z31Qong

Hello, this is my first thread and my first post here, please help to your best ability, i would very much appreciate it.

Ive had an 85 z31 vg30 automatic for a few months now.
about 170,000 on the engine.

When i go to start it, it will turn over, but it cranks VERY slow. Used to turn over in a split second but it takes much longer, and much slower crank now. Battery was just replaced 2 weeks ago. Replaced the negative cable to the battery which seemed to provide temporary relief, but is now back to its slow cranking self again. What is it?

Can ANYONE PLEASE help, i use this car for my work and its very crucial that i figure this out, fast. Any DIY pointers would be helpful, as the local shop is killing my wallet. Very new to cars and Z's in general, so any help and speedy replies would be GREATLY appreciated.

rogerz

bad starter. bad positive cable. poor to no ground from your negative cable. if you are grounding through the bell housing and not directly to the frame that be your issue dude.
work on negative should have been a clue

86tcoupe

do a starter draw , battery draw, voltage drop, charging , turning torque tests


I am having slow cranking in my car from the hot soak with conditions here

95 degrees plus 70+ humidity . it struggles 15 -20 min. after shut off

rogerz

from your post I doubt you have the equipment and knowledge to do what 86T suggests . at least go to a battery shop and have them do a load test. I was having all sorts of issues with my 83 (which had a new battery). kept telling myself can't be the battery but finally went back and had them do a load test. battery was tu so they replaced with new one that was good. all problems disappeared. Z'S DON'T LIKE LOW VOLTAGE. heat soak is a bunch of crap unless you are driving thru Death Valley at WOT then pull over and stop for a minute and try to restart.

z31Qong

Thank you all for the fast replies.
As Rogerz said, yes, i have very little knowledge or experience with anything like this before, so the more info i can get relating to each thing you guys point out would be helpful. Ill consider doing a load test on the battery, couldent hurt.

Like said before, i greatly appreciate every bit of help i can get with this and it would mean alot to me to be able to be taught about my car from other actual Z31 owners, so thank you.

If anyone has any other questions you want to ask that might help diagnose a problem, please feel free to ask. Thanks.

rogerz

here is my fairly complete list of things to do to prevent future problems.
Get your battery load tested. Be sure you have clean, tight corrosion free terminals on both ends of your battery cables. Be sure the ground (negative) cable goes to a bolt into the frame before going to the starter. grounding through the starter is not a reliable connection. Z's don't like low voltage. causes the electronics to act funny. it is possible to have enough amps to crank but not enough voltage to run the electronics. If you have one size fit all cheapo clamp on terminals they are a problem waiting to happen. Usually on a rainy night around Oh Dark Thirty.

Clean the connectors for the maf or afm, ecu and tps. Deoxit by CAIG is probably the best connector cleaner on the market. spray with CorrosionX after cleaning and before putting together this will help prevent any further corrosion. DON'T USE DIELECTRIC GREASE.

Replace outer tie rod ends, and ball joints. replace the bushings with poly (don't forget to lube them as directed unless you like squeaky things). New shocks. Get new boots for power steering. all those things will make you think you are driving a different car. doing them piece meal is a waste you won't see a great improvement until you do the complete job. You need to get the car realigned after messing with the front. Have your tires in good shape and rebalance. Rear bushings nice too but more work and you won't notice as great an improvement. Rear shocks also because if the fronts are gone so are the rears. if car squats when you jump on the gas the rears are gone. If you have the electro adjustable shocks they are DEFINITELY GONE.

If you are doing a turbo car shocks (electro adjust I think may be only on the turbos) then you need the adapter plates to fit modern shocks to the car in the rear. Easiest way is find an n/a at the junkyard and take the mounting plates. They may be available thru NAPA (listed) but I had the n/a plates.

The negative cable on the original wiring had a square copper plate about 6 inches from the terminal that bolted to the body with an M8 bolt located below and toward the outside from the M6 bolt that hold the battery clampdown bar. My guess is the cables or the battery are your problem. To remove the cables look down just forward of the battery and you will see the head of an M6 bolt that holds a clamp that secures the cables. Then you can take them out and inspect to see what is wrong if anything. If the square copper piece is missing get a short cable with an eye on the end that will reach that M8 bolt (or any convenient bolt that goes into the frame) then take our cable that goes to the starter to a shop and have them crimp on an eye. then run that from wherever you started to the starter. if you got those loser one size fit all terminals on the ends of your cable take that to the shop and have them crimp on standard solid lead terminals. A good battery shop (ie NOT WALMART AND NOT SEARS) can do all this fairly cheaply. Did one of my 86 and cost less than 20 bucks. you have to take the cables in however cause labor for them to take out cost more than a new battery. If you get a battery get an Interstate. Best batteries I have ever used in the last 60 years. Again grounding thru the bell housing is iffy and leads to odd things happening.

be sure the battery is securely held down so it doesn't tip or slide around on the battery shelf.

rogerz

more advice.
Take the schematic from the FSM down to kinkos and have them blow it up to 11x17. Much easier to read unless you are a keen eyed twenty something. get fsm at xenonzcar.com

nissan fsm beats the knockoff manuals like chilton and the like.

ken99

This is symptomatic of a spun or galled main bearing, especially if the engine spins much better once it has cooled down.

z31Qong

thanks for the replies. So i got the FSM and im looking at this diagram of my starter, and everything it says to check and replace is so small of a part that its almost impractical i would think. Might as well just get a new starter for about $70 right? I highly doubt it could be the battery itself, could possibly be connections or cables but im just not sure. Im sure theres a number of other things it could be, but like mentioned above i have very little knowledge about these kinds of problems, so can anyone weigh in on that?
Sorry if it seems like im asking the same questions, i just sometimes dont even know where to begin to start doing some of the tasks mentioned above. Thanks.

86tcoupe

wow ...don't need a bellhousing ground ! really thats laughable rogerz or was it a misprint

heat soak condition does exist in hot climates ,it is a fact whether you understand it or not ,they teach about it at Nissan training center and occurs 5 to 20 min after eng. off ,I said in extreme conditions ,you barely get out of the 80,s in Wa.
obviously you haven,t been to Dallas in the summer

I know he probably cannot do the tests he needs to diagnose but stated most of them anyway . turning torque the big one as to rule out engine problems easy to do if you can get under it ,easier on a lift .
which could very likely be a problem ,you may have a number problems
diagnosing can save you from wasting $$ on unneeded parts

Bobs 84 300ZX

Hi and welcome to the forum!!!


When there is about 170,000 miles on your car and after you see what my underside and stater condition looks like (150,000 miles on mine). I would think that yours could very well be similar to what mine looks like. The old cliche; "Out of sight, out of mind". The ground locations on mine were very dirty and had corrosion on them. So you may want to look at yours and check these out and clean them. For what it is worth. Good luck on your project. Thanks, Bob