Operating Temperature
 

Hi all. Over recent months I have had new belts, thermostat, water pump, 2 speed fan and radiator. Temp is rising to 110 in stop start traffic before high speed fan brings it down. Operates at 92-97 in free flowing traffic. Getting cool air in passenger footwell and hot in drivers. Any idea what could be causing 110 operating temp and is this a problem?

Sure you don't mean low speed fan? All fairly normal, the fan's doing it's job but your heater matrix is probably blocked.

Regards

I beg to differ Mike. The slow speed fan should run well before 110 degrees is reached.
Dave,

First of all and most importantly, your profile says that you haven't got a car. :duh: If we are to help you with any degree of accuracy you need to tell us which engine you have. This is essential information in order to diagnose cooling system problems. So please could you correct your profile straight away. Please don't tell us in a posting and leave your profile as it is. Many thanks.

To answer your question in general terms:

• Fan resistor open circuit.
• Air lock in cooling system.
• Expansion tank cap seals flattened.
• Other defect in cooling system preventing proper pressurisation.
• K-seal.

Yes, it's a problem.

Simon

Sorry Simon misread the post to mean 100. Specsavers ?

Mike

2.5 V6. Cooling fans coming on at 100 and 106.in traffic. It will cool down to 92 via fans and driving. Then will go back to 105 plus when it hits traffic again. Sometimes it will go down from 105 to 92 in seconds. I've also had it sat on the driveway at home and the low speed fan at 100 soon cools it back to 92. So it seems to do this high temperature thing only whilst driving and when in lots of stop start driving.

So what is the problem?

It occurred to me that the temperature fluctuations were quite large and I would have thought that the slow speed fan would have kept things in check most of the time. Is it normal for the high speed fan to come on regularly in stop start traffic? I have also seen 110 which worried me a little.

You've fitted a new 2-speed sytem in your KV6 I believe?


TC

Yes, normally the low speed fan should keep things in check. But with that, you can see 105 degrees.
I would try and clear all debris out from behind the fan motor. There most likely is quite a bit sitting in the "shadow" of the fan motor. That means no air is passing here.
How have you read your temperatures?
And how do you drive?. Coming off a highway and stopping in stop start traffic will mean a lot of pent up heat has to be released.

Yes it's a new two speed fan that is coming on at the correct temperatures according to the OBD. The issue seems to arise when it hits heavy traffic after a fast drive on a motorway or similar. If I leave the car for a couple of hours it will soon display high temperatures again particularly in stop start traffic. If I leave it overnight and then go for a leisurely drive on A roads and little stop start traffic, then it will operate at about 92-96.

Kv6
 

Dave, I think you are referring to the slow speed triggering at 100 increasing to the medium speed at 106, am I right?
There's a problem with your cooling system. It should not need the medium speed at all if it's working correctly as you say here:
You are absolutely right.
No.

See my post no. 3 for possible reasons for this.

Simon

The heat imbalance from each side of the cab heater is a sign that the matrix is silted up. A hosepipe back-flush with the inlet/outlet hoses detached from the system may well fix it.


Did the reported temperature/fan activity start when the new fan was installed? Is it an MGR fan or after-market?



TC

Thank you for the responses. The two speed fan system is working at the correct temperatures according to the OBD so perhaps this is a pressurisation issue. I will buy a new expansion tank cap and if that doesn’t work I will get a reputable garage to refill and bleed the coolant to eradicate any possible air lock. Lots of niggly problems for what otherwise is a good car to drive.

Apologies for my confusion Dave. I see that you have said several times that you have a 2 speed system. Thanks for the correction.
I would urge you to do that yourself but if not, print the MGR procedure specifically for the KV6 and give it to them.

Simon

Any info on this Dave?

TC

Hi TC. I do not know if it was doing this before the fan change. The failure of the previous three speed fan system prompted me to change the fan. Why do you ask? Have you seen this before? It is an MGR fan.

Since the low speed is working normally, the effect you describe - -

"The issue seems to arise when it hits heavy traffic after a fast drive on a motorway or similar."
- - sounds to me like a heat soak effect, as alluded to by Kaiser.

There's a simple way to check this. Repeat the routine so the 'high' speed operates after a brisk run. As soon as it's safe to do so (within say 5 minutes) park up and turn the engine off. If the fan continues to run (for up to 10 minutes from the point 'high' speed came on, then it's heat soak and a normal function of the system. You can see this in the operating parameters of the older 3-speed system. Unfortunately, MGR never got to produce a similar diagram for their later 2-speed models, but a similar function will be retained. However, if the fan stops when you turn off the ignition, there's probably another factor to look for.



https://www.mediafire.com/convkey/4b...1flzbr4u6g.jpg
When replacing the original 3-speed system with a plug'n'play 2-speed, you obviously drop one of the old settings. I can't remember which one, but it doesn't really matter. You only have two speeds.

