My ‘97 Mk1 1.8i has and is running brilliantly, except that in the last couple of days since the much warmer weatherI’ve notice my temperature gauge climbs to the Hot zone by the time i get home after 9 miles of motorway and some idling in traffic near home. In colder or normal temperatures it is stable (just to the left of middle on gauge); but it’s these hotter ambient temps that appear to push it to the H. Once moving at a reasonable speed it retreats to the middle more with the ram air effect, and i know the fan is kicking in and working.
Do any of you guys have the same thing? Is it a 5 thing? If not, any ideas? I’m not sure if i should be concerned or not. It runs fine even when showing Hot but its a little disconcerting and it my first summer with the car so can’t compare it to last year. (Did we have a summer last year?)
Reads to me like a radiator cap,thermostat, or air/sludge blockage issue. However, Thermostats are designed to fail open, thankfully. How does the coolant look in the header tank? Murky or fresh? Air in the system? Neither of our 5’s go to the red and never have.The needle ought to at worst tip past the halfway mark just a tiny bit even in the most hot circumstances so no, it’s not normal. At the risk of stating the obvious, check that winter leaves or detritus is lodged in the radiator. Maybe a pheasant or two? !
Failing radiator, failing fan, radiator cap failure, dying water pump, could be a range of things. You can test the fan motor though; the bushes can wear out (unfortunately, its non-serviceable), but the fan should really last the life of the car, unless its coming on too often, if there is some other underlying problem why the car is running hot.
Check the coolant level in the expansion tank; are you loosing anything. If so, suspect failing radiator cap, or the plastic top of the radiator has failed.
Test the fan; is it spinning as fast as you expect. Worn fans tend to turn at variable speeds, and a bit slow.
Thanks for the pointers and advice. I also nmanaged to the friendly guys at Autolink too on the w/e and they reckon a radiator efficiency issue as the most likely cause at this stage, and after checking rad on their advice, there appears to be patches of it that have differing temperatures to the touch, more on the fan side than anything so thats a double ineffeciaency whammy. So a failing rad makes sense, it will also be the reason why the car warms up really quickly too I suppose and I thought it just had a fantastic heater system!
And just to finish this thread (for future searchers):
The temperature gauge normally has a dampener on it; it won’t normally move around too much with water temperature; if it does move to the right, the engine is HOT.
This gauge can be modified to simulate a linear response (by changing a resistor). So, make sure you are looking at a standard gauge, rather than one that has been modified by a previous owner. If the car is really running hot, there is usually some other signs as well. Somewhere out there, someone has renewed the tax on my old red 1991 Roadster (J485 GAL), that I sold back in 2005 (with 140k on it), and that car had a linearised gauge (so the gauge needle does move around a bit).
My mk1 1.8 colling system is playing up as well so a little advise is also needed. My car seems to overheat but the gauge only ever goes to just below half way, the coolent in teh expansion bottle bubbles and leaks out of the overflow after a long and/or hardish drive thou the radiator always seems full. we thought it may be an air lock as the car had been sitting for 6 months so we flushed the system and replaced all the fluid but it still does it. we also checked that the fans where coming on and the drivers side one does but the passenger side doesn’t (my car has aircon). any ideas on what i should (or my mechanic little bro more to the point) shoudl try/replace first. cheers in advance for your help.
I’m no expert so I’d give Autolink or Mazda mender a call as they know their onions and diagnosed my problem. I would have thought an air lock too would have been prime candidate. But it sounds like you might have more than one issue possibly. Maybe a faulty temperature sender and/or thermostat?? Are you getting the correct amount of fluid out as well as in?? And I assuming you ve not got a radiator with patches of differing temperatures.
Well first off it sounds like your fans are connected the wrong way round the cooling fan is on the pasenger side and the Aircon fan is on the drivers side as the wiring been messed with?, just beacuse you have flushed the system does not mean that the rad is free from years of build up(lime scale) it blocks the flow in the rad so does not work correct, when she gets up to running temp,do you have anyway of testing the temp of the rad on both side where the rads are, maplins have a offer on at the min, £20 for a lazer pointer temp gauge, worth getting to check if the temp is low and a safe way to check so you don’t lose didgets, if the temp is lower on one side to the other by a lot,then it’s a new rad.
It may be a faulty pressure cap, if pressure isn’t maintained the coolant will boil at a lower temp. It could also be a blowing head gasket, perhaps have the coolant tested for exhaust gas.
I got it wrong about the fans it is my passanger side that is coming on so at least the wiring is correct.
I arrived home last night to be greated by a puddle under the car which wasnt there in the morning when I left and the car hadnt been used since sunday night.
this time no coolent left in teh bottle or in the rad. think i’m just going to save the hassle and by a new rad & cap, temp sender, thermostat and then pray it isnt my head gasket.
… Both of my thermostat failures have failed closed. I don’t know how they could be rigged to fail ‘open’ as their resting state is ‘closed’, hence failure in the closed position…
Sorry about that. In the early days of my ownership, I was assured that OEM ones are indeed designed to fail open. I just accepted it as I knew no better.
Perhaps, and I’m only guessing, this is one reason why we are recommended only to fit pukka OEM examples.
When mine failed, it failed open and being an auto…whose ECU “talks” to the engine ECU, I was stuck in 2nd for around 20 miles in cold weather before the engine got to full temp to allow change ups…all to do with Japanese emission standards seemingly. Odd, but there we go.
Had a very minor leak on the rad of my old Eunos. Bought a dirt cheap brand new one from eBay which to my untrained eye looked virtually identical to the OEM part. There are new rads on sale at the moment at under forty quid delivered. A twenty year old rad is bound to have quite a bit of sludge build up and can’t see that any amount of flushing will bring it back to full efficiency. Seems like good preventative maintenance to spend about fifty quid and do rad, cap and thermostat.
Yeah!