Skellzor65 Posted December 15, 2023 Report Share Posted December 15, 2023 Hello, I just purchased an 86 720 that has transmission problems. Basically it has an automatic trans and at the least the torque converter is out. The moment you put it in drive it throws it in first and will kill the motor if you don't get going immediately. The vehicle came with a 5 speed manual trans to swap, but I would like to keep it original and just fix or replace the automatic. It seems like I am in a minority with that kind of thinking lol. I can't seem to find any shops to rebuild the trans or any that can get a re-man trans. Am I better of just trying to swap the 5 speed in or is there a reasonable solution to putting in an auto? Quote Link to comment
datzenmike Posted December 16, 2023 Report Share Posted December 16, 2023 That's not the transmission. Try reverse it will do the same. Is this a Z24 or a Z24i? The engine should easily be able to idle in gear and under load. It could be any to all of the following... Timing set incorrectly. One side (intake or exhaust) plugs not firing Intake vacuum leak Valve lash not set Blown head gasket or burnt valve. All of the above will cause a very poor idle under load. Do a tune up and get a vacuum reading at idle. It should be 18Hg or more indicating good suction. Quote Link to comment
Skellzor65 Posted December 16, 2023 Author Report Share Posted December 16, 2023 I hope your right. I'll try the things you have suggested. The plugs and wires are new so theoretically it shouldn't be that. I know it has some vacuum problems because the previous owner has some things miss matched, such as the vacuum advance tied in to the intake and not the carb. It does run pretty well when cold but it struggles to idle when warm. Quote Link to comment
datzenmike Posted December 16, 2023 Report Share Posted December 16, 2023 Ah so it's a carburetor and not a Z24i with EFI. Good because I'm not much good with the throttle body injection. Yes get it tuned up and sort out the hoses and vacuum lines. The vacuum advance goes to the base of the carburetor. A good strong idle will easily hold against an automatic in gear. If you do some of your own work get an '86 720 factory service manual (FSM) it will have all the vacuum hose routing and tune up specs. 1 Quote Link to comment
DwayneOxford Posted December 16, 2023 Report Share Posted December 16, 2023 (edited) Nissan_Truck_1986_Factory_Service_Manual.pdf Edited December 16, 2023 by DwayneOxford Quote Link to comment
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