Overheating Series 3

[deezgunz]

I searched the forum and didn't find an answer to my overheating issue so I figure a new post may help me out.

Vehicle is a 1973 Series 3 88 NAS. The vehicle is overheating and losing power as a result. The temp gauge is off the chart and the top rad hose is very hot. The bottom rad hose is cool.

The truck is relatively new to me so I figured on doing a complete flush to include opening the engine block drain cock, replacing the hoses, water pump, thermo and all the appropriate gaskets. When flushing the rad from the top down and from the bottom up there was some brown water but nothing major. I filled up the system with 50/50 but the problem persists.

Any suggestions are appreciated. Thanks!

[SafeAirOne]

Umm....let's see...Might check:

Fan belt is still there

Radiator not clogged

Radiator fins not jammed up with junk

Nothing obstructing ram-air from getting to the radiator (no fuel cans/water cans/winch/rad muff)

Water pump pumping water

Thermostat installed and functioning properly

Ignition timing correct

Fuel mixture not too lean

Head gasket not blown

Engine oil present and in the correct quantity

Good oil pressure


Stuff like that...

[gwmaxhunter]

Hi, i see there is a good list i am impressed. also bad temp gauge, there could be a coating of rust inside - wait the engine would be hot but not transfer heat to the coolant, scratch that. fins on the water pump could be corroded so bad there not even there anymore so bad coolant flow. some shops have a do-dad that uses a laser to check temperature on things id check to see if it is actually getting to hot and go from there........its hard to fix what isnt broken..... P.S. passages going to the head can be rusted closed or badly restricted or have a hardened gob of silicone stuck in them.........valve guides very worn they suck in air and the engine runs very lean no matter what you do....post an answer when you got it licked i am curious about this one...

[deezgunz]

Update:

I loosened the heater hose at the engine block at fluid leaked so there is a flow going to the block. I loosened the drain cock on the engine block and a flow of coolant came out. This shows there is a flow through the engine. I'm going to get my hands on a IR thermometer to get some readings.

I was fixed on the idea that the problem was the cooling system but now I believe its a faulty voltage stabilizer.

[Revtor]

does your gas gauge read seemingly normal? On mine (2a) the voltage regulator feeds the gas gauge and the temp gauge. so if they're both wacky then thats likely the culprit.

Also just because you have a flow of coolant doesn't mean you have a sufficient flow!

[SafeAirOne]

Also just because you have a flow of coolant doesn't mean you have a sufficient flow!

More notably, the coolant flows through the heater circuit and through the engine no matter if the thermostat is open or closed. A bad thermostat could be preventing the hot coolant from flowing to through the radiator circuit.

[I Leak Oil]

Hot top hose, cool bottom hose.....I guess that's relative but I don't think the bottom hose should be cool. Cooler than the top yes....
The only thing between the two hoses is the radiator.

[deezgunz]

Update:

I took temp reading with an IR therm and resistance/ohm/voltage readings and all checked ok. (BTW I bought an extra multimeter and a IR therm from Harbor Freight and paid $17 after I used an online coupon. Not pro grade stuff but accurate and both products got excellent reviews).

While conducting these tests I saw coolant on the fins of the engine side of the rad. I took off the plastic grill and there was coolant on the fins as well. There was coolant around the cap and pooling of coolant in the crease where the top and body of the rad meet. I also blew compressed air through the rad fins and more coolant blew out of the rad. Conclusion is a shot rad. Do you guys/gals agree? Below is a vid of my findings.
View My Video

[mearstrae]

Looks like it needs serious attention, If there's a good radiator shop in your area you could take it there and get an estimate for recore or repair. Might be cheaper that getting a new one, and if they're really sharp they might modify it for better cooling. Could look for a used one, but you always run the risk of ending up with the same problem in a short time.

'95 R.R.C. Lwb
'76 Series III Hybrid 109
'70 Rover 3500S

[Revtor]

Where are you located? There is a good classic car radiator shop on Long Island that does good work if you want to keep your original piece. There might be a place near you who can solder up a radiator or tell you if its too far gone to salvage. Otherwise it's time for a new one. I don't know the quality of the current replacement parts.