Spike, what would you recommed for removing the scale in the heater core, assuming there is any in there? I have flushed with presssured water front, back, sideways, over and under. Not sure if there is any way to determine is in fact there is any scale. I have tried by passing the heater core with a foot of heater hose, it didn't seem to make any difference. Phil

 

I would start with a over the counter radiator cleaner.
Then move to something like CRL or vinger water.
Then make sure you flush it with clean water between "doses" to make sure there is no cross contamination between cleaners and/or coolant.

 

Distilled white vinegar is an excellent cleaner.

Eric

 

Well, I had some time this weekend so I decided to flush out the heater core. As some may recall, my DII 2000 was running at normal temps 195 to 204 but at idle, it would climb up to 210, 215 and even 225 on occasion. Mind you, I am in San Diego and the outside temp is around 60 degrees this time of year. I noticed a slight leak coming from the heater core inlet pipe where it connects with the intake. There is an o-ring on the inlet pipe that ended up having a slight crack in it. I decided to flush out heater core at the same time. I used the Prestone Flush product, Because I was only trying to flush out the heater core, I mixed some boiling water and the prestone and poured it into the heater hose lines which I had disconnected from the heater core inlet and outlet pipes. I used vice grips to clamp the pipes. I let the hot mixture sit in the heater core for about 30 minutes at a time. I thoroughly flushed with clean water after each soaking. I then blew out the heater core with about 50 lbs of air and filled it with distilled water. I did not notice any contaminents coming out of the heater core. Bleed the system (by the way, if you are having issues with getting the heater core purged, try disconnecting the heater hoses, fill with fluid, fill the pipes, to the extent that you can, and hook it all back up. Then remove the bleed screw, lift overflow res. and fill till the fluid comes out of the bleed hole. Replace the bleed screw, refit the overflow res. and top off the fluid. Start, run and listen, you should not hear the waterfall sound. Check fluid level again the following morning.
Anyway, after the soak and fill, no difference. Same temp readings on my Innova 3130. Temp gauge in the truck was right at mid-line. Running 195 to 204, idle climbed to 220, ac on dropped to 210 to 212. Today, I changed out the fan clutch. It seemed to change the temp for the better slightly. Running temps are the same, idle temp from 208 to 218, ac on 208 to 215. ac fan works, serp belt routed correctly, truck running great, temp gauge right at mid-line. William at The Rover Group, nice shop, albeit a bit pricey at times, told me not to worry. He has complete faith in the truck gauge and said that the idle temps that were showing were completely normal and not to worry. Still, I remain concerned. Maybe I should just pitch the Innova and forget about it. O-ring worked great, no more slight leak or tail/tale coolant smells or drips in the driveway. I really want to trust this truck but am lacking faith at this point. Outside temp today is 73 degrees, truck is running great. This thing is driving me crazy. I am about to switch to the conventional thermostat bypass, sorry DiscoMike I know how you feel about those, but this pressure valve thermostat is killing my mental wellbeing. Thoughts! Phil

1999 DI sold, just waiting for the paperwork to finalize
2000 DII 133,000 miles
2001 DII

 

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Thanks for the info on the thermostat defects. What is that statement based on. Do you have an article or webpage? thanks Phil

 

No, I discovered the problem and suspected the problem was affecting more than just a few. I contacted one of the senior members (who wants to stay anonymous until the official investigation has been completed) and he relayed the particulars of my evaluation to a retired UK Corporate Engineer who started the ball rolling at LR. Anyway it is a long story already and it is just getting started. What has been relayed back so far; it appears the defect is isolated to LR factory replacements. The after market thermostats like those offered by AB should work as intended.

 

Do you know how the thermostats were defective? What is the consequence of the defect? IE is it the pressure valve? Do you know what the time period was when the defective thermostats were being offered? thanks phil

 

I do not know. They appear to be inhibiting coolant flow through the radiator. The engineers preliminary finding, to my understanding; a spike in thermostat failures recorded at dealerships. I was told out of approximately 500 replacements 300 failed. Personally; I have been chasing the problem for a good six months. The thermostat was the first thing I tried; it was no help so I didn't suspect it. After replacing head gaskets, water pump, radiator, flow checking the block and heater core it was still overheating. I reach down and felt the bottom radiator hose and it was ice cold. The outside temp was 3 Deg; the hose was literally ice cold. At that point I took the original and new thermostats inside and boiled them on the stove; they both opened so I really don't understand it. I went to Lowes and bought 3 2.5" nipples 1 tee couple and an 90 Deg elbow all 1" galvanized and put together a thermostat bypass. My Disco II has been running cool and happy even since. I relayed this information to a well known senior member of this forum who had been waiting my outcome because there is a group of at least five other members experiencing the same symptoms. He then contacted his retired LR engineer buddy who within just a few hours of communications discovered the trend mentioned above. My new thermostat from AB will be here in the morning, I'll install it first chance I get. If the fail returns I'll reinstall my bypass, eat some crow and not worry about it anymore. As long as it isn't overheat I'll be happy. I came up with the fix last Friday; this has already been the longest stretch without a problem since I bought it.

 

thanks for the update. I look forward to seeing how the new thermostat works out. My temp issues seem to be at idle or when the truck is not at rpm levels above 1000. The gauge in the truck is reading normal but the scan temp show it climbing at idle. A local shop told me not to worry about it that the truck temp gauge was good to follow. I don't have that much faith at this point. Keep us posted. Phil