pwrcat4000 Posted September 22, 2016 Report Share Posted September 22, 2016 So back moving again thanks all I am having a bit of a cooling problem that I have diagnosed to the 45 year old radiator So what are my options it looks like 510 rads are cheaper than 521 rads. Has any one researched option's on what works. I know my 620 rad from the parts truck wont fit with out a lot of mods. I am driving the 521 daily. (well I want to) Things I have already done Checked coolant (someone would have said it) New waterpump New 190 thermostat Adjust timing to 10 deg BTDC Adjusted valves Switched from the L16 Carb and intake to the L20B (though it might me too lean) 1 Quote Link to comment
racerx Posted September 22, 2016 Report Share Posted September 22, 2016 Sometimes when ur carb is too lean ur car will overheat and whatever you do stay away from.those alum rad. The one. Heard thats good is koyo brand but very pricey. I would see if any other radiator will fit. I had a fiero 85-87 rad in my datsun for 10 yrs before it started leaking. 1 Quote Link to comment
banzai510(hainz) Posted September 22, 2016 Report Share Posted September 22, 2016 try a different Rad cap? whats the proplem.? which you should have said first. I run a 160 stat in my truck. that would be a (54mm Generic size) new hoses? a soft lower intake hose will collapse when reved up. I wouldnt worry about the carb as most webers are bigger anyway than a stock carb and all run fine in my experince If I remeber right yo have a L 20 in there now? does the head use a water line or not as not all later L20s have water passage. so they might need to be drilled. But then your using a L20 intake also . So Im only Mind Reading wehat you have. If didnt over heat before cant be the radiator. Its motor related. or hook up related. But a 160 stat is cheap to try first. 1 Quote Link to comment
racerx Posted September 22, 2016 Report Share Posted September 22, 2016 What ever you do stay away from Autozone Tstats, failed 2x on me. Gates are good ones. Can you try to get your rad recored? 1 Quote Link to comment
DanielC Posted September 22, 2016 Report Share Posted September 22, 2016 I have been driving 521 trucks since the mid 1970's. At that time I used a 521 to pull a two horse trailer all over the pacific north west. I have climbed Cabbage hill, east of Pendelton, OR with the horse trailer, and full sized horses, in 90 degree summer heat. Second gear, about 5,000 RPM, full throttle. You are from Kansas, Cabbage hill is a few miles of a 6% grade. My 521 did not overheat with a stock radiator. More recently, the 521 I am driving now runs a stock radiator. I use it to haul hay, and quite often wood pellets, a ton at a time. It too does not overheat, again with a old L-16 engine, and the stock radiator. If the radiator core is clean, I do not think the radiator is the issue. In my experience, a stock Datsun 521 has more than enough radiator to keep the engine cool. 2 Quote Link to comment
racerx Posted September 22, 2016 Report Share Posted September 22, 2016 Run w out stat and see if it overheats. If it does then its your engine or temp gauge or stat or heater core. 1 Quote Link to comment
flatcat19 Posted September 22, 2016 Report Share Posted September 22, 2016 Run w out stat and see if it overheats. If it does then its your engine or temp gauge or stat or heater core. All cars will overheat without a thermostat. I've already proven this experiment. Ground the sensor wire to verify gauge works. Use a laser thermometer to verify you're actually overheating. With no symptoms stated were all just guessing here. 3 Quote Link to comment
racerx Posted September 22, 2016 Report Share Posted September 22, 2016 U sure, i ran mine for several hours w out a stat and did not overheat. This is how i found out that the stat i bought at autozone was defective. As a matter when i first bought my 510 many moons ago, it did not have a stat and would barely get 1/4 of the way and this is driving it around town. 1 Quote Link to comment
banzai510(hainz) Posted September 22, 2016 Report Share Posted September 22, 2016 In colder climates running w/o a stat will show colder.In Very HOT areas the vehicle still may overheat as the water dosent get a chance to cool in the rad. Most time the stat is ususally closed until the water is release into the rad then stays there to cool off before being let in again. if you swapped the whole motor w stat housing maybe the sender resisitance is slightly different But most are the same. You could put the old sender housing on and see if it changes 1 Quote Link to comment
Lockleaf Posted September 22, 2016 Report Share Posted September 22, 2016 Do everything diagnostic they suggest. If you have done all that and still feel like you need better cooling, consider installing an oil cooler. Oil coolers can drastically reduce the load on the cooling system. You can install one for under $100 and keep your radiator right where it is. 1 Quote Link to comment
pwrcat4000 Posted September 23, 2016 Author Report Share Posted September 23, 2016 Heat is what killed my last L20B (dropped the valve seats out of the head) Currently I run about 1/8" over the black line if I drive normally on a hot day, but when i turn it off it goes way high (no circulating coolant) so I leave it running at idle when parked which has been working and it not optimal. The only thing that I have not changed is the rad. When I run a garden hose, on the rad when its hot, it drops the temp to the black line at idle. If I drive it for a while (1 hour or more) it continues to build heat, but it never gets to the red. I should have mentioned before but I am running the L20B stock water pump with the fan/clutched and no shroud. When I burned down my last L20b I was using the L16 water pump and the non clutched fan with the shroud. (still smoked the valve seats) I have to think it is the radiator I have had it professionally cleaned and leaks repaired back in 2012. "Winter is coming" and it will probably be a non-issue soon, still I would like to correct the hot running I am having now (at 100+ atmospheric temperature.) It has to be the radiator! That is the only variable in the system that has not changed? 1 Quote Link to comment
tr8er Posted September 23, 2016 Report Share Posted September 23, 2016 Check your clutch. 1 Quote Link to comment
DanielC Posted September 23, 2016 Report Share Posted September 23, 2016 The fan shroud is important. When the truck is not moving, it allows more air to be sucked through the radiator. Without the fan shroud, a lot of the air the fan moves just circles around the fan blade tips, without being pulled past the radiator. If you have a catch can for the radiator, and a radiator cap that allows coolant to moves in and out of the radiator, as it contracts, and expands, that will increase the efficiency of the radiator. Check the ignition timing. Slightly retarded timing exposes more cylinder walls to combustion heat, and then that energy just goes into the coolant, instead of moving the truck. If the truck is running too warm, turning on the heater helps cool the engine. The heater is just another radiator. I would also do a good flush of the cooling system. Remove the block drain plug above the starter, remove the thermostat. Remove the radiator, put the radiator hoses back on the block. Fill the block through the lower radiator hose, with a garden hose, and when the block is full, and water comes out the top rad hose, blow compressed air into the block drain plug hole. Repeat this process until the water comes out clean. Do the same process with the radiator, blowing air into the radiator drain hole. You can also partially fill the radiator, when it is out of the truck, and shake it vigorously, to help dislodge crap inside it. Flush the heater too. This keeps the heater valve turning easily. Refill the radiator with good antifreeze. I have found the most economical place to get antifreeze is Walmart, even the mini neighborhood Walmarts have good name brand antifreeze, and a few aisles over you can get distilled water to mix with the antifreeze. If you have nothing to mix it in, buy one gallon of premixed antifreeze, then use that empty bottle to mix a half gallon of full strength antifreeze, with a half gallon of distilled water. Buying a gallon of 50/50 mix, and a gallon of full strength antifreeze, and two gallons of distilled water gives you three gallons of coolant. The engine, radiator, and heater take about two gallons, and you have a third gallon to top off the cooling system later. 1 Quote Link to comment
banzai510(hainz) Posted September 23, 2016 Report Share Posted September 23, 2016 Did you try a 160 stat??????????? untill then STOP!!!!!!!!!!!!! If you dont have a bypass I drill a 1/8 hole in top of the stat (whY I dont know but seemed to help) water pump is not the proplem. you never mension the the water line to the manifold if your head has the water passages or not.( I dont know if it means anything But just wondering) If your head drop a valve seat cause was hot then it would POP the gasket and warp the head also 1 Quote Link to comment
Cheetahking Posted September 23, 2016 Report Share Posted September 23, 2016 Did you try a 160 stat??????????? untill then STOP!!!!!!!!!!!!! If you dont have a bypass I drill a 1/8 hole in top of the stat (whY I dont know but seemed to help) This is helpful as it allows the water to warm up more evenly. With the stat closed there can be an issue where the water on either side of the stat is at a high differential until it warms enough to open 1 Quote Link to comment
wayno Posted September 23, 2016 Report Share Posted September 23, 2016 If you take the radiator out, lean it upright against a wall, stick a garden hose in the top outlet and see the water coming out of the lower outlet just as fast, the radiator is not likely the issue unless you painted it with a heavy coat of paint. It is very important that you have the thermostat bypass as mentioned, this bypass has an important function, it lets hot coolant out of the head so it can get to the thermostat, if you don't have the bypass the coolant in the head will get super heated and start making popping noises inside the head/block, when the thermostat does finally open cold water hits that hot block/head, the headgasket will only last so long before it blows, it may last a month, or only a day, but it will blow. Now if you used the L16 thermostat housing without a bypass hose, then you need to drill a hole in the thermostat itself, as that is the bypass, it allows the hot coolant to get out of the head to the thermostat to heat it up so it can open, if the thermostat was in the head like the A14/15 series heads/blocks then you would not need a bypass, but the L block has the housing on the