captain720 Posted April 2, 2017 Report Share Posted April 2, 2017 (edited) I have officially caught the Datsun fever and now I have two. I have been watching craigslist for about 7 months looking for a parts truck and I thought that I had finally found one, an 86 720 "running on 2 cylinders" with no title and a rusted out bed. So I went to Yakima and picked it up last night, and sadly it was running good enough to take it for a test drive, and it has a rebuilt tranny that feels AMAZING and a brand new clutch it just sounds terrible and is down on power. So the guy is going to work with me on the title thing and if I can't get that fixed then it will be a parts truck for sure, otherwise you guys might be able to convince me to drop the front end or maybe make a flat bed dually, totally looking for input on this one. I will do a wet and dry compression test and check for spark on the plugs (seriously hoping for a spark issue because I can easily fix that, valves or heads make me nervous). It had an optima in it so I was super jacked up about that, but then he took it out. 😕 :crying: :yawn: Oics!!! Seriously clean weber install Flatbed? oh and no power steering. And it has a surprisingly clean coolant reservoir, it kinda looks like it was parked under a carport with the back end hanging out and the cab mostly covered. That or used to haul saltwater at the Bonneville races (although underneath it looks very solid). Edited April 15, 2020 by captain720 Title 2 Quote Link to comment
flatcat19 Posted April 2, 2017 Report Share Posted April 2, 2017 Was this for sale on CL near Yakima? Think it has been posted there for close to a year or so. Where is Washington are you located? 1 Quote Link to comment
captain720 Posted April 2, 2017 Author Report Share Posted April 2, 2017 I found it when the add said 12 hours old and immediately texted the guy so I hope not. Yeah CL in Yakima, I am in central Washington, close to Wenatchee/Plain area not that far away. There is a surprising amount of rats in this state. 1 Quote Link to comment
720inOlyWa Posted April 2, 2017 Report Share Posted April 2, 2017 Well, you are catching up with me.... I just got my third. Don‘t ask me how to stop. I can tell from the front of the head that it has been oozing oil for years without the valve cover coming off or anyone caring enough to wipe its chin there with a shop rag. so you will have to do it. In fact, step one from my point of view is to spend a weekend cleaning everything you can under the hood to see if it is leaking any fluids, and where. And for sure, the best, first 25 bucks you spend on that truck should be spent of a year appropriate Nissan shop manual. It is blue and they sold a shit ton of blue 720s. If the bed bothers you, keep your eyes peeled at the Yakima wrecking yards and a good bed will show up. Make sure it is a King Cab bed as they are not intechangeable. I would think you could fetch it back nicely if you mapped out a plan, made list, and attacked it, one problem at a time. It will turn around and reward you more quickly tan you expect, if you do... Good luck, and welcome to compulsion! 2 Quote Link to comment
captain720 Posted April 2, 2017 Author Report Share Posted April 2, 2017 Thanks, I made a list with my 4wd and it has worked out ok!! It hasn't broke down for about 700 miles now and I actually replaced some things before they broke so I thought I need a new challenge. :-) I might just let the bed be and weld a plate or two over the holes. I will look for the actuall shop manual, I have the Haynes but it has not helped that much. I will likely be taking the head off after a compression test and from the sound of it I might get to do a valve guide or two. When I say the front of the block/head I noticed how ugly that was too, rag and carb and choke cleaner will fix it. I rally like how much these little trucks teach me when I wrench on them, and thankfully the most expensive lesson I have learned is what happens when you timing chain falls off (yeah new engine for that one). 1 Quote Link to comment
flatcat19 Posted April 2, 2017 Report Share Posted April 2, 2017 I found it when the add said 12 hours old and immediately texted the guy so I hope not. Yeah CL in Yakima, I am in central Washington, close to Wenatchee/Plain area not that far away. There is a surprising amount of rats in this state. I'm in Tri-Cities. There's a small handful of us here. Yakima too. He must have refreshed his ad. That truck has been for sale for a while. I recognize the Toyota wheels. Good to see another one saved. 2 Quote Link to comment
720inOlyWa Posted April 2, 2017 Report Share Posted April 2, 2017 Nissan shop manual is the key. By far the best work reference that I have. Read through that, and you will be ready and willing to perform major surgery with a perfect assistant. Ebay always has them. 1 Quote Link to comment
datzenmike Posted April 2, 2017 Report Share Posted April 2, 2017 Those wires are too long, maybe from a V8? They may be molded on ends but if not, they could be shortened to make it look neater. Front bumper position is a give away it was or has hit something. Good thing its not an '84 or newer... they had the to piece bed sides that the seam rusted out. First chance, re torque the head bolts. Engine cold from over night. Loosen one bolt and torque to 60 ft lbs then onto the next. Any order you like but only one bolt at a time. The Z24 was known for blowing the HG every 100K. Re-torque every year. Lack of power? Check the both intake and exhaust side has spark. 2 Quote Link to comment
