Hey all,
Just happily joined the LR ranks a few hours ago. 1998 discovery w/ 129k on the clock. I'm very happy with her, the fact that she passed a pre-buy inspection by a very good LR mechanic, and that everything on the car works.


... except maybe the cooling system.

In bad traffic (Los Angeles, anyone? ) I noticed the temp gauge ticking ever closer to red. It'd go down when I'd rev hard (higher revs = more revs of the coolant pump? Or greater speed = more air over the radiator?). I never let her go passed the high "safe" mark, but I did have to run the heater full blast on the last few blocks home.

Help?

 

Not a good LR mechanic if she's running hot. You have air in your coolant system. Take it back to your "good LR mechanic" and say WTF? Or back to the source... Any LA ocean sounds from the passenger side?

 

Well in the mechanic's defense he didn't drive or run the car long enough to overheat her, it takes quite a while. Otherwise the inspection was absurdly thorough and I was very impressed. Not to mention drooling over the fleet of tricked out defenders parked in their lot.

After she cooled down I bled the coolant system with the heaters on full blast and definitely got some bubbles out of her. Let the truck idle for a while and monitored the temp gauge, which stayed at a about the 1/3 mark the entire time, as well as for a quick spin around town.
And yes, I recall some burbling fluid noises from the pass side under the dash. Bubbles in the heater core, I assume?

 

Have you checked both sets of fans? Are your electric ones running, is your mechanical fan clutch warn out?

 

Assuming it's running well...
Easiest things to check/do:
Make sure radiator fins aren't clogged, flush it out from the back side with a hose
AC fans
Viscous clutch
thermostat
Have your radiator rodded.

 

The fan clutch feels okay, it turns a little more freely than the one did in my BMW, but there is definitely resistance when turning it...

I heard the e-fans run for a while after shutting the engine down. Testing further I saw that only the left side fan ran when I hit the A/C switch (Is it designed to work this way or is the right side fan not functioning correctly?). The engine wasn't warm for that test, as I was only verifying whether the fans functioned at all.

After bleeding the system she ran at 1/3 mark the entire drive to work today, with a decent portion of that drive in traffic. However, it is noticeably cooler today than it was yesterday, so obviously that could be a factor.

 

Test the fan clutch both cold and at operating temp. Should be more resistance when cold.

 

If you only have one fan working, I would retest, with the a/c on let it idle and see if the second fan comes on, if not you have a bad fan and that will cause your issue.

 

It is always a good idea to rinse your radiator once a year, I do mine every spring.
With a cold engine of course.

 

I'll try that too. Am I good just shoving a hose in between the block and radiator and spraying her out, or should I remove the fans?