Since recent work my MGF VVC shows a worrying rise in coolant temperature when the car is idling, not moving.
The recent work was head gasket replacement (second one in four years of concession use), new thermostat and housing, conversion to waterless coolant. All work was done by specialist MG mechanic.
On the move, temp is rock steady, one notch below half on gauge, even with air con running. Idling at traffic lights or in slow city traffic, and with fans switched on (bypassed by previous owner and fixed by my auto electrician) temp starts to rise. If I can get on the move asap the temp returns to normal.
Has anybody else had the same issue and solved it please?
If the fans are working as they should, then it can only be either poor coolant circulation or partially blocked radiator. Air in system, failing water pump, or radiator would be my guess.
You mentioned the fans having been bypassed by the previous owner.........due to that little nugget of information, I'm thinking the problem might a historical one that predates the resent works.
Your water pump may have cavitation damage, therefor lacking efficiency And yes the radiator may be internally blocked (The tubes full of crap). or externally blocked (the heat exchange fins blocked with other crap)
But 1st bleed the cooling system from all 3 bleed points. This is easy to do but must be done in the correct sequence. For how to do it you'll find the process in the workshop manual which is downloadable for free from the library section of this site, or look in the "How To's" section of this site for lots of tips and how to guides also free.
Where are you approximately located, this info may help us find you help locally if you need it.
"Keep calm, relax, focus on the problem & PULL THE BLOODY TRIGGER"
How long ago was the work done by a specialist MG mechanic? Because my first port of call would be that person! But on low revs the water pump isn't pumping as fast as it does when the engine in running at a normal road speed. But take it back to the specialist first.
Thank you for the response Cobber.
Unfortunately, the points raised were covered in the head gasket work, and the car now runs waterless coolant, so the cooling system was thoroughly cleaned out as part of the job.
I did notice something strange while testing yesterday. After a short run and the engine left idling, the temp began rising as expected, but when the temp gauge was one graduation short of the red, I switched on the air con. The coolant temp quite quickly dropped towards the normal zone. Do the radiator fans run faster when the air con is switched on even though the engine doesn't? I also noticed that the engine bay fan did not switch on at any time during this test.
One last question please - since the work was done, the alternator belt frequently squeals briefly on start-up and sometimes when driving in wet weather. Does this suggest that the alternator may not be delivering enough voltage to the radiator fans (there is a relay in the circuit)?
I'm located about 160kms south of Perth in Western Australia.
Yeah OK regardless of what coolant is used the bleeding procedure will be the same and should still be done as part of the process of elimination.
Now as to the fans, Yes air flow is increased when the A/C in switched on, A/C equipped cars have an extra radiator fan. this kicks in when the A/C is activated.
So given that everything calms down when the A/C is use tells me your normal fan will need checking for correct operation and your engine bay fan not working is also a problem that needs sorting.
The belt slip is a matter of some concern, you need to check the belt, I'd just replace it anyway and check that the water pump, alternator, idler pulley, A/C compressor all run free, you might have looming bearing problems, and their relative mountings are all good, failure of this belt is not going to do you any favours, especially if it breaks and finds it way into getting tangled it the timing belt.....game over!
You should really have an auto elec bench test that alternator to be 100% sure it's up to the job, however removing it to bench test is a pain in the arse, but at least load test the electrical system to see that it's putting out sufficient grunt to run everything. There are battery/alternaor load testers out there that are cheap and cheerful and go all the way up to hideously expensive. Any half decent Auto elec should have one. it's a pity you're not in Melbourne you could buzz over and we'd throw one of mine on it.
Although whilst reduced current to the fans wont have them running at optimal performance, I really don't think that's the source of your problems. but checking it out is easy and it's another part of the process of elimination. Even if it doesn't solve your current problems you're heading other potential problems off at the pas!
As a matter of interest which brand of waterless coolant is being used?
I also don't think the waterless coolant is a contributing factor to your dramas. I'm just curios.
"Keep calm, relax, focus on the problem & PULL THE BLOODY TRIGGER"
Thank you for that quick response and wealth of information. I will be working my way through those ideas as a priority, starting with the alternator belt (hope I can find somewhere cheaper than Rimmers - their freight cost is through the roof now, never used to be) and then on to my friendly auto sparky (choice of two good ones in our little town).
The waterless coolant is Evans high performance waterless engine coolant.
The belt is something you should be able to source locally. it ill have numbers on it that will tell you the length, and count the number of ribs. Just take it into your local parts shop and drop it on the counter they'll be able to measure it even if the numbers have worn off.
"Keep calm, relax, focus on the problem & PULL THE BLOODY TRIGGER"
The belt slip is a matter of some concern, you need to check the belt, I'd just replace it anyway and check that the water pump, alternator, idler pulley, A/C compressor all run free, you might have looming bearing problems, and their relative mountings are all good, failure of this belt is not going to do you any favours, especially if it breaks and finds it way into getting tangled it the timing belt.....game over!
Re reading the first post and acknowledging that on the run the temperature is acceptable does that not suggest that the rad is functioning as it should?
Not had or got air-con so knowledge is a bit limited. So what happens if the air-con is off but the heater is set to high?
It does sound to me like a failing pump as suggested earlier in this topic.
Checking for air locks and bleeding as suggested by the acknowledged experts would however be a good first step obviously.
Surely noisy bearing somewhere is equally concerning. Is it the alternator or from somewhere else such as the water pump?
Offline
Offline
