Comrade_Charlie Posted April 20, 2009 Share Posted April 20, 2009 The other day I threw a batter in my Z, the wiring harness is pretty much gone for that, so I rigged a push button up to the starter, and got it spinning. The good news is it has good compression(78 na engine). I got close to 190psi on all cylinders if I did the compression test right, dont think yuo can mess it up, except for not having it at WOT. but I had the oil pressure sending unit out to see if oil was coming out, it did after turning it over a lot. and with the valve cover off I could see the cam was getting oil, and oil was running to the back of the head and draining. all good signs I think. What im wondering is about the oil pump. I took it off when I had the engine out, just to replace the gasket on it. and didnt prime it or nothing but also didnt let the oil drain out of it. and put it back on. since oil is going everywhere does that mean I dont need to. or do I need to hook up a manual oil pressure gauge and see what its doing, would it show any psi just from spinning with the starter? I was turning this engine over for a good 30 minutes to a hour off and on with all the spark plugs out. Oh and this engine is sposed to have like 110,000 miles on it, and hasnt ran in 10 years someone told me. I want to get it running in the next 2 weeks, not driving, just running. just got a z31 harness. Quote Link to comment Share on other sites More sharing options...
Carl Beck Posted April 20, 2009 Share Posted April 20, 2009 I believe that in order to get really useful information - you run Compression Tests on an engine that is up to normal operating temps. Metal expands with heat - and without heat you really don't know how good/bad things like rings are sealing up against the cylinder walls etc. With an engine that has sat for so many years - you really don't know if your good results are caused by good cylinder/piston sealing OR a good ring of rust around the tops of the pistons. I sure hope you put some light oil down into the cylinders - and let it soak for a day or so - BEFORE you started cranking the engine over. FWIW, Carl B. Quote Link to comment Share on other sites More sharing options...
Comrade_Charlie Posted April 20, 2009 Author Share Posted April 20, 2009 Yea there has been oil(atf) in the cylinders for a while before I started doing this, because i thought there was water in the intake and I didnt want it to rust the cylinders if they wernt already. Quote Link to comment Share on other sites More sharing options...
Pharaohabq Posted April 22, 2009 Share Posted April 22, 2009 if you're getting oil to the cam, I'd say it's a safe bet the pump is getting oil. But yeah, you should get it started and heat it up then check your compression. I think you'll see a difference. It's probably one at 190 psi cold. mine is 170 cold. and runs okay. You should check your injector plugs for corrosion. it always seems that's a big culpret when the L28 isn't starting. Phar Quote Link to comment Share on other sites More sharing options...
Comrade_Charlie Posted April 24, 2009 Author Share Posted April 24, 2009 Its not close to being able to start, when i got this car it had no engine, trans, wiring harness... I was merely doing a compression check just to see if its worth throwing money at this engine. plus I was seeing if the oil pump was working since I took it off to put the 83 turbo shaft for the 83 turbo dist with the z31 CAS wheel in it, and I had heard that you need to prime the oil pump. I put in a good set of 300zx turbo fuel injectors in it already, and it has a known good z31 maf, I have a 84 300zx turbo ecu, and a 300zx turbo wiring harness waiting to go in it. If the engine is good I expect this thing to be stout, na engine, turbo, z31 fuel system.... I just need to check ignition timing, block off the egr port on the intake manifold, wire it up, get my fuel system up, put antifreeze in it, hook up a oil pressure gauge(all of the stock wiring harness is gone by the previous owner), im going to use a mechanical guage0-60 or 0-80psi, and try to crank it up. Ive never done wiring but it looks fairly strait forward with the the wiring diagrams of the z31 wiring harness from z31performance.com Im hoping to have it running in 2 weeks... to actually run I think I only need the dist wire, and the fuel injector wires. Atleast that is how it is on my z31, you can run that thing with 3 spark plugs, the dist wire, and 3 injector wires, its a trooper. Quote Link to comment Share on other sites More sharing options...
Pharaohabq Posted April 24, 2009 Share Posted April 24, 2009 well hey, sounds like you've got a plan. I know the Z31 engines are troopers, mine got hit by a semi and still starts.. sputers a little tho, but it runs. I think it's on 5 cyl right now. I'm gonna part it out tho. ... Someday... You'll need some of the other sensors from the Z31, maybe MAP, and temp sensors. I don't remember if the Z31 used a MAP sensor... Phar Quote Link to comment Share on other sites More sharing options...
Comrade_Charlie Posted April 24, 2009 Author Share Posted April 24, 2009 It uses a maf, I already have it hooked up to the turbo on my 280z. People use z31 ecus on the l28 with the l28 CHTS with out problems, im just going the extra step and using the whole harness since the stock harness is all messed up... Ill just have to splice in the right conectors, I have a complete l28et 1981 harness, its cut in places but complete. Also planning on using a z31/maxima alternator... Quote Link to comment Share on other sites More sharing options...
cali260Z Posted April 25, 2009 Share Posted April 25, 2009 190 psi? thats really good compression, mine turned out 123 psi after sitting for a year or 2 and I thought that 123 was good. yours should fire and run like new if thats the case Quote Link to comment Share on other sites More sharing options...
Comrade_Charlie Posted April 30, 2009 Author Share Posted April 30, 2009 It wasnt showing to good of compression, but i had all the plugs out and was oiling up the cylinders and kept turn it over letting the oil come out if it needed to for a while then checked compression, if I get it running and warmed up, ill check it again Quote Link to comment Share on other sites More sharing options...
Comrade_Charlie Posted May 1, 2009 Author Share Posted May 1, 2009 Might give up on the 280z for now if I get the engine running good. im getting a maxima 1982 with a l24e in it, might just swap everything into it, lower it, throw my momo rims on it and call it a week LOL. That would give me time to work on the rust on the 280z, id hate to get the car running then not have it safe to drive..... if something is running im driving it Quote Link to comment Share on other sites More sharing options...
misterZ Posted May 5, 2009 Share Posted May 5, 2009 190 psi? thats really good compression, mine turned out 123 psi after sitting for a year or 2 and I thought that 123 was good. yours should fire and run like new if thats the case Whew... I feel better now about my 132 psi--Comrade, let us know if you get it running and a warm reading. You really don't want that L24e ... don't give up! Never surrender the et!!...or sell it to me! IMO--dump the 4-speed and get a 5-speed from a 77-78; you'll be glad you did and you can find them here on occasion at a good price! Quote Link to comment Share on other sites More sharing options...
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