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