Disco 2 overheats while moving, but not while sitting
Mudding
Joined: Dec 2009
Posts: 153
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From: Novato, CA
I noticed you mentioned that you cleaned out what was in front of the radiator "yesterday" when you replaced it. Did you start experiencing these problems when you replaced a cooling part recently?
from your post above: 2. in front of the radiator was cleaned out yesterday when the new radiator was installed
from your post above: 2. in front of the radiator was cleaned out yesterday when the new radiator was installed
Super Moderator
Joined: Jan 2011
Posts: 16,322
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From: Savannah Georgia
1. Murphy's Law comes in a multi-volume set. Nothing says you can't have strange gauge problem AND real over heat.
2. Define overheat - if you believe that to be above 212F, that might be a place to aspire to, but many Rovers peak past that.
3. Let us leave the gauge alone for the moment. If the Autologic coolant temp reading and the IR of the pipe that exits the intake manifold are close, like within 5 degrees, I would believe them. The coolant sensor is very close to that outlet. Pix of same on a D1, you can see the location of the coolant temp, and just left of it the gauge sender (D1 has two on top). Point is that water coming through that spot is about as close to the monitored sensor as you can get.
4. Water pump wobble would only have gotten worse, until it leaks, and eventually comes off with fan slicing radiator. Pix of old pump impeller (mine). When they wobble, internal spacing is small and they start eating aluminum.
5. So you have normal temp at idle, if under 30 minutes, and normal temp above 50 mph (an assumption on my part, as you said warming happens below 40 mph). We will return to the gauge, but let us think about what would make you warmer at 35 mph, but not at idle or freeway cruise speed.
Number one could be thermostat. It is remote from the block, and depends on hot coolant reaching it, mixing with radiator output, and raising thermostat wax pellet to 180 - 204 F. That remote metering is done by four holes in the top axial leg of the stat. Coolant at that point is flowing downhill. If flow was slow, stat would close up some or all the way, because it is not hot enough. IMHO the number of sample holes could be increased with a drill bit. May not be enough space to enlarge the existing. More flow through metering holes would reduce time lag. Ina D1, the whole stat body sits in the coolant. Pix attached. Sometimes these holes get clogged with coolant system trash broken loose by work. ould also think that air flow around all these parts can cool them off too far, impacting operation. Could be tested with some pipe insulation and zip ties.
A. Air flow - at 50 - 60 mph, air is moving through radiator pretty quick. At lower speed, not so much. It would be normal to have some variation.
Air restrictions can include:
trash in radiator fins (mud, leaves, plastic, cardboard). There are three rows of radiators, they are just called AC condensor, tranny oil cooler, sometme also and engine oil cooler, and the main radiator. Should be able to shine a bright light from fan side and see it when looking from the front.
Fan turning the wrong way - blowing toward grille, it subtracts from air flow and at certain speeds flow = 0. Might not notice at idle; and high speed, where outside wind wins. Those unbelievers can hold a pizza box out the window at 60.... You can actually drive the truck without a fan ths time of year, as long as you don't stop for long periods. When my WP died, I drove 30 miles home after pulling off fan to avoid damage. Fan blades cupped sides go toward engine. Both AC cooling fan and main fan.
Something adding to heat on radiator, like tranny overheating (check fluid under truck, and tranny/transfer case ovrtemp idiot light doesn't leave codes), or AC running high head pressure on compressor.
[full disclosure, My D1 came from a used dealer, electric fan wired to blow wrong direction, AC compressor cycling with over pressure shutdown switch, fan clutch so wimpy it would stop when AC turned on, the electric fans going the wrong way overwhelmed it. Plus bad thermostat and radiator full of calcium]
Fan shroud removed. Every little bit helps.
B. Coolant - assume a 50/50 mix, but if by accident straight coolant was installed it won't cool nearly as well. Filled to correct level and bled? Ha done member who reported the line from base of coolant container was twisted and prevented installing full 13.1 quarts. Have had a post fom a person 2 gallons low (no heat). Any bubbles in coolant (like the waterfall noise under the dash)? Bubbles can be air, exhaust gas (head gsaket), and steam (cracked block / slipped liner).
