For the last week and a half I have been fighting the overheating gremlin. First I thought it was a faulty hose clamp on the water pump hose at the thermostat. There was spray from that location at the first sign of overheating. So I replaced all hose clamps with screw clamps instead of the stock tension ones. Bled and refilled coolant...hot air in cabin. Ran for of an hour in driveway and around neighborhood at 9 oclock position. Thought i had it. Next morning, Half mile from home temp started up....turned around and back home....maybe 30 seconds.....shut off and coasted thru neighborhood to house. Ordered thermostat from AB, installed along with belt and new idler pulleys that needed to be replaced. Bled and refilled coolant....hot air in cabin. Ran for 30 minutes at 9 oclock position. Next morning, drove kid to school (15 minutes away) then to work. Ran hot going up ramp.....off to the side of road. let it cool down then did a quick top off, pouring in 50/50 mix until it flowed out bleed screw....then last 1/2 mile to work. Lunchtime was spent repurging air out of system so I could get it to Mechanics shop that afternoon. Did not get there. Heater stopped blowing hot and i shut it off and coasted to stop on side of interstate. Rollback to shop. They suspected a faulty water pump even though that one had less than 10k on it. Still same issue....idles normal, gets hot under power except that now the is a huge loss of power. What should be the next step? HELP!!!

 

1. You say you ordered the new stat, but has it been installed? There have been posts about a run of bad stats, that fail to open properly. Also, stat operation could be changed by metering holes being plugged with trash. Pix attached.

2. Heater stopping in a D2 is a bad sign, since hot coolant is always going through it.

3. If you don't have dramatic loss of coolant, heater should work. Only part involved is water pump. So you could have bad belt route, if recent work was done with belt. See Discover Defender Maintenance Tips, Accessories, Parts & More at Roverparts.com

Or weak pump, impeller could be loose on shaft, etc. You could order a gasket for water pump and inspect. Any wooble to existing pump? Pix of old wobbling pump, they eat aluminum.

4. Loss of power could be coolant being burned in combustion chambers. Any coolant in oil (milky) or white smoke from exhaust?

Attached - page on cooling system flow.

Having a scanner to read live data (coolant temp in degrees) vs depending on gauge would be good. Gauge shows 9:00 if normal. How high did you get, and did warning light also come on?

 

Thank you for taking the time to help out

I was hoping for a scanner for Christmas.....Christmas might be a couple weeks late this year.

Warning light did illuminate the second time it overheated as well as check engine soon. Check went off the next morning.

 

Would double check belt route.

Tests in morning this time of year will show white smoke at first as condensation goes away. Engine would need to be fully warmed up and still smoking.

Consider the Ultra Gauge, which does a lot of scanner things and displays various things from the OBDII port, including coolant temp, with alarm set points, about $70.

A recent post had a fellow with a stat that just would not open, he tested it with boiling water from a tea kettle. Seems like your must be opening some. See https://landroverforums.com/forum/di...tat-you-46037/ for more info on the stat. Did your new one have four holes or two holes in the top?

We did not talk about Dexcool, which will make sludge in radiator and heater core. This reduces cooling capacity and can cause overheat. But it does not switch on/off like a switch.

When you changed the stat, does the hose from the "side leg" go to the water pump?

 

yes. that was also the one that showed leakage at the beginning of all of this.

 

Could have radiator problem, partial blockage. Would allow idle, but heat up with normal use. After truck warms up, check fins top to bottom (engine off), should be close in temp, not a big "cold" area at the bottom. Indy shop can flush radiator and in some cases rod out any build up of calcium, etc. about $70 - $100. New rad is about $228 and up.

Stat may be zombie and need swap out again.

BTW - F250 was $400 on www.govdeals.com, ranger truck from local state park, needed coolant temp sensor, it would only idle at 2000 when warmed up. My parts getter for the Disco.