q-tip Posted April 29, 2016 Report Share Posted April 29, 2016 I have an L16 long block you can have if this engine is shit, its tired but it runs. Quote Link to comment
MicroMachinery Posted April 29, 2016 Report Share Posted April 29, 2016 Take the cap off the radiator. If there are bubbles when running, you know it's an HG or crack somewhere. If not, no worries. Could just be coolant passages stuffed up with rust and sediment, blocking flow. 1 Quote Link to comment
flatcat19 Posted April 29, 2016 Author Report Share Posted April 29, 2016 Not bubbling. So I've been thinking bad coolant temp sensor. Lots of corrosion on wire/connector. Connector broke off while dinking with this. Put alligator clip on wire. First drive was great. Normal temp whole drive. Second drive, hot. Non-contact thermometer giving me weird readings. Doesn't help that housing is right above exhaust. Quote Link to comment
flatcat19 Posted April 29, 2016 Author Report Share Posted April 29, 2016 I have an L16 long block you can have if this engine is shit, its tired but it runs. Thanks. I have an L18 to swap in. Just don't have the full gambit of replacement parts while doing a swap. Or a cherry picker. Quote Link to comment
S30Jay Posted April 29, 2016 Report Share Posted April 29, 2016 Have you had to add any coolant through all of this? Sounds like HG is likely to be no good, usually it's leaking or blowing out the exhaust in a white cloud...or mysteriously disappearing with no obvious cause. Not sure about 521s, but I've seen air bubbles in the cooling system cause symptoms like this. Quote Link to comment
flatcat19 Posted April 29, 2016 Author Report Share Posted April 29, 2016 Coolant has stayed full. I have been given zero signs of HG failure. Zero obvious signs I should say. Waiting for wife to return so I can take another drive. Working on recovering my bench seat at the moment. Quote Link to comment
DanielC Posted April 29, 2016 Report Share Posted April 29, 2016 Where did you get the thermostat? They commonly are made cheaply, and work the same way. The L-16 cooling system is really simple. A water pump circulates water between the engine and radiator, and a thermostat controls the water flow. If the pump is decent, and the radiator is not plugged up, pretty much the only other point of failure is the thermostat. Go to Nissan, and get a good one. A stock L-16, in a 521 can pull a two horse trailer up cabbage hill. outside of Pendelton, In the summer and not overheat. That is second gear, 5,000 RPM, about 35 MPH. Quote Link to comment
flatcat19 Posted April 29, 2016 Author Report Share Posted April 29, 2016 Thermostat was Gates brand. 180°. Pretty sure it is opening and closing. Maybe I'll change it again. I know my local Nissan does not stock this thermostat. Quote Link to comment
q-tip Posted April 29, 2016 Report Share Posted April 29, 2016 True test for thermostat is out it in a pot of water with a candy or meat thermometer and check when it opens. 1 Quote Link to comment
flatcat19 Posted April 29, 2016 Author Report Share Posted April 29, 2016 Done already. Just got done with another drive. Gauge says hot...laser thermometer says less than 200 out of the head. I'm gonna keep rocking it. At least to the car show tomorrow. If it blows, it blows. Then I'll know for sure...motor time. 2 Quote Link to comment
flatcat19 Posted April 29, 2016 Author Report Share Posted April 29, 2016 Also shopping for a 3 gauge set. Volts and temp are my main wish. 1 Quote Link to comment
KoHeartsGPA Posted April 29, 2016 Report Share Posted April 29, 2016 So...guys.... Freshly boiled radiator, new thermostat w/hole, new water pump, flushed block, flushed heater core, fresh 50/50 antifreeze...still overheats. Overheats worse than before. I used to be able to lay hands on the radiator for minutes. Now it's burning fucking hot. Normal temp when I took off on my initial drive. Pegged the second I took off. I have a tiny leak on the back of motor, can't see it though. Fuck. If I'm going to replace HG I might as well just swap my motor out. Can't afford a swap right now. Definitely did not bring enough tools home this weekend. Ok now my head is spinning....you said that last night, couple questions.... -What did you mean by "boiled over"? To me it means coolant is gushing out as soon as you over heat... -what about that "tiny leak"? Did you figure out where that's coming from? Cuz now everything seems normal....except my head is spinning from those posts from last night....I'm hella confused now lol Quote Link to comment
Rick-rat Posted April 30, 2016 Report Share Posted April 30, 2016 Also shopping for a 3 gauge set. Volts and temp are my main wish. I have an Equus mechanical water temp gauge you can have, white face, red needle. send me an address if you want it 1 Quote Link to comment
flatcat19 Posted April 30, 2016 Author Report Share Posted April 30, 2016 Ok now my head is spinning....you said that last night, couple questions.... -What did you mean by "boiled over"? To me it means coolant is gushing out as soon as you over heat... -what about that "tiny leak"? Did you figure out where that's coming from? Cuz now everything seems normal....except my head is spinn bying from those posts from last night....I'm hella confused now lol Never seen my radiator boil. Had my radiator boiled out by a pro. Quote Link to comment
flatcat19 Posted April 30, 2016 Author Report Share Posted April 30, 2016 I have an Equus mechanical water temp gauge you can have, white face, red needle. send me an address if you want it Word. I'll PM you when I get home. Thank you, sir. Quote Link to comment
Lockleaf Posted April 30, 2016 Report Share Posted April 30, 2016 These are from a 720 4x4. Both are independent gauges, standard 2 3/8 ish size. They match pretty closely to the factory gauges in the older stuff. I'm have a set in my 71 510. I think they look the best. 720 oil pressure sending unit will go right in the place of you stock sending unit and allow you to retain your oil light in addition to the gauge. EDIT: I misread. You said temp, not oil pressure. Oh well. Quote Link to comment
flatcat19 Posted April 30, 2016 Author Report Share Posted April 30, 2016 I have a friend who works at a local parts house. He found me a new temp sensor in town. He had been hunting all day. So I'll have a new sensor to install tonight while listening to the blazer game!!! 1 Quote Link to comment
HRH Posted April 30, 2016 Report Share Posted April 30, 2016 Keith, did you use the infrared temp gun and scan the entire radiator? If it's clogged you'll find hot and cold spots of 40 degree or more difference. And question, has it boiled water out of the radiator during heating ever? If it hasn't, it's not overheating. In which case the gauge is probably fluffed. If you're only getting 200 degrees at the thermostat housing, that's not very far out of normal operating temp for an infrared gun if I remember correctly. 1 Quote Link to comment
datzenmike Posted April 30, 2016 Report Share Posted April 30, 2016 Can't trust the gauge. What if it's lying and you don't have an over heating problem at all? IR the thermostat housing where the sender is when it's 'reading' very hot and when cool. Is it really hot or just 185F? Hot when revved up and low when idling sounds like the volt regulator in the gauge cluster is fuckt. The temp gauge may be following a charge of the revved up alternator. 1 Quote Link to comment
flatcat19 Posted April 30, 2016 Author Report Share Posted April 30, 2016 Mat...freshly hot-tanked radiator. IR temp gun reads right around 180-200 all the time. I was in the garage today revving it up...I watched the gas gauge go up as the temp gauge go down. I'm driving the thing. Fuck it. Placing a Ratsun business card over the temp gauge during my cruise tomorrow. 2 Quote Link to comment
HRH Posted April 30, 2016 Report Share Posted April 30, 2016 Lol, just unhook that temp gauge and wire in a cheap new one with the copper wire. If water isn't boiling out of the radiator, I'd say you're good. 2 Quote Link to comment
flatcat19 Posted April 30, 2016 Author Report Share Posted April 30, 2016 Made it to the show. 30 miles. Gauge pegged; no mechanical signs of overheating. And I'm not the only Datsun here. I'll get ya some pics later. 2 Quote Link to comment
datzenmike Posted April 30, 2016 Report Share Posted April 30, 2016 I think false alarm. The gauge info is faulty and telling you something that is not to be trusted. Sender is easy enough to change. It's a variable resistance to ground by temperature. Cold.. resistance, hot grounded. I guess you should consider the possibility that the wire between sender and gauge may be rubbing a ground? Is the gas gauge acting odd? Jumping up or down? (wild mood swings?) Could be the gauge volt regulator and on the 521 it's an external plug in You may be able to pry the case apart and clean the contacts but failing that just get another. 2 Quote Link to comment
flatcat19 Posted April 30, 2016 Author Report Share Posted April 30, 2016 There is a member around here that makes a regulator replacement. I'll PM him; install when doing my LED swap. Never got my temp sensor last night. 1 Quote Link to comment
Draker Posted April 30, 2016 Report Share Posted April 30, 2016 For what it's worth, the Canby truck had the same issue. Would show hot, but you could pop the cap and grab the hoses with your hand and everything was just fine. We did 700+ miles and over several mountain passes. If it's not puking coolant out everywhere.. It's something wack with the gauge.. gotta be. 3 Quote Link to comment
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