74 B210 A13 Overheating in hot weather, new head, 2 core rad.

[74 B210]

I all Datsun lovers.  I am having a problem with overheating on my b210, some background 74 B210 coupe, stock engine A13, new elec. dizzy, upgrade

new upgraded rad, from a local shop 1 core to a 2 core stock rad.  flows great like new. new thermostat, stant, 170. new water pump GMB.  60 series 5 spd trans upgrade, stock rear end. 

My problem is the car runs great overall, but heats up in hot weather, recent trip to SLO from San Jose CA and hit paso robles and got on the first H mark then turned heater on and dropped a 

1/2 inch. drove home to 150 miles, at night 60 to 72 F and temp stayed right in the middle all the way driving 70 to 75 mph.  I have a mechanical after market temp gauge and when idle it 

reachs 160 170 and stays right there, but the needle flutters...  but when engine off, the needle moves fluidly up to 190 and then cools off.  around down stays in the middle,  but any load or hills, freeway the temp begins to climb...  I am at a loss, the head is freshly rebuilt, values are lashed to the FSM 74!  maybe air in the system...? spark plugs set to factory, stock carb.  runs and idles like new, no misses, when it got hot, the gauge hit 215, system flushed, several times to clean out. new antifreeze, 60 water 40 concentrate.  when I got the car cooling system had no thermo stat in it...  rad was junk rust, got my 77 b210 one and had it rebuilt new cores and upgrade size..

 

[datzenmike]

Have my doubts about after market temperature gauges, their quality and how accurate they are. This is the trouble with gauges that give numbers verses the stock gauge that has a simple 'run range'. Raw numbers can cause owners to think something is wrong where being within a run range signifies it's normal. Was it running normally with the stock gauge?

 

After shut down there is a thing called heat soak. This is the normal increase of engine coolant temperatures when the water pump stops circulating. 190 is within reason. So what are the high readings out on the highway?  Seems normal to me to run slightly warmer in hot weather. I would also expect a 180F thermostat not 170. This would run about 185 normally.

 

Buy (less than $20) an IR gun (infra red) or borrow one and shoot the thermostat housing after a shut down and compare it to the 190 gauge reading.

 

Does it get hot enough to expel coolant out the overflow?

[bottomwatcher]

All that new stuff you didn't mention timing. Are you timed right?

[74 B210]

Hi all. I have not been able to work on the car for a while,  to answer questions, the timing is set to 5 degrees, and the car ran 

in the middle normally in town but the normal temp is outside is around 70s's. when it heated up the outside air was 95F and the car got up to 

the first mark of the H, my gauge said 220 215. almost to the H, running 65 70 MPH,  it never over boiled over, 

when I shut it off the gauge goes up to 190, then slowing over time comes down...  I will do a combustion gas test, for a blown head gasket tues, or wed.

but its a new gasket properly torqued down. 

[john510]

15 hours ago, 74 B210 said:

Hi all. I have not been able to work on the car for a while,  to answer questions, the timing is set to 5 degrees, and the car ran 

in the middle normally in town but the normal temp is outside is around 70s's. when it heated up the outside air was 95F and the car got up to 

the first mark of the H, my gauge said 220 215. almost to the H, running 65 70 MPH,  it never over boiled over, 

when I shut it off the gauge goes up to 190, then slowing over time comes down...  I will do a combustion gas test, for a blown head gasket tues, or wed.

but its a new gasket properly torqued down. 

Don't know if this will help but my 510 has a new cooling system and is well maintained.When the weather is warm and i'm on the freeway it actually runs hotter than around town driving.If i lower my speed and RPM's a bit it runs cooler.

[KELMO]

I have 2 1200's (of the "A" motor family). Both of them have almost the identical set up of each other. Mechanically the only differences are that one has a weber carb and a 4 SPD (green 1200) where the other has an original carb and a 5 SPD (grey 1200). Both have the larger 210 radiator.

 

On the grey car, I am 90% sure I put in the lowest temp thermostat (160/170 not entirely sure which) and this car never runs over the halfway point; Winter, Summer, no matter what the outside temp is. I did this because it was running way hotter than I was comfortable with and once it would hit the 3/4 mark, better watch out because it started moving to the "H" in a hurry.

 

On the green car, I am not sure which thermostat was installed but it tends to run at the 3/4 mark (at least in the Summer months. Datzenmike will tell you that this is normal for most Datsuns, but it just makes me uncomfortable considering past experience with the 1200.

 

Did the new Stant thermostat have the "toggle" valve in it like the OEM would?

 

The thermostats I am using are OEM (Nissan).

 

[Stinky]

Get an IR thermometer and check the readings at the top of the radiator, block or hot radiator hose and cold radiator hose.

 

A hot radiator means that the heat is not getting out....lack of air flow.

A cold radiator and a hot block water exhaust means poor water flow.

There should be a dif, between the 2 hoses of about 20dgrees....if my memory is correct.

 

Especially on a new car, gages are set to run in the middle and are idiot gages....IOW, it is designed to show normal over, say a 30 degree range, because most of us freak out over 210 when it really ain't no big deal, till they see it on THEIR car.   Now, I see that is not your case, I just threw that in. 

 

Your gage rising after shut down is normal....the heat is in the block, and when you stop circulating the water it collects there.

 

Timing?   Lack of air flow (not what I'd expect on the freeway).  Did you say, how hot was it outside....around 100.

 

BTW, you were probably turning over 3,500 rpm on a continous basis.

[datzenmike]

On 8/2/2022 at 12:35 AM, 74 B210 said:

Hi all. I have not been able to work on the car for a while,  to answer questions, the timing is set to 5 degrees, and the car ran 

in the middle normally in town but the normal temp is outside is around 70s's. when it heated up the outside air was 95F and the car got up to 

the first mark of the H, my gauge said 220 215. almost to the H, running 65 70 MPH,  it never over boiled over, 

when I shut it off the gauge goes up to 190, then slowing over time comes down...  I will do a combustion gas test, for a blown head gasket tues, or wed.

but its a new gasket properly torqued down. 

 

 

 

A leaky head gasket would push compression into the water jacket. Pressure would exceed the pressure relief valve on the radiator cap and coolant would be expelled out the overflow. The rad would need constant topping up. It rad levels don't change, the head gasket is fine.

 

Going to 190 is normal after shut off and is also called heat soak.

 

 

1/ Feel your lower rad hose. If soft, it may be collapsing from water pump suction when the engine is revved up on the highway.

 

2/ Fan belt loose???? Do you have clutch fan???? Spin the plastic fan blades with your finger. Should be quite firm to spin.

 

3/ Rad may be clogged with hard water scale inside the tubes. Rad then becomes restrictive to flow at high speeds. For $5 get a bottle of CLR. Place radiator face down with upper/lower openings up. Pour in as strong a mixture of CLR and water and let sit over night. I left mine for 3 days, won't harm copper and brass or solder. Dissolves calcium and limestone.

 

 

[74 B210]

thanks datzenmike for all the things to check. I did install a new head gasket and the rad hoses are 

brand new.  i ended up using a alum. rad 3 core from a 78 holden for australia. with elec. fans and they kick

on and cooling is great.  I did run more rad flush in the system and it cleared up more.  But when I got the car the 

engine was severally neglected!  lots of scale and rust.

[datzenmike]

When you get it corrected always use a quality 50/50 antifreeze / distilled water mix. Always top up with distilled water.