Hey guys! Ok, I've read so many threads on here trying to figure out my overheating problem... some threads match certain symptoms, and other threads seem to match the other symptoms, but no thread that I've found so far has nailed my issue, so I hope my post doesn't saturate the forum, but I'm desperate.


Ok so here are my symptoms on my 1998 D1: I can drive the beast around all day on mostly flat terrain at freeway speeds or around town usually no problem. But if I get stuck in stop and go traffic or have to drive up much of an incline it is guaranteed to start to overheat (the warmer the weather, the quicker the overheating happens). The only time it has climbed in temp at freeway speeds is when it was a really hot day, but it still didn't reach the upper line on the temp gage like it does in stop/go traffic or up hills. Also, when the temp starts to rise at idle (stop/go traffic), it will usually start to go down a bit once I start driving and air starts passing through the radiator again, but then will rise again at idle or under a load (hill).


Things I have done so far to try and remedy the problem:
Changed thermostat - no difference.
Burped cooling system - no difference.


Tests I have done with results:
Brought engine temp up to warm (not overheating), shut it off and felt radiator for cold spots. The upper half of the radiator was noticeably warmer than the whole bottom half, not sure if that is normal or could be the culprit?.?.?
Tested fan clutch. While engine was cold, there was a good amount of resistance but would still rotate (it would move about 2-3 blade positions when I would spin it while cold). Then I brought the engine temp up to normal (not overheating) and watched the blade as I shut the engine off and it spun freely probably 3-5 complete rotations before coming to a stop. Then I spun by hand and there was less resistance than when the engine was cold. Not sure if this is the way it should work or not. I am hoping that you experts will be able to provide me with some solutions or at least next steps.


I also do have a slight coolant leak from a hairline crack where the metal nipple (haha nipple) on the top driverside corner of the radiator attaches to the metal hose - forgive my ignorance on what the proper name of that hose/nipple. (pic attached). I doubt this is the culprit of overheating, because my coolant level is still fairly high when overheating occurs, but would I be able to just jb weld (etc...) that crack to prevent further leakage?


Thank you guys in advance!


Jordan

 

You fan clutch is shot. If you drive at high speeds, there's enough airflow to cool, but stuck in traffic the fan is not pulling enough air because the clutch won't lock up. See if the front is blocked with mud that you can clear out, but most likely you will need to replace it. Consider replacing the water pump at the same time since there is a high probability that the bearing is shot and the shaft is wobbling, which can be the cause for the clutch to fail.

There's some people that have posted clutch test procedures. I haven't found them to be totally reliable, but when your clutch is good, you will hear a loud wooshing noise from the fan. It really blows a ton of air when it's actually locked up either because it's been sitting overnight (and the fluid has settled causing it to be locked up until it spins for a bit) or because it is hot.

 

The crack is probably not uncommon (I had one in the same spot) because that hard line puts some stress on the joint. The best solution is to pull the radiator and take it to someone that can braze (melt bronze) around it or solder it (tin/lead). A brazing torch is less common to have around, but you may have a torch you can use to solder it yourself, one just like you find at the hardware/home store to solder copper pipe. JB or an epoxy putty could work but it's worth getting it done right.

 

^exactly- Also a lot of leaves and crud can be trapped between the AC condenser and the radiator, make sure to blow all that out.

 

Hey guys, thanks so much for the replies! I ended up taking the fan clutch off and it was gunked up pretty good with mud all around the metal coil spring so I thought that could be the culprit. I cleaned that really well, installed back onto the rig and took it for a test drive a few nights ago while the outside temp was about 40 degrees F. I live on top of a 3 mile long constant hill, so that is a pretty good test for this. It did ok until the last half mile of the hill, where it started overheating again. Went straight home and through on the new clutch and went for the same test drive and it didn't overheat which I was super happy about... then I drove it the next day around town for a bit and then on my way home, the temp climbed again at the last half mile of the hill (outside temp was maybe 50 deg F, so still pretty cool). I was pretty bummed of course. I didn't try to diagnose further that night, I had to take some time away from it haha!


