Heater Hoses Mess..cry for help from the Uk

[UkMark]

Bl..dy Denmark , no Vikings or raw herring here , just her majesty's finest grumpy .

Gonna flush and back flush it to death at the weekend , will double check for heads , but no smoke , no oil .

Have to say say it's not the original motor so the rad could be too small...plus not checked the cap ( how you do this I don't know ) , I think chuck it and get a 7 bar new one ?

Lastly I could be overfilling perhaps , the light is a red herring and it's not boiling ...need the temperature gun yo arrive yo know for sure .

[UkMark]

Quick thought ...the heat sender unit in the block is a single button one, is this correct for idiot lights or a gauge ( again it's not the original engine) I an reading on the board there are two types ...

[PanelDeland]

Single button sender would be right but might not be the right resistance one. Have you actually put a thermometer on it to see if it's hot? That would be a good first step. You may be trying to trace a problem that isn't there while the sending unit is a problem.

[UkMark]

I know right , waiting for a thermometer to arrive in the post , still over flows water though ....

[davepl]

I'm not sure if anyone was actually implying it, but just to be safe, the lack of thermostat or restrictor plate cannot and will not cause an engine to run hotter. That's an old wive's tale based on something about "coolant moving too fast to cool down" nonsense.

The thermostat is of course still needed, but as you likely know it's to bring the temp up to operating (whatever the set point of the tstat is) temp quicker.

On that old design with the bypass hose going to the radiator it'd seem to me that you're always going to be cycling some coolant through the rad, even when cold and the tstat is closed, so that design must take longer to warm up. Later designs still cycled it through the heater core, but not the radiator itself.

Anyone know why they did this? It clearly wasn't necessary as they later abandoned it. Unlike big blocks the small blocks already have an internal bypass that serves the purpose of the BBC bypass hose. I guess it'd help clear trapped air but at quite a cost, IMHO.

[Savidio44]

I think the heater bypass is causing the problem. Why is it bypassed? Does it leak? If not, why not hook it up to see if your situation improves. If not, it appears to me the heater is bypassed incorrectly. Run the hose currently running from the top of the intake to the top of the water pump. Pull the plug out of the top of the waterpump and install the correct size fitting to match the size of the hose. Block off the radiator port.

[68C15]

Thermostat upside down WILL make it act like a blown head gasket. The end with brass cylinder goes on bottom.

With no overflow reservoir you need the radiator to be filled 2" below cap when cold.

Fan blades should be half in shroud and half out

Cluster with light takes a different sender (actually a switch) than one with gauge. A gauge sender will turn light on with varying brightness (faint, but still varying) when used with light cluster

[adricar1]

if its not fitted, fit an expansion bottle. otherwise as previously stated the wate level should be left 3 inch down from the top of the radiator for expansion on the water. My rad cap i use is a 16lb cap, and expansion bottle, no problems with water coming out the rad. when it was not connected that was a different matter.

[davepl]

I've thought more about my blanket "missing thermostat can't cause overheating", and while it's an edge case, I should point it out because I missed it.

As we all know the lower rad hose is bigger than the top. This is avoid creating "suction" on the intake side of the water pump. Drop the pressure enough and the coolant would boil even at room temp, which is called cavitation (your boat prop can do the same).

The height (weight) of the water positively pressurizes the engine by a small amount. The water pump operating against a restriction (restrictor plate or thermostat) can create additional pressure. If you were right up against a cooling problem where the coolant was starting to boil in the heads, the extra pressure of the water pump working against a restriction might be enough to stave off that boiling for a few more degrees.

What the pressure amounts are and how much it increases the boiling point and whether any of it actually matters I don't really know. But I figured I'd point out my own error. Still, though, there's no such thing (within reason) as water going through the cooling system "too fast".

Ideally as you stress the cooling system you want the coolest fluid possible in the block. The coolest fluid can be found at the bottom of the rad, so the sooner you can pull that in, the better. The sooner you can get the hot fluid back into the radiator out the top to make room for cooler stuff to enter, the better. You still always have coolant in the motor at all times either way, and its speed doesn't affect its ability to pick up heat, so the only variable is how cool the coolant is. Slowing it down only means hotter water in the block. Extrapolate that as far as you can towards infinite flow with no viscosity or cavitation (which happens with hydrogen or helium near absolute zero, but not relevant here) would be ideal. Stopping coolant flow altogether would be the worst case.

[UkMark]

Heater core was leaking and a new one is finally in route to me , gonna hook this up lower the water level an inch , replace the rad cap to 7 bar , flush it out and fingers crossed .

[mechanicalman]

Originally Posted by davepl

I've thought more about my blanket "missing thermostat can't cause overheating", and while it's an edge case, I should point it out because I missed it.

As we all know the lower rad hose is bigger than the top. This is avoid creating "suction" on the intake side of the water pump. Drop the pressure enough and the coolant would boil even at room temp, which is called cavitation (your boat prop can do the same).

The height (weight) of the water positively pressurizes the engine by a small amount. The water pump operating against a restriction (restrictor plate or thermostat) can create additional pressure. If you were right up against a cooling problem where the coolant was starting to boil in the heads, the extra pressure of the water pump working against a restriction might be enough to stave off that boiling for a few more degrees.

What the pressure amounts are and how much it increases the boiling point and whether any of it actually matters I don't really know. But I figured I'd point out my own error. Still, though, there's no such thing (within reason) as water going through the cooling system "too fast".

Ideally as you stress the cooling system you want the coolest fluid possible in the block. The coolest fluid can be found at the bottom of the rad, so the sooner you can pull that in, the better. The sooner you can get the hot fluid back into the radiator out the top to make room for cooler stuff to enter, the better. You still always have coolant in the motor at all times either way, and its speed doesn't affect its ability to pick up heat, so the only variable is how cool the coolant is. Slowing it down only means hotter water in the block. Extrapolate that as far as you can towards infinite flow with no viscosity or cavitation (which happens with hydrogen or helium near absolute zero, but not relevant here) would be ideal. Stopping coolant flow altogether would be the worst case.

Had a car come in, complaint was "heater stops working on highway, but works well around town".
Electric fans.

Replaced MISSING thermostat, problems solved. Fans were regulating engine temp around town, too much airflow on the highway. No overheating, just "underheating".

When I break in a rebuilt engine, I use an old thermostat with the guts torn out to make a restriction so that it does not form air bubbles or heat up rapidly. I do this because I like tight piston to wall clearance and figure if I'm going to bite a piston it will likely be during break-in. After the cam is broke in I'll put a thermostat in it and break in the valve springs. Won't lean on it till after the first oil change.

Mom said I'm a little "windy"?

[davepl]

7 bar? That's 101.5psi. You'll need some serious hoses, that's for sure.

[UkMark]

just got back from a buying trip in Europe, quick fiddle with my new temp gun and the bloody thing is not overheating at all.
The button sender/switch on the block is for a gauge i i think, and its wired to an idiot light since the engine swap which is clearly showing hot when its not.
dont really want to add gauges inside, so guess i need to swap the switch/sender out on the block to a two prong version to switch the idot light properly..is that correct?
the only headache is the only wire remaining in the green one, the other red wire needed for the sender is cut back.

[TheSeeker]

I think my heater hoses are backwards. Top to top and bottom to bottom. The heater gets hot but what is the adverse effects of having it hooked up this way?