Cold weather driving advice?

[metalmonkey47]

Hey guys, looking for any advice for cold weather driving you can give me.

 

My 620's struggling to heat up in 20 degree weather, with a brand new thermostat (Nissan 192 degree). I'm having issues driving under loads because the engine refuses to heat up, no matter how I drive. Up hill under load the trucks making shit power and miss-firing like crazy, even after I let it heat up for 10 minuets. It won't get to the first notch on the gauge.

 

 

I've heard of using cardboard in front of the radiator to restrict some of the air flow. Is this an issue?

[Laecaon]

I have done the cardboard. Rain sucks on that though... Weird that your truck is not warming up. I have a 195 and on a 30 degree night I hit 3/4 on my gauge...

 

Have you checked your thermostat on the stove?

[Str8_69]

Higher temp thermostat? Cover radiator with cardboard?

[Skib]

blocking off half the radiator brings your heat up quicker.

[Farmer Joe]

let it warm up longer...

 

its been a solid 19* all last week, and just for a little bit of the window to defrost takes 10min..

 

my shit doesnt really reach operatin temp till like 10 miles into the drive to work..

 

dont expect so much from a 30+ yer old truck...

 

15-20min is the min..

 

rule of thumb^^ lol

[INDY510]

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Don't turn on the heater until the truck is fully warmed up ...... . or else it won't

[Xander_42]

Don't run the heater until you're up to operating temp. (Damn, beat me to it Indy)

 

You could also cover the rad with some kind of tape or plastic, so that the rain/snow doesn't destroy it. We used to do this on water cooled karts when racing in the cold to keep the coolant temp in the right range. We used duct tape, but we didn't care about getting gummy crap on the rad (you might).

 

If you had an electric fan instead of a mechanical, it would only be on when it was up to temp. (Although I think 620s have fan clutches so the fan isn't moving much air until it's up to temp).

 

Could also be that your carb needs to be re-tuned/jetted for the lower temp (given that's it's pretty hot there in the summer).

 

Definitely do a stove and visual check of the thermostat to make sure it isn't failed open, and that it's not opening too soon.

 

Stupid ideas from here on down:

 

Do what Alaskans do? Block heater/head-bolt heater. Just a thought, and a pain in the ass. Could also store it in a heated garage if that's at all an option.

 

I wonder if there's something that you could do with your oil? Maybe run it a little low (not dangerous, but just like 1Q low) so there's less thermal mass to heat up. Or maybe a lower or higher viscosity coule help it heat up quicker (I have no idea if that would work, maybe somebody else does?).

 

Underdrive the water pump to flow less coolant/ get a shitty water pump.

[metalmonkey47]

Weird that your truck is not warming up. I have a 195 and on a 30 degree night I hit 3/4 on my gauge...

 

Have you checked your thermostat on the stove?

3/4 up the gauge? Now that's got me curious... I'm running 1/2 the gauge and that's about the warmest I've ever seen it get. For the price of a thermostat, it makes more sense to me to just run down to Nissan and get a new one and test before installing..

 

 

 

Higher temp thermostat? Cover radiator with cardboard?

 

I'm running the highest temp available @ 192. Cardboard is step 2.

 

let it warm up longer...

 

dont expect so much from a 30+ yer old truck...

 

Generally, 15 minuets is what it takes to warm it up. I give her some extra time every morning, usually get up and start the truck before I even get ready to go to work.

 

SH'es reliable right now, but I'd like to try and make it easier to drive in the cold. 20 degree starts are hell.

[Jayden71]

180 stat on the 521 in 10 degree weather I see temp gauge movin. I don't drive it till its 180.

40 year ol truck, gotta carress her and treat her a lil nicer

[metalmonkey47]

xander, good advice.

 

 

I actually considered using an electric fan after my pay check comes in and figure that should sold the majority of my issues.

 

 

 

I re-adjusted the carb earlier last month (December) but it may need to be dialed in a little better since it's a little colder now then it was.

 

 

 

 

 

 

 

 

 

 

 

 

I'd LOVE to get a block heater or park in a warm garage, but those options are out of the question..

 

 

My dad gave me shit for the cardboard idea because he's 100% convinced I shouldn't need it, but he grew up on domestics. Coming from a guy who drove Cuda's and 400 fueled C10's, it's hard to listen to him give me advice on cold weather driving in my 2.0L truck.

[Xander_42]

I actually considered using an electric fan after my pay check comes in and figure that should sold the majority of my issues.

 

Look into the stock Taurus fans (they're popular on old RX-7s, so there should be lots of info on RX-7 club) they apparently flow a crap ton of air, are easy to wire up, and you can find them at any wrecking yard for like $15. No idea if they'd fit a 620 rad, but it couldn't hurt to look.

[EricJB]

Never seen it happen on a Datsun, but could the carb be icing up?

[datzenmike]

Replace the thermostat. By the time you take it out test and put a new gasket on you might as well. Blocking the rad runs the risk of overheating it. If your thermostat is working properly you won't need it.

 

If the outside temps are around freezing and it is damp you may have carb icing. Do you have a warm air supply for the carb or did you replace the Hitachi with a Weber? Symptoms of icing are stepping down on the throttle more an more and going slower and slower. Will often idle just fine but severe lack of power.

