ssprague Posted September 16, 2018 Report Share Posted September 16, 2018 I've been driving my 85 720 2wd for a couple years, keeping the oil changed and it's been running good. Bought it with 67000 on it and its at 94000 now. Alternator went out a few weeks ago and I replaced it, then back to running good. Last week I parked it at work, and on the drive home I noticed whenever I accelerated, especially lugging at all or going up hills, it knocked (not sure if that's the correct term). It does it in all gears, more in the lower end of each gear and mostly goes away toward the top end. It also doesn't do it when idling, or when Im under the hood manually giving it throttle. I did notice the carrier bearing was shot, so I replaced that hoping it would help but its the same. I've done some internet digging, but I'm unsure what to do. I'm going to do some more testing tomorrow, and hopefully post a video but it's hard because it doesn't do it at idle. Thanks in advance. Sam 1 Quote Link to comment
ssprague Posted September 16, 2018 Author Report Share Posted September 16, 2018 https://vimeo.com/user89603662/review/290164333/d6423550a3 Here is a video i took this morning, it is definitely coming from the front, can't tell if it's up top or down below, checked for obvious loose things just feeling around, nothing loose. Any help is greatly appreciated, this is my daily driver! Sam 1 Quote Link to comment
datzenmike Posted September 16, 2018 Report Share Posted September 16, 2018 Not seeing the vid. 1 Quote Link to comment
weldingrod Posted September 16, 2018 Report Share Posted September 16, 2018 The only thing I see that is obvious is the knock is only there under load. Running gear noises also have a tendency to telegraph through the system and sound as if they were someplace else. Not much help, I know, but maybe (hopefully?) somewhere other than the engine. 1 Quote Link to comment
bottomwatcher Posted September 16, 2018 Report Share Posted September 16, 2018 Does the noise go away while driving in 4th gear only? 1 Quote Link to comment
wayno Posted September 16, 2018 Report Share Posted September 16, 2018 I would look at the exhaust manifold, they are known to crack on the back side where you cannot see the crack, it could make a knocking sound and it would come on slowly/get worse over time. 1 Quote Link to comment
ssprague Posted September 16, 2018 Author Report Share Posted September 16, 2018 Can you still not see the video? You have to click the link, it should work. It does it in all gears, even reverse. A lot of the bushings underneath need to be replaced, could that really be what it is? I hope so. I will do that Wayno but I haven't heard this noise before, it just started doing it coming home from work. Thank you all for your help. Heading to my buddies house hopefully get it figured out before work tomorrow. Sam 1 Quote Link to comment
datzenmike Posted September 16, 2018 Report Share Posted September 16, 2018 Sorry, we couldn’t find that page Make sure you’ve typed the URL correctly, or try searching Vimeo. You could also watch one of the videos below instead. Try it yourself. Maybe I have to join and log in? not happening. 1 Quote Link to comment
bottomwatcher Posted September 17, 2018 Report Share Posted September 17, 2018 Start simple. Enough oil on the dipstick? Otherwise trace down the symptoms by telling us what specifically by gear, load and what has changed recently. Your original post did cover the issues but there are some clues missing. Keep it simple as to what is going on. The small details will wake up the memories of folks who have had the issues before. I have had my 720 30 years but will need some reminders. Fixed everything but can't remember everthing. Good luck and these engines rarely have a total meltdown. 1 Quote Link to comment
nl320what Posted September 18, 2018 Report Share Posted September 18, 2018 Might be bad gas, clogged fuel filter, low fuel pressure... water/junk in the tank... purge that gas out and fill up with premium and Fuel Cleaner with PEA Treatment on the label. 1 Quote Link to comment
ssprague Posted September 21, 2018 Author Report Share Posted September 21, 2018 So I started toward my buddy's house and blew a head gasket. There was about an inch and a half of coolant in the cylinders when we pulled the head. It was blown between 3 and 4 I believe(the ones farthest from the front of the truck?) Put on the head gasket, then couldn't get the timing chain on, the tensioner let loose...so we pulled off the timing cover and I figure since I'm in there I'm going to put in a timing kit. Problem is I think we moved the bottom end with the top end off and now we have the head back on and sealed. I'm guessing that's bad. Any way to check that? Also going to have to set the ignition timing I suppose. I don't know a whole lot about mechanicin but I'm learning fast. :0 Any tips for setting the timing would be greatly appreciated. I've read a bunch of previous posts on here and gleaned that the 1st cylinder being at TDC on the compression stroke, both exhaust and intake valves on the first cylinder should be closed, and that the cam sprocket then has marks to put on the little dowel so that the #1 matches up with the mark we made (which won't matter with a new chain anyway...) and to put the guides on, chain on, then the tensioner and then the timing cover. Thanks everybody for all the help, I really appreciate it. PS Datzenmike I clicked the video and it worked for me, not sure what's going on there sorry. Wish me luck! Sam 1 Quote Link to comment
datzenmike Posted September 21, 2018 Report Share Posted September 21, 2018 Turn the crank pulley till the first cylinder is at TDC and the timing mark on the pulley is at the 0 in the timing scale. Look through the top hole on the cam sprocket and down and you should see a V or U notch. On the thrust plate behind it is a small horizontal etch mark. The sprocket should be on the #2 hole. The notch should be directly below or just slightly to the right of the etch mark above it if the cam is times properly. It should look like this... If it's wildly out you may be a tooth off so move the sprocket one tooth and see. You should be able to use the #2 hole. Never unbolt the cam sprocket without secureing the tensioner with a wedge or a special plastic tool. Quote Link to comment
datzenmike Posted September 21, 2018 Report Share Posted September 21, 2018 When done and still at TDC unbolt the distributor from the timing cover and look in the hole. You should see this... Note there is a large and small half moon that only allows the distributor to fit in one position. If it is not at 11:28 unbolt the oil pump and drop the drive spindle above it. With help re-position it like the picture above and bolt everything together. The timing will not be affected./ 1 Quote Link to comment
ssprague Posted October 16, 2018 Author Report Share Posted October 16, 2018 Just wanted to say thank you for your help everyone, and for the play by play of the timing datzenmike that helped out tremendously. It's running back like it was now, thank god parts are cheap! Now I just have to start replacing my front end suspension, yay! Thanks again. Sam 1 Quote Link to comment
Draker Posted October 16, 2018 Report Share Posted October 16, 2018 If you get in a bind, there are a lot of us datsun guys around eugene. 2 Quote Link to comment
Madkaw Posted October 17, 2018 Report Share Posted October 17, 2018 It amazing how all the Nissan L motors are the same -4 or 6 cylinder . 1 Quote Link to comment
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