My F1 still runs the original 8BA flathead. The radiator core is brand new 21st century construction. Te truck runs around 140f . I have checked the existing stats and they are marked 160f . I am guessing they are working as they were both closed when I inspected them. Do you think with the modern radiator core I should use higher opening stats to try to increase the cruising temperature ?. If so how high should I go. I am primarily trying to get the heater to give out some heat, At the moment it blows just about luke warm. BTW the heater appears to be new...perhaps an aftermarket item, with a 3 speed fan.

Suffolkman

 

I run 180 degree stats. The engine needs to get up to temp to run efficiently. You can test stats by placing them in a pan of hot water on the stove and watch the temp as they open.

 

How are you measuring the engine temp, with an infrared gun?
I'm running 160's and year-round the temps at the thermostat housings is close to 190. I was out in it last night, air temps about 32F/0C, and it runs at the same temps as when it's 80 out. Warms up fast and heater really puts it out.
I don't know what brands are available over there. The highest quality ones here are Robertshaw 330 series thermostats (#330-160 = 160 deg, 330-180 = 180 deg). There is also a Subaru thermostat that fits right and is a 170 deg stat, but I don't have a number for it.

 

The motor runs around 140f, I am only going with what the (new) Dolphin temp gauge is telling me. I do have a domestic infra red gun....where and how do you take a temperature reading ?. We are approaching winter over here now, but typically temperatures rarely fall much below freezing. Do you think my comments about the new core could mean I may need to run a hotter stats ?. I have heard about Subaru stats being a substitute. I have not tested the stats I have taken out, but obviously they must be opening for the truck to not be overheating.

Suffolkman

 

I took readings on the thermostat housings, and at a couple places on each head. It might be worth testing the Dolphin gauge by sticking the sender in a pot of hot water.

 

Update, I tested the thermostats in boiling water and tested them with a thermometer. They are working fine. I have put them back in and run the engine up to temperature. Now I may have jumped the gun, I did not test the temperature at the heater hoses in the cab before i removed the stats. But testing them now, the hoses in the cab are cold. Under the hood the hose that comes out higher on the block is hot there. But the lower hose which comes from the block lower front is warm for the first few inches, then runs cold. Perhaps it is airlocked ?. Their is also a tap on it where the hose leaves the block.This is very stiff to turn...maybe it is not open fully ?. I am thinking I will have to drain the system again and check the flow through the heater hoses.

 

You are on the right track. If the valve is open then you have an air pocket. With the engine at operating temp, you can bleed the air at the heater/hose connection. I use one of those hose removal tools(hook) and insert it under the hose just enough to let any air out. Can be a bit messy, but works.

 

Pray it isn't the valve is stuck shut. They are near impossible to get out of the head in my experience. Even with the head on the bench they usually break off, a nasty piece of work to get the remains out.

 

Might be time to consider you may have a heater core that is full of junk and allowing no coolant to circulate thru. Not that uncommon to find a stopped up core.

 

Thanks to all for their replies. Ross, the tap I am talking of is the one on the front of the engine low down...is that still in the head ?. The heater to me anyway looks new, so if that is correct then I would not expect that matrix to be blocked. Next chance I get I will drain the whole system down and put a running hosepipe in the system to see if that tap is open. If it is flowing I will try and flush the heater through and connect it with the hoses full of coolant. Possibly I could clamp both hoses before connecting them to the block to ensure they are full ?.

 

See 8575 in pic from 1948/56 truck catalog (final printing 1964):

 

The lower connection is normally on the passenger side (for LHD) water pump. No valve there. The connection in the middle of the PS head is usually a valve usually stuck in one position, and is hell to remove from the head.

Is your truck RHD? Sitting in the driver's seat, which side of the truck is the heater on?

 

My truck is LHD, it spent all of it's life (until 2017) in Nevada. It is the connection you show in your photo that on my truck has the valve on. So my truck as yours the heater is on the passenger side. The connection on the PS head has no valve on.

 

So this seems to indicate 150 degree thermostats used on 8 cyl F1 ?.

 

Part of your problem is your water flow may be backwards. Hot water comes from the head (typically that is where the shutoff valve is located, not at the pump), goes through the heater core, then returns to the engine at the water pump. The pump pulls the water through the heater system from the head. The "cold" water is then sent back into the engine with the water from the lower rad.