Thebadinvestment Posted June 16, 2014 Share Posted June 16, 2014 Alright I have a 1987 z31, base model, 5spd, and with a vg30e w/ upgraded head work. This was my project and I finally got it running correctly and idling fine. I could actually take my foot off! Then, the thermostat would open and coolant started leaking from the radiator cap. After that happened the engine started to dip in rpm and go back up a couple times then it died. So I replaced the overflow/ radiator cap lock part and it didn't want to start after. It would backfire out the exhaust, but wouldn't start. Again, everything is timed because it idled fine before replacing that small part. So I should be getting fuel, compression, and spark, right? I have a new coil now, that I accidentaly dropped because one end of the box opened and it fell out. Could that be the problem? NOTE: the stock coil was on when it idled correctly, and when it didn't start after I replaced the overflow/ radiator cap lock. I have a new rotor, cap, wires, spark plugs, battery, fuel filter, TPS, most vacuum lines, and terminals. I also cleaned the MAF to see if that would help. Still nothing. My father thinks it may be bad gas that sat there for ~6 months. It doesn't backfire anymore, it just cranks. I've tried having the accelerator down to see if there is just too much fuel, doesn't do anything still. I'm not trained in any automotvie technician or mechanical field. I just understand the basics so far, so if anyone knows the problem try to explain it in more lamens terms. Nothing too technical, but I'm not dumb. If you need more info just ask. Quote Link to comment Share on other sites More sharing options...
NewZed Posted June 16, 2014 Share Posted June 16, 2014 Alright I have a 1987 z31, base model, 5spd, and with a vg30e w/ upgraded head work. Then, the thermostat would open and coolant started leaking from the radiator cap. After that happened the engine started to dip in rpm and go back up a couple times then it died. The cooling system is always pressurized, so the thermostat opening is not what caused the cap leak. It could just be a bad cap or it could be signs of a head gasket leak. Pull all of the spark plugs and look for signs of coolant. When the engine runs combustion gases get pushed in to the cooling system. Then, sometimes, when the engine stops running the coolant pressure pushes the coolant in to the leaking cylinders. That's just one possibility. There could be other things going on. Do you have the FSM? They're free to download at nicoclub.com. http://www.nicoclub.com/archives/nissan-300zx-factory-service-manuals.html Quote Link to comment Share on other sites More sharing options...
Thebadinvestment Posted June 18, 2014 Author Share Posted June 18, 2014 Well this is a freshly rebuilt engine. So, a leaky head gasket isn't possible, because I installed it properly. I checked the plugs and cylinders there isn't any coolant just fuel. The piece the radiator cap locks onto, that has the overflow hose connecting to it was the bad part. I do have a Chilton Service Manual, but that has no organization or really helpful info. I'll take a look at the nicoclub FSM to see if I can find anything. Quote Link to comment Share on other sites More sharing options...
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