1983 Datsun Driving Me Insane
 

Hello fellow Z Enthusiasts, I'm at my whits end here from this Darn Datsun. I've got a 1983 Datsun Maxima, and I can't for the life of me figure out how to get this thing running properly.

A-little backstory on the car;

The car used to belong to my grandfather, and when he passed away my father inherited it and drove this old girl everyday for 5 years to work, All the way up until the point the engine slipped its timing gear, then it sat for another 7 years until I was old enough to understand cars and not hurt myself while working in the garage. After purchasing a new timing chain and replacing the old one, the car ran fine. Well, my brother was using the car while his was in the shop during this last summer, but the dummy doesn't know a THING about cars and never checked the oil, water/coolant level, etc.; pretty much everything that you need to check on old cars to make sure they dont explode while driving them. Well, this time he didn't check the water level, called my father asking "why it was overheating all the time". And as he was driving it back to our house, the poor car blew the head gasket. Months of work down the drain (and wallet, mind you). It sat for another 2 months, until we managed to get the money to buy a new gasket. (Now THAT was one heck of a time, trying to figure out how to take the head off) We eventually got it replaced, but and hooked everything back up, but upon starting the engine we realized it wouldn't drive correctly.

Let me explain;

When you started the engine, it would idle great. It revved in idle like a dream as well.

Then you'd try driving it; Ohhh boy, was there a problem. The thing would lurch and pop forward worse then a dang blender paired with a v8 engine runnin on 3 cylinders.

Back to the garage I suppose.

Everything looked fine, but we read in the manual that the oil pump timing gear needs to be 5 degrees past the time marks at 8degrees past TDC. Well, we were off, so we tried setting it how the book looked.

Tried again.

Cranked and backfired, and eventually got it started that way, but even then it ran so bad that it would die when you gave it just a tiny bit of gas.

Back to the garage...

We noticed that when we turned the distributer clockwise, it would run better, so we decided that instead of setting the Oil Pump Timing Gear at 5 degrees PAST the timing marks, we'd set it 5 degrees BEFORE the timing mark, still at 8 degrees TDC.

Started it up, and amazingly it ran. It ran actually pretty good, which was surprising because it was the complete opposite of what the book called for. Our engine, a L24E non-Cali engine runs OUT of time, not IN time. But it was still out of time and not "drive able" (still lurched) and after hooking up a timing light to the engine, we discovered that the car would idle at 20 degrees, then drop down to 0 when you gave it gas, which would explain the lurching and backfiring.

We thought we'd messed up on timing chain, so we checked that but it looks just like its supposed to.

After a month of trying to time the car with the Oil Pump Timing Gear, we called 9 to 9 and Tom said that we needed to reset the computer. He said no matter what we did, the engine was fighting to put the engine back in time, so after a quick reset, we'd need to retime the engine again and it should be good.

Well after resetting the computer and retiming the engine, the engine wouldn't even start this time. After fiddling with the Distributer and Timing Gear again, we got it running, and the engine now advances correctly when you give it gas. It no longer drops to 0, it goes up with the RPMs.

We then tried driving it...

Same thing again, only this time worse. It lurches so bad it could give you whiplash if you weren't careful. We think it may be a vacuum line, but they look hooked up correctly and we can't find any leaks, so we are literally going insane trying to figure out this engine.

If anyone's been through the same problem or has an idea on what the problem might be, let me know what I could do to try and fix this.

Thanks!

Welcome to ZDriver!

I just went through a similar issue on Jaromgi's 280zx Turbo this last fall. I was chasing timing problems and eventually figured out that the timing chain was one tooth off, then I was able to reset the oil pump / distributor shaft correctly. After I got them both aligned correctly, I could set the timing spot on and it ran like it should.

I suggest checking the timing chain by setting the engine to TDC cylinder 1 (ABSOLUTE 0* AT THE TIMING MARK). Then pull the valve cover and verify that the score mark on the cam plate is right at the U-channel on the cam sprocket gear. See this post:
https://www.zdriver.com/forums/240z-...e-l28et-30099/

Also, at TDC, the distributor rotor should be pointed just down from straight forward towards the front of the car (~8:30 looking straight on the distributor).

Lastly, unplugging the ecu does nothing since it doesn't retain any diagnostic codes. :)

Thanks, I'll check it out today and see if anything is off. It still amazes me, could one tooth off on the chain really cause this many headaches?

My answer to your last question: yes. One tooth off would mis-align your firing, your cams, everything. I am surprised it would start at all - but it would definitely limp on fewer than 6 legs.

Nismo tells it straight. I am wondering if there is a way, using the available manuals, to remove the chain, make sure everything is aligned correctly - by locating and realigning what is out of alignment - and then reinstall the chain. I guess everything would have to be factory marked and probably wasn't - so it isn't that simple. I would check that approach out. It's like starting over from scratch but if it's a chain position issue, I wouldn't be sure any other way. Somebody here knows how to do this and can tell you.

Every time I have switched out a timing belt on my Z31s, I buy the factory-marked OEM belt (aftermarket belts have no marks) and make sure nothing is rotated between belt removal and belt replacement. Maybe somebody didn't do that with your chain. Or a bad tensioner let the chain skip? Weird. :017:

Yes there is a way. The tricky part (not really "tricky) is making sure the chain tensioner doesn't pop out when you remove the cam sprocket by using a wood wedge in between the chain at the guides. This is a VERY common rookie mistake that then requires pulling the timing cover and loosening the oil pan to fix the popped tensioner.

Align engine to TDC cylinder 1, and check the cam mark alignments (as I stated above). If it's off, adjust to correct location. Since each tooth equates to about 1/2" of chain length, you can really only set it correctly or incorrectly... there's no "close enough". Same with the distributor shaft alignment.

OK, cool, OldZNewLife. Nismo nailed it. You need to be sure about your chain position/alignment. Ain't easy but that Z needs to be on the road again. Ask for more help if you need it. Motor/timing experts are available in your area, no doubt - and we are here, too. :045:

Great original post, by the way. You covered all the important ground. :045: