Hello

I've recently bought my disco II from an auction site. After I had replaced all four rotors and brakes, I was really looking forward to driving my disco, but unfortunately have been plagued by overheating problem since. Here's a quick run-down, I am hoping you guys can help me find a solution!

The overheating problem was first noticed after I drove it for about 5 minutes, or about 1-2 miles and it became red hot. I filled the coolant, checked for leaks but no visible leak was found. After some research, I thought the problem may be TS so I replaced the TS (amazon, PEM 100990 by Atlantic British). The old TS had some debris inside. After TS replacement, the car operated bit longer, about 15-20 minutes where the temperature remained in normal operating temp for 5-10 minutes - but it would overheat again. When it overheated, I noticed coolant would spill out of overflow reservoir tank. Next, I thought perhaps it was due to air in the coolant system, so detached the reservoir tank and placed it elevated, filled the coolant, and let the engine idle with cap off. After about 10-15 minutes, after the engine warmed up, I noticed bubbles entering into the reservoir tank, which quickly became boiling bubbles of hot coolant. At this point, I thought maybe I had a blown head gasket problem - tested for this with combustion leak testing kit. The tester fluid remained blue and did not turn yellow, actually it became purplish as coolant bubbled into the tester kit and mixed with blue tester. I was relieved to find that blown head gasket probably isn't the cause at this point, but the problem remains unsolved. Now, I'm suspecting:

- still bad TS? I just replaced the TS but I read it's not uncommon to get faulty TS...my purchase was from 'Atlantic British', but it was like $30
- bad or clogged radiator?
- water pump issue?
- could it still be head gasket issue???

Thank you for your input in advance!!

 

Welcome.
In all honesty, it can be any or all of those items can contribute to your overheating problem.
Did you purchase a 190 degree or 180 degree thermostat? Some of the Disco 2 thermostats sold online open at 190F/88C° and others at 180F/82C° degree temps:
PEM100990 - Cream is 190F/88C° with Hard Spring (Designed for TD5 and V8 applications)
PEM100990B / PEM101020 - Black or Cream is 180F/82C° with Hard Spring (Designed for a V8 and used as a stopgap with Freelander K4 engines)
PEL500110 - Grey is 180F/82C° with Light Spring (Freelander K4 engines)

The majority of us Disco 2 owners replaced the stock thermostats for the 180F/82C degree (Freelander) thermostat.

To quickly check to see if your water pump is bad/seized, carefully remove the bleed screw in the "t" coolant hose fitting and start the engine for a short time. Watch Out!!!! If a geyser of coolant shoots out of the bleed port, the pump is good and is spinning .

 

Blown head gasket + clogged radiator

 

Buy a ultraguage

do you know what the actual temperature is ??

You need to do a lot of reading here. Just search

 

It could be a radiator, air, bad reservoir cap, or bad fan clutch. An IR gun is super handy along with a scangauge II or ultragauge.

 

Thank you all for your kind replies.

Could you explain how IR gun will be helpful? If the top hose is hot while bottom hose is cool, then the problem lies in TS, type of thing?

While we're in this subject, what is the direction of flow of the coolant? Does it go from block -> top hose -> radiator -> bottom hose -> TS -> back to block (with Y bypass somewhere in between)?

Thank you guys

 

Google the RAVE Manual and read through the cooling section. It has a diagram of coolant flow.

Rent a pressure tester from autozone and see if it holds 20 foot pounds for 20 minutes, and inspect for leaks.

You could have a bad Viscous Fan clutch as well.

All you you can do is dismantle and inspect the parts as you go.

Take our the radiator, flush it, make sure it is OK.

Also, to test whether or no it is the thermostat, although with thermostat closed and heat blasting, it should not overheat, bypass it, and run without one, which will keep the engine very cool. If it still overheats you have eliminated the Thermostat.

Check your Auxiliary fan while you are at it, it should come on at 210 I believe.

Get an OBDII tool to monitor temp and do not let it get over 215 again, if it does, something is wrong.

 

If you found debris in the coolant, I would flush the system multiple times with distilled water and see if that makes a change. Cheaper than replacing the radiator first. I had an overheating engine too (but not as bad, 220F at red lights) and there wasn't only one thing that fixed it. I replaced the thermostat, coolant, fan assy, all step by step and got improvement every time. Engine still runs too hot in my opinion (204F max), next I will replace the radiator.

 

220 at red lights is how it was designed from the factory. It's how they all ran from new. It is not dangerous or a sign of anything bad unless you have already taken measures to operate at a lower temperature like you have been doing.

As usual it is always best practice to be aware of your temps to get a baseline and then you will know when something strange happens.

As suggested in another thread, you might want to check your lower shroud to make sure it is mounted securely and correctly.

 

That doesn't mean necessarily, it is good design for engine longevity. From what I read, there is a tendency by manufacturers to increase engine temps in order to improve fuel economy and reduce emissions, but you pay for that in the long term with more engine wear, in worst case with catastrophic failure. Also, I didn't like the AC fan coming on all the time.