ok so my built motor has about 1300 miles on it and i checked the compression. cyc#1. 160 cyc#160 cyc#3 160 and cyc#4 130. so i put a cap of break fluid in cylinder 4 and cranked it couple times and then started it. it smokes white smoke for couple of minutes and after the smoke was gone i checked the compression again and it was at 135. so i redid that procedure again but this time after i put the break fluid in the cylinder, i checked the compression right a way it was at 160 like all the other cylinder. i looked through the spark plug hole and did see the break fluid sitting on top of the pistons. so i connect the ecu back and started the car to burn the break fluid. then i checked the compression again and it went back to 135psi. what could be the problem over here. i really hope its something small. thanks in advance.

 

Rings are worn, cylinder could potentially be washed out, ring gap could be wrong, cylinder could be out of round... Anything is possible. Only way to fix it would be a New set of rings.

 

Upside down piston ring ??

 

Those compression numbers are all pretty awful. Whats the compression ratio of the motor? Ive had new motors with zero miles, zero run time have higher compression numbers than that.

 

Doesn't it depend on the gauge what he is using though?

 

Maybe if it was defective. Test it on a good engine.

 

could be a vitara motor or a 1st gen dsm lol (or any other engine with less than 8:1 static)

even so that 135 is low and inconsistent

 

Yes your usually just looking for a variance in any if the cylinders.

OP, why are you using brake fluid and not engine oil?

 

That's what normally look for. I'm not bothered that much about how high or low the numbers are..

 

I mean i normally look for even cylinder pressures. We don't know what motor or internals he has so 160 could be good... But you want no more than a 10% variance between cylinders... Anymore than that and its time to re-ring the motor. So 160 x .1 =16. 160 - 16 =144.
There isrt anything you can do to.bump the numbers permanently... By doing the viscous fluid in the cylinder trick you've ruled out the headgasket so we know its a ring problem.

I too am also curious why he used brake fluid... Maybe it was the only thing he had?

 

the pistons are Wiseco and don't remember exactly what the compression is, it is something like 9-1-0 or something like that. i put break fluid rather than oil because i thought the cylinder 4's rings are stuck and needed lil help to sit in there. I am using a Mac compression tester and i was just looking for consistency throughout the cylinders.

 

i used break fluid because couple people suggested to use break fluid. what you guys suggest to use to help sit in the rings that might be stuck? thanks.

 

There's something actually wrong with it . You need to tear the engine down and find it. Things like this don't just go away.

 

i've never seen stuck compression rings (unless it's been sitting forever and rusted in there). stuck oil control rings won't show up on a compression or leakdown test.

 

*BRAKE* not break.
and brake fluid won't free up anything... thats what oil is for and you are not going to break loose rings free by dropping some fluid in a cylinder. you need to physically pull the motor apart. that is the only way to fix a ring problem

 

Thank you.. Im amazed how many posts I read and people have no clue how to spell brake.

 

It seems like grammar, punctuation, white space, and spelling (yes, i still use the oxford comma lol) have long since gone out of the window on this site.

 

Sounds like you will need to open. And it is not a good idea to use a incompressible fluid.
You can bend a rod like that?

 

You dont fill up the cylinder. You're supposed to add only half an ounce. The purpose is the oil will settle at the lowest point which is the rings and will temporarily improve the ring seal. If this increases the cylinder pressure significantly then that indicates the rings are not sealing well.

 

While we are on the subject... Letting WD-40 sit in the cylinder works much better tthan oil to free up stuck rings... Clearly this isn't the case here. It's either installation error or worn parts. I have seen poor ring filing that causes the ring to hang up on the groove due to a bur. Regardless OP, "it's time for you and the 'Mad Scientist' to rip apart the block and replace the piston rings you just fried"...