how to do a compression test on the sr20det to make sure it’s work? thanks!
same way you compression test any motor
I have a s13 redtop clip for sale if you wan’t
i mean what tool do i need? how to do it? what pressure it show if i test it? thanks!
well, to test the compression… you would use a compression tester.
c’mon guys… it takes the same amount of time to be a smart-ass as it does to help the guy out :roll:
Jacky, to avoid embarassing yourself in the future try researching before u ask questions… there’s a whole world of info out there.
You need the transmission and starter intact to do a compression test. Otherwise, you have no means of turning over the engine. For sake of argument, you can’t do a compression test by turning it by hand quick enough either.
Another way to test an engine is by doing a leakdown test. A leakdown test will tell you if the rings seal, and if the valves seat tightly. This test simply shows if the engine allows any blowby, but you need to be a bit more mechanically inclined to perform this.
Compression tests can be somehow misleading, because due to the age of a motor, it could have a lot of carbon buildup, which would lead to higher cr readings.
I didn’t check the website yet, but I’m sure it has more detail than what any of us will tell you now.
This is a very simplified explanation of it:
You gotta remove the spark plug on whatever cylinder you’re doing the compression on. Insert compression gauge into the sparkplug hole, and turn over the engine. Check the reading and repeat to see that you’re getting a constant reading. Do the same for the other cylinders.
You know what… just research this topic on the net and it will probably give you tons of feedback on this subject. The last thing I wanna do is mislead you.
but i don’t know how to turn the engine. the engine is sitting in my garage. thanks!
^^ two messages up someone told you that you need the trans hooked up, then use the starter. Quite frankly if you can’t figure it out from there you really shouldn’t have a SR20DET sitting on your garage floor. I can only presume that you intend to install it in your car, if you can’t figure out how to turn it over then your car will be off the road for a long time…
Here’s the play by play…
Required stuff…
- charged battery
- ground cable from-ve on battery to engine
- power cable from +ve on battery to big terminal on SR starter (remove the one that’s there, or use it)
- wire to starter solenoid (this is instead of teh wire that should be there, black and white I think) don’t connect the other end to anything.
What to do…
- remove plastic cover that says “ntercooled turbo” requires metric allen key.
- remove coil packs (4), requires 10mm socket
- remove spark plugs (4), requires small spark plug socket and extension
- install compression tester in clyinder #1
- crank the engine by holding the lead from the starter solenoid onto the +ve battery terminal
- crank the engine through 5 compression strokes
- write down the reading on the compression tester
- repeat for the other three cylinders.
Note: before doing a compression test I usually change the oil and filter, and remove the oil pan and bang out an dents. Remember this motor probably hasn’t be run for a long time. You’ll need to get up oil pressure before you start it. Now is a s good a time as any to do this. Even if you don’t want to do this right now, make sure that at the very least there is oil in the motor (often they fall over during shipping and the oil drains out), an dthatthe pan isn’t dented… if it is you may be cranking the moor “dry” anyway as a dented pan restricts the oil from going into the pickup.
Report back on what your readings are… I’m willing to bet that they won’t be even, you’ll have 1 or more likely 2 that are low.
-Martin.
What you want to find:
- Make sure readings in each cylinder are close
- If they are less than 130 i think it is, then the engine is poop
- Over 140 is good
*this is for a hot compression test
without oil pressure it’ll be awfully hard to check compression …
Unfortunately, you’re either going to have to have the motor torn down and rebuilt (which you should anyway really) or installl it to find out.
Yes you could hook it all up on a stand and fire it up in theory, but if you aren’t an experienced mech … the thought of you firing up an engine on a stand with just a wastegate shooting fire … I wouldn’t recommend it.
More total BS.
So your rings seal when they’re dry? And your valves seat dry? What magic oil do you use?
Or were you going to suggest he prime the oil pump with a drill and use a breaker bar on the crank?
how come?..
im just curious…
how come?..
im just curious…[/quote]
Here’s a thread that I posted to on another forum on this subject
http://www.nissaninfiniticlub.net/forums/showthread.php?s=&postid=494922#post494922
-Martin.
Oh oh… here we go again. And I was just starting to like you 
Please read the “Note:” at the bottom of my original post. I recommend getting oil pressure up before/while doing a compression test. This does not mean that you can’t do one without oil pressure.
Yes rings seal when they are dry. The compressions rings barely see any oil if they did your motor would burn lots. The oil rings scrape excessive amounts of oil off the cylinder bores and leave just enough to lubricate the piston skirts.
Yes it’s better to do a compression test hot, as that’s when all the tolerences are their closest to real life. Unfortunatly that doesn’t happen very often or mean a cold compression test has no value.
Yes the valve seats would be dry, are you suggesting that if there were oil pressure they’d be covered in oil somehow? What kind of motor do you have, one with worn valve guides and no seals?
The hydraulic lifters would certainly benefit from having oil pressure but that would only influence the opening of the valves, they are closed by the valve springs.
No I didn’t suggest priming the oil pump with a drill but that is an option in some applications like the L series datsun motors using a specially modified distributor drive, I think I have one if you need to borrow it…
A breaker bar on the crank? That must have been something that your suggested, nothing about breaker bars in my post.
If you’re trying for some reason to discredit my posts you’ll need to try harder as IMHO you’re not doing very well.
-Martin.
It’s not a war, we’re debating differences of opinion. It’s all technical so not out of place in the tech forum. If you read it you might learn something, but if it bothers you so much then don’t bother.
-Martin.
It’s not a war, we’re debating differences of opinion. It’s all technical so not out of place in the tech forum. If you read it you might learn something, but if it bothers you so much then don’t bother.
-Martin.[/quote]
That’s why i deleted Maurice’s post.
If anyone is going to get banned, it’s gonna be Maurice. :twisted:
As you were gentlemen.
Definitely not a war, or how do they call it now … oh yeah, I’m not “hatin’” heh, and no, not trying to discredit what you wrote … you claimed what I posted was total BS … and was curious as to which part.
And now I see it … :oops:
Aww, and I was almost liked … the story of my life 
And in my defence I never said dry valve seals … I said “valves seat dry”
You’re entirely right though … it won’t really matter on compression - depending on how dry the motor is and where the oil has ended up. Although spinning a dry motor is never a good idea. I have seen an imported engine with rust in the cylinders and I’m glad the owner was smart enough to actually take a look before installing it. Yes it was warrantied, but at least he didn’t have to try to start it to find out.
I don’t think anybody should just drop a motor in fire it up and be on their merry way. As good of an indicator as a compression test is, I think everybody should be wary when using a used engine.
I’ve seen a few “importer” skids coming in with motors on their sides, and even once upside down.
And as for my “theory” of starting a motor on a stand … to do it with an SR20 is not something I’d want to have to try, but it could be done.
As for priming it with a drill, and a breaker bar … that was actually directed at those who said you needed to hook up the starter to run a compression test. You can do it by hand … although turning a fresh 12.5:1 motor with a bar can be a feat of strength.
I’m sorry if anyone sees this as mean-spirited … admittedly I opened my mouth a bit too wide, and I’m glad someone like Martin was here to point it out.
We’re all learning, and apparently I still have a way to go 