running cold ???

[Stupid_fast]

Hi Ratsun !

 

I've got an L20b with R1 side drafts, cam, fiero radiator and a clutch fan setup.  Temp gauge is an autometer electric short sweep. 

Thermostat is a 180*, I've swapped it out and verified working tested by stove/pyrometer. (and i have like 3 of them... all tested to same result)

 

In traffic sitting on a hot day(80-90*) it will reach 180* after sitting a few minutes and sit there never overheats and usually idles under 170*.

 

While cruising on the freeway the temps will run really cold, most of the time on warm days it will sit around 150-160*, when it gets cold and at night the temp will drop down under 110, and the motor will start to run lean and pop out the carburetors unless I run with the choke on.  

I've put a piece of cardboard in front of the radiator and its enough to keep the engine from going lean and popping.  But It still runs cold around 130s-140* at 60-65mph.  Ambient temperatures are nearing under 30 degrees ( 0c) lately.

 

 

Now, while back road spirited driving the temps are still quite cold so my tuned mixture is okay, but drifting the motor gets quite hot due to the limited airflow, I've installed an electric pusher fan to compliment the cooling system for drifting and it works fine, temps stay aorund 170* usually.   Now that the engine gets hot to 'normal' operating temps, it starts to run really rich and bog in the low end due to being tuned cold.

 

 

So basically how do I get my motor to run warmer while rolling so I can lean it out and have it run properly at full temps???  I'd install a 190* thermostat, but coolant usually starts to spit/boil out when it gets over 180.  Maybe the carbs are getting too cold, would it help to run coolant through them? 

[banzai510(hainz)]

I have no proplems running in the cold with my mikunis. as the airspeed is slower than going thru a weber DGV.

If you have a 3 core try a 2 core.

Or just cut a cardboard out

 

510 wagon drifting??????

[Stupid_fast]

Cardboard works OK.  But sucks in the rain, gets all wet hard to re-use cause I pull it off for parking lot shenanigans.  :sweat:

 

The heater is COLD too. I guess just block off more of the radiator ???

 

 

 

1400718_798301113518378_2137036540_o

[Sealik]

The heater is COLD too. I guess just block off more of the radiator ???

 

 

If the engine is getting colder at highway speeds the thermostat should start closing to increase engine temp

Sounds like it's sticking open???

 

You should have some heat from heater.....circulation issue?

Temporarily bypass heater?

[Eagle_Adam]

 

If you have a 3 core try a 2 core.

 

 

 

This ^^^ 

[datzenmike]

 

If the engine is getting colder at highway speeds the thermostat should start closing to increase engine temp

Sounds like it's sticking open???

 

You should have some heat from heater.....circulation issue?

Temporarily bypass heater?

 

.

I agree, the function of the thermostat is to keep the engine at operating temp. This means opening to cool and closing to keep it warm. It should be able to maintain it within a tight range of +- 10 F

 

Do you have a by pass hose from the thermostat housing down to the lower return hose from the rad?

 

Cheap thermostat. Try a good $12 thermostat.

[Stupid_fast]

 

This ^^^

 The fiero aluminum is the only rad I have ..

 

 

If the engine is getting colder at highway speeds the thermostat should start closing to increase engine temp

Sounds like it's sticking open???

 

You should have some heat from heater.....circulation issue?

Temporarily bypass heater?

.

I agree, the function of the thermostat is to keep the engine at operating temp. This means opening to cool and closing to keep it warm. It should be able to maintain it within a tight range of +- 10 F

 

Do you have a by pass hose from the thermostat housing down to the lower return hose from the rad?

 

Cheap thermostat. Try a good $12 thermostat.

 

I'll go get more thermostats from another brand and test. Wouldn't be surprised if autozone stuff was my issue. When I pull them out cold they're closed...

 

I do not have a bipass hose. Its setup like L16 cooling. Has 1/16th 'jiggle' valve bypass thingy.

 

 

Heater is noticeably warmer when the water temp rises, and noticeably cooler when it drops on the freeway. I have a functional heater valve and I can turn it off with a small effect to the running temp. I need heater to defrost the windows and keep my fingers from freezing on the steering wheel!

[Eagle_Adam]

start with a nissan thermostat 

 

[banzai510(hainz)]

make sure the heater cock valve is fully open underneath. look by the gas pedal and up behind the core make sure valve is open.  Should get some heat.

 

looks likes you got the awnser before I posted

 

I bet the stat is good.

[Stupid_fast]

@hainz,

 

The petcock is a NOS new one it works perfectly. The cable is broken I have to open/close it manually.

 

The heater works fine when the temperature gauge reads 160+ its quite hot like it should be. Heater is only cool when water temp 120 and below especially at speed when it has a nice amount of airflow through it.

 

 

@Eagle_adam, thank you for that part number.

[datzenmike]

I bet the stat is good.

.

Yes I bet it opens just fine but does not close properly to hold the temps.

 

Get an expensive one....

[Stupid_fast]

how do you tell what direction to install a thermostat ??

 

I flipped it on the way that the diagram (hayens manual) shows and now it overheats. 

 

new thermostat, I stove tested it and it seems to be opening/closing properly.  I need to order the nissan one no way to get it locally AFAIK.

[Sealik]

Jigger valve straight up

[I'm BLUE]

how do you tell what direction to install a thermostat ??

