Nissan 240SX Forums banner

SR20det Bad compression!?!?!? help!!

11K views 13 replies 5 participants last post by  elliascool  
#1 ·
So i decided to go get a compression test when one day my oil dipstick flew open and shot oil everywhere .....
we tested and every cylinder was different , cyl 1: 105, cyl 2: 110, cyl3: 115, cyl 4 :120, there were all pretty much around there give or take a few psi. and this wasnt on a cold crank, the engine was nice and hot..

also there was a bit of oil inside and on each spark plug , he said i need a new valvecover gasket and new plugs .. so im gonna do that next week.

we came to the assumption of bad rings and or valves, so im sad as shit right now ... dont have money to fix this, idk what to do.
i knew driving it i felt that it was missing ponies ... sucks ...
 
#4 ·
Probably bad rings. Pressure probably snuck through the rings and caused the dip stick to fly off. I'm pretty sure you'd be able to do it yourself. Though the rings are at the heart of the engine, it's really nothing complicated to get to. You don't need to get your motor pulled, though it's be easier due to more space. It's always good to take advantage of those Automotive classes during those early years in highschool.
 
#5 ·
idk i did the test again on my own today and after running the car so it was hot, and they came out 85, 90,90,95 wtf.... thats complete shit. stupid imports idiots didnt do the compression test and my 30 day warrenty is over ....
 
#6 ·
Are you doing the Compression test correctly? Make sure you remove the fuel pump fuse. Pull out the crank sensor. Full throttle.

ALSO... Put a teaspoon of oil in each Cylinder. If the compression psi suddenly go up, then it's bad rings. That will give you the answers you need. Don't be too bummed man, it could be far worse.
 
#7 ·
Compression tests are inconsistant and I usually dont even bother with them. Trying to target a number such as "this engine should make 180psi" is stupid because depending on what brand compression tester you get you could get anywhere between 80psi to 200 psi average per brand. The only thing I take to heart about compression testers is if their readings are consistant from one another. Your numbers are consistant. Engines dont usually wear out evenly believe it or not. Your chances of having all 4 cylinders evenly screwed are slim to none. If you had one cylinders come up between 0 psi to 70 psi you should worry.

Now your dipstick popping up does not mean you have a major issue, at least on an sr (believe it or not). The sr is plagued with crank case ventilation issues, especially if you start making more than stock hp. Post a picture of your engine bay. Im willing to bet your crank case ventilation is set up less than ideal. You also want to check your dipstick and tube. Is the oring in good condition? is the plastic chipped? Does the tube give good neck tension/retention?

I had found on my last engine that I was making enough power to pop it up sometimes still even with a new tube, dipstick, and the engine being freshly built. I had a threaded section of pipe braised onto the dipstick tube flush with the top of it. I had washer ground down flat on one side and welded on top of a threaded pipe cap. The dipstick can still be used to check oil levels but the tube can be sealed off in order to keep the stick from poping up.

You should do everything possible to make this a less common occurrence before taking this route and the only reason I felt it so necessary in my instance is because I run on e85 and the vapor coming from the crank case is very much a fire hazard.
Post a picture of your current engine bay setup so I can tell you whats wrong.
 
#8 ·
Image

from what i realized and heard its cuz i need to get a breather hose since my oil catch can setup is blocked off.. but i went to every auto store and the little breathers rubber inlet is too small to fit on the fitting comming out the sr cover..
 
#9 ·
that is routed so entirely wrong on every level. When in boost, blow by has no where to go at all.

It needs to have a hose from lower block to T to catchcan to turbo inlet or exhaust with check vlave and venturi from vibrant performance.

Dont run that junk hose either, get stainless steel braded because that stuff will get weak when hot and collapse or catch on fire.

There are even better ways of doing it than that but it will require some modding.

Take your plug off NOW, but dont just leave it like that, fix it right
 
#11 ·
He's talking about the front hole on the valve cover you have plugged. Breather isn't the answer there either. Makes a mess and is a pressure leak
 
#12 ·
well then idk he says
"It needs to have a hose from lower block to T to catchcan to turbo inlet or exhaust with check vlave and venturi from vibrant performance."

which is the hose from the lower block? is that the hose that i got coming from the lower part of engine into catch can? the 2nd hose..

also that needs to be T'd into catchcan then turbo inlet? the turbo inlet is that airfilter going into the turbo right? and exhaust? and whats check valve and venturi from vibrant performance?!?!

sorry im not well known on all this yet...

ik on stock sr's i see where i have it blocked off it goes into the hose that the air filter is on the end of .. that goes into the turbo "turbo inlet" right?

this is how its setupd stock right?
http://images03.olx.ca/ui/9/00/50/1...s13-red-top-engine-transmission-harness-ecu-free-shipping-canada-1289943240.jpg

but i cant run it like that since mines not the rubber hose, i got the piping and i got no inlet to pug it into.
i see alot of people run it like i have it with a breather tho...
http://www.nicoclub.com/wp-content/uploads/2009/12/ras02.jpeg
 
#14 ·
yea ok i get it now i didnt realize the T you were talking about was the piece on the valve cover the hoses go into lol!

Today when i turned on the engine i remembered to take out the block off the T and i heard a decent amount of preassure being released, yea i get it now , from the back bottom of engine straight to the T then to the catch can then to the turbo inlet...

so i need new hoses, and idk how ima go about making it go into the turbo inlet since i have no hole or plug to put a hose into..

also the catch can is it ok mounted there? even if i run the hoses right?