California Datsun Engine Overheat Season

[datson4life]

its suppose to be 110 degrees today and its been like this for a good week maybe, when i run my 521 on the freeway at these temperatures my engine temp rises to about 205+ degrees, so i have to go like 60 mph to keep it at 200 degrees steady.............oh and im running no thermostat

 

what are the normal temperatures and the high risk temperatures for a datsun engine?

 

running l16 block with a87 peanut head and weber 32/36

[captaingamez]

first put your thermostat back in

 

 

then replace your radiator.

 

think about this, the thermostat when fully open does not make your engine overheat, theres not alot of space for water to flow when it is fully open, so for your engine to be getting hot, there is even less flow in your radiator than in a stock working thermostat, therefore, my theory is that your radiator is too clogged to be efficient anymore, if you have a known good radiator, it could be running rich or lean. check your coolant hoses but thats probably not it.,what does it do when its idling for a long period of time?

 

to be honest, 200 degrees sounds a bit hot to me, thats usuallly the temp that I heat heads up to to extract the valve guides, its probably not hot enough to cause an issue, but it should ideally be lower.

[Zeusimo]

I'm Running At 180 With 165 Thermostat

[Guest roseyroseyrose]

unfortunately i have a tiny pinhole in my radiator, the temp gauge doesnt work and i live in az...i just dont screw the radiator cap on all the way, i carry jugs of water in the bed, and i keep my nose open for that watery overheat-y smell...

i still need to check the thermostat sender wire to see if thats why my gauge doesnt work, so maybe ill do that on my way out the door today in an attempt to correct that problem at least...so far, i havent overheated at all, ive been lucky, especially with the extreme heat weve been having!

[72240z]

usually running hot at speed means cooling system inefficiency. I agree with capt, put the thermostat back, a lower temp one, and get a new rad. Prior to doing all that though flush the whole system. 
You can go even further and install a rad with more rows and use water wetter. 

It could be rich or lean contributing but a proper cooling system should keep that condition under 200 degrees imho. 

[72240z]

unfortunately i have a tiny pinhole in my radiator, the temp gauge doesnt work and i live in az...i just dont screw the radiator cap on all the way, i carry jugs of water in the bed, and i keep my nose open for that watery overheat-y smell...

i still need to check the thermostat sender wire to see if thats why my gauge doesnt work, so maybe ill do that on my way out the door today in an attempt to correct that problem at least...so far, i havent overheated at all, ive been lucky, especially with the extreme heat weve been having!

 They sell leak stop product that work if you dont have the money for a rad. You can use an egg too but it wont last as long. 

 

Def fix that gauge, that 15 dollar problem could end up costing you 100x that. 

[DanielC]

I used to tow a small two horse trailer with a 521.  The engine temperature would climb, going up a 6% grade, about 35 MPH, second gear, about 5000 RPM.  This was in the summer,  climbing Cabbage hill, east of Pendelton, OR.  In 95 degree heat.  I would turn on the heater if the engine temp got higher than I was comfortable with.   less of an inconvenience to sweat a little, and keep going, than be stranded on the side of the road.

 

See the other notes about the radiator.  Another possibility is the rings are worn.  With worn rings, hot gasses go by the piston, and make the engine hot, instead of being used to push the piston down.  Also make sure the ignition timing is not retarded.  Late ignition timing exposes more of the cylinder walls to hot gases, and the energy just goes into the cooling system, instead of pushing the piston down.

[Dawa]

number one, DO NOT USE LEAK STOP. that shit will clog up other parts of your system like within the block and within the cores.

 

2, in hot climates its better to run about 90% water, with 10% coolant or additive for anti corrosive and water pump lubrication.

 

first off, flush your rad. drain all the shit thats in it now, then fill it with water and run that through the system then drain it. complete this process til the water runs clean and clear. then use either prestone or vinegar to flush the build up within there.

 

i run this headlight funnel for cooler air to the carb

besides improving power, my theory is that now the intake mani is running a little bit cooler because its 

sucking in cooler than engine bay air, as well as since i dont have it routed straight to the carb its also

cooling down the entire bay as a whole.

 

i did notice a power gain as well as the temp gauge not creeping up so high at higher highway running

rpms.

[72240z]

That leaks top shit is a myth. As a mechanic I've used it (properly) multiple times then rebuilt some of the same engines years later with no negative side effects what so ever. Most of the bad press comes with stop leaks from before I was born which used coagulants or people who add bottle after bottle for years. Then people with no real experience parroting what their father told them or they read once. Most modern stop leaks using aluminum powder can be ran then drained of the excess leaving just the particles that plugged the holes in the system. Matter of fact a person can just dump a spoon full of extremely fine aluminum oxide in their rad and that will stop most leaks. Then once it does just drain and refill their system.  