Of course, the heat soak events may be more frequent and from less obvious situations if there's an underlying cooling system/coolant problem.

TC

The symptoms which Dave is describing are exactly what happens when a system isn't pressurising properly. The cooling effect becomes highly dependent upon road speed and running temperature varies widely. I've been through this years ago with my SD1. I eventually found a failed brazed joint on the expansion tank. So I'm not sure that it is a heat soak event.
I would suggest that the chart applies to the 2 speed resistor fans as well since the control software is within the ECM and it cannot "know" which type of fan is plugged in, particularly as 2 and 3 speed fans were fitted to cars in an apparently random fashion up until the end of production.

So since it's said that the 'heat soak' condition triggers the medium speed which doesn't exist on a 2 speed fan, I'd like to ask if any KV6 owners with 2 speed fans have witnessed this.

Simon

Thanks. The fan has not continued to run after switch off so I think it could be a pressure issue. New cap ordered from Rimmer Broa so let’s see if that works.

Ah OK. but the temperature increase under the driving conditions you note - - The issue seems to arise when it hits heavy traffic after a fast drive on a motorway or similar.- - are consistant with heat soak (dissipation) from the brisk activity. It's a perfectly natural effect, but is clearly exacerbated by loss of coolant.


TC

[QUOTE=SD1too;2775726]I didn't say the ECU knows what type of fan is fitted. It's simply down to the differences in motor brush and relay wiring and is totally independent of the ECU. So, when the 2-speed replaces a 3-speed all four brushes in the motor are permanently in circuit and it runs at what might be described as 'medium' and 'high' speeds. In effect, the old low and medium duties are both provided by 'speed 1' in the new system.

But to justify your doubt you should also ask if any KV6 3-speed owners have witnessed heat soak operation. I'd expect similar statistics since the potential for engine-off 'after boil' exists whether it has a 3-speed or a 2-speed fan. I can confirm that the MEMS/2-speed triggers heat soak cooling in the 1.8T - for up to five minutes as I recall. I note the KV6 is set for up to ten minutes, logically because of its larger thermal capacity. I don't think heat soak is covered by RAVE, the MGR diagram is from elsewhere.


TC

All evidence is potentially useful but on the face of it the "heat soak" condition would not trigger the fan on a 2 speed system. This is because the connection which the ECM earths (UY) to achieve this is not connected to the fan control box at all! This is why I am interested only in the 2 speed system.
That's incorrect I'm afraid. The chart which you have reproduced is from RAVE.

Simon

The heat soak cooling on a 2 speed fan certainly works.

:smilie_re: https://the75andztclub.co.uk/forum/s...d.php?t=297755

I've just re-read that thread and charlie_22 actually says the opposite. Here's an extract from his opening post describing that his fan doesn't run after stopping the engine:
Unfortunately he doesn't ever tell us whether or not his coolant temperature reached the threshold of 115 degrees so the thread doesn't help us.

Simon

I have re-read the thread too and you are quite correct! :}

Sounds like the cars heater system needs a good clean out on the liquid side of things for the cold and hot footwell.
The fan on the cars coolant Rad I would expect to run full time engine on or off if the sensor was above 115 degrees. Your fan has four speeds or three depending how you look at it.
1: not running
2: low speed
3: medium speed
4: high speed
Hope this helps


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Poor flow through the heater won't cause high coolant temperature Alan.
Dave's fan has two speeds, as he states in the post you've quoted.

Simon

So the KV6 'after-boil' protection is likely absent where a 2-speed fan is fitted? It seems implausibe and something that should be checked out. Just needs a few volunteers and a hot summer.



TC

Plus, I would contend, a faulty cooling system.

I have the original 3 speed fan. I have never heard the radiator fan operate after stopping the engine, even in the hottest summers (after all, the coolant temperature has to climb to 115 degrees).

Simon

But that doesn't prove much does it.
Maybe try hauling a big caravan, at the limit, in hot weather, perfect cooling system and you hit a road block. That's volunteering.


TC

I shall clarify a couple of points if I may Simon, in the interest of preventing confusion.

There is a facility within the SA string of ZCS coding to differentiate between there being a two or three speed fan fitted, and the PWM output of the ECM is adjusted accordingly to which type is fitted ;)

Two speed fans were fitted to all cars of 4D model years from VIN 324474, anything else was not originally fitted at the factory.

