My first overheat
Discussion
I'm scared of what lurks under the bonnet of my 97 5.0 chim, so would appreciate some advice...
Last night I drove about 30 miles to pick up my wife. Switched off engine for 10 mins whilst waiting for her. When I started again, the revs were high (1300 instead of the usual 1000) and the temp guage soon went over 90 (never done that). Cabin heater fans were blowing only warm air instead of the usual inferno, and a light breeze of cold air when heater blower switched off. I pulled over to let it cool a bit for 10 mins, then drove off again. Revs settled this time, and on the motorway for 25 mins had temp guage reading its usual 70 - 80, and heater fans a bit warmer. Back in traffic for 10 mins near home, temp rose high again, getting to about 95 before I got home. Phew! Both rad fans cutting in at about 90 as usual.
Now, I've been checking the coolant each week, and topping up the expansion tank (blue capped bottle at front of engine). Should I really be topping up the swirl tank (brass screw-topped bottle in middle of engine)?
My guess is that I've been topping up the wrong bottle, its expelled some coolant under pressure (though no signs of spillage) and drawn some air in, hence cool heater fans intermittently.
If this sounds like an air-bubble, is this the bleed procedure... remove swirl tank screw-cap, remove expansion tank blue cap, start engine and run to hot, filling swirl tank and loosening rad bleed screw periodically until no air escaping, then screw everything back on?
If it doesn't sound like air-lock, what else? ooer!
>>> Edited by tobeee on Friday 17th October 08:05
Last night I drove about 30 miles to pick up my wife. Switched off engine for 10 mins whilst waiting for her. When I started again, the revs were high (1300 instead of the usual 1000) and the temp guage soon went over 90 (never done that). Cabin heater fans were blowing only warm air instead of the usual inferno, and a light breeze of cold air when heater blower switched off. I pulled over to let it cool a bit for 10 mins, then drove off again. Revs settled this time, and on the motorway for 25 mins had temp guage reading its usual 70 - 80, and heater fans a bit warmer. Back in traffic for 10 mins near home, temp rose high again, getting to about 95 before I got home. Phew! Both rad fans cutting in at about 90 as usual.
Now, I've been checking the coolant each week, and topping up the expansion tank (blue capped bottle at front of engine). Should I really be topping up the swirl tank (brass screw-topped bottle in middle of engine)?
My guess is that I've been topping up the wrong bottle, its expelled some coolant under pressure (though no signs of spillage) and drawn some air in, hence cool heater fans intermittently.
If this sounds like an air-bubble, is this the bleed procedure... remove swirl tank screw-cap, remove expansion tank blue cap, start engine and run to hot, filling swirl tank and loosening rad bleed screw periodically until no air escaping, then screw everything back on?
If it doesn't sound like air-lock, what else? ooer!
>>> Edited by tobeee on Friday 17th October 08:05
By the sounds of things its not that far from normal. A little paranoia is good, but I think that as long as you keep it below 110 then you will be fine. Actually, the temp gauge isnt calibrated so it could be anything from 90 to 120...!!??!?
However, it is really strange as to the cooling effects of the current weather. You can be trundling along at 60 and get 85 on the gauge. Then low and behold change direction (say into the wind) and the temp drops to 75...?!?!? Its all very odd indeed.
Mine had an airlock, and a flush of the system fixed that. But worth overfilling (not overflowing) and let the fluid flow out of the relief bolt at the top of the radiator. This should just be liquid and not air bubbles.... mine had air bubbles and once expelled it works much better...
But there seems to be little rhyme or reason to the temp sometimes. Just as long as it stays below 110 then you should be fine....
However, it is really strange as to the cooling effects of the current weather. You can be trundling along at 60 and get 85 on the gauge. Then low and behold change direction (say into the wind) and the temp drops to 75...?!?!? Its all very odd indeed.
Mine had an airlock, and a flush of the system fixed that. But worth overfilling (not overflowing) and let the fluid flow out of the relief bolt at the top of the radiator. This should just be liquid and not air bubbles.... mine had air bubbles and once expelled it works much better...
But there seems to be little rhyme or reason to the temp sometimes. Just as long as it stays below 110 then you should be fine....
OK, thanks for that. So if I assume for now it's an air-lock, was my description for bleeding correct? I've read loads of conflicting views! Presumably the engine must be heated up when the various caps (swirl AND expansion?) are off in order for the water, and air bubles, to flow towards the rad bleed screw...