Headlight funnels that are not routed to anything actually working is another myth. They only came about for people to mimic track cars with proper routed intake funnels. I feel like everyone who thinks that removing a headline has a real impact on anything doesnt quite understand the dynamics of air flow through an engine bay. Many air tunnel studies including the one over at HBZ have proven the most efficient way to have air coming into the engine bay for cooling is by sealing the entire front end and having just one single small hole ducted through the rad then out somewhere else, usually the hood or cowl. Then a separate one ducted directly to the intake(s). This is for many reasons but the one thats easiest to explain is that with so many openings the flow under the hood normally is extremely erratic, just adding a hole in front of something doesnt mean the air is going there, in fact in this instance its most certainly not. Air will take the path of least resistance so sealing the front end and leaving just a small hole for the rad creates a high pressure point in which the air is forced through the rad and if only one exit exists it will create a stream and flow much better. The case with a properly ducted intake funnel is the similar but with the ducting the air is not lost or heated in a torrent of hot air from the rad and actually finds its way to the intake. 

This is not my opinion or theory's, these are the facts coming from the wind tunnel data over at hbz. I'm sure lots of people would love to argue the butt dyno or that one day doing that thing the car didnt get as hot but thats not real data. There is a reason ALL pro race cars use the methods they do, its proven science.  

[Z-train]

1)That leaks top shit is a myth.

 

 

2) Many air tunnel studies including the one over at HBZ have proven the most efficient way to have air coming into the engine bay for cooling is by sealing the entire front end and having just one single small hole ducted through the rad then out somewhere else, usually the hood or cowl.

1)Yep.

2)This builds up pressure within the nose and there is only one place for the pressure to "relief itself"....thru the radiator.THe tigher the nose is sealed,the more pressure,the more pressure,the more air thru the radiator.

[banzai510(hainz)]

yesterday Mine was getting hot also.

thought about putting that ChiCom(chinese) Champion 3 row in.

 

heat wave will be over here in a day or so.

[spitznoz]

water wetter works for me 

[Dguy210]

I've patched some radiator pinhole leaks (e.g. damaged fin) with black silicone. The trick is to get the area really dry and make sure the silicone is worked into the pinhole. Then let it sit for at least 24 hours. I tried this originally as a temp fix for a damaged fin (near the fan) on an otherwise good radiator, but it worked so well I never bothered doing anything else. Been holding about 10 years now B)

[datson4life]

im running new water pump and the radiator has recently been taken apart and all rows cleared and cleaned, theres a name for that but i forgot.........im gonna install a thermostat and see what happens, my timing is where it should be, maybe advanced a little bit, another issue is that the truck is running super rich, ive been told carb need smaller injectors

 

so 200 degrees is too much??? cause thats where ive been driving it at

[captaingamez]

yesterday Mine was getting hot also.

thought about putting that ChiCom(chinese) Champion 3 row in.

 

heat wave will be over here in a day or so.

if your talking about the chinese aluminium radiators, I have had nothing but good experience with them, my buddy has been running one HARD for 2 years now, as daily driver and track car and that rad holds, hes never had an issue.

[king bee66]

i blew a headgasket on my front wheel ka24de altima last week in texas.  the work replacing it has led me to conclude that 2 overhead cams is 1 too many.  :P

[captaingamez]

im running new water pump and the radiator has recently been taken apart and all rows cleared and cleaned, theres a name for that but i forgot.........im gonna install a thermostat and see what happens, my timing is where it should be, maybe advanced a little bit, another issue is that the truck is running super rich, ive been told carb need smaller injectors

 

so 200 degrees is too much??? cause thats where ive been driving it at

assuming all that is true and correct as you said, I am gonna lean towards the rich issue combined with possibly bad rings.

 

 

Edit: also its called "Rodding the radiator"

[Guest roseyroseyrose]

I've patched some radiator pinhole leaks (e.g. damaged fin) with black silicone. The trick is to get the area really dry and make sure the silicone is worked into the pinhole. Then let it sit for at least 24 hours. I tried this originally as a temp fix for a damaged fin (near the fan) on an otherwise good radiator, but it worked so well I never bothered doing anything else. Been holding about 10 years now B)

my pinhole is right on the top. is there a brand name to this black silicone? comes in a tube? id be interested in trying this...

[Dawa]

Headlight funnels that are not routed to anything actually working is another myth. disagree.

They only came about for people to mimic track cars with proper routed intake funnels. ive heard that, too.

I feel like everyone who thinks that removing a headline has a real impact on anything doesnt quite understand the dynamics of air flow through an engine bay.

Many air tunnel studies including the one over at HBZ have proven the most efficient way to have air coming into the engine bay for cooling is by sealing the entire front end and having just one single small hole ducted through the rad "most efficient, yes, but that doesnt mean other methods are 100% comletely inefficient 

then out somewhere else, usually the hood or cowl.

Then a separate one ducted directly to the intake(s). agree

This is for many reasons but the one thats easiest to explain is that with so many openings the flow under the hood normally is extremely erratic, agree

just adding a hole in front of something doesnt mean the air is going there, in fact in this instance its most certainly not. disagree, and in fact you prove me right below by saying

"Air will take the path of least resistance "such as straight through a 5" radius hole into the low pressure zone of the engine bay, rather than around the hole

so sealing the front end and leaving just a small hole for the rad creates a high pressure point in which the air is forced through the rad and if only one exit exists it will create a stream and flow much better.

The case with a properly ducted intake funnel is the similar but with the ducting the air is not lost or heated in a torrent of hot air from the rad and actually finds its way to the intake.  agree it works best/most 

efficiently, but that doesnt mean that 0% of the air inducted by the headlight funnel makes it to the induction system 

 

This is not my opinion or theory's, these are the facts coming from the wind tunnel data over at hbz. I'm sure lots of people would love to argue the butt dyno or that one day doing that thing the car didnt get as hot but thats not real data. There is a reason ALL pro race cars use the methods they do, its proven science.  

 

if i hadnt seen the actual (bad) result of some guys using the stop leak stuff, i probably wouldve said something similar to 

"ive heard/read stop leak is bad." but if youve ran it and seen ok results then i guess that speaks for itself.

 

as for the funnel:

1, i am aware of the whole placebo affect, but when i take the same hill everyday from work and the months before my 

truck struggles to get up it at 4grand and the next day and following weeks it climbs that mofo like a mofo all the way up

to 5grand, that speaks to me. as well as that same hill that used to make my my temp needle climb, does so no more. 

this was not done in conjuction with any other work, not even maintenance such as spark plugs, etc. 

 

i completely agree that for it to be more effective i need it routed straight to an enclosed

carb, and i am working on making a carb hat, as well as making an undertray for the bay to help increase cooling 

capacity by decreasing the addition of turbulent air. 

 

lol "In closing" i agree my route isnt the most efficient, but i have seen the results, not just felt them. if you want to chalk

that off as butt dyno and placebo effect, thats fine with me, but i had to contribute the rest of my side. 

[captaingamez]

firstly, a lone hole still provides a place for air to channel, unless theres other holes in your fascia (yes i called the front of the car a fascia)

 

think about it, the headlights, the grill, the bumpers, the radiator,  the everything!!, its all more restrictive to air flow than the hole, so since all fluids (yes air is a fluid in this situation) find the path of least resistance, the hole WILL MOST DEFINITELY allow more air to get into the carbs, period, no ifs, ands or buts about it. and I do not say this as a matter of opinion or theory either, I have seen results on the dyno in quite a few very similar situations. there is seriously measurable results in the way of 5-10 horsepower dependent on the car and aerodynamics, this is also the reason you see ALOT of cars dyno with the hood off, a vaccuum is created in the engine bay at full rpm, assuming thats where your intake is.

 

and this quote comes to mind "doing a dyno run with the hood on is like doing a compression test with the throttle plate closed"

 

 

 

secondly as was said already, the stop leak stuff ONLY WORKS CORRECTLY when its used PROPPERLY. you do not just dump the stuff in and head down the road per say, draining and flushing is required, how many people actually do that?, im gonna guess %20 or less.

[Dguy210]

my pinhole is right on the top. is there a brand name to this black silicone? comes in a tube? id be interested in trying this...

Just 100% black RTV. I was pretty broke at the time so I'm sure it was just regular old GE silicone. Top might be more difficult, is it the seam or a hole on the tank?

[captaingamez]

it should however be noted that the hole's presence will concordantly reduce that much air from going through the rad, and also create that much more pressure in the engine bay which could negatively effect cooling,by diverting air from coming through the radiator due to the added pressure.

[datzenmike]

200 F won't hurt anything but the motor may ping slightly because it's tuned for a lower temp. Most motors are designed to run near this temp, newer ones close to boiling. The higher the temp the more efficient (not more powerful) as there is less heat differential between the hot gasses pushing the pistons and the metal parts of the motor. A cold motor absorbs more heat and there is less to push the pistons. This is why a cold motor runs like shit until warmed up.

 

Running without a thermostat allows the motor to run over a wide range of temperatures. (read above) It is designed to run close to 190-200F for peak efficiency, economy (and low emissions) With or without a thermostat the top temp is dependent on the heat the motor makes, the air temp outside, how well the rad sheds the excess heat, air flow through the rad, water flow through the rad.

 

1/ Naturally a turbo motor will make more heat than the same n/a motor. Did you upgrade your cooling system?

2/ If hotter outside it will be more difficult to get rid of the heat.

3/ If your rad is too small it will have more trouble shedding heat.

4/ Air allowed to leak past the sides of the rad or holes in the rad support... is air not helping with the cooling. Some hoods have a rubber gasket that seals against the top of the rad support. An air dam at the lower front will prevent air from getting under the front of the rad... the increased air pressure forces air through the rad. Bugs, leaves and dirt blocking the cooling fins or fins that are bent over blocking air flow are not good. Fan shrouds increase the fan's efficiency.

5/ Tubes blocked by hard water lime buildup will have a harder time ridding the extra heat. A slipping belt will not pump water properly. Soft bottom hoses can collapse from the pump suction.

 

A proper cooling system should work with outside temps at 115F or more.

[Z-train]

It's 106 here today.Indicator is a little more than half-way.This is a factory three core rad with shroud.

[darrel]

Rodding the radiator. I have a crappy vid posted in my 240z thread. The rod they use is flat that fits the radiator tube which clears the whole tube.