Brian :D

We are talking about the KV6 here not the diesel so I'm not sure where a "PWM output" comes into it. :shrug:

Could you please tell us exactly how the fan control is modified following these coding changes for both KV6 and diesel ECM. Without that information we are no further forward.

Simon

Could somebody provide me with MGR instructions to fill and bleed the cooling system? Thanks.

Simon you are quite correct but the control circuit has three, and it can not know what fan is fitted, what happens is the slow and medium speeds become speed 1 and the high speed remains the same. Hence the need for a resistor heat sink on the wiring.
So the three speed protocols still apply.
As to the possible poor water flow you are correct it would not cause a high coolant temp but it could cause the poor heat transfer on the passenger footwell.
The only way to check the possible overheating would be to run the engine and take digital temperatures of the coolant temp.
Then remove the engine thermostat and see what the difference in the graphs are on the same protocols used with the stat in place.
This will allow to determine if the engine is running hot or not or if a sensor is off. You can buy adhesive colour strips in 5 degree and 10 degree increments. These small inexpensive strips are often used in CHP units worldwide and also in motor sport. There great for a reference check.
Hope this info helps any confusion I caused.
Basically the fan runs at two speeds but the car thinks it has three.
Which is one of the reasons we fit heat sink resistors to protect the fan.
Alan



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Just thought I would bring Dave’s original post back into the thread. Then make a Statment I have made many times. Just because a thermostat is new does not mean it is working properly. It is just a tin full of paraffin wax after all. Also where are you getting your temperature readings from. I am hoping the answer to the latter is live time OBD2 readings as that is where the car is getting its info from.
Alan


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Just another thought Dave your post states that you have changed water pump stat and rad. Was this because the car was overheating?
The car now has a two speed Fan what did it have before you changed it?
Very silly question, are you sure the coolant system is air lock free?


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Here it is Dave.

Simon

Thank you for the various responses. The readings are being taken from the OBD pressing 19 - 7. The water pump and belts were changed when I purchased the car in July. The radiator and thermostat were changed as both were leaking. The fan was changed as I lost low and medium speeds on the previous 3 speed fan. I have fitted a new radiator cap and the system is holding pressure but does need a little top up every week. The pressure dissipates when the car has cooled down and there is no visible white smoke from the exhaust apart from at start on a frosty morning. The oil is clear. I have heard the sound of gurgling water from behind the dash at start/idle so the next step is to ask a reputable local garage to bleed the system to see if there are any air locks. Unless someone has another idea? Thanks.

Your gurgle will be an air lock they can be very difficult to chase out the system. I still suspect the stat is either opening late or not fully opening. If the weather down South is even 10 degrees warmer than up here, just now, I would not expect the car to be getting that hot in traffic in the summer yes I would expect the car to be calling for its fan every five mins in the town. Have you access to a digital sight thermometer to check on temperatures.
It could be the sensor is off. If you want a lone of one PM me and I will stick one in the post all I ask is when you are finished you return it. If you do want to borrow I will get one of the grand kids to go into the bowels of the garage and look for my engine diagnostic pit lane box I think there may be some colour change temp strips still in there if they are there and are in the correct temp range I will stick them in and you can stick them to the engine which will give you the block temperatures. Better on your car than in a box hiding for twenty years.
Alan


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Completely different principle I'm afraid. The 75/ZT systems, including the temperature gauge, operate digitally. This means 'electronic data' are sent over shared, multichannel 'buses' rather than by the old analogue, electromechanical way.


TC

Before global warming :D
When cars were cars and men were not afraid!

The 75/ZT systems are actually partially digital, this principally being intercommunication between ECUs (including the instrument pack). Otherwise there are still a large number of electromechanical and analogue devices to be found. In the case of the temperature gauge, the 75/ZT's coolant sensor is a thermistor (just like the part fitted to David's SD1 built over thirty years ago). Its output is analogue as far as the ECM.

Simon

I thought I would provide an update. Upon further investigation coolant was found in the V of the engine due to a leak in one of the pipes close to the thermostat. A thermostat kit was purchased from Rimmer Bros and so far, the problem appears to have gone away. It will slowly reach 100 degrees in heavy stop start traffic and the fan cools it to 94 quickly. Normal operating temperature is in the region of 89 to 93. Fingers crossed it continues to behave.

Can only speak for the 1.8t - but a few years ago my first inkling something not quite right was the 2 speed cooling fan running when the car was parked and engine off - had A leaking IMG.

I can honestly say, this is the only problem I DIDN'T have with my SD1 :icon_redface: