????? To Flush Or Not To Flush, That Is The Question ?????

I have a 1970 CJ5. 134F. 66K miles. Runs great. Noticed some rust in the 1 year old radiator. ( plastic tanks with aluminum core ) New water pump. Should I use a chemical flush? I have been warned that a motor this old may suffer consequences. I looked in the thermostat bore and it is rusty. What should the pressure on the cap be? I guess the cap rating?

 

I never flush anything. Do you have antifreeze in the coolant? A bit of rust is going to happen as you have water in a cast iron block. Its not going to rust out or anything and even if you did flush it, the new water is going to react with the iron and create rust again. I have been told to never drain the water out of old house hot water radiators because the water becomes "dead" and won't rust the cast iron radiators as long as you dont flush it.

 

3lb cap. Most caps are for a 13lb system though.

 

Flushing a coolant system is always a good idea.
The point is to get loose debri out and to keep from clogging the radiator or thermostats and such. On iron once you have that protective layer of iron oxide adding new coolant does virtually nothing to the iron. It doesn't on old house radiators either, that's an old wives tales.

Here's another tip for you, never put any tap water in your cooling system use de ionized water or distilled water. One of the reasons to use 50-50 mix, it's already distilled. This will help your radiator and heater cores last much longer, not to mention keeps the inside of your block cleaner.

Most motorcycle manufacter's tell you to not use tap water in you radiator specifically for this reason.

 

Thanks for clearing that up. I will be changing my routine.

 

Most motorcycles don't have radiators. Those that do, you have to have special fill for them because different anti-freezes react to the aluminum alloy used for building the engines in the first place.

 

In this day and age most motorcycles do have radiators.
My Suzuki recommends nothing special other than antifreeze.

 

Most antifreeze nowadays is rated for aluminum since most heads and radiators are made of it.

 

The radiator guy who repaired MM's radiator told my dad that a yearly drain and replace of antifreeze is as important as a routine oil change in an engine. The newer the car, the more important this is. He said that as soon as the PH balance starts to change, bad things start to happen.

It's definitely not something I'd ever abide by, mainly because I don't want to double the value of my junk with a gallon of antifreeze, but it was interesting to hear. And after seeing the inside of MM's water pump and thermostat housing, it definitely made me think.

 

I can't believe that thing ran.

 

And boy, did it!