Running Hot Since L20B Installed

[rcjone]

Well, I put in a new thermostat, no change

This morning I got timing reset, 3℉ retarded. Haven't tested yet, 20℉ cooler than Tuesday.

 

Dogs can understand human verbal instructions, hand signals, whistles, horns, clickers, beepers, scent ID's, electromagnetic energy fields, and  Frisbee flight paths.

What do humans understand?

[rcjone]

had the timing reset friday, was 3 points retarded. cant test yet as the weather went from 106 to 76 in 3 days, will need to drive it when its 90 +

[rcjone]

timing was 3 points retarded, will need 90+ temp to see if that fixed the issue.

[rcjone]

Latest updater:

New radiator cap.

Reset timing, was 3 points retarded.

 

The weather got warm again so I ran errands and all is the same temp wise.

 

It will be 100 tomorrow so I'll do some stop/go as a further test, can't think

of anything else to try.

 

A guy phones the local hospital and yells, 'You've gotta send help! My wife's in labour!' The nurse says, 'Calm down. Is this her first child?' He replies, 'No! This is her husband you idiot!'."

[rcjone]

Here is the latest; temp went back to over 90 so i went on few errands, lotza idling and @ 1 time got 205 @ idle.

New rad cap and the timing was set to 12 btdc, was 3 points retarded,

At these temps the carbs kinda stutter, on takeoff and driving a steady state,

 

 

 

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[datzenmike]

This morning I got timing reset, 3℉ retarded.

 

 

had the timing reset friday, was 3 points retarded.

 

 

timing was 3 points retarded, will need 90+ temp to see if that fixed the issue.

 

 

Reset timing, was 3 points retarded.

 

 

and the timing was set to 12 btdc, was 3 points retarded,

 

wtf, How many times did you set your timing? and it was retarded 3 degrees each time? so you advanced it to the correct amount? or you had to retard it 3 degrees?

[rcjone]

Was reset 1 time, 1 week ago, I get excited...Sorry if I baffled you.

However the results still stand.

 

 

 

ARTIFICIAL INTELLIGENCE IS NO MATCH FOR NATURAL STUPIDITY.

[Buzzbomb]

As Datzenmike sort of suggests, why don't you ADVANCE your timing more to see if that helps? If your baseline is 12, which I would imagine is right for a stock motor, which yours doesn't seem to be, advance it to 13 or 14. See if that makes a difference. If it makes it a little better with no pinging, advance it to 15 or 16. Keep going until you get a little detonation/kickback when starting, and back off from there to where it runs best. I've never heard of cars running cooler with retarded timing. I'm no expert at tuning Datsuns, but I would imagine that they are like any other car with a standard type ignition. Advancing the timing (ie. adding MORE degrees BTDC) in a reasonable fashion allows it to run cooler, while retarding the timing is best for emissions tests because it runs hotter.

[rcjone]

i will keep that in mind if i cab find a American made timing light,

'i went to Sears and looked @ the Craftsman labeled ones, made in China,

So i don't gave 1 yet.

 

 

 

 

 

 

Buy American, the job you save may be yours.

[Buzzbomb]

How did you get a baseline without a timing light? Instead of getting a Chinese made Craftsman light, just cut out the middle man and go to Harbor Freight and get their timing light. They have a nice dial back light for 29.99(?). I'd like to buy American also, but the problem is there are no more American made timing lights. If you get a used one, you don't know if it has ever been dropped.

 

BTW- I have a stock L20b in my 720. On a hot Summer day, my temp gauge can creep up to a few needle widths less than 3/4 on the gauge. It's well below the line before H, but higher than on a 60 degree day. From what I've read in the owner's manual, which is original to my truck, it's normal for it to run hotter on a hot day at high speed or going up a long steep hill. Just to be on the safe side, I checked it with a multimeter with a temp feature, and at that point it is at 205. That's not too hot, IMHO. I run a 195 degree thermostat..

