BobLoblaw Posted March 1, 2008 Share Posted March 1, 2008 (edited) My '81 Datsun/Nissan 280zx has been the most reliable car I ever owned. Just recently, the engine has started to miss and 'pop' a little bit, and coolant has been disappearing slowly. The car has been hesitant, and jerky since the idle problem, and will nearly stall at stoplights. Sometimes it will idle fine, but more often than not, it's rough. I replaced all the fuel injectors and check the connections: everything seems like it's working well (in theory) but the bad idle persists. This morning, I started it up and noticed that there was white smoke coming from the exhaust until the car was at operating temp, then it went away. My guess is that it has to do with my loss of coolant (smoke didn't smell like burning oil). Could this be the cause of my rough idle? What should I do to fix this? I should also note that I have cleaned all possible connections with a file and alcohol. Any help would be greatly appreciated!!! Edited March 1, 2008 by BobLoblaw Link to comment Share on other sites More sharing options...
94extreme Posted March 1, 2008 Share Posted March 1, 2008 head gasket. Link to comment Share on other sites More sharing options...
GhostPath Posted March 1, 2008 Share Posted March 1, 2008 Yup, common problem for the older L-series engine. You will probably find that the headgasket cracked/failed between the #5 and #6 cylinders (the ones towards the back of the bay). White smoke + disappearing coolant = car is burning coolant. Link to comment Share on other sites More sharing options...
BobLoblaw Posted March 1, 2008 Author Share Posted March 1, 2008 (edited) Yup, common problem for the older L-series engine. You will probably find that the headgasket cracked/failed between the #5 and #6 cylinders (the ones towards the back of the bay). White smoke + disappearing coolant = car is burning coolant. So the failed head gasket is the reason for my poor idle? Just wondering, what does a head gasket replacement cost at a shop normally? Is there anything else I should do while replacing the head gasket (e.g. valves). Ghostpath, do you have experience with L28 engines? It sounds like you know about them a bit. Could it be anything else? The white smoke is just here until the car warms up. Someone told me (not a Pathy person) that it could be my PCV valve. Is there any chance of this? Edited March 1, 2008 by BobLoblaw Link to comment Share on other sites More sharing options...
GhostPath Posted March 1, 2008 Share Posted March 1, 2008 So the failed head gasket is the reason for my poor idle? Just wondering, what does a head gasket replacement cost at a shop normally? Is there anything else I should do while replacing the head gasket (e.g. valves). Ghostpath, do you have experience with L28 engines? It sounds like you know about them a bit. Could it be anything else? The white smoke is just here until the car warms up. Someone told me (not a Pathy person) that it could be my PCV valve. Is there any chance of this? Yeah, I have some experience with it. I'll post back later - I have to go into work today, didn't want you to think I was ignoring you. Link to comment Share on other sites More sharing options...
94extreme Posted March 1, 2008 Share Posted March 1, 2008 So the failed head gasket is the reason for my poor idle? definitely could be my PCV valve pcv has nothing to do with moisture and white smoke is water burning off. pcv recirculates crankcase gases back into the intake.. pollution control device. cost: you'll have to call around your area.. it always depends.. call the dealer too.. sometimes they can be competitive. straight 6 should be cheaper then a v6. and as to doing anything else while there.. probably depends on how many miles you have.. there are at least couple of Z forums out there. Link to comment Share on other sites More sharing options...
zonianbrat Posted March 1, 2008 Share Posted March 1, 2008 I think MZ is correct. Sounds like a bad head gasket. As far as other things to think of..it depends on how much money you want to throw at it. Might not be a bad idea to have the heads machined and valves checked. Link to comment Share on other sites More sharing options...
BobLoblaw Posted March 2, 2008 Author Share Posted March 2, 2008 (edited) Hey guys, Thanks for you help. I am a member at zcar.com but you guys have been more helpful that the Z guys!!! I sure am happy I bought a Pathy! NPORA 4 life. I just wanted to say that when I started my car up today there was no white smoke at all. I let the car cool down then just started it again 5 mins ago. Once again, no white smoke. This problem is really starting to bug me. Why won't this $#^$#!#$ just run properly!!! Could it be a failing fuel pump? How do I test if my fuel pump is working properly? Would a valve problem cause a rough idle and loss of acceleration? Any other theories on what could be wrong are welcomed with open arms! Have a good weekend everyone. Edited March 2, 2008 by BobLoblaw Link to comment Share on other sites More sharing options...
mws Posted March 3, 2008 Share Posted March 3, 2008 Start with a compression test. You can get a gage at a tool store for under $25, or you can pay someone $100 to do it. It's not hard, just takes time. It will tell you quite a bit. If you find one or two cylinders very low, that will confirm you have a problem that no amount of superficial work will solve (going to be head gasket, crack, or something else pretty serious). If all are good, then it could be something "easy". Link to comment Share on other sites More sharing options...
BobLoblaw Posted March 4, 2008 Author Share Posted March 4, 2008 Start with a compression test. You can get a gage at a tool store for under $25, or you can pay someone $100 to do it. It's not hard, just takes time. It will tell you quite a bit. If you find one or two cylinders very low, that will confirm you have a problem that no amount of superficial work will solve (going to be head gasket, crack, or something else pretty serious). If all are good, then it could be something "easy". I did a compression test with a mechanic friend of mine and each of my cylinders checked out at approx 140psi, which are good test results (anything lower than 110psi is bad I think). That's what makes this problem so weird. Where is my coolant going? Why is the idle so poor, but not poor enough for the car to completely stall? Link to comment Share on other sites More sharing options...
mws Posted March 4, 2008 Share Posted March 4, 2008 The next step would be a leakdown test. This requires pressurizing each cylinder with compressed air and monitoring how much air is leaking out and where it is going. Depending on where you here a hiss, you can learn a lot. If you pressurize a cylinder and start having coolant welling up out of radiator neck and then eventually air bubbles, then you definitely have a head gasket problem or a cracked head/cylinder. If you hear it hissing out of a neighboring cylinder's spark plug hole, it is definitely a head gasket. But those would usually be accompanied by low compression test readings as well. Link to comment Share on other sites More sharing options...
BobLoblaw Posted March 5, 2008 Author Share Posted March 5, 2008 The next step would be a leakdown test.This requires pressurizing each cylinder with compressed air and monitoring how much air is leaking out and where it is going. Depending on where you here a hiss, you can learn a lot. If you pressurize a cylinder and start having coolant welling up out of radiator neck and then eventually air bubbles, then you definitely have a head gasket problem or a cracked head/cylinder. If you hear it hissing out of a neighboring cylinder's spark plug hole, it is definitely a head gasket. But those would usually be accompanied by low compression test readings as well. Okay, I'll try that. This problem is really weird. When the engine is warm, it'll start and run like normal. If left idling, the idle will progressively get worse.....but not so bad that it stalls. The dash lights will flicker. The part that baffles me is that it would run properly at first. The white smoke that I saw (that started this topic) hasn't come back at all. Thanks again to everyone who has posted. I really do appreciate everyone's ongoing help. Link to comment Share on other sites More sharing options...
94extreme Posted March 5, 2008 Share Posted March 5, 2008 well if compression in all cylinders is good then it's not head gasket or cracked head. water in fuel? fill up at a cheap station recently? add gas drier (heat) to the gas and see if things improve in a day. but that still doesn't expalain missing coolant.. bypass hose? <-- search; slick = author Link to comment Share on other sites More sharing options...
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