outside of the head where it is cooler. Also it was mentioned that the lower radiator hose can collapse, I have seen this happen, they used to sell rad hoses with springs inside of them to stop this from happening, I suspect that when the engine is revved, the water pump can move more water than the thermostat will let thru the hole, so the lower hose gets sucked flat and stays flat till you let off the pedal. I have several rigs around here, 2 of my trucks have cowls, 2 of them don't, one of the 2.5 diesels without a cowl even has had the fan blades trimmed because the blades were going to hit the radiator hose, I have no cooling issues with this truck, it has a 2 core modified J13 radiator, but the work truck that has a cowl with an LZ2.3 hybrid engine does have an issue on the hiway, it get warm and stays warm for quite a while after I get off the freeway, it has a 3 core radiator, but this work truck is loaded with debris and is pulling a trailer, I am likely hauling around a ton and a half extra weight every time I drive it. I used an L16 thermostat housing on the work truck engine without a bypass when I first put the LZ23 engine in it, I had overheating issues, the temp needle was all over the place, one day it just over heated going about 50mph down a flat straight country road, I lost the head gasket a couple weeks later. 1 Quote Link to comment
flatcat19 Posted September 23, 2016 Report Share Posted September 23, 2016 My heating "woes" sound exactly like what you describe. Where you say your temp needle is...is only about 190*. Not hot at all. I talked at length about this with Wayno when I was at the Blue Lake show and on the NWD forum with him leading up to the show. For that show, I drove 240 miles straight at 60-75mph then came to a dead stop when I hit Portland rush hour traffic. Needle was a tick or two past the mark on gauge. Again...that's about 190*. When stopped, it climbed to 75% until I started rolling/applying gas to rev. I have a 521, stock L16, 4 blade fan, fan shroud, 185* stat with jiggle valve cut out and hole enlarged. I also had an intake leak due to my carb mounting bolts/adapter for Weber being loose. Those I did not know at the time; unknown lean condition. Overthinking it. Worrying more. Get a laser temp gun from Harbor Freight($10) to verify temps. I will also be installing AUX gauges over the winter. Maybe installing a 160* stat like Hainz has suggested as well. 1 Quote Link to comment
pwrcat4000 Posted September 26, 2016 Author Report Share Posted September 26, 2016 The fan shroud is important. When the truck is not moving, it allows more air to be sucked through the radiator. Without the fan shroud, a lot of the air the fan moves just circles around the fan blade tips, without being pulled past the radiator. If you have a catch can for the radiator, and a radiator cap that allows coolant to moves in and out of the radiator, as it contracts, and expands, that will increase the efficiency of the radiator. Check the ignition timing. Slightly retarded timing exposes more cylinder walls to combustion heat, and then that energy just goes into the coolant, instead of moving the truck. If the truck is running too warm, turning on the heater helps cool the engine. The heater is just another radiator. I would also do a good flush of the cooling system. Remove the block drain plug above the starter, remove the thermostat. Remove the radiator, put the radiator hoses back on the block. Fill the block through the lower radiator hose, with a garden hose, and when the block is full, and water comes out the top rad hose, blow compressed air into the block drain plug hole. Repeat this process until the water comes out clean. Do the same process with the radiator, blowing air into the radiator drain hole. You can also partially fill the radiator, when it is out of the truck, and shake it vigorously, to help dislodge crap inside it. Flush the heater too. This keeps the heater valve turning easily. Refill the radiator with good antifreeze. I have found the most economical place to get antifreeze is Walmart, even the mini neighborhood Walmarts have good name brand antifreeze, and a few aisles over you can get distilled water to mix with the antifreeze. If you have nothing to mix it in, buy one gallon of premixed antifreeze, then use that empty bottle to mix a half gallon of full strength antifreeze, with a half gallon of distilled water. Buying a gallon of 50/50 mix, and a gallon of full strength antifreeze, and two gallons of distilled water gives you three gallons of coolant. The engine, radiator, and heater take about two gallons, and you have a third gallon to top off the cooling system later. It is running hot at idle, but just a little bit. When I drive the truck it continues to build heat, it never gets to the overheat line but gets about half way to the overheat mark. I have checked the coolant before I start in the morning (FYI I check all the fluids every morning before I drive the truck) I have considered a catch can don't know why it does not have one stock? Timing is retarded 10 BTDC I thought that this was the recommended timing. I see your point though. I think it has to be the radiator since it is the same problem as my other motor and it is the only thing than has not changed My heating "woes" sound exactly like what you describe. Where you say your temp needle is...is only about 190*. Not