[rcjone]

Took my car to a shop I've been going to for 12 years. They were nice enough to set for free. Can't get that just anywhere!

 

 

 

"A low voter turnout is an indication of fewer people going to the polls. "

- George W. Bush

[rcjone]

I know that this is a long time ago an far far away..(Star Wars fans unite) but this is my update:

Rebuilt rad and same issue. Just glad I always use Amsoil...

The best milage I have gotten has been 20.5 which is Way better than the 16 when 1st built.

The engine will keep pulling as long as I have the stones to keep the pedal down... ! Real strong, good builder.

[ggzilla]

Good to hear it is running good.

Even though it still has the same temperature reading.

 

 

New mechanical temp gauge

The most likely thing is that the temp gauge is incorrect.

[datzenmike]

New mechanical temp gauge.

 

Missed this. Throw it away and get the stock one working.

[rcjone]

Missed this. Throw it away and get the stock one working.

2 weeks ago I had my carbs balanced, timing set(again) by a master datsun guy (41 years on Dimes). he had a infrared temp tester. the temps matched....

[ggzilla]

So what did master datsun guy diagnose the temperature problem to be caused by? Because if you have a 160 degree thermostat, the radiator coolant should not go more than 10-20 degrees above that.

 

Hopefully you have the stock Datsun fan, and not some electric aftermarket fans. Those give a lot of troubles.

[rcjone]

So what did master datsun guy diagnose the temperature problem to be caused by? Because if you have a 160 degree thermostat, the radiator coolant should not go more than 10-20 degrees above that.

 

Hopefully you have the stock Datsun fan, and not some electric aftermarket fans. Those give a lot of troubles.

 

I have a 7 blade (yes indeed) stock fan, no clutch. The thermostat is 180℉ . He did not diagnose the temp issue, he had other things he needed to and just dropped them to help

little ole me.

[datzenmike]

Lets assume the motor and internal cooling system parts are fine for a moment. Whats left is getting rid of the excess heat in the coolant and returning it to the motor. This would break down to two things: Insufficient coolant flow or insufficient air flow or heat transfer.

 

Lack of or low coolant flow could be the lower rad hose collapsing from pump suction at highway speeds.

Rad simply too small.

Damaged pump from cavitation at high RPMs. Covered in scale. Some rebuilt pumps use cheap stamped impellers.

The Z series motors use a much larger internal cavity and impeller to move more water. They have a clutch fan and a larger plastic fan than the stock L20B fan. I know you have the L16 fan only. This larger pump might be an option.

Glazed fan belt slipping or loose or oily.

 

Lack of air flow/heat transfer could be dirt/leaves/bugs or plastic bag blocking the front of rad. Even the grill, intercooler or oil cooler or fog lights can hinder air flow.

Missing shroud. My 710 has a metal shroud below the rad and covering the sway bar area to create a low pressure area behind the rad.

Damaged fan blades. Not enough blades... the L16 had 4? L20Bs were 7?

Rad coolant tubes scaly with deposits. Or any scale/rust from the block that transferred to the rad. Mix 50/50 water and white vinegar and fill and rum up to temp. Empty and rinse the next day.

Missing/rotted rad fins between tubes. These will flake off and block air flow.

 

 

Overheating at idle low speeds only is likely lack of air flow through the rad.

 

Overheating at speed only is likely lack of coolant flow. Scaly rad, collapsed hose

[zerow]

Riddle me this: What is the condition of your heater core?

 

If "Unknown" is your answer, do this for me:

Get a 180 degree U shaped elbow, 5/8" diameter and tie off the ends going through the firewall with it, completing the circuit.

 

IF your heater core is plugged, the coolant/water mixture is getting caught up at the "bind", causing your system to overheat. The system is doing its best with a clog, but cannot move past it, and giving you fits and an overheating problem.

