Thread: Who is running a PEL500110 thermostat in their D2

Reading the information from RAVE regarding the coolant system:
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Thermostat - Main valve
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The thermostat is used to maintain the coolant at the optimum temperature for efficient combustion and to aid engine
warm-up. The thermostat is closed at temperatures below approximately 82C (179F). When the coolant temperature reaches approximately 82C the thermostat starts to open and is fully open at approximately 96C
(204F). In this condition the full flow of coolant is directed through the radiator.
The thermostat is exposed to 90% hot coolant from the engine on one side and 10% cold coolant returning from the radiator bottom hose on the other side.
Hot coolant from the engine passes from the by-pass pipe through four sensing holes in the flow valve into a tube surrounding 90% of the thermostat sensitive area. Cold coolant returning from the radiator, cooled by the ambient air, conducts through 10% of the thermostat sensitive area.
In cold ambient temperatures, the engine temperature is raised approximately 10C (50F) to compensate for the heat loss of 10% exposure to the cold coolant returning from the radiator bottom hose.

By-pass flow valve
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The by-pass flow valve is held closed by a light spring. It operates to further aid heater warm-up. When the main valve is closed and the engine speed is below 1500 rev/min, the coolant pump does not produce sufficient flow and pressure to open the valve. In this condition the valve prevents coolant circulating through the by-pass circuit and forces the coolant through the heater matrix only. This provides a higher flow of warm coolant through the heater matrix to improve passenger comfort in cold conditions.
When the engine speed increases above 1500 rev/min the coolant pump produces a greater flow and pressure than
the heater circuit can take. The pressure acts on the flow valve and overcomes the valve spring pressure, opening
the valve and limiting the pressure in the heater circuit. The valve modulates to provide maximum coolant flow through
the heater matrix and yet allowing excess coolant to flow into the by-pass circuit to provide the engines cooling needs
at higher engine rev/min.
=======================================
Driving a 2001 Discovery TD5 in hot climate and reviewing the listed thermostat temperature:

PEM100990 - Cream is 88° With hard Spring (Designed for Diesel and V8 applications)

PEM101020 - Black or Cream is 82° With Hard Spring (Designed for a V8 and used as a stopgap with K4 engines)

PEL500110 - Grey is 82° With Light Spring (K4 engines)

I'm confused:
1. What is K4 Engine?
2. Assuming driving at 2000rpm at desert area (hot weather), 2500rpm on steep hills climb (desert area) and 2850rpm on freeway (~ 100KM/h speed) what is the best choice?
3. While driving bumper to bumper at hot ambient 35C and above with rev at ~ 800rpm, does the PEL500110 diverts more hot water towards the heater-matrix (in cabinet heat radiator) cooking the passengers...?

1. Freelander engine 4 cylinder

2. If the standard 88 deg thermostat starts to open at 82deg & fully open at 96,
you have an advantage of the 82 deg thermostat starting to open in the high 70's & fully open in the low 80's.
No matter where you are, in hot weather, by the thermostat opening at a cooler temp you have a chance of your engine running cooler.
This doesn't mean you engine will always run at 82 deg, especially towing, it can still reach high temps
it just means the thermostat is fully open, with full flow at that temp.

3.this won't happen when the thermostat is open as your cooling system has flow through the thermostat.
you need to understand how an inline thermostat works, when thermostat is closed, coolant is forced through the bypass valve on the thermostat, (comes from top rad hose)this is where thermostat gets the heat from to open.
The bypass valve is small so when the thermostat is closed, a larger volume of coolant is re-circulated through the engine & heater matrix untill the thermostat opens & it has flow

Hope this makes sense

Thank you for the educated answer.
Some more info I'm not clear:
1. Since I'm "used to" a 91C-96C at offroading and this is normal run today, although I had removed the EGR system from the engine theoretically it should run hotter since the Exhaust gas recirculation NO2 emissions is not there... using the PEL500110 should take me towards ~ 86C-92C i assume, am I basically in the right direction here?
2. Is there any issue with the temps going up and down damaging the head? or I should expect a steady temp about 5C less of what I have today?
3. What about "having lower temp" is not efficiently burning the fuel (It's a 2001 Discovery TD5)?
4. The ECU can "think" the engine is "cold" and it's to inject more fuel to reach it's engineer planned Land Rover to be at 91C to 96C, any real in that theory I read in the web (could not find any proof for this anywhere)?

Originally Posted by Pedro_The_Swift

very happy with mine (yes I said it,,)
car telling me 40 outside Torque telling me 88deg at 100kph,
idleing for 6-7 minutes (left car on and aircon on for passenger Guiness) and it showed 90, 30secs later back to 88.

add late 30's and ocean humidity and its a good day to be at the Alex Surf Club!!!

Pedro you might have told me before but what Stat is your truck running?

Cheers

Sent from my SM-G900I using AULRO mobile app

Originally Posted by assafde

Thank you for the educated answer.
Some more info I'm not clear:
1. Since I'm "used to" a 91C-96C at offroading and this is normal run today, although I had removed the EGR system from the engine theoretically it should run hotter since the Exhaust gas recirculation NO2 emissions is not there... using the PEL500110 should take me towards ~ 86C-92C i assume, am I basically in the right direction here?
2. Is there any issue with the temps going up and down damaging the head? or I should expect a steady temp about 5C less of what I have today?
3. What about "having lower temp" is not efficiently burning the fuel (It's a 2001 Discovery TD5)?
4. The ECU can "think" the engine is "cold" and it's to inject more fuel to reach it's engineer planned Land Rover to be at 91C to 96C, any real in that theory I read in the web (could not find any proof for this anywhere)?

most of the thermostat chat on here is from V8 owners,

yes too cold an engine temp will make the TD5 misfire,, but thats at startup only,
I have never heard of any TD5 fuel map injecting more fuel to raise engine temps,, The much later TDV6's will do this to burn/clean the diesel particulate filter,, not something TD5 owners have to worry about.

Originally Posted by ozscott

Pedro you might have told me before but what Stat is your truck running?

Cheers

Sent from my SM-G900I using AULRO mobile app

this will require a bit of searching,,,

Bought from Roverlord Sept 2014,,
how time flies
its was stamped 82, actual part number requires more effort

To add to the data in this thread I can confirm that running a PEL500110 in a TD5 actualy increases operating temperature by at least 5 degrees.

Normal genuine thermostat and normal driving around Cairns on a humid 32 degree day gives 92 degrees at the back of the head and 91 from the nanocom. Coolant pressure is 9psi.

With PEL500110 temperature tops out at 100 on the same route and same conditions. Coolant pressure sat at 11psi. The system was thoroughly bled after the chageover to the PEL500110 BTW, so there was definitely no trapped air.

So it was definitetly a good side by side comparision. The PEL500110 came in a bearmach box and was not stamped with a temperature. However this thermostat had a support bridge which was significantly thicker that the genuine thermostat and this may have affected flow rate.

BTW I have tested the flow rate from a TD5 water pump and it is not that flash - far less that the rate from a 20mm hose connected to a town water supply!

My 2 cents - if you own a TD5, then do not go to the trouble of changing your thermostat to a PEL500110. You will definitely run hotter by 8 degrees.

Needless to say the genuine part went back in the next morning. If anyone wants this PEL 500110 to test further then PM me and Ill send it too you.