cooling issues

[christopher0227]

so i got this 73 620 about 4 months ago had to fix last guys mistakes but now its running good and all but its overheating i checked thermostat its good i bought a new radiator cap its good also got a different water pump now the only thing i can think of is the radiator itself also it has after market temp guage its the sunpro guage it has 100,160,190,210,230,250 degrees does anyone have the same one or something similar where should the temp sit also it has the l20b engine i would post a pic but im new to the site and dont know how

[Javin]

http://community.ratsun.net/topic/691-how-to-post-pictures-and-keep-online-photo-albums/

There is your link for how to post pictures. As for the over heating thing I am not sure. My overheating had to do with me sitting idle and my fan having issues along with the lack of fan shroud. Does your over heat while moving or when sitting still?

[MicroMachinery]

Have you flushed the cooling system yet? Also, what kind of advance are you running at? Are you running lean? A dirty cooling system, too much advance, and a lean running engine will all make you run hotter than normal. What is wrong with the factory temp gauge?

Also, 73 620's came with an L16 stock. I don't think it matters, but if you have a radiator designed for an L16, an L20b IS 25% more displacement, which means it's going to be required to dissipate more heat.

[christopher0227]

http://community.rat...e-photo-albums/

There is your link for how to post pictures. As for the over heating thing I am not sure. My overheating had to do with me sitting idle and my fan having issues along with the lack of fan shroud. Does your over heat while moving or when sitting still?

 

it overheats while sitting still after about 10 to 15 mins

[MicroMachinery]

it overheats while sitting still after about 10 to 15 mins

 

Does it have a fan shroud? That can affect the idling temp.

[Javin]

Same thing mine did. (slow moving traffic killed me...). If you start moving again does the temp go down?

[christopher0227]

Have you flushed the cooling system yet? Also, what kind of advance are you running at? Are you running lean? A dirty cooling system, too much advance, and a lean running engine will all make you run hotter than normal. What is wrong with the factory temp gauge?

Also, 73 620's came with an L16 stock. I don't think it matters, but if you have a radiator designed for an L16, an L20b IS 25% more displacement, which means it's going to be required to dissipate more heat.

 

not i havent flushed the cooling yet and dont know if im running lean i dont know why he put the aftermarket guage in how would i go about flushing the system

[christopher0227]

Does it have a fan shroud? That can affect the idling temp.

 

no it doesnt have a shroud and it also has an electric fan

[christopher0227]

Same thing mine did. (slow moving traffic killed me...). If you start moving again does the temp go down?

 

i havent had a chance to drive it yet because i had to fix all his mistakes and i also have a 240sx so i didnt want to drive the truck if it was overheating

[Javin]

i havent had a chance to drive it yet because i had to fix all his mistakes and i also have a 240sx so i didnt want to drive the truck if it was overheating

 

Gotcha. I was just trying to figure out if it was an airflow problem. Beyond that I am useless.

[christopher0227]

Gotcha. I was just trying to figure out if it was an airflow problem. Beyond that I am useless.

 

thanks for the help sir gave me more ideas

[MicroMachinery]

Flushing the system is easy. If you want to do it right, there's a kit that you can buy that T's into the line that goes to your heater core. You can buy the kit at a Napa, and it should have instructions with it. Basically you drain the system(while cold, of course), and fill it with a cooling system cleaner(comes with kit). Run it for like, 15min at idle, then drain it out. Let it cool back down, then fill it with water and run the engine with the hose attached to your "T" in the coolant line. With the radiator cap off, and the radiator drain fully open, run the engine with the hose turned on. It's important to keep the engine running so that you circulate the water, and it's important to keep the water on, so that you don't run out of cooling medium. I usually let it run for about 15min; at that point the water coming out should be clear. Shut the water off and THEN shut the engine off and let all the water drain out. Replace the drain plugs, and cap off the "T". With ALL water drained out, let the engine cool, then add 50/50 distilled water and coolant. Run and bleed out all air. It's easier than it sounds, but it does give you a water park in your driveway, so be warned.

[christopher0227]

thank you also if the heater core is bad would this affect it

[MicroMachinery]

thank you also if the heater core is bad would this affect it

 

Bad.. leaking? If it's leaking, just take it out of the equation by looping the lines that go to it together. Where they join, you can put the "T" in, without having to cut hoses. If it's just flat out plugged, then this can help unplug it.

[Javin]

thank you also if the heater core is bad would this affect it

 

lol I wouldnt know that, I bypassed my heater core cause it was leaking. I would assume If the heater core is blocking fluid flow then it wouldnt complete the path.

[christopher0227]

Bad.. leaking? If it's leaking, just take it out of the equation by looping the lines that go to it together. Where they join, you can put the "T" in, without having to cut hoses. If it's just flat out plugged, then this can help unplug it.

 

where is the heater core on the 620 im not fimilliar with the older cars

[hang_510]

where should the temp sit

actual temp should be near what the thermostat is rated, usually 180*

 

 

look in the rad and see if there is any calcifaction along/across the cooling tubes.

you may need to have cleaned, AFTER flushing the entire system first, this includes the heater core, if it doesnt leak.

[Javin]

under your dash. this is mine opened out of my truck.

In the truck left side of this pic it is the black thing. The red is my hose leading to(from?) the engine

[christopher0227]

under your dash. this is mine opened out of my truck.

In the truck left side of this pic it is the black thing. The red is my hose leading to(from?) the engine

 

thats what i thought that was ill check on my next day off keep you guys posted thanks for the help

[christopher0227]

where could i buy a new one from napa or autozone ?and how much would it cost if anyone knows

[Javin]

A new??? Heater core? Not sure.

[banzai510(hainz)]

also got a different water pump

 

I told ya another pump wasnt going to work.

as for the heater core. it helps cool the motor if the valve is open but if you close the valve the truck really should not overheat in normal washington temps(maybe on 93 deg days even mine get near HOT!!!!)

 

you need to make sure your rad is clean and see if its flow tested. I personally dont fuck around and would get a new rad if your looks like a rusty pc of shit.Or have it roded out.

also ck the lower hose and make sure its not soft and collapseing. if so replace it.

 

if now your sure you have no leaks(heatervalve closed) see if your still using water. Its dissappearing. maybe a slight water vapor at the exhaust?????? then I say head gasket.

 

if your looking for a cheap fix closes advice I can give is a 160deg stat with maybe a 1/8 hole drilled on the top

 

if this overheats up from a dead cold motor in 15mins it has to be the rad or a headgasket

[MicroMachinery]

Junkyard radiator is probably cheaper than one of those 160/deg thermostats. Aren't those thermostats $60-$80? Ridiculous.

[banzai510(hainz)]

160 54mm is the generic size as datsun dont list a 160 on most parts books that I see.STANT makes them less than 10$

[hang_510]

i just remove the little floating brass plug to ensure some floow

 

STANT makes them less than 10$

$4.99 at the 3 local parts houses...