I decided I will drain the cooling system, take the radiator off to see if I could fix the leak near the bung, and flush the radiator. I may also replace the water pump while I'm at it. I see this one on ebay - anyone thoughts? Fits Land Rover Discovery Range Rover Water Pump with Gasket Metal Impeller | eBay


I drove the rig down the hill today to pick up jugs of coolant and then let it idle for about 8-10 minutes before I tackled the 3 mile hill. Towards the end of that 8-10 mins, the temp began to climb (outside temp around 65-70 degrees). I started driving and the temp went down slightly. Then I got to the hill and the temp reached the top line of the safe section about 1.5 miles up and I had to pull over and shut her down to let her cool. after about 10 mins I fired her up and temp was level so I drove the remaining 1.5 miles up the hill, within the last half mile it was reaching very close to the upper line on the temp gauge and then it went down pretty quick for no apparent reason and then it started climbing again. Makes me wonder if I need to burp the system again? That is something I will make sure to do once I put the radiator back on and fill the system.


I am also wondering if the temp sending sensor/gauge could be bad. Would these symptoms line up? Haven't been able to find out the symptoms of a bad temp sending sensor/gauge and I don't have a temp gun or meter to hook up to my computer to read the actual reading.


Well, just thought I would give you all an update. Please let me know if you have any tips or questions. Thanks again you guys!


- Jordan

 

"I see this one on ebay - anyone thoughts?"


Don't waste your money on a cheap-o water pump. Get STC4378 in the Airtex brand with the brass impeller.

Looks like this...
Rover Water Pump (STC4378) Replacement Fits Discovery, Range Rover & Defender Vehicles


AB normally has these on sale for $129.00


Shop around, but get the Airtex.

 

Have you checked for leaves blocking air flow?

If coolant gets out air gets in

If by touch your rad is noticeably cooler in one area, figure rad is clogged

You need an ultra gauge or similar to know what the actual temp is that gauge on dash reads cold normal( wide range there) overheat, figure anything above 9:00 is overheating

Try a 180* thermostat

My moneys on leaves or bad rad

 

The gauge on the dash is not your friend. Look at other posts and you will see pictures that show digital temperature (from the OBDII scanner plug) and gauge are not close. Bad on a D1, absolute terror on a D2. if temp gauge is above 50% you are way hotter than you want to be. My D1 stays down in the lower third of the range. It is just the nature of these machines, they did not build accurate gauges. Saved the budget for the alarm system. On the D2 temp gauge is computer controlled to point at 50% until head gasket is almost fully roasted, then it moves up.


A rule of thumb on the radiator, if temp measured at bottom and at top of fins varys more than 10F (use a point and shoot infrared thermometer) then radiator has scale buildup inside. On a D1 it is a copper core radiator, and a small shop near me will boil them out, take off a tank, and rod it out, and solder up leaks for $75. Look for a place that does bus radiators and heavy equipment. They pay the bills, the Rover tea cup is small potatoes to them.


A new aluminum rad is available for D1 for about $235. On a D2 rebuild is not economical, just buy a new one. The passages are too small and side tanks brittle plastic.


The reason the shop manual is called the RAVE - Rovers A'int Very Economical.

 

Thanks again guys! You all are more than helpful as I diagnose my issue. Here's my update:


I took the rad to a shop and had them flush/pressure test and it passed. While chatting with the guy at the shop, I mentioned that I replaced the fan clutch with a new one and he said just because it was new, doesn't mean it was good. So I swung by Oreilly's and picked up another fan clutch (the one for a 2000 Chevy Express van 4.3L no a/c - this one was the Murray brand. My first new one was the Duralast brand from Autozone). I went back home and installed the radiator back on the rig and put the Murray fan clutch on since the duralast failed. I let the fan clutch sit vertical on the rig for 24 hours (which is something I saw to do on another post). I also installed a 180 degree thermostat tested in a pot of water on the stove. With my fingers crossed and my breath held I took her down the hill, through the drive through at Jack in the Box (I got 2 tacos and a jumbo jack with cheese in case you were wondering ha!). She did fine through the drive through at idle (outside temp was maybe 55-60 degrees so not very warm), but then when I went back up the hill she climbed in temp at about 2.5 miles per usual. So defeated! haha but I'm up for the challenge. I haven't seen any visible coolant leaks since getting the radiator patched up, but I did notice that the coolant level was a little lower so I am guessing it is leaking into the engine and getting burned up. Possible head gasket? Oh, and also there was no leaf/mud blockage between the AC condenser/radiator.


So what would you all suggest my next move be? Pressure test the whole cooling system? Block test with the blue liquid to look for gas fumes in the cooling system? replace the water pump (or maybe at least pull it off to check the condition of the umpeller/bearing?). Hook an ultra gauge up to the computer to see actual readings? All of the above? If so, what order would you guys suggest.


Thanks again you guys, and I hope you all are getting in plenty of roving this year already! - Jordan