Yep, I wouldn’t worry about it. I’ve had mine 4 yrs and no problems with temperature. I did a trip in June to France, sat in ‘Bastille French’ holiday traffic in scorching 30+ degree heat for about an hour, just crawling along in first gear. The temperature never once went over 85.
Yet a few weeks after I returned to the UK, in our so-called heat, which was not as hot as France. I was driving through Boston, Lincs and got caught in a little traffic for about 10 mins, and I watched as the temp rose and then sat at 95 degree….!! Bizarre…! Maybe we have a different kind of heat here in the UK…? I wouldn’t worry about it, until it gets into the 100+
jj
Yet a few weeks after I returned to the UK, in our so-called heat, which was not as hot as France. I was driving through Boston, Lincs and got caught in a little traffic for about 10 mins, and I watched as the temp rose and then sat at 95 degree….!! Bizarre…! Maybe we have a different kind of heat here in the UK…? I wouldn’t worry about it, until it gets into the 100+
jj
Def. sounds like air in the system, had simailar symtoms in 450, heater blowing cold air is a dead give away that air is in the system and coolant not circulating. Either there is a leak in the system, or combustion gasses are leaking into the cooling system. With heater set to hot, fill the swirl tank, fill the header tank to half. If still occuring and no obvious leaks, get a test to see is combustion gasses are present in coolant (not sure what this is called) also after a spirited run check the coolant hoses, if combustion gasses are pressurising the system they will be rock solid. Also get radiator checked for blockages. Hope this helps.
cheers.
cheers.
I'm sorry but the advice of not to worry if the temp is below 110 is misleading. It indicates a fault. If left it could develop into a very expensive fault like new heads or a siezed engine. It might be the guage is misreading but equally it could be the engine is trying to tell you something.
It's like playing Russian Roulette a la Derren without the advantage of being able to fix things in your favour.
95 in traffic is normal. See the bible 2 for a detailed temp chart and what goes on.
It's like playing Russian Roulette a la Derren without the advantage of being able to fix things in your favour.
95 in traffic is normal. See the bible 2 for a detailed temp chart and what goes on.
tobeee said:
Now, I've been checking the coolant each week, and topping up the expansion tank (blue capped bottle at front of engine). Should I really be topping up the swirl tank (brass screw-topped bottle in middle of engine)?
Can't solve your problem, but in normal circumstances checking and topping-up is via the blue-capped expansion tank. Halfway up is the correct level, though my Griff 500 seems to run about 1/2" below.
Looked like it was losing a few inches off the expansion tank each week, but from information I've picked up here and in the bible, it might just be that its been rejecting excess under pressure and settling at a comfortable level. After the overheat yesterday, the level was lower than usual though. Could be a leak somewhere - I guess I'll have a go at bleeding it tonight, and book it in somewhere (Barnet?) for a check-up.
You've checked the fans which is the first suspect - the next most likely explanation is low water or an air lock - especially in the rad. Any time the heater blows cold instead of hot is a potentially serious problem, this suggests you have had nil water flow for a significant time. As the heater cools down, so the cylinder heads will be heating up and if the engine is working hard they can quickly get hot enough to cause damage. This is the main reason you should stop and check you still have a fan belt any time the no-charge warning light comes on. Losing the heater, or gradually running the battery down, isn't a problem. But these faults will also destroy your engine very quickly if ignored.
The heater was just not blowing the volcano-like temperature I'm used to - mind you, I did have the roof off and it was pretty chilly, so maybe the heater's a red herring! I use the car daily (20 miles a day) and check the water etc at least weekly, so can't imagine any damage has been done. I stopped before I saw 95 on the gauge, and only really panicked then as it's been consistently 90 and below in the three weeks I've owned it.
I'll do some air-lock checks tonight, then take a view. Thanks all for your responses.
I'll do some air-lock checks tonight, then take a view. Thanks all for your responses.
GreenV8S said:
Any time the heater blows cold instead of hot is a potentially serious problem, this suggests you have had nil water flow for a significant time.
in the first instance check the swirl pot, If it's full it's unlikely that the radiator is empty If the swirl pot is empty I'd top it up and bleed the rad (bolt at the top near the screenwash fill hole)
Take ti for a spin and check it again
If air has got into the system, filling the expansion bottle won't help
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