compression results? uh oh...

[sacline]

Did compression test today.
Dry:130-140-125-60
Wet: 140-150-130-90
The car runs good, pulls hard. Steady idle doesn't bog down, no smoke except for at idle blueish smoke from bad valves seals, doesn't leek any fluids, no mix of oil and coolent, what do these results tell me and since cylinder 1 is shot why doesnt the car run like crap? Thanks....

 

[mebetter]

If the car ran fine what drove you to do the compression check?

 

[sacline]

I just bought it a month ago. I have ben replacing things such as coil pack, plugs, wires ect....just wanted to check compression...ended up with looks like bad results...but as i said it runs good. Does it have bad rings?

 

[untouchablecc]

That is a hell of a drop. I know you dont want to hear this but if this is your daily you should start saving. You definetly have low compression due to ring wear but that cyl 1 is scary low. I almost want to say one of the valves might not be sealing properly.

 

[gieri002]

Were the tests done when the engine was warm/hot both times or was one a cold test? It seems to be rings since the numbers went up with oil, but I'd expect a greater increase.

 

[sacline]

Car was warm.. i do have blow by at idle...would that make greater chances rings are bad?

Time for a swap. But why would my car drive good with bad rings and bad valves?

 

[BogusSVO]

More testing is needed.

Do a leak down test.

#1 cyl will wear faster than the rest since it is the coolest cylinder, due to the water pump being in front of it.

The leak down test will show if it is rings or valves.

#1 cyl may have a valve that is not seating properly, and shows in a compression test.
But when it runs it does seat due to it having more of a load, and the amount of time it hits the seat.

It would be an ever so slightly bent valve(s).
It is very rare to see, I can only recall 3 times in 20 years that I have ran across this issue.

 

[daren_p]

Were the tests done when the engine was warm/hot both times or was one a cold test? It seems to be rings since the numbers went up with oil, but I'd expect a greater increase.

The oil trick doesn't typically work on DSM's since the pistons are normally dished. You add oil, the oil just sits on the top of the piston. Which increases compression results, but not because its making the rings seal better.

 

[sacline]

Thanks. A bad valves makes sense to me since the car runs good and pulls hard.. if i were to take the vc off and visually inspect the valves what would i look for? And being bad rings i would have smoke and loss of power correct? The only thing that tells me the rings Are bad is blow by at idle which isn't that much...ill do a leak down here shortly..

 

[BogusSVO]

Pulling the VC would not show a slight bent valve.

Leak down test, or pull the head and have the valves in that cylinder ground would be the only way.

 

[sacline]

Ok ill get to a leak down test hopefully tomorrow. I looked down thru the spark plug wells.into the cylinder and all of them look brand new! Not one seems to have any carbon build up or oil on it at all!? Car has 145k on her....shouldn't i especially if rings are bad, have carbon build up? Thanks for help bogus svo.

 

[Firsts tuner]

So bad readings, but good performance? Maybe it's just me but I think I would try another pressure tester. I have 3 and they all read different, so I add up all three readings and divide by three to get an average. Not really nessicary, but the cheap testers you have to hold on the spark plug hole vary greatly from the better quality ones that actually screw into the spark plug hole.

 

[sacline]

Yea im using a "sun" compression tester. It is a bit old. Regardless somethings wrong and mind as well swap it. Too bad its my dd. Ill post up a leak down test in a day or two just to pin point the problem.

 

[white92talontsi]

As Bogus stated it could be a bad valve. Most of the time if it is a exhaust valve you will get some puttering out of the tail pipe.

If it is an intake valve you will actually get a slight misfire at idle just like if you unplugged the injector but as soon as you give it some throttle the misfire would be gone.

Make sure number 1 is at TDC when you do the test. You will be able to hear it go either out the tailpipe or in the intake manifold. If it is the rings you will hear it in the crankcase.

 

[sacline]

Thanks. Im really hoping it a valve that way i can slap a rebuilt one on and call it good until i can get a rebuilt block. I do hear puttering out the tailpipe and it does have a slight miss at idle and goes away wen i drive. Leak down test tomorrow i think.