Decipher my compression numbers - Zilvia.net Forums | Nissan 240SX (Silvia) and Z (Fairlady) Car Forum

Kreator · 02-18-2005, 08:12 PM

Ok, bought a KA from a certain shop (whose name i'm not going to disclose yet), was told the engine was pulled for an sr swap, and is supposedly in perfect condition. Engine was out of a 97 240sx w/ ~85K miles on it.

Well i finally got around to testing compression on it. The results:

1 cyl - 190psi
2 cyl - 140psi
3 cyl - 60psi
4 cyl - 60psi

tested the last two with added oil, and compression bumped to 90psi. Now I'm not really sure how to interpret these. The tests were done with the engine out of the car, by hooking up the battery to the starter. Obviously the engine hasn't been run in some time (3 months about), but the first cylinder compression is throwing me off. Guesses anyone? Bad headgasket? Leaky rings? I hope to get around to do a compression test on sunday, will post some more info.

Mr. Spool · 02-18-2005, 08:19 PM

I did that on an engine, was told that it should still be good, well it wasnt, needless to say that ones gone, stay away from this engine, infact throw it through the shops window. they new it was bad, heck they probably had to tow the car in becouse it smoked so bad.

Var · 02-18-2005, 08:40 PM

was the battery still strong..ie was the starter spinning just as fast for the last 2 cylinders? Probably was or you would have mentioned it. Assuming the test was done properly..

usually when the oil trick works that means the rings are bad.

AlligatorBling · 02-18-2005, 08:55 PM

the incosistant numbers are puzzling... did you go to 240sx.org and follow the sheet there? thats the best one ive seen.... tells you EVERYTHING you should do. is there anyother strange factors that you havent mentioned? the first number is strong, and the drop... ill do some looking around on it.

Kreator · 02-18-2005, 09:43 PM

well, once the we got all 4 measured, we went right back to the first one and got the same number of 190psi

well obviosly the engine wasn't warm as its out of the car, all spark plugs removed, throttle body wide open. I'm really puzzled by the drop. If i got 60psi on the first one, i'd know i'm prolly doing something wrong. But having the first one measure fine and then the last 2 so bad is quite confusing.

as for the oil trick, you are probably right, but still it only went up to 90psi. Where is the other 90? Im guessing leakdown is what i should shoot for. There is obviously something wrong, i just see if anyone can guess for what it is, rings, headgasket, valves...

Again the way we tested it: the engine is sitting on the tire. Hooked up the batter to the starter motor with a switch. Opened up the TB, pulled all sparks out. 4 cranks per cyllinder. Umm thats it. I can hardly imagine if there would be any difference between how we tested #1 and #4.

Something weird is going on, the shop is supposed to be specializing in evolutions and i cant see the reason for them to rip me off for one 240sx engine (they have a 240sx project car). And they kept telling me the engine ran strong and was in good condition. They either openly lied (but then whats the point of saying its good all the time) or they didn't know, but then i cna hardly imagine how you can not notice 2 cyllinders not running.

RBS14 · 02-18-2005, 11:24 PM

it's fucked up. give it back to them and get your $$ back. You should be able to find another ka, they aren't that hard to find.

thx247 · 02-19-2005, 12:44 AM

sounds bad to me, hole in the gasket somehwere between the two cylinders? I dunno, don't get it.

Kreator · 02-19-2005, 06:48 AM

well *local* 97 engines with 80K on the clock are pretty rare. In fact this is the first one i saw in md for the past year. Plus i'm not quite sure they will take it back, as it's not their business to sell engines, they just had a left over they got rid of. I'll be emailing them after i the leakdown test,

Blah, if its the headgasket, i can live with it, get the guys to cover the cost of it and shouldn't take more then 4 hours to replace it. especially since the engine is out of the car already.

AlligatorBling · 02-19-2005, 09:20 AM

Quote:

Originally Posted by thx247

sounds bad to me, hole in the gasket somehwere between the two cylinders? I dunno, don't get it.

thats what i was thinking....

02-18-2005, 08:19 PM	#2
Mr. Spool Zilvia Addict Join Date: Jan 2003 Location: East Side, Michigan Age: 44 Posts: 622 Trader Rating: (0) Feedback Score: 0 reviews	I did that on an engine, was told that it should still be good, well it wasnt, needless to say that ones gone, stay away from this engine, infact throw it through the shops window. they new it was bad, heck they probably had to tow the car in becouse it smoked so bad. __________________ 96' SE Turbo'd Super 60, S-AFC, SMIC, 370cc Injectors, Open Air BOV, Warblo 255 pump, Stage 3 Clutch Kyb agx, Sportline Springs Full body kit, Bomex rear, Drift sides, r34 front gunmetal rims, yok tires

