Overheating at high speed
Discussion
My OH's late Mark 1 1.8 has never moved its temperature gauge above the mid-point in its 150,000 miles.
Yesterday on the A34 I was driving it at a good L2 speed and I noticed that the temp had crept up almost to the top.
I backed off and very gradually it cooled down, heating up again whenever I went up a long hill. Whenever we got on to a single carriageway road it swiftly cooled down to the mid-point and stayed there.
On getting home I had a good look round under the bonnet. The radiator was a bit low (maybe 1 litre max?) on water, but there were no signs of leaks or drips anywhere. It hasn't lost any overnight.
There does seem to be a patch of splattered oil in front of the engine. Related?
My diagnosis of the symptoms is that something is preventing water moving round the cooling system quickly enough, so either:
Water pump dying
Radiator full of muck
(both the above are the originals so have done a fair tour of duty)
Water level low enough to prevent efficient flow
Thoughts?
It rarely goes on dual carriageways so I think I'm happy to let my OH keep driving it 15 miles to work and back until I can get it to the garage in about a week - as long as I keep an eye on the coolant level.
Yesterday on the A34 I was driving it at a good L2 speed and I noticed that the temp had crept up almost to the top.
I backed off and very gradually it cooled down, heating up again whenever I went up a long hill. Whenever we got on to a single carriageway road it swiftly cooled down to the mid-point and stayed there.
On getting home I had a good look round under the bonnet. The radiator was a bit low (maybe 1 litre max?) on water, but there were no signs of leaks or drips anywhere. It hasn't lost any overnight.
There does seem to be a patch of splattered oil in front of the engine. Related?
My diagnosis of the symptoms is that something is preventing water moving round the cooling system quickly enough, so either:
Water pump dying
Radiator full of muck
(both the above are the originals so have done a fair tour of duty)
Water level low enough to prevent efficient flow
Thoughts?
It rarely goes on dual carriageways so I think I'm happy to let my OH keep driving it 15 miles to work and back until I can get it to the garage in about a week - as long as I keep an eye on the coolant level.
Johnnytheboy said:
It feels like oil - gonna ring the garage today!
Don't forget coolant has antifreeze etc in it.It used to be quite common on MX5 forums to hear this exact story and for it to be the rad was clogged up with the usual gunk you get in there after a while. A new rad or a damn good flush out fixing it.
Munter said:
Johnnytheboy said:
It feels like oil - gonna ring the garage today!
Don't forget coolant has antifreeze etc in it.It used to be quite common on MX5 forums to hear this exact story and for it to be the rad was clogged up with the usual gunk you get in there after a while. A new rad or a damn good flush out fixing it.
I've fitted a 'proper' temperature gauge to my Mk1 & at motorway speeds (80+mph)in the high temperatures we've seen this week, it's running at 90-95 degrees, but the standard gauge doesn't move a millimeter!
That's with new radiator & water pump/coolant last year, so these cars do run hot anyway, without any blocked rads etc!
That's with new radiator & water pump/coolant last year, so these cars do run hot anyway, without any blocked rads etc!
MX-5 Lazza said:
It will be the rad. Sounds like you got the right diagnosis.
Temp gauge isn't a true linear gauge. It basically shows cold, warming, "normal", boiling and FUBAR. Anything above "normal" is a problem and jumps to FUBAR very quickly.
What temps are you showing on a proper temp gauge, just out of interest? With fresh coolant & new standard rad, mine's running at 90-95 degrees on motorway run in the recent hot weather Temp gauge isn't a true linear gauge. It basically shows cold, warming, "normal", boiling and FUBAR. Anything above "normal" is a problem and jumps to FUBAR very quickly.
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