 

Spring side goes down.

[Stupid_fast]

Jigger valve straight up

Spring side goes down.

 

 

straight up ?? it looks like its plugging itself with the spring down.

 

 

so every parts store sells the wrong damn thermostat ??? gonna go drill a 1/16 hole as per something i read from hainz a while ago... 

[datzenmike]

The coil goes to the engine side or on an L series downwards.

[Stupid_fast]

Okay I fixed it.

 

 

Jiggle valve is upside down from oreilly/autozone/shitty parts store/ect.

 

So I had the thermostat upside down to have proper jiggle valve orientation, so the spring is facing upwards and water pressure holds the thermostat open causing a cold running motor.

 

 

I raped the jiggle valve a little with the vice grips and got it out, popped it in the other side and mamed it a bit with my new hammer to stay in place.  Jiggle valve is now the proper way up to let air and a small amount of coolant bleed through.

 

 

Went out for a rip.

 

 

Water temp I never saw under 165* , I measured various points on the block and head a few times throughout the run with a pyrometer and it stayed consistent. 

 

I can't believe I've been running cold this whole time.  It pulls strong to 7k now uphill in 2nd, 3rd gear.   Feels great, more smooth and eager to make power. 

I feel dumb that its been running this way for so long.  Probably put a huge amount of wear on it running cold. 

 

aaaand now I have uncovered another issue.. the rpms seem to linger a bit on the top end.  Seems the carbs are in need of a re-tune at the correct engine temp.

 

 

 

Thank you Ratsun gurus for the advice and comments ...  As always pointing me in the right direction. 

[ggzilla]

Jiggle pin can face up or down either way. Spring must face toward engine side.

 

Glad you got it fixed!

[Stupid_fast]

@ggzilla, my setup is like stock L16, there is no bypass.  The jiggle pin is what allows vapor/air to bleed out and coolant to flow over the thermostat and open at temp. 

 

Without a bypass if you do not have some sort of bleed the thermostat will never open due to a pressure pocket that forms and blocks coolant from reaching the thermostat. 

 

By the time the thermostat is hot enough to start opening (165-175 degrees) the water temp is already above 210 ... Thus jiggle valve, or simply remove the jiggle valve and run the hole open.  as long as the air has somewhere to bleed out.

[ggzilla]

Yep.

[wayno]

The hole/jiggle valve is to let the cooler water out of the lower housing and let hotter water out of the head to hit the spring and let it open/work properly, that you got it to work with the spring up is amazing to me, watch you temp while driving down the freeway, if it goes up and down a lot, it is only a matter of time before it stays up and you over heat.

Here is a link to a video that clearly shows the spring goes towards the engine, and away from the hose.

https://www.google.com/url?sa=t&rct=j&q=&esrc=s&source=web&cd=2&cad=rja&ved=0CDIQtwIwAQ&url=http%3A%2F%2Fwww.youtube.com%2Fwatch%3Fv%3DRIC6Z4D6Q3E&ei=8MKmUt73A4jyoASS5oKADw&usg=AFQjCNHwvVUySwNJSFPdOuZ47CgtxQy30Q&sig2=0HYrNj3_1lucZBDajOuPcQ

 

If you have trashed the L20b lower thermostat housing, you definitely need a hole in the thermostat, look at the size of the hole that the L20b bypass hose housing had, it's a big hole, there is a lot of fluid bypassing all the time, not just a tiny little hole like the L16 thermostat has.

[ggzilla]

The L16s had jiggle-valves except the very early ones. The 1969 L16 service bulletin says: "fitted with a jiggle valve to improve defrosting performance". A later Datsun service bulletin says it will "shorten the warm up period" but unfortunately didn't go into further detail.

 

When installed vertically, Datsun recommended the jiggle valve be installed at the 12:00 position (straight up). But on the L16 it is installed horizontally so there is no "straight up" possible. Some say the thermostat should be rotated so the jiggle valve is at the highest point of the housing (following whatever slight angle the L16 thermostat housing is at).

 

Early Datsun thermostats had an air bleed built-in, which type was replaced by the jiggle-valve type. Stant thermostats have either a bleed, check valve or a jiggle-valve. Stant doesn't make a thermostat that blocks air. Although the bleed is not near as large as the bypass hose... and the L-series seems to have a problem in general with thermostat housing flow and with the temp sender location. In 1978 they changed to the 3-bolt housing and dealers used to put it on L20Bs that were marginally overheating and it fixed the problem. Nissan revised the thermostat housing once more after that when they increased the outlet to a larger diameter, and used larger hoses. This was to (yet again) prevent overheating issues. It seems to have worked.

[datzenmike]

If you have trashed the L20b lower thermostat housing, you definitely need a hole in the thermostat, look at the size of the hole that the L20b bypass hose housing had, it's a big hole, there is a lot of fluid bypassing all the time, not just a tiny little hole like the L16 thermostat has.

.

Wayno the juggle valve should remain small here's why. The by pass hose does not enter the rad but returns to the pump inlet and just recycles the warmed water. Water flowing through the jiggle valve displaces cold rad water. If the jiggle valve hole were that big it would be almost the same as the thermostat being open, and would continually cool the motor during the critical warm up period. The motor would take way longer to warm up.

[Eagle_Adam]

glad you got  it fixed!