C. Heater core - hot coolant is always flowing through the heater core when engine is running. At idle, the bypass valve in the thermostat reduces water flow to a trickle, unless thermostat is open. The heater re-circulates itself. Heater core can be full of gunk (dexcol sludge, etc.), can be reverse flushed with garden hose and checked for flow. A clogged heater core might impact how fast the main thermostat gets enogh hot coolant to operate.
Back to the gauge - you mention wire from sender to gauge, the sensor goes straight to the ECU, the ECU pulses ground to the gauge pointer and the warning light. 219 F is not overheat poitionon the gauge. So I think you still have some sort of gauge wiring issue.
2. Define overheat - if you believe that to be above 212F, that might be a place to aspire to, but many Rovers peak past that.
3. Let us leave the gauge alone for the moment. If the Autologic coolant temp reading and the IR of the pipe that exits the intake manifold are close, like within 5 degrees, I would believe them. The coolant sensor is very close to that outlet. Pix of same on a D1, you can see the location of the coolant temp, and just left of it the gauge sender (D1 has two on top). Point is that water coming through that spot is about as close to the monitored sensor as you can get.
4. Water pump wobble would only have gotten worse, until it leaks, and eventually comes off with fan slicing radiator. Pix of old pump impeller (mine). When they wobble, internal spacing is small and they start eating aluminum.
5. So you have normal temp at idle, if under 30 minutes, and normal temp above 50 mph (an assumption on my part, as you said warming happens below 40 mph). We will return to the gauge, but let us think about what would make you warmer at 35 mph, but not at idle or freeway cruise speed.
Number one could be thermostat. It is remote from the block, and depends on hot coolant reaching it, mixing with radiator output, and raising thermostat wax pellet to 180 - 204 F. That remote metering is done by four holes in the top axial leg of the stat. Coolant at that point is flowing downhill. If flow was slow, stat would close up some or all the way, because it is not hot enough. IMHO the number of sample holes could be increased with a drill bit. May not be enough space to enlarge the existing. More flow through metering holes would reduce time lag. Ina D1, the whole stat body sits in the coolant. Pix attached. Sometimes these holes get clogged with coolant system trash broken loose by work. ould also think that air flow around all these parts can cool them off too far, impacting operation. Could be tested with some pipe insulation and zip ties.
A. Air flow - at 50 - 60 mph, air is moving through radiator pretty quick. At lower speed, not so much. It would be normal to have some variation.
Air restrictions can include:
trash in radiator fins (mud, leaves, plastic, cardboard). There are three rows of radiators, they are just called AC condensor, tranny oil cooler, sometme also and engine oil cooler, and the main radiator. Should be able to shine a bright light from fan side and see it when looking from the front.
Fan turning the wrong way - blowing toward grille, it subtracts from air flow and at certain speeds flow = 0. Might not notice at idle; and high speed, where outside wind wins. Those unbelievers can hold a pizza box out the window at 60.... You can actually drive the truck without a fan ths time of year, as long as you don't stop for long periods. When my WP died, I drove 30 miles home after pulling off fan to avoid damage. Fan blades cupped sides go toward engine. Both AC cooling fan and main fan.
Something adding to heat on radiator, like tranny overheating (check fluid under truck, and tranny/transfer case ovrtemp idiot light doesn't leave codes), or AC running high head pressure on compressor.
[full disclosure, My D1 came from a used dealer, electric fan wired to blow wrong direction, AC compressor cycling with over pressure shutdown switch, fan clutch so wimpy it would stop when AC turned on, the electric fans going the wrong way overwhelmed it. Plus bad thermostat and radiator full of calcium]
Fan shroud removed. Every little bit helps.
