wolfmandu Posted July 28, 2016 Report Share Posted July 28, 2016 Hello my fellow Datsun heads. Wolfmandu here. I have a 1978 620 pickup that I am basically doing all the work on myself. My son and I are about to move north of San Francisco in about a month. We'll be doing a 9-hour drive from L.A. to get there. Our convoy will consist of my son in his old Volvo wagon (with Roscoe the Rotty in the back) and me in my Lil Hustler 620 and hauling my trailer (which is made up of a similar year Datsun 620 truck bed and was built by a great trailer company years ago). I want to be sure I've taken the best pre-cautions I can and have dealt or deal with the obvious things that could go wrong on the longest trip I'll have taken her on since I bought her 6-months ago. I have installed a new alternator, fuel-pump, radiator, battery and clutch. My main problem recently has been the cooling system which was solved by installing the new radiator but only after I pulled the new thermostat I put in. My understanding is that this is only a quick-fix and I should figure out why the thermostat isn't opening pretty soon. If peoples' experiences with pulling their 620 thermostats are positive (or negative) please weigh in. I did flush the engine (which has a low 45,000 miles but had been sitting since 1994) about 15 times before I installed the radiator but I did not buy any flush product and let it sit in the engine for a day or two and then flush it. Should I do this? Could that be the thermo problem? As I said before, any and all advice is quite welcome on what I should check before my long trip. I don't want my son and our dog stuck on the side of the road with me, in the crazy recent heat, surrounded by our lives loaded into the Volvo and my Datsun 620 (and trailer). I have a month to try to avoid that outcome. I forgot. The most recent fix was the oil pressure plug that screws into the block and has a wire that connects to the gauge. That went bad and dumped a full-engine's oil all over the freeway and the scrap-yard I made it into. Luckily I towed it home and fixed it with no harm coming to the engine. Before I go I just want to say how great I think this site is. Everyone helping each-other out and expecting nothing in return is a great thing to witness and experience. My Datsun will be with me the rest of my days and I'm learning how to really fix a vehicle's problems WITH her. I don't have a lot of mechanical experience and all your help so far has been priceless. Thanks again and please weigh in on your advice for getting her ship-shape to set sail for the "Redwoods' of northern California. all the best, W 1 Quote Link to comment
Draker Posted July 28, 2016 Report Share Posted July 28, 2016 If you have to pull the thermostat, I wouldn't call the issue fixed. I would call it... mitigated. We would need some more info to help you through the cooling issue. 2 Quote Link to comment
Charlie69 Posted July 28, 2016 Report Share Posted July 28, 2016 While the thermostat is out I would run a bottle of flush through the system be sure your heater valve is open. Be sure and flush with clear water to get all the flush out of the system. Fill with fresh water and check for leaks (drive it short distances for a day or two). no leaks drain and install anti freeze and distilled water in a 50 to 50 ratio.. Quote Link to comment
datzenmike Posted July 29, 2016 Report Share Posted July 29, 2016 You are reLIEing on the gauge to tell you that you are over heating. All my Daysun I have had tend to run about half way up into the 'run' range and maybe a needle width higher in hot weather. Additionally the sender may be faulty. I suggest borrowing an IR (infra red) gun and 'shooting' the thermostat housing when warmed up. It should be close to 190F but not higher. With luck you may find that you never had a problem. Running hot causes are lack of air flow and lack of coolant flow. You need both to transfer heat from coolant to air. Lack of air... Always run with a fan shroud. It increases the fan's efficiency at low speeds. Try to spin the fan blades by hand. They should be very firm to move but turn smoothly. They should not be loose or spin free. If loose the silicone oil inside as leaked out. Lack of coolant.... Rev engine well while watching the lower rad return hose. Does it collapse from water pump suction? Rad hoses always rot from the inside out and may look ok. Feel it and see if the hose is too soft. If the heater is faulty, were the two heater hoses joined together? This is a no no as it recirculates hot water from the head right back into the engine and puts a huge load on the rest of the cooling system. Plug these two hoses. Also... Ignition timing that is badly retarded dumps huge amounts of heat into the exhaust ports... and into the water jackets around them. Timing should be 12 degrees BTDC on a '78. A carb that is running a very lean fuel mix will run hotter than a proper air/fuel mix. Pull your plugs and look at their color. Very clean and bright white porcelain insulators are an indication of a lean mix. A good color is a light tan. Quote Link to comment
racerx Posted July 31, 2016 Report Share Posted July 31, 2016 Good luck in your trip, make sure ur insurance covers towing, bring lots of tools, coolant and not sure if your running points on volvo but bring extra. Also dont get tstat from autozone go to a nissan dealer. You need a stat. 2 fails of tstat from autozone convinced me to buy elsewhere. Give me a buzz if you get near san jose. Quote Link to comment
an_orange_s2k Posted August 2, 2016 Report Share Posted August 2, 2016 best of luck on your trip! i recently did a 8hr trip when I purchased and drove my 620 from Bend, OR to San Francisco, CA. Quote Link to comment
wolfmandu Posted August 2, 2016 Author Report Share Posted August 2, 2016 Thank you so much everyone for your input. Sorry it took me a few days to respond but I wasn't near my truck or computer. I will try all of the things you suggested and let you know. 1st thing I'm going to do is go out and but a Nissan thermostat as mine is from Autozone. Then I will focus on the rest. I love this site. Long live your and my Datsuns! Quote Link to comment
racerx Posted August 4, 2016 Report Share Posted August 4, 2016 Gates tstat are good also. Not sure why the stats (Stant) from Autozone failed 2x. Quote Link to comment
Cardinal Grammeter Posted August 4, 2016 Report Share Posted August 4, 2016 Us Studebaker nuts throw a distributor, alternator, starter, water pump and fuel pump in the trunk with a good set of tools just in case. I am considering a 700 mile parts run and I'm thinking I'd just take a fuel pump with my 74 620. It has new alternator, starter, water pump. Quote Link to comment
racerx Posted August 4, 2016 Report Share Posted August 4, 2016 along with those, always good to have a gasket maker in the glove box. 1 Quote Link to comment
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