11 replies to this topic

[brivinci]

So, awhile back I had an issue where my upper rad hose burst and my car overheated. Because the temp sensor is in the intake manifold, it never gave me any indication that the motor was getting hot. It didnt help that it was pouring down rain so I could not see that all the water was escaping out. Since then I have installed a VDO electronic temp gauge and a sensor in the head, where earlier cars have them.

 

So, now I have the stock gauge and the VDO to reference and there is quite a bit of difference between the two. The cars gauge stays perfectly steady nearly all the time. (the sensor is newer and the manifold was completely cleaned out. Correct 88 thermo installed) While the stock doesn't move, the VDO seems to range from 82 and as high as 110c. Typically its around 93c (it reads in fahrenheit so I'm converting). Its been extremely hot here and during a long highway drive I notice it hit the 104 and then 110c mark. That seems too high, no? The rad is the newest style sold by Mini Spares and the aux fans works perfect. At 70mph on a 35c day, maybe I'm asking too much. Just want to make sure I am not doing any damage. 

[Sprocket]

I've got a standard type Mini temperature transmitter screwed into the top of the BMW16v head (where one of the core plugs used to be) and the coolant temperature sensor is fitted into an MPi thermostat housing and sandwich plate. The temp gauge reading changes consistently with the ECU temperature reading.......... temp gauge never goes much above midway.

 

I've never measured the temperature on an SPi the way you have so cannot compare, but the temp readings i'd have thought should be at least somewhat similar. What you have to consider is the location you have your temp gauge is right under the thermostat, and at 105c the thermostat would be most definitely fully open. The fact that the coolant temperature sensor is in the bottom of the inlet manifold is going to loose some heat as it heats the inlet manifold, lose 20 degrees? i'm not so sure. If you also consider the OEM electric fan switch is in the bottom of the rad where its much cooler than at the top, and set to come on at 98c, the engine has to be stinking hot with the temp gauge needle in the red before the electric fan kicks in, while the Minispares two core rad and switch, the fan is set to come on at 92c (remember, this is in the bottom of the rad where its cooler)

 

You could run a wire from a standard Mini temperature sender in the head up to the 13 way connector in the bulkhead, cut and splice it onto the Green/Blue wire leaving the Green/Blue wire from the ECU disconnected, this works the gauge no problem. Its difficult to compare readings from two different areas when the measuring systems are not the same especially when one doesn't really have a scale.

Edited by Sprocket, 05 September 2018 - 09:37 PM.

[Bat]

Hi,

I think there's probably a certain amount of damping of the gauge signal by the ECU to keep the driver panic level to a minimum?

Certainly other manufacturers do it...

Cheers 

[brivinci]

I guess I can assume that if the factory gauge stays where it should (providing all the water hasn't fallen out of the engine of course. ha) then the motor is within the "factory specs". Wondering if seeing 105-110c on an A-series is ok.

[Sprocket]

How do you know the VDO gauge isn’t reading high?

[brivinci]

Honestly, I don't know. If it was accurate, where should I start to get nervous? 

[Screwdriver]

These can be your friend!

 

https://www.cooperca...e-magnolia.html

[Bat]

Hi,

Past 105oC is where I'd start worrying!

The MPI fan doesn't come on until 98oC for instance...

Cheers 

[viz139]

MPi fan kicks in at 105oC and drops out at 98oC . I ran an MPi engine on a carb and fitted a standard temperature sender and Smiths temp gauge which read half way between N and H. When I tested a standard MPi with an infra red stat I found ..."Normal" was about 103oC as oposed to earlier 1275 engines which seem to be about 95oC,

[brivinci]

Maybe it was just the day (being such a hot one) and maybe the VDO gauge is off a bit...or maybe it’s the location I have it reading from. I mean, I’m not sure what else I can do here. Everything is as good as it can be. Mini Spares rad, silicone hoses, late rest water pump (With improved impeller), correct thermostat, new sensors, cleaned out everything, working aux fan, block hot tanked during rebuild. I’d have to imagine that all should add up to a perfectly functional cooling system. I’ll certainly going to keep my eye on it all on those super hot days.

The one thing that is always on the back of my mind is the oil temp. I have a VDO temp gauge and sensor to install but haven’t decided on the location. There are a lot of places that are easier to install but provide less than ideal readings. But, if the oil temp is getting too hot, the water temp doesn’t stand a chance. The motor is putting out about 85bhp now but I’m not just going to throw a cooler on before I know it’s needed as I’ve seen so many do.

Actually, on the aux fan, does that do anything at speed or is it only there to help when the revs are low and the fan isn’t spinning fast?

Edited by brivinci, 10 September 2018 - 10:52 PM.

[mina08]

its fine, mine does the same, i have an extra temp sensor in the thermostat housing and reads quite differently from the manifold temp, between 80 and 110, the only time i have seen my manifold temp get to 3/4 is when i have been sitting in long traffic just before the fan kicks in

[brivinci]

Thanks for the info!