B. Coolant - assume a 50/50 mix, but if by accident straight coolant was installed it won't cool nearly as well. Filled to correct level and bled? Ha done member who reported the line from base of coolant container was twisted and prevented installing full 13.1 quarts. Have had a post fom a person 2 gallons low (no heat). Any bubbles in coolant (like the waterfall noise under the dash)? Bubbles can be air, exhaust gas (head gsaket), and steam (cracked block / slipped liner).
C. Heater core - hot coolant is always flowing through the heater core when engine is running. At idle, the bypass valve in the thermostat reduces water flow to a trickle, unless thermostat is open. The heater re-circulates itself. Heater core can be full of gunk (dexcol sludge, etc.), can be reverse flushed with garden hose and checked for flow. A clogged heater core might impact how fast the main thermostat gets enogh hot coolant to operate.
Back to the gauge - you mention wire from sender to gauge, the sensor goes straight to the ECU, the ECU pulses ground to the gauge pointer and the warning light. 219 F is not overheat poitionon the gauge. So I think you still have some sort of gauge wiring issue.
Last edited by Savannah Buzz; Dec 16, 2011 at 08:10 PM.
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8th Gear
Joined: Dec 2011
Posts: 8
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I must say thank all of you for your help. I think that the problem has been repaired. The new temp sensor was bad. I got one out of a working Disco 2 and when I installed it everything was fine. Stupid crap parts...
Warning to all out there, the Temp sensors made by FAE maybe bad out of the box.
Warning to all out there, the Temp sensors made by FAE maybe bad out of the box.
Super Moderator
Joined: Jan 2011
Posts: 16,322
Likes: 88
From: Savannah Georgia
IMHO running temp may decrease a bit at constant 45 - 60 mph. The factory spec for the stat is begins to open at 180, full open at 204. But that is the temp at the stat, which is decreased by number of holes in the top of the stat, and some cooling of the sample water by the airflow. A remote stat is going to run differently from one in the engine block. Some people do that in-line stat conversion, get down to 180 -183. I also believe that increasing the number of small holes in the top of the stat will increase the quantity of hot water and make stat open a little more, reducing your temp. The factory sets the electric fan to come on at 212, and restore at 202. IMHO that is evidence that some engineer thought that 204 was just too hot for always operation.
4th Gear
Joined: Feb 2012
Posts: 4
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did u ever have any luck with this issue? I am possibly going to look at an 03 sd and they are selling because of overheating issues. They have apparently replaced radiator, fan tstat and water pump ans still overheats only while driving.
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Joined: Jan 2011
Posts: 16,322
Likes: 88
From: Savannah Georgia
decarpenter -
If you are planning on it, take a chemical test for exhaust gas in coolant, will confirm if head gaskets is leaking exhaust to coolant. See https://landroverforums.com/forum/di...-gasket-47775/.
Could also be fan belt route making water pump run backwards. See atached belt route. Could be fan on backwards, the cupped side of blades go toward engine block.
Overheat from Head Gaskets and cracked heads usually very hard upper hose, gurgling water fall sound under the dash (bubbles passing by), white smoke out the rear, loss of coolant.
Beat them way down on the price, it would cost them $500 for parts if the DIY a head gasket, or $1500 - $1700 for s shop to do it, and $2500 or so at a dealer.
If you are planning on it, take a chemical test for exhaust gas in coolant, will confirm if head gaskets is leaking exhaust to coolant. See https://landroverforums.com/forum/di...-gasket-47775/.
Could also be fan belt route making water pump run backwards. See atached belt route. Could be fan on backwards, the cupped side of blades go toward engine block.
Overheat from Head Gaskets and cracked heads usually very hard upper hose, gurgling water fall sound under the dash (bubbles passing by), white smoke out the rear, loss of coolant.
Beat them way down on the price, it would cost them $500 for parts if the DIY a head gasket, or $1500 - $1700 for s shop to do it, and $2500 or so at a dealer.
Last edited by Savannah Buzz; Feb 26, 2012 at 09:35 PM.
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