117

No. The valves are closed when the piston is at TDC on the compression stroke. It doesn't matter if it's piston 1, 2, 3, or 4.

Put #1 at TDC on the compression stroke, pressurize the combustion chamber, and see where the leak is coming from. It would be good to have a leak down tester so you know how much leak you have, but if you just want to see if you have an excessive amount of leak then doing it without a gauge should suffice.

Then rotate the crank and put #3 at TDC of the compression stroke, repeat. Then #4, etc.

If you get a leak down tester, anything under 10% should be ok. 10% is a little high, I'd be happier with anything 5% and under. My track car is something like 1%, 2%, 2%, 4% when tested at 100 PSI. All engines leak, so don't be freaked if you hear something.

toomspeed

it dosent mater witch cyl you start on, tdc or bdc, will work fine for you. just make sure the valves on that cylinder are closed all the way. thats why i think its eazier with the valve cover off, you can see the lube on the cam and they MUST to be 180 away from the valve. (pointing to the sky)

117

True, it usually doesn't matter if you're using TDC or BDC, but TDC is where most of the cylinder wear occurs, and it's where the piston is located when the engine is making power for that particular piston.

You can look at the cams, but make sure you're at TDC or BDC when you pressurize the combustion chamber. If not, the engine crankshaft will turn, and depending on how much pressure you use, it can turn with a significant amount of force.

toomspeed

bump

meanshyguy

I'm back with compression results: No 1 cyl= 195, No 2 cyl=175, No 3 cyl=180, No 4 cyl=190. This are the results after doing a compression test. I will do the leak down test tomorrow, and where do you get that gauge or what is it called and what does it hook up to? What do you guys think of the results? The car currently has over 800 miles since it was rebuild.

117

That's on a hot engine with the TB butterfly completely open (i.e. at WOT) correct?

meanshyguy

No sir, I didn't know I had to completely open the TB, the engine was not hot and I didn't press the gas at all, if I have to do it again I'll do it tomorrow cuz I'm getting ready to go to work, and thanks everybody for your patience since I'm barely learning how to mess with the car and I love it.

117

Yes, a compression test needs to be done at WOT with the engine at normal operating temp. Pull the fuel pump fuse to keep fuel from being pumped into the combustion chamber.

meanshyguy

What I did is I disconected the fuel injector connectors, and for how long should I keep my foot on the gas all the way to the floor? Do you know where and how to use the leak down test gauge and where to get it? Will this tests be able to let me know exactly what's wrong with my engine?

117

You hold the gas pedal all the way down while you're cranking the engine for the compression test. Disconnecting the fuel injectors is fine.

Leak down gauges can be found online at most race/tool shops. I've never seen a local auto parts store that carried one. I have an almost brand new OTC leak down tester I'd be willing to sell.

Compression and leak down tests do not tell you the condition of the oil control rings, so keep that in mind. A leak down test will tell you if there is a problem with the compression rings, intake valves, or exhaust valves, though.

slamdlude

http://search.harborfreight.com/cpis...ster&Submit=Go This is the leakdown tester I have. It is cheap and it works.

meanshyguy

Thanks for the link, I got to work today so hopefully I'll have time to atleast do the compression test again, this time done right, I have hopes that the compression numbers are gonna go up, they told me according to my build Psi should be around 215.
I think I'm on my own now, ****, I'll probably rebuild it myself, or atleast do most of it.

PirateMcFred

You should temper your recomended PSI readings with regard to your location. At 5500 feet elevation I got 175 psi on my 11:1 static compression H22A build. I took the car to ~500 feet elevation and it went up to 240 psi. That was with the same compression tester. Different compression testers will give you different numbers, so be aware of that. If you know anyone in your area that has a similar, successful build you can "calibrate" your compression tester on a good engine first, then test yours for a comparison.

-P

meanshyguy

My brother has a stock H23, I'll do it on his, my numbers should be higher than his, I really don't know many people here with preludes, it's like a big, little town here, shops and mechanics suck, you can't even find someone that doesn TIG welding. I got a day off tomorrow so I'm gonna be on the car all day if possible, thanks guys!!

wraith646

All the things that everyone will be a good thing to check but to start off with is. Check the timing at the the diss. Then check the timing at the cam to crank. The over heating can be caused by the timing or a air pocket at the temp sensor. The next thing that you want to do is to check the valve clearance. If the compression is as high as you said. If the intake valves don't open and you are still tring to seat everthing it may be pulling that thick oil that you are using on a brand new rebuild past the new rings and freshly howned walls.

meanshyguy

Ok so I got my new compression readings today, this time I did it right.
Cyl 1= 195 psi
Cyl 2= 180 psi
Cyl 3= 185 psi
Cyl 4= 200 psi
This was done with the engine at normal operating conditions and with the gas pedal all the way to the floor.
My brother's stock H23 were as follows
Cyl 1= 170 psi
Cyl 2= 175 psi
Cyl 3= 185 psi
Cyl 4= 190 psi
My numbers are slightly higher than his as I expected, but I will be doing the leak down test as soon as I get the tested sometime this week and get a shut off valve for the compressor, so are my compression numbers pretty low? The last cylinder showed higher compression so I'm not sure of the reason why but hopefully the leak down tester will help me find out.

Widebody93

Were the oil pin/head dowls installed?
OPEN your TB please shine a light in there do you see alot of oil?

meanshyguy

Everything was perfectly installed according to the mechanic, who hasn't called me since he found out about the problem. I'm ready for the worst.
Will check the tb first thing tomorrow morning, thanks. Do I have to unbolt the tb or just look through the butterfly? I'm anxious to get my leak down tester.

Widebody93

Just open the Throttle body, no need to replace a gasket

92bluepreludeSi

That was pretty stupid to run the car on a stock h23 ecu... my advice to you is to get a tuning software like ectune and learn to tune the car yourself using the chipped h22 ecu you have.

117

What's your approx. static CR? A friend of mine that I race with came over this weekend to do a compression and leak down test. His static CR is around 10.5:1. We could only do the compression test on cylinders 1 and 2 before his battery started to lose some power (it's a very small battery). His compression test numbers were 210 PSI on #1, and 205 PSI on #2. #1 might have been 215 PSI, but I can't recall with 100% certainty. Keep in mind this is with the engine turning over a little slower than it should have been. This was with an OTC brand compression tester. As was previously stated different compression testers will yield different results, as will altitudes, but I figured I've give you some numbers for comparison. I have no idea if the DFW area is higher or lower than El Paso.

We did a leak down as well. Numbers weren't too bad. 1%, 2.5%, 2.5%, 3.5%.

117

After doing a quick search, it appears that El Paso is quite a bit higher in altitude than the DFW area, so keep that in mind.

PirateMcFred

He did a back to back stock H23 versus his. If he's got a run of the mill H23 vtec with Type-S pistons he should be at 11.7:1 or more static. If the head's been milled it'll go up quick from there. My 11.7:1 nonVTEC with big cams makes 185psi at 5500' elevation with a tiny 14 pound Odyssey PC680 turning it over.

El Pisso is at 3000' and should be cranking out a LOT more than 180psi unless the tester's got 4 feet of hose on the end of it. He's got issues.

OP, get a leak down test and start saving for some .25mm OS pistons and a tunable ECU.

meanshyguy

I'm already planning to rebuild myself if I have to, I got manuals and videos, and well you guys to help me whenever I get started depending on what the leak down tester tells me, I know it's gonna take me some time. Isn't there problems honing FRM, I was thinking of getting another block instead, that's if I have to, has anyone here done this .25mm os type s piston build on stock FRM?

vinuneuro

How to have FRM honed