over heating at motorway speeds HELP
Discussion
As has been said above, you now need to be looking at stat, pump, air locks & any collapsed hoses or pipes partially blocked.
As the engine is running under partial load and running fine when it needs a low level of cooling.
But not so when under a heavy load and needs more cooling there must be something causing restricted cooling water flow.
As the engine is running under partial load and running fine when it needs a low level of cooling.
But not so when under a heavy load and needs more cooling there must be something causing restricted cooling water flow.
SlimJim16v said:
FordPrefect56 said:
Honest to god, do any of you people who try to be helpful actually know the tiniest thing about engines? If the thermostat was stuck closed it would overheat all the time, as it would if it were water pump or head gasket. If the thermostat was stuck open it would never overheat and take ages to get up to temperature, if ever. The main thing that causes over heating at high speed but not low is a knackered radiator. Blocked, fins rotted away, whatever.
Yep, this.FordPrefect56 said:
E-bmw said:
As has been said above, you now need to be looking at stat, pump, air locks & any collapsed hoses or pipes partially blocked.
So basically every part of the cooling system? That narrows it down, lol.He's flushed the system, good first step, he's changed the radiator, wouldn't be my second step but it's done now, next step is thermostat and so on, methodically.
Might be a silly question but what happens with the temp gauge? OP only mentions warning light coming on, is it fair to assume that if overheating when at motorway speeds then backing off allows the gauge to drop, and booting it again causes another rise?
Hello chaps.
As a quick round-up, here are the steps we have completed so far...
1. Flush - new coolant
2. Flush again - new coolant
3. Flush at local garage (they were replacing a top mount) - new coolant- new rad cap
4. New thermostat - flush - new coolant
5. New radiator - flush - new coolant
6. new 02 sensor - new airflow temperature sensor - new fan sensor, air filter (bit of a long shot but would eliminate any poor running issues)
So step 7 is new water pump and will have the cambelt done. Unfortunately this is beyond us so it's going into the garage.
Step 8 will be the head gasket.
Here a shot if the temp gauge. Interestingly, this is as high as it goes when at motorway speed, slow down and it will drop down again slowly, speed up and it climbs quickly.
As always, any advice greatly appreciated.
As a quick round-up, here are the steps we have completed so far...
1. Flush - new coolant
2. Flush again - new coolant
3. Flush at local garage (they were replacing a top mount) - new coolant- new rad cap
4. New thermostat - flush - new coolant
5. New radiator - flush - new coolant
6. new 02 sensor - new airflow temperature sensor - new fan sensor, air filter (bit of a long shot but would eliminate any poor running issues)
So step 7 is new water pump and will have the cambelt done. Unfortunately this is beyond us so it's going into the garage.
Step 8 will be the head gasket.
Here a shot if the temp gauge. Interestingly, this is as high as it goes when at motorway speed, slow down and it will drop down again slowly, speed up and it climbs quickly.
As always, any advice greatly appreciated.
Edited by Itsallicanafford on Sunday 29th May 14:00
Edited by Itsallicanafford on Sunday 29th May 14:08
That's a valid point, it could be a problem with a sensor. On the other hand whilst it's not unknown for temp gauge to rise when an engine is worked hard it's usually minor shifts ime. In fact the only time I've experienced this was firstly a stat which wasn't opening fully, and secondly on my old GPS RS2000 rally car where the cooling system was inadequate on long stages, even two Kenlowe fans running permanently couldn't cope. You'd switch the fans on, thus overriding the thermostat switch, a mile or so before the stage start, and by the end of a 20 miler the engine would be fizzing gently.
Second thought about op problem, if used for track days does it have an oil cooler? Worth it I reckon.
Second thought about op problem, if used for track days does it have an oil cooler? Worth it I reckon.
You seem to be throwing an awful lot of time and money at this but only a miniscule amount of thought! From everything I can see so far you don't actually even know whether the engine is overheating and haven't tried even the most basic of tests to find out. The warning light shouldn't come on until the engine is close to melting and certainly not when the needle is still in the normal part of the gauge. On my car the warning light is set for 125C. Your manual should say what it is on your own car. Anything from about 118C upwards probably depending on the system cap pressure. The radiator fan should be on long before this. Maybe from somewhere between 105 and 110C.
Sit the car on the drive. Rev it gently to get it hot fast. Does the radiator fan come on? Where is the needle on the gauge at this point and has the warning light come on. The fan should be on long before the warning light and before the needle reaches the red. Does the fan cool it back down quickly? Does putting the heater on full help with this? Is the radiator hot all over? Does properly hot air come out of the heater? Does it use any coolant at all? Have any of the hoses been re-routed from their correct positions or is all the cooling system still standard? Are there any high spots in the hose runs where air could be getting trapped? Can you get it hot enough to create steam or lose any coolant before the fan kicks in? Does the warning light only indicate excessive temperature or is it also designed to indicate low coolant level? Did you ever think to check the manual to find out?
