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Diagnosing cooling issue

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  #1  
Old 05-19-2016 | 04:03 PM
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Default Diagnosing cooling issue

Hello All!

I have an '03 Discovery II that seems to have a couple bugs in the cooling system. It has new top hoses and tee and a new stock thermostat. It seems to be running hotter than I'd expect. For example:

1. At 60 mph, transmission in Drive, tach at 2000 rpm the temp reported by the ECU via an OBD II device is 217 F.

2. At 60 mph, transmission in 3rd, tach at 3000 rpm, ECU reports 206 F.

So higher RPMs, but same forward speed and ambient temp, and I get a lower coolant temp.

Now I'm scratching my head trying to understand whether that could be the radiator or the fan clutch, or both.

Also, the auxiliary fan never seems to come on. I can pull in the driveway at a temp over 212, shut the engine off and not get the fan. I thought it was supposed to come on anytime the engine temp was over 212, vehicle running or not?

Thanks for helping me think through this. I don't want to start throwing parts at it just yet. I'd like to try to understand what it's doing!

Best,

- Jason
 
  #2  
Old 05-19-2016 | 04:21 PM
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You need to put in a Genuine LR grey 180* thermostat for starters. Then monitor temps. And yes your auxiliary fan should be on at 212*. The fan should also work when AC is on and outside ambient temp is around 80*. I don't think it needs to be 80 for the fan to run though, mine seems to run at a lower temp.
 
  #3  
Old 05-19-2016 | 04:29 PM
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Thanks, Motorhead. This is the thermostat I put in:

Thermostat Discovery Series II (Part # PEM100990)

Is that the one you're talking about? If not, where's the best place to get the good one?!

Thanks,

- Jason
 
  #4  
Old 05-19-2016 | 04:31 PM
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Get an OEM 180F Thermostat, then grab yourself a 99-02 Fan Blade and either the Hayden 2991 fan clutch or comparable unit (your 03/04 is a one piece unit). On the efan, test it with power directly to it or just jump the relay and see if it powers up. Also check for any blown fuses.

Then after that monitor your temps and report back.
 
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  #5  
Old 05-19-2016 | 04:42 PM
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welcome. some good advice so far. also make sure to search earlier threads, lots of good solutions already out there.
 
  #6  
Old 05-19-2016 | 04:42 PM
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1. At 60 mph, transmission in Drive, tach at 2000 rpm the temp reported by the ECU via an OBD II device is 217 F.
Mine's about 188F at same speed. Suggest you get new 180 F thermostat. Many say go with the LR gray soft spring but linked one's working fine for me.
Category

2. At 60 mph, transmission in 3rd, tach at 3000 rpm, ECU reports 206 F.
Water pump may be suspect.

radiator or the fan clutch, or both
Generally fan/clutch issue will cause higher temp at idle.

I can pull in the driveway at a temp over 212, shut the engine off and not get the fan.
Fan should come on when AC on or coolant very hot upon shutdown.

Electric cooling fan switching points:
For A/C system:
⇒ On When vehicle speed is 50 mph (80 km/h) or less and ambient
temperature is 28 °C (82 °F) or more
⇒ Off When vehicle speed increases to (62.5 mph (100 km/h) or ambient
temperature decreases to 25 °C (77 °F)
For engine cooling during normal running:
⇒ On 100 °C (212 °F)
⇒ Off 94.5 °C (202 °F)
For engine cooling at ignition off (to counteract heat
soak):
⇒ On If, within 10 seconds of ignition off, intake air temperature is 60 °C (140
°F) or more and engine coolant temperature is 110 °C (230 °F) or more
⇒ Off After 10 minutes or if engine coolant temperature decreases to 100 °C
(212 °F)
Your current temps are to0 high and may want to start with drain flush of system, the thermostat and possibly a water pump.
......
 

Last edited by number9; 05-19-2016 at 04:45 PM.
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  #7  
Old 05-19-2016 | 04:50 PM
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  #8  
Old 05-19-2016 | 05:35 PM
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Wow! Thanks, everyone, for the ideas and quick replies. Got some parts ordered. Going to to try the flush/tstat/water pump first and see if anything changes.

Your help is much appreciated!

- Jason
 
  #9  
Old 05-19-2016 | 09:09 PM
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You need to bleed it first. Don't start throwing parts at it until you change the stat and then bleed it.


You can use the method in the book, or imo what's better is parking on a steep hill.
 
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  #10  
Old 05-20-2016 | 12:00 AM
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I also own a 2003 that I got exactly 1 year ago and within the first month every single piece and part of the cooling system broke/faulted or was on its way out. I mean even the plastic lines. Replace EVERYTHING and refill it with the green ethylene-type antifreeze, distilled water, and a whole serving of coolant additive (it works.) Even all of the small rubber hose connecting the plastic lines at the radiator/tank/manifold needs to be updated with new hose and run it directly to point-B where the factory plastic pipes went. Those 210+ temps with DexCool corroded everything from the inside. The AC fan will do nothing for your operating temps but it needs to be in working order nonetheless. Having been there and done that, just update everything on the coolant system because it's all **** from the inside, out.
 
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Last edited by chubbs878; 05-20-2016 at 12:16 AM.


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