hot at all. I talked at length about this with Wayno when I was at the Blue Lake show and on the NWD forum with him leading up to the show. For that show, I drove 240 miles straight at 60-75mph then came to a dead stop when I hit Portland rush hour traffic. Needle was a tick or two past the mark on gauge. Again...that's about 190*. When stopped, it climbed to 75% until I started rolling/applying gas to rev. I have a 521, stock L16, 4 blade fan, fan shroud, 185* stat with jiggle valve cut out and hole enlarged. I also had an intake leak due to my carb mounting bolts/adapter for Weber being loose. Those I did not know at the time; unknown lean condition. Overthinking it. Worrying more. Get a laser temp gun from Harbor Freight($10) to verify temps. I will also be installing AUX gauges over the winter. Maybe installing a 160* stat like Hainz has suggested as well. "stat with jiggle valve cut out" not sure I understand what you mean Temp gun is on my wish list maybe next paycheck :) 1 Quote Link to comment
Charlie69 Posted September 27, 2016 Report Share Posted September 27, 2016 This is the jiggle valve Flat is talking about. Have you flushed you cooling system? 1 Quote Link to comment
flatcat19 Posted September 27, 2016 Report Share Posted September 27, 2016 That is the jiggle valve I am talking about. 2 Quote Link to comment
pwrcat4000 Posted September 27, 2016 Author Report Share Posted September 27, 2016 I'll check it out I don't remember if my stat has that thanks for the picture! 1 Quote Link to comment
tr8er Posted September 27, 2016 Report Share Posted September 27, 2016 Check your clutch. Check your FAN clutch. Sorry if that was not clear 2 Quote Link to comment
wayno Posted September 27, 2016 Report Share Posted September 27, 2016 It all depends on if you transferred things from one engine to the other, if you did use the same things on both engines, then they would also have the same thing in common like the engines have the radiator in common. All of us have been talking about the same things, thermostats with a hole in them or the the thermostat housing having the bypass hose, does your thermostat housing have the bypass hose, if it does, then you don't need a hole in the thermostat. Are you using the same radiator hoses, does the lower one have a spring inside it to keep it from collapsing? Once warm can you remove the radiator cap and see the coolant flowing by the hole? Have you removed the radiator and stuck a hose in the upper hose outlet and watched the water coming out the lower outlet, that is free and is a good indicator of coolant flow, if it starts coming out the upper outlet the hose is in, and doesn't come out the lower outlet very fast, well then the radiator is likely the issue. You can even do the water hose test without removing the radiator from the truck, just remove the hoses from the radiator outlets and stick the hose in the top outlet and turn it on. The biggest question I have is does the thermostat housing, not the top that the radiator hose slips on to, the part that holds the thermostat itself have a bypass hose? The hose comes from the top of the outlet that the lower radiator hose connects to on the engine, it goes to the intake manifold and the thermostat housing via a "TEE", the L16 thermostat housing doesn't have this hose. New thermostats don't have the hole anymore, the parts store just sell whatever will fit in the thermostat hole, as that is what the computer tells them to do, they don't know shit about these Datsun engines. 1 Quote Link to comment
tr8er Posted September 27, 2016 Report Share Posted September 27, 2016 Heat is what killed my last L20B (dropped the valve seats out of the head) Currently I run about 1/8" over the black line if I drive normally on a hot day, but when i turn it off it goes way high (no circulating coolant) so I leave it running at idle when parked which has been working and it not optimal. The only thing that I have not changed is the rad. When I run a garden hose, on the rad when its hot, it drops the temp to the black line at idle. If I drive it for a while (1 hour or more) it continues to build heat, but it never gets to the red. I should have mentioned before but I am running the L20B stock water pump with the fan/clutched and no shroud. When I burned down my last L20b I was using the L16 water pump and the non clutched fan with the shroud. (still smoked the valve seats) I have to think it is the radiator I have had it professionally cleaned and leaks repaired back in 2012. "Winter is coming" and it will probably be a non-issue soon, still I would like to correct the hot running I am having now (at 100+ atmospheric temperature.) It has to be the radiator! That is the only variable in the system that has not changed? So... It runs 1/8" over normal? And gets hot when the coolant stops flowing? I think you should just drive it. Stop idling when you park, and just park it. If you really want to, install an electric fan. Often those can run after the engine is off. But I doubt it's worth the time figuring it all out. Keep the oil fresh, keep the radiator full, get the bubble out of the return hose, and have fun. 1 Quote Link to comment
banzai510(hainz) Posted September 27, 2016 Report Share Posted September 27, 2016 whty don't you just try a 160 stat? 54mm is the size. 1 Quote Link to comment
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