It ain't rocket surgery. Just fairly rudimentary tests and thought process before lashing out on things that weren't faulty in the first place. So far it could just be a dodgy temperature sender triggering the warning light too soon and it's never overheated at all.
Sit the car on the drive. Rev it gently to get it hot fast. Does the radiator fan come on? Where is the needle on the gauge at this point and has the warning light come on. The fan should be on long before the warning light and before the needle reaches the red. Does the fan cool it back down quickly? Does putting the heater on full help with this? Is the radiator hot all over? Does properly hot air come out of the heater? Does it use any coolant at all? Have any of the hoses been re-routed from their correct positions or is all the cooling system still standard? Are there any high spots in the hose runs where air could be getting trapped? Can you get it hot enough to create steam or lose any coolant before the fan kicks in? Does the warning light only indicate excessive temperature or is it also designed to indicate low coolant level? Did you ever think to check the manual to find out?
It ain't rocket surgery. Just fairly rudimentary tests and thought process before lashing out on things that weren't faulty in the first place. So far it could just be a dodgy temperature sender triggering the warning light too soon and it's never overheated at all.
FordPrefect56 said:
You seem to be throwing an awful lot of time and money at this but only a miniscule amount of thought! From everything I can see so far you don't actually even know whether the engine is overheating and haven't tried even the most basic of tests to find out. The warning light shouldn't come on until the engine is close to melting and certainly not when the needle is still in the normal part of the gauge. On my car the warning light is set for 125C. Your manual should say what it is on your own car. Anything from about 118C upwards probably depending on the system cap pressure. The radiator fan should be on long before this. Maybe from somewhere between 105 and 110C.
Sit the car on the drive. Rev it gently to get it hot fast. Does the radiator fan come on? Where is the needle on the gauge at this point and has the warning light come on. The fan should be on long before the warning light and before the needle reaches the red. Does the fan cool it back down quickly? Does putting the heater on full help with this? Is the radiator hot all over? Does properly hot air come out of the heater? Does it use any coolant at all? Have any of the hoses been re-routed from their correct positions or is all the cooling system still standard? Are there any high spots in the hose runs where air could be getting trapped? Can you get it hot enough to create steam or lose any coolant before the fan kicks in? Does the warning light only indicate excessive temperature or is it also designed to indicate low coolant level? Did you ever think to check the manual to find out?
It ain't rocket surgery. Just fairly rudimentary tests and thought process before lashing out on things that weren't faulty in the first place. So far it could just be a dodgy temperature sender triggering the warning light too soon and it's never overheated at all.
As ever, many thanks for the reply, much appreciated.Sit the car on the drive. Rev it gently to get it hot fast. Does the radiator fan come on? Where is the needle on the gauge at this point and has the warning light come on. The fan should be on long before the warning light and before the needle reaches the red. Does the fan cool it back down quickly? Does putting the heater on full help with this? Is the radiator hot all over? Does properly hot air come out of the heater? Does it use any coolant at all? Have any of the hoses been re-routed from their correct positions or is all the cooling system still standard? Are there any high spots in the hose runs where air could be getting trapped? Can you get it hot enough to create steam or lose any coolant before the fan kicks in? Does the warning light only indicate excessive temperature or is it also designed to indicate low coolant level? Did you ever think to check the manual to find out?
It ain't rocket surgery. Just fairly rudimentary tests and thought process before lashing out on things that weren't faulty in the first place. So far it could just be a dodgy temperature sender triggering the warning light too soon and it's never overheated at all.
Too be honest, we have done most of the above tests, but I will pick up on a few points:-
If you sit on the drive and rev it, it wouldn't bring the light on, it really seems to be only under driving load and above 50mph.
The fan does come on but I thought it was coming on quite late so changed the sensor in the rad. The rallye does has an interesting fan design (might be common with other 8 valve TU engines) in so much as it has one fan and an empty carrier for a second). The fan being on or off really doesn't seem to touch the water temp.
I know of some Rallyes which have a second fan retro fitted, I'm going to PM the owners to see why exactly.
The heater works fine, good heat.
The original rad was hot all over.
The pipe work looks in it's original configuration, the pipes all look ok when cold or hot.
The manual states the temp gauge should sit in the normal area (the picture I posted earlier shows it at the very top of normal.) the manual states the light comes on when the car is over heating.