captain720 Posted April 2, 2017 Author Report Share Posted April 2, 2017 Thanks Mike! Head bolts retorque is on the list at the top, I also need to do it on my 4wd as the warranty on that engine is almost up. When I took it out it wouldn't fire in 2 cylinders until I hit about 2k rpms so I think the intake plugs are not all firing. I will get my compression test and spark tests done asap. Also the tach starts to bounce about 2k as well. 1 Quote Link to comment
captain720 Posted April 10, 2017 Author Report Share Posted April 10, 2017 Got at title now so...... Let the wrenching begin!!! 2 Quote Link to comment
captain720 Posted April 15, 2017 Author Report Share Posted April 15, 2017 I put my timing light on all of the wires just to see if they all had spark and could make it flash. All but the 3rd intake and the 2nd exhaust ones made the light flash, so I tried a new plug wire and nothing really changed so I scraped the contacts on the distributor cap and they were extremely corroded on the cylinders without spark. So I bought a new cap, rotor, and ngk plugs. Any thoughts? Should get the compression test done tomorrow. 1 Quote Link to comment
datzenmike Posted April 15, 2017 Report Share Posted April 15, 2017 New cap and rotor.. try it. 1 Quote Link to comment
captain720 Posted April 17, 2017 Author Report Share Posted April 17, 2017 Compression test #4 130lbs #3 120 lbs #2 0lbs #1 0 lbs, when I took the valve cover off and looked at the top of the valves the front 2 we're both up and the last 2 we're alternating up and down. Is there a spring or something that makes them go up and down that need replacing? I think the front ones are stuck open, if I crank it with the cover off will bad things happen? 1 Quote Link to comment
captain720 Posted April 18, 2017 Author Report Share Posted April 18, 2017 Looks like I might be looking at valves or a really bad head gasket. Should be able to get a socket on the crank pulley and see if the valves "go up and down", which way do I turn it? 1 Quote Link to comment
wayno Posted April 18, 2017 Report Share Posted April 18, 2017 Doesn't matter which way you turn it, what counts is that all the valves go up and down, and that the valve lash is correct. If they all go up and down and the valve lash is good, then I would suspect head gasket, but that doesn't mean there is something else wrong, are all the spark plugs tight? 1 Quote Link to comment
captain720 Posted April 18, 2017 Author Report Share Posted April 18, 2017 Sadly the plugs are tight, on number 1 we checked exhaust and intake side because I couldn't believe 0 pounds and we took the plugs out and put them back in again. I am gonna test the tester on another vehicle though just to make sure though. 1 Quote Link to comment
flatcat19 Posted April 19, 2017 Report Share Posted April 19, 2017 If the tester worked on 3 and 4...Um, it works. If you do a wet compression test on the same cylinders what are your readings? Spin motor to verify lack of movement to #1 and #2 valves. Valve lash needs to be checked next. Leak down test would be next in your flow chart. This will tell you if the cylinder pressure loss is leaking out intake valve, exhaust valve, or crankcase. A compression test only does so much. I use a compression test to decide what the next line of diagnosis is. That's it. Not as a legit answer to a problem. 1 Quote Link to comment
captain720 Posted May 21, 2017 Author Report Share Posted May 21, 2017 I just ripped into it. :thumbup: Its not my daily so I just decided to learn as much as I could and ripped in! I found the problem. Had a bit of excitement when a washer fell down the timing tension er void, but got it out and now I am on the clean up/put back together stage. I had to wait for a driveway to tear it up in so that is why it took so long. I would have happily done it on the street, but neighbors.......... 1 Quote Link to comment
captain720 Posted May 21, 2017 Author Report Share Posted May 21, 2017 Also what is valve lash, how do you check it, and what is it supposed to be? 1 Quote Link to comment
Lockleaf Posted May 21, 2017 Report Share Posted May 21, 2017 Valve lash is the gap between the valve stem and the rocker arm when there is no tension on them. It is checked with thin pieces of metal called feeler gauges. Each one is a specific thickness. Pick the one you need and set the gap using that one. 720s are supposed to be set when the engine is hot. There is a lock nut and a threaded shaft that you adjust to set that tightness. Watch a couple you tube videos. The concepts are fairly universal for mechanical valve lash adjustment. I don't remember the 720 lash setting. 1 Quote Link to comment
flatcat19 Posted May 21, 2017 Report Share Posted May 21, 2017 Did you block the timing chain tensioner before removing the cam gear? Valve lash: .010/intake .012/exhaust Adjusters are on the passenger side of head. 14 and 17mm wrenches to adjust. 2 Quote Link to comment
flatcat19 Posted May 21, 2017 Report Share Posted May 21, 2017 Just noticed....you didn't roll motor to TDC before taking this apart. Tsk, tsk. Blocking the timing chain doesn't matter now as the timing cover will still need to come off now. 2 Quote Link to comment
captain720 Posted May 21, 2017 Author Report Share Posted May 21, 2017 Thanks. Do you use a razor blade to clean off old head gasket? 1 Quote Link to comment
flatcat19 Posted May 21, 2017 Report Share Posted May 21, 2017 Thanks. Do you use a razor blade to clean off old head gasket? Razor blade, WD-40, and green scratchy pads. 2 Quote Link to comment
captain720 Posted May 21, 2017 Author Report Share Posted May 21, 2017 What happens when you take the valve cover off without reaching TDC? I thought I got there, I looked at the timing mark. Is the timing mark off? 2 Quote Link to comment
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