Vehicle & Technical > Discovery
V8 Viscous Fan
Range Rover Blues:
Possible blocked rad due to old age.
When it starts to get hot, try putting the cab heater on full bore and open the windows, does it make a diffenrece?
alternatively it is loosing water and once there is enough air in there to stop the water going round it boild over. Take it for a slightly shorter run and see if any water has escaped, ideally before it overheats.
P.S> fill the coolant via the brass plug on top of the heater supply pie, not via the expansion tank. If you havn't done this it will have air in the heater matrix.
300TDi Disco:
--- Quote from: Range Rover Blues on May 07, 2009, 18:56:33 ---Possible blocked rad due to old age.
When it starts to get hot, try putting the cab heater on full bore and open the windows, does it make a diffenrece?
alternatively it is loosing water and once there is enough air in there to stop the water going round it boild over. Take it for a slightly shorter run and see if any water has escaped, ideally before it overheats.
P.S> fill the coolant via the brass plug on top of the heater supply pie, not via the expansion tank. If you havn't done this it will have air in the heater matrix.
--- End quote ---
I have just completed a water pump change on mine. and i filled the whole system up through the radiator. I waited until i couldn't see any bubbles in the rad the screwed the cap in. Been round the block a few times and then checked the expansion bottle for pressure. I got a little bit of air rush out then went for a longer drive and it's now fine. I have got rid of the viscous unit and put and electric fan from a mondeo, engine is quite now)
SteveGoodz:
--- Quote from: Range Rover Blues on May 07, 2009, 18:56:33 ---Possible blocked rad due to old age.
--- End quote ---
Good thought. How do I check for a partially blocked rad?
--- Quote ---When it starts to get hot, try putting the cab heater on full bore and open the windows, does it make a diffenrece?
--- End quote ---
Certainly does. I drove most of the way back from Gaydon on Sunday with the windows open and heater on full blast. Got pretty damned hot inside the car I can tell you :(
--- Quote ---alternatively it is loosing water and once there is enough air in there to stop the water going round it boild over. Take it for a slightly shorter run and see if any water has escaped, ideally before it overheats.
P.S> fill the coolant via the brass plug on top of the heater supply pie, not via the expansion tank. If you havn't done this it will have air in the heater matrix.
--- End quote ---
I'm pretty sure that I've got all the air out of the system and it doesn't lose water except when it's boiling out of the expansion tank.
Range Rover Blues:
Ok, all sounds reasuringly like a blocked rad and nothing worse.
I checked mine with a laser thermometer, a non-contact optical one I'd borrowed but basically if you get cold spots near the corners that's a sign of a crusted up rad, also it's age will suggest it and the condition of the insides of the rad and header tank if you can see, but the best way to tell is by swapping it I find.
The fact that the cab heater can keep the engine cool speaks volumes, if the water stays in until it gets too hot then I don't think it a head gakset or worse, new rad I say.
SteveGoodz:
Thought I'd update this with what's happened recently.
I fitted a brand new viscous coupling and changed the thermostat. No difference, except that the new coupling is noisier than the old one :doh: Anybody want to buy a BNIB viscous coupling? Only been used for about 10 miles :D
My tame mechanic checked for head gasket leakage using one of those syphon things that samples the air in the coolant expansion tank. Ran the engine for quite some time and the liquid stayed a nice blue colour ... so the heads are okay. The system was pretty well pressurised though. As soon as we cracked the filler cap off boiling hot water came out - no steam/hot air first.
I removed the cowl from around the radiator to get access to see if there are any cold spots. Hmm, what constitutes a cold spot? After a short run with the temp gauge reading normal (just about half way up the gauge) the top third of the rad is uncomfortable to touch for more than a second or two and it gets cooler as you feel further down. At the bottom I could comfortably leave my hand there indefinately - it's warm but not really hot. Trouble is, I don't know how much cooler the bottom should be than the top anyway.
This morning I deliberately got the engine really hot - needle almost into the red [-X - the top of the rad was <insert Anglo-Saxon word for fighting> hot! Too hot to touch without going OUCH!! Bottom half of the rad was a lot hotter than before but I still don't know if that's right or not. The problem is a new rad is like mega-bucks and I'd rather not spend that much dosh only to find it's not the problem :-$ Anybody got a known good used one for a reasonable price or one I can borrow for a couple of days?
Whilst pondering the problem this morning I heard what sounds like steam escaping and water boiling. The sound is coming from somewhere around the inlet manifold/plenum area. I also realised that the valley gasket is damaged (i.e. almost non-existent) at the front and the seal and clamp are missing. I'm gonna have to replace the inlet manifold gasket anyway but is this likely to be the cause of the problem or, as I'm inclined to think, just a symptom.
This is really starting to pee me off as it's stopping me from getting the blasted thing muddy :'(
Suggestions/ideas anyone?
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