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Discussion Starter #1
"Newbie" Ok, I'm at a loss! My 92 Classic is overheating/running hot and I don't know what else to do. I have done the following. Also, I'm not losing any coolant. The top rad hose is hot while the bottom hose is warm. I did notice some silt a bucket that I drained the coolant into.The confusing thing to me is that during the day the temp will go 3/4 up just below the "red" zone, but I drive it at night at speeds of 70-75 mph and it never reaches halfway. The engine runs great and smooth, no idle issues, starts up without any problem. Any help will be truly appreciated.

1. New expansion tank
2. New thermostat 160 F. I'm in Southern California and gets hot
3. All hoses have checked out
4. Heater core has been bypassed.
 

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1970-1995 Range Rover Classic
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have you replaced the fan clutch? If youve got some sediment as you say it may be worthwhile to flush the cooling system.
 

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Discussion Starter #3
No I have not changed the fan clutch, would that make a difference from driving at night versus the day? I can drive the same speed at night and the temp doesn't even get halfway. Thanks for the response!!
 

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1970-1995 Range Rover Classic
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Sounds very much like a silting radiator, RRCs are well known for this. You could try flushing it, but I would suspect that this may only delay the inivitable (new radiator). It may also be that the fins are clogged up with dirt which reduces the efficiency. After a 10 minute run from cold, check top and bottom hoses, if there's a big temperature difference, then coolant isn't flowing through the rad. properly.

Alternatively, it could just be that the temperature sender is knackered
 

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Discussion Starter #5
Thanks for the direction! I will attempt flushing the rad, but from what I have read, it may ultimately need to be replaced. I will let you know. Thanks again!
 

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Reverse flush the radiator if possible - works better.
 
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The fan only comes into play at slow or no speed. When driving the forward motion of the truck keeps the engine cool.
 

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Are you running your AC when you temp gets up to 3/4?
 

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Discussion Starter #10
Well, I reversed flushed and same problem exists. I did notice that the top hose coolant is boiling. Could air is the system be causing this? Not sure if I bleed the system correctly or not (If anyone has specific step by step I would appreciate it). I'm still not losing any fluid, and my expansion tank is hot as well.
 

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Check timing and electric fans.

Mine runs cool at 90F ambient and no mechanical fan at all. just the stock electrics in front of the rad. If timing and electric fans are OK, you might try pulling the fan/clutch and running it naked.
 

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2010-2012 Range Rover MkIII / L322
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BrainStem said:
Well, I reversed flushed and same problem exists. I did notice that the top hose coolant is boiling. Could air is the system be causing this? Not sure if I bleed the system correctly or not (If anyone has specific step by step I would appreciate it). I'm still not losing any fluid, and my expansion tank is hot as well.
Could mean that there is air in the system and it needs bleeding or (worse) that air is getting into the system from somewhere else. :think:
 

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Discussion Starter #13
Update, I have been concerned that while trying to bleed the system the thermostat would never open, so went and replaced it (again) and now the when running the TStat opens. I found something new, when the temp goes up the expansion tank cap is releasing air. I'm not loosing any coolant, but you can hear the air being release. Could this be a bad tank cap? Also, I think I may have some air trapped in the system, but I'm not sure of the process to bleed it. I have searched the site, but have not come across a step by step guide that explains it. Anyhow, thanks everyone for your help!!

Recent order

1. new expansion tank cap & sensor
2. Switch - Fan - Temperature
3. Coolant Temperature Sending Gauge
 

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Discussion Starter #14
The mystery may have been resolved! a bad cap! I will continue to test, but the cap seems to be the root cause of the overheating.
 
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