAL.

are you resetting the compression tester ?