IF the heater core is not plugged, then you have an air lock in there, and it needs to be addressed. Run the heater full blast (I know, I see you are from California, so bear with me) and see if the temperature drops slowly. The system will slowly push the air out depending on how level the truck is, how level the heater core is, etc. etc.

Which thermostat housing are you running? Is it from an L20B or from a 280ZX? Which sender are you using? Might the sensor be older and possibly corroded (or shorted) causing an improper reading?

 

Hopefully one of these will address the problem. And quickly.

[rcjone]

Lets assume the motor and internal cooling system parts are fine for a moment. Whats left is getting rid of the excess heat in the coolant and returning it to the motor. This would break down to two things: Insufficient coolant flow or insufficient air flow or heat transfer.

 

Lack of or low coolant flow could be the lower rad hose collapsing from pump suction at highway speeds.

Rad simply too small.

Damaged pump from cavitation at high RPMs. Covered in scale. Some rebuilt pumps use cheap stamped impellers.

The Z series motors use a much larger internal cavity and impeller to move more water. They have a clutch fan and a larger plastic fan than the stock L20B fan. I know you have the L16 fan only. This larger pump might be an option.

Glazed fan belt slipping or loose or oily.

 

Lack of air flow/heat transfer could be dirt/leaves/bugs or plastic bag blocking the front of rad. Even the grill, intercooler or oil cooler or fog lights can hinder air flow.

Missing shroud. My 710 has a metal shroud below the rad and covering the sway bar area to create a low pressure area behind the rad.

Damaged fan blades. Not enough blades... the L16 had 4? L20Bs were 7?

Rad coolant tubes scaly with deposits. Or any scale/rust from the block that transferred to the rad. Mix 50/50 water and white vinegar and fill and rum up to temp. Empty and rinse the next day.

Missing/rotted rad fins between tubes. These will flake off and block air flow.

 

 

Overheating at idle low speeds only is likely lack of air flow through the rad.

 

Overheating at speed only is likely lack of coolant flow. Scaly rad, collapsed hose

[rcjone]

Rad is 3 row, rebuilt about 4 months go.

No leaves et.

The bottom shroud is in place as is the 1 behind the 7 blade fan. Blades look ok.

Hoses are not collapsed @ idle, I checked that 2 days ago. @ speed, who knows.

The hoses are fairly new.

i do have an oil cooler in front of the rad but that was installed to help with the overheating. Waste of $.

The heater core has been blocked off for a decade. This is California after all :).

L20B thermostat housing with a mechanical sender as about 10 people said it's the gauge, It wasn't.

New water pump, belt...Hummm.....

[banzai510(hainz)]

new motors might run hot.

I would make sure it dont boil over but wait for a 65deg day and run it again and see where the temp gauge goes.A 3 row should cool it for sure.If not then soemthing is blowing in the system.

 

to ck for hose collapse rev motor and look

[albyneau]

Without reading EVERY post (on my way to work) D-Mike's right~ 160 t-stat is way too cold! Your engine won't run @ 160, it's just the t-stat will OPEN at that. If the coolant doesn't stay in the motor long enough it will absorb & transfer less heat to the radiator~ the end result being the stat's almost nonstop cycling, or possibly just staying open nearly all the time. The cabin heater removes some heat as well- even when not in use- also effecting overall running temps.

 

The simplist starting point is the t-stat~ change it out for a 180-190, and see what happens. You don't need that 160 anyway....

 

After that you could have some "tolerance stacking" of symptoms as well~

 

Scott

[datzenmike]

Try someone else's rad.

[wayno]

Check your radiator hoses close, they need to be round from one end to the other. This heater core thing is not the issue, they were put together with a valve to close that circut, the factory thought about this issue. I have had a L20b in my truck for years without issues, I now have a LZ23 in the truck with the stock L16 radiator without any issues, heater fan on or off, hauling heavy loads, while dragging around a trailer that weighs close to a ton itself, BTW, I do have trailer brakes. When the radiator cap is off while the engine is running, do you see the water moving in the radiator?