Overheating

[blueosprey90]

I know nothing about the 122 Amazon, but generally speaking, if your ignition timing is retarded it can cause, or at least contribute, to overheating. In the case of retarded timing, fuel is still burning very hot when the exhaust valve opens, causing the exhaust port to be very hot and this heat is quickly transferred to the coolant. Also not good for your valves or your head.

[Ron Kwas]

Tf;

It was not clear to me that were talking about an electrical gauge/sensor, so I sent you to the 122 Temp Indicator page, and that's obviously all about the oe "filled thermal system" type which is different from yours...but the issue is still indicator accuracy, and it looks like you have confirmed this as the root cause of your "overheating"...I would check R value of sensor vs temp...you could even graph this out and compare it to what it should be (manufacturer data)...I would expect you can find this info on the net (Gargle is your friend!)...otherwise, try some troubleshooting by substitution...cost of buying another gauge setup is little compared to what you've spent up to now...OR, you could just add an accurate BP mark to the gauge face, and be done with this long Tango...I don't wish to add insult to injury, but one of the first things I would have done if plagued by (apparent) "overheating" and before spending all the time, effort and money you did, is verify the messenger was giving me good info...

I call getting the air out of CS "burping", because the term "bleeding" is associated with another system... (for a non Exp Tank CS), run engine with Rad Cap removed, Heater Control Valve open, to TStat opening, and keep refilling Rad as its level drops...squeeze upper Rad hose and release quickly to pulse Coolant and agitate bubbles, and free up air in the CS which might be hanging up in corners, high spots, or flow eddys in the casting. (Surfactant, to make "wetter" water, helps with this, but is not absolutely necessary, just always use 50% ethylene glycol/distilled water for Coolant!) Replace Rad Cap, drive a day of two, recheck, top up as necessary...Closed CS with Exp Tank is the same, except add filling of ET.

Cheers

[foo]

Test the radiator valve itself - put it into a cup and pour in hot water. - does it open?

[Thowdfella]

Unfortunately this saga still goes on. The car has now started "running on when I turn off the ignition. Also, I got a laser thermometer from Halfords and this tells me when pointing at the engine that it is approaching 100 degrees so it is overheating despite everything I have done.which includes jacking up the car and squeezing the hoses to expel any air - with the heater turned on fully!
I have ordered a new water pump as I can't think of anything else. Does anyone know how to check the water pump tolerances?

[c1800]

There are 2 types of water pumps, one with a cast impeller, typically oem, and one with a stamped impeller. Reportedly the cast impeller circulates better at idle and reduces the likelihood of overheat in stop and go traffic. Somewhat hit or miss when ordering, some listings have a picture. I recently bought a Volvo OEM pump, came in a blue box, but was made in China. Mine is operating fine though.

[Thowdfella]

This saga still goes on. The car has started running on when ignition switched off. Bought a laser temperature sensor from Halfords and it shows the engine being close to 100degrees.. struggling to think of the next step soordered a new water pump. Does anyone know how to check the tolerances of a water pump?

[c1800]

Originally Posted by blueosprey90

I know nothing about the 122 Amazon, but generally speaking, if your ignition timing is retarded it can cause, or at least contribute, to overheating. In the case of retarded timing, fuel is still burning very hot when the exhaust valve opens, causing the exhaust port to be very hot and this heat is quickly transferred to the coolant. Also not good for your valves or your head.

Have you checked your timing with a strobe light? As noted, if timing is off it can contribute to overheating. It can also contribute to “run-on”.

I know of no way to check a water pump for “tolerances”, not sure I know what you mean by that.

[arcturus]

Correct me if I'm wrong but over running, pinking is caused by over advancement. B18? the water distribution pipe in head can get clogged.Did you point laser at head or block.The heat rises to the top but the water can be cooler. Check temp' at return to rad'

[Dibble]

Originally Posted by Thowdfella

Having read Rons very informative article complete with diagrams I have done the following. Put the original thermal sensor in boiling water and it goes across to the H Mark which is just a bit short of 100 degrees on Rons picture.
My thermostat is 82degrees when it opens and again Rons pic shows that as being over the half way mark so perhaps my engine is not overheating.
Incidentally the brand new electrical sensor when put in boiling water read122 degrees on the brand new gauge so crap but which one - the sensor or the gauge?!!!

I had an overheating problem on my restored 120. It had not been running for approximately 15 years and I did lots of the things you have done to no avail so would open up the heater with the Hot switch down to about 3/4 and fan on and it would operate as it should do. This continued for about 6 years and then for no apparent reason it operated properly and I didn't have to open the heater but I still keep an eye on it. Not much fun the heater being on in the summer! Give it a try.

[blueosprey90]

"Removed cylinder head and had unleaded conversion and overhauled.
Flushed engine with hose pipe and also with cleaning fluid."


Again, I'm the guy who knows nothing about the 122 Amazon engine, but Arcturus says "the water distribution pipe in head can get clogged".

My sense at this point is that water is not circulating properly through the engine. When I have broken down an engine with a cast iron block and head, I have done a lot of work with a variety of stiff brushes, screwdrivers and picks to remove as much rust from the water jacket as possible - usually in a soapy bath. Then I've taken it to the machine shop for further cleaning, preferably with a caustic bath or some other means of chemical removal. Then on return, I have worked it over again with the brushes, etc. in my own soapy baths until no more rust comes out. It is amazing how much rust comes out of the water jacket even after the machine shop has cleaned the engine. It is tedious, messy, but sounds necessary in your case.

There are a variety of chemicals and acids that might be used by the shop, but mechanical means is also important. Do a search on "descaling a cast iron block" or even "descaling a boiler". Flushing engine with hose pipe and cleaning chemical might be OK for mild rust build up, but sounds inadequate in your situation.

Good luck.