In regards to if it is actually over heating, apart from the light, when you stop you have a nice puddle of coolant forming under the car as it escapes through the filler vent. This happens when the rad has not been over filled. Also, in the 1500 miles I have done in the car, it never used to do this, water temp was good , registering around half way after spirited driving.
As far as the spend is concerned, I'm less worried about this than loosing a precious track day as with small kids these are my life line to sanity! The 106 really needs to be 100% fighting fit as although it gets driven at least once a week for my 50 mile commute to keep it in shape, on track days it's going to typically do 300 road miles and 100 track miles so it needs to be in first class nick to cope with this. Also, a lot of these parts I've changed I would file under preventative work, you should have seen the state of the 02 sensor! All in I think I have spent £150 odd on parts as they are all standard 106 so cheap.
I think the cam belt/ water pump change is prudent now as I should have done this when I purchased the car 6 months ago as there is no record of it being done as the car has no history.
Thanks again for the ongoing help, much appreciated.
I was almost ignoring this thread as knew it would probably be daft.
But....2 pages in and its seems the OP doesnt even know what temperature things are getting to, or whether it actually is overheating or not ?
Which is kind of important when trying to chase an overheating issue.
Relying on crappy and terribly inaccurate OEM style gauges...and French ones at that. Not really any sort of proper diagnostic.
Even more so when the OP doesnt seem to offer any actual signs/symptoms of overheating
But....2 pages in and its seems the OP doesnt even know what temperature things are getting to, or whether it actually is overheating or not ?
Which is kind of important when trying to chase an overheating issue.
Relying on crappy and terribly inaccurate OEM style gauges...and French ones at that. Not really any sort of proper diagnostic.
Even more so when the OP doesnt seem to offer any actual signs/symptoms of overheating
Right one more thing, I had two Pugs with a TU engine. Both of them started this chucking out water from a vent after a hard run, though didn't have overheating problems. Both were initially diagnosed as head gasket failure, combustion gases detected in coolant, on the second one that solved it, the first one needed a replacement of a porous cylinder head.
Itsallicanafford said:
Hello, the symptoms have been the gauge and also the puddle of coolant on the floor after every use.
But it is true we haven't done any formal diagnostics apart from the checks highlighted above, what would you suggest?
So there is no evidence of actual overheating but there is some evidence of a small leak.But it is true we haven't done any formal diagnostics apart from the checks highlighted above, what would you suggest?
Obviously I would suggest getting an accurate indication of temperature and tracing that leak lol Then go from there.
This encapsulates the difficulty with trying to help people on here. So often you only get a bit of the story to start with, the bit they thought was relevant which in this case was vehicle speed. That points straight to radiator as a first point of call. However now we find there's a lot more to it although much still appears to be contradictory. To start with you said it never boiled over and now you say it loses water from the fill vent with puddles under the car!!! I also find it hard to reconcile the fan supposedly not doing much with the warning light not coming on at all when the car is stationary. Either the fan is cooling the engine sufficiently to stop it overheating or it isn't. It can't be both.
It makes absolutely no sense that you say this issue never manifests below 50 mph however hard you drive it but does so immediately at cruise at higher speed. The engine load and combustion chamber pressures are really not that high at cruise even at 70 mph. If this is a gasket leak or porosity issue manifesting when combustion chamber pressures blow into the cooling system then you should be able to generate those pressures at any speed or just by blipping the throttle hard on the driveway. You're also generally using higher revs (if this was anything to do with the water pump) when you're on B roads and accelerating all the time than when you're in top gear at cruise. In other words it's vanishingly unlikely to be the water pump if that's what you're really thinking of paying for next.
Too much not making sense here. Maybe you really only see the overheating after it's lost enough water and that only happens on a longer, higher speed trip. If you want to pay for something sensible then get a pressure test and a sniff test done.
It makes absolutely no sense that you say this issue never manifests below 50 mph however hard you drive it but does so immediately at cruise at higher speed. The engine load and combustion chamber pressures are really not that high at cruise even at 70 mph. If this is a gasket leak or porosity issue manifesting when combustion chamber pressures blow into the cooling system then you should be able to generate those pressures at any speed or just by blipping the throttle hard on the driveway. You're also generally using higher revs (if this was anything to do with the water pump) when you're on B roads and accelerating all the time than when you're in top gear at cruise. In other words it's vanishingly unlikely to be the water pump if that's what you're really thinking of paying for next.
Too much not making sense here. Maybe you really only see the overheating after it's lost enough water and that only happens on a longer, higher speed trip. If you want to pay for something sensible then get a pressure test and a sniff test done.
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