Overheating Volvo DL--how to pinpoint/fix the problem

Hi,

My 1980 240 DL has been overheating (boiling radiator). This happens
after a few miles of driving (10 miles) even on flat freeway in not
very hot weather.

The fan runs fine, and I can feel it pushing hot air backwards
(testing this only when standing still, of course). So I guess it's
not the fan clutch.

For further testing, I have disabled the thermostat, meaning that I
have clipped out the valve completely so that now the thermostat is
always completely open (there is just a hole where the valve was
(since I've clipped out the valve).

Still overheating!

So I guess the next things to test are:

1. Is the radiator completely blockec?

2. Is the water pump defective?

Any suggestions for simple tests for those? I'd also be happy for any
other suggestions for how to go about solving this problem.

Thanks,
Wolfgang,
Santa Barbara, CA

 

There have been other suggestions, but ...

What coolant have you been using ? Topping up with hard water will
cause scale build-up, which wrecks heat exchange properties. The block
and radiator may need a de-scale.

 

I had the same problem on my 87 240 DL with 196 k & removed the radiator
to replace it but noticed the road grime, so laid it flat & sprayed
something like "Greased lightning" all over the vanes from side to side &
top to bottom, front and back,, actually, any strong cleaner will work, but
I let it soak in till it was almost dry, then shot it with the garden hose.
I was amazed at what came out. So, I did the whole thing again & got almost
as much. I might add that it worked better by spraying the hose from the
engine side out. After 3 or 4 times, I was satisfied so I put it back in &
topped it off with new antifreeze & haven't had a problem to this day. This
will definitely help your cooling system, regardless.
I hope you get this in time to try it before you wind up spending
unnecessary $$ & time on it or creating more problems. Try it,, you'll be
amazed. Oh,, and put a new "fail safe" thermostat back in it. It needs it to
run properly.
Good Luck
Richard