[albyneau]

While your low temps indicate a possible problem, operating in consistently cold temps can create a problem of it's own. Any engine forced to operate at excessively cold temps will suffer in performance and economy. Some big rigs have a device called a shutterstat, which is basicly a venetian blind in front of the radiator operated by it's own independant thermostat~ a fancy, self-adjusting piece of cardboard! You'll see those that run seldom in harsh temps will have a 2-piece vinyl block snapped over the radiator inlet~ an economical yet asthetically appealing piece of "cardboard". Choking radiator airflow dates to the dawn of internal combustion engines, and once other variables have been eliminated is a sound choice~ but one only made by those not suffering from Alzheimers.

 

If you consistenlty operate in these kinds of temps, you could build a fairly cheap manual shutterstat~ operated by a cab-mounted choke cable, or better still a diesel throttle lock~ a choke cable w/ twistlock function.

 

Peace~ and warmth!

Scott

[DanielC]

The radiator in a Datsun 521 truck will keep the engine from overheating pulling a two horse trailer, with two horses up Cabbage hill, east of Pendleton, Or, in 95 degree heat in the summer.

 

When it is below freezing, trust me, you can block a good part of the the radiator, and not overheat, if the engine is in good shape. Get a pizza box lid, cut off all but one flap. you can probably slip the top of the box between the radiator, and core support, and fold the flap over the core support to hold the cardboard in place.

Watch the temperature gauge the first time you drive it. If it gets too warm, cut part of the cardboard off.

 

DO NOT RUN LESS OIL! You can use a lighter weight oil.

 

Make sure you have the hot air from the exhaust manifold going to the carb.

[Z-train]

Here in Tucson when it's below 50,i have to block half the radiator to get it to 180(which is the t-stat rating.And trust me, all is functioning as intended under the hood.Wether it's cold and blocked or warm and not blocked,the temp comes up to 180 and sits there like it should.

[INDY510]

[metalmonkey47]

Alright, so I put in a new 192 degree t-stat and stove tested it and the new one. Both opened around 190 degrees (not exactly 192, but good enough.)

 

It was still no better so I blocked 50% of the radiator with 2 ply cardboard and it helped, but I'm still not heating up. I drove hard 20 minuets @ 45-55 mph and it was still only about 1/4 on the gauge.

 

 

 

 

It ran pretty good, so i suppose I'll take what I can get.

[HRH]

Check your jetting, you may be running too rich, the extra fuel is cooling the engine to the point where it can't build heat like it should. Easy to check, pull a plug after at operating temperature for a while of sustained driving. Get it up on the freeway and run at 3000 rpm, then shut it off and coast to the side with the clutch in. Remove plug, take reading. If black, too much fuel.

 

The other thing on 620s is the heater valve loves to get clogged with shit. If you're running halfway on the gauge, your motor should be full warm. In which case, you should have heat. Put your hand on the radiator, is it hot? (Don't burn yourself) If it is, then go down in the footwell on the driver's side, and physically push the plunger for the heater valve with your fingers. Usually what will happen is all of a sudden you'll have instant hot heater!

 

The annoying part about this is it will shut itself off after a period of time. Solution is to replace the heater valve or get a stick or something to poke the valve open every time you drive it in cold weather. I had to prep my heater for every trip up here in the frozen north. Not nearly as bad as Canada, eh?! ;)

[banzai510(hainz)]

Is this a 3 core Rad????????

 

Also I notice If one doesnt use a water heaterline type intake if too cold the carb can freeze.

the Later 620 use a nasty stove pipe exhaust manifold that when hot the flap open and heats the manifold (they are mated together)

 

I ran a 3 core in my 521 and it was way to cold

[Boaty]

I think you have more going on than what meets the eye.

 

I was able to drive my L20B in near-zero degree weather in Central Oregon, and the only hard part was getting it started without chokes. (SU's without cables hooked up).

 

Besides the gauge not peaking, what else are you using to determine temperature? Let it warm up for awhile, check that water with a temperature probe. I never trust a gauge that's that old to be 100% accurate, and besides what temp is the "E" in "TEMP"? I'd guess about "E".

 

As Hainz said, if you're not running the water line to the intake manifold, it may be icing up your carb - not very common to see, but it's possible. Once she starts acting up, take a visual on your carb and see if it's making ice.

 

If the thermostat is opening up, it IS reaching temperature. If it keeps opening and your temperature keeps spiking, that radiator is doing too good of a job. I think everybody in cold weather has at least once in their life used cardboard in front of the radiator. Nothing wrong with that if you need it. Does it warm up in your driveway, and go too cold once you get on the road a ways?

 

I'd start tracking it down one step at a time.

Carb clean?

Good fuel?

Confirmed thermostat temperature?

Timing not ghastly retarded?

Plugs aren't fouling (causing shit performance) and are gapped correctly?

What are you using for coolant, 50/50? 60/40? 70/30?

Good cap & rotor?

Good plug wires?

 

I've never had a problem with my engine heating up, as I said, even in near Zero degree weather. (Which HATED 20W50, btw)