02-18-2005, 08:40 PM	#3
Var Post Whore! Join Date: Sep 2003 Location: Norcal Age: 43 Posts: 5,032 Trader Rating: (0) Rides Gallery: Var Feedback Score: 0 reviews	was the battery still strong..ie was the starter spinning just as fast for the last 2 cylinders? Probably was or you would have mentioned it. Assuming the test was done properly.. usually when the oil trick works that means the rings are bad. __________________ Hi

02-18-2005, 09:43 PM	#5
Kreator Nissanaholic! Join Date: Mar 2002 Location: MD Age: 41 Posts: 1,975 Trader Rating: (0) Feedback Score: 0 reviews	well, once the we got all 4 measured, we went right back to the first one and got the same number of 190psi well obviosly the engine wasn't warm as its out of the car, all spark plugs removed, throttle body wide open. I'm really puzzled by the drop. If i got 60psi on the first one, i'd know i'm prolly doing something wrong. But having the first one measure fine and then the last 2 so bad is quite confusing. as for the oil trick, you are probably right, but still it only went up to 90psi. Where is the other 90? Im guessing leakdown is what i should shoot for. There is obviously something wrong, i just see if anyone can guess for what it is, rings, headgasket, valves... Again the way we tested it: the engine is sitting on the tire. Hooked up the batter to the starter motor with a switch. Opened up the TB, pulled all sparks out. 4 cranks per cyllinder. Umm thats it. I can hardly imagine if there would be any difference between how we tested #1 and #4. Something weird is going on, the shop is supposed to be specializing in evolutions and i cant see the reason for them to rip me off for one 240sx engine (they have a 240sx project car). And they kept telling me the engine ran strong and was in good condition. They either openly lied (but then whats the point of saying its good all the time) or they didn't know, but then i cna hardly imagine how you can not notice 2 cyllinders not running. __________________ кто болеет за Зенит, у того всегда стоит!

02-18-2005, 11:24 PM	#6
RBS14 Nissanaholic! Join Date: Feb 2003 Location: Santa Cruz/San Diego Posts: 2,271 Trader Rating: (0) Feedback Score: 0 reviews	it's fucked up. give it back to them and get your $$ back. You should be able to find another ka, they aren't that hard to find. __________________

02-19-2005, 12:44 AM	#7
thx247 Zilvia FREAK! Join Date: Jan 2003 Location: bay area Posts: 1,455 Trader Rating: (0) Feedback Score: 0 reviews	sounds bad to me, hole in the gasket somehwere between the two cylinders? I dunno, don't get it. __________________ Finally down to 1 car again. Thank god.

02-18-2005, 08:12 PM	#1
Kreator Nissanaholic! Join Date: Mar 2002 Location: MD Age: 41 Posts: 1,975 Trader Rating: (0) Feedback Score: 0 reviews	Decipher my compression numbers Ok, bought a KA from a certain shop (whose name i'm not going to disclose yet), was told the engine was pulled for an sr swap, and is supposedly in perfect condition. Engine was out of a 97 240sx w/ ~85K miles on it. Well i finally got around to testing compression on it. The results: 1 cyl - 190psi 2 cyl - 140psi 3 cyl - 60psi 4 cyl - 60psi tested the last two with added oil, and compression bumped to 90psi. Now I'm not really sure how to interpret these. The tests were done with the engine out of the car, by hooking up the battery to the starter. Obviously the engine hasn't been run in some time (3 months about), but the first cylinder compression is throwing me off. Guesses anyone? Bad headgasket? Leaky rings? I hope to get around to do a compression test on sunday, will post some more info. __________________ кто болеет за Зенит, у того всегда стоит!

02-18-2005, 08:55 PM	#4
AlligatorBling BANNED Join Date: Dec 2002 Location: Virgina Age: 43 Posts: 856 Trader Rating: (0) Feedback Score: 0 reviews	the incosistant numbers are puzzling... did you go to 240sx.org and follow the sheet there? thats the best one ive seen.... tells you EVERYTHING you should do. is there anyother strange factors that you havent mentioned? the first number is strong, and the drop... ill do some looking around on it.

02-19-2005, 06:48 AM	#8
Kreator Nissanaholic! Join Date: Mar 2002 Location: MD Age: 41 Posts: 1,975 Trader Rating: (0) Feedback Score: 0 reviews	well local 97 engines with 80K on the clock are pretty rare. In fact this is the first one i saw in md for the past year. Plus i'm not quite sure they will take it back, as it's not their business to sell engines, they just had a left over they got rid of. I'll be emailing them after i the leakdown test, Blah, if its the headgasket, i can live with it, get the guys to cover the cost of it and shouldn't take more then 4 hours to replace it. especially since the engine is out of the car already. __________________ кто болеет за Зенит, у того всегда стоит!