Cooling System issues - Running Hot

[G60michael]

I figured that the old 1978 G60 was due for a Cooling system flush, I have noticed the last few drives its been getting a bit hotter than usual, so I ripped into the cooling system to see if I could find the issue.

The water was a completely rusty color, and was in need of a flush out, the thermostat which I reckon is as old as the truck itself, is opening to early and is not fully opening either, is neither fully closing either closing up and the radiator cap is definitely not doing its job. It appeared the radiator may have also been a bit clogged.

I Cannot here any Water pump noises, so during the week ill grab a new thermostat, Radiator cap and some corrosion inhibitor and hopefully will see it back to normal.

Took it for a Test drive after flushing it all out and didn't skip a beat but its still running very hot.

Ill get a new cap and thermostat or am I better of looking further, any suggestions.

Note: No Water Present in Engine oil yet
Note: Prior to flush, Radiator was usually only half full before driving it nearly evertime I went to use it I filled it up full everytime.

Any help ASAP is awesome, Cheers in advance mike

[Esteban]

Michael, a couple of notes regarding your current status:

It's normal to loose some coolant after you fill it to the neck, since these cars don't have an expansion tank. It's normal that the level remains about 1 inch, (2-3 cm) below the neck after driving. Don't fill it every time. It's not needed, and also, won't help in the troubleshooting.

If it was driving normal a few weeks ago, then it will be of concern what you describe. But you need to check if the actual temperature is high, or it's just the gauge that's going to the hot position more than before. I'm having this problem with my gauge, that the needle goes to the max level every time. But I check with an infrared thermometer, and the temperatures are ok. I will recommend to anyone getting one of this IR meters. A must. Don't know the price in Australia, but here in the States you can buy one for around $30 or less with discounts. In mine, if I measure the temperature at the thermostat housing, it will give me a reading close to the rated one of the thermostat.

Do the flushing of the system as you told us.
Inspect the radiator cap to ensure that it is working properly. Must be of 7 psi (0.4 - 0.5 kg/cm2)
Get a 170°F (76°C) thermostat. As long as the diameter is correct, all will work (this is not a temperamental German car)
Make sure the the fan belt is at the correct tension (out of my own experience, badly worn water pumps still carry the task in these engines, unless the rear cover is totally corroded and with big holes!)

One possibility of overheating can be caused by a blown head gasket. Gases from the combustion could be entering the cooling system. They will increase the pressure inside the system, and then you'll loose more water, and it becomes a vicious circle. There are special kits to check for this, but the old school one will be with the following steps:

- engine must be cold
- remove the fan belt, to prevent the water pump from moving.
- remove the thermostat, and leave the housing open. Add or remove coolant accordingly to just below the neck of the housing.
- start the engine and try to see if bubbles are showing at the thermostat housing
- please note that the engine will start heating up, so the test must be done in the first couple of minutes.

Please take some pictures while you're at it.

Good luck.

[Esteban]

Forgot to include this picture:

Lecturas temperatura A.jpg

In this case, the thermostat is the one I fit for the winter, and is rated at 180°F (82°C) and the IR probe is reflecting that. However, my gauge at the panel is reading 212°F (100°C).

Taking measurements at other places in the engine, radiator, etc, gave me peace of mind, since I was beginning to be concerned.

The following picture is a comparison from a worn water pump and a new one that I installed two years ago. The temperature readings were the same with the two pumps. Check how badly eroded is the impeller on the old one.

Water pumps compared.jpg

[G60michael]

Thanks heaps esteban I also fogot to include you can here bubbling in the radiator when you remove the cap even when cool.

[Esteban]

Thanks heaps esteban I also fogot to include you can here bubbling in the radiator when you remove the cap even when cool.

This could be just the movement of the water in the system. I guess you'll need to rule out some blow-by combustion gases with the procedure outlined before.

If you do a system flush, one area of attention should be the petcock drain at the rear of the engine, next to the starter. If you open it, water might not come out due to clogging. You'll have to remove the petcock valve, and then with a stiff wire (clothes hanger works great) start digging into the clogged material. Make sure to run some water while you work in there. You'll be surprised the amount of material collected there.

[Swerve]

My money is on a faulty thermostat

[moore_rb]

How did the radiator passages look when it was empty? were they all caked up with Calcium, or are they nice and clean ?

are you running with the shroud on the fan? or no shroud?

[Swerve]

Update Mike, how'd you go ? get it sorted ?

[ferdy]

I would say the radiator is clogged,bubbling is a concern but could be caused by the clogged radiator worst case scenario blown gasket.
I very much enjoy your explanations and your detail Esteban,your dedication and consistency to help is to be commended and apuaded o
Fernando

[rocky2002]

I would like to find a water pump for a 1969 patrol.I live in Amarillo,Tx.