Radiator return temp

[Madmark]

Anyone know the return side of the rad temp under normal driving . I've fitted a second temp gauge which Is on return side of the rad and when going up hill it get's up to around 70 degrees. The standard dash gauge doesn't move from middle.

I'm worried when towing it may get to high and over heat. It soon drops again to 40 degrees when on the flat just not found a big enough hill to see how far the temp would go

Oh and my viscous is fixed solid so I know it's not that

2002 tdi 2.7

 

[solarman216]

The bottom hose is extremely variable depending on load, ambient air temp, air flow through the rad etc, but if your fan is roaring all the time, (viscous failed seized) then at 70 c it would suggest you have a problem with your rad, Rick

 

[makeitfit]

Also note that the temp gauge is working off the ECU and also none linear.
So mid range gauge is just the ECU telling you things are good enough for now, nothing to see here, away you go :bobby:

 

[solarman216]

OK I can see a bit of info is required here, so start with a cold engine the pump circulates water around the block, closed circuit, as it gets up to temperature the stat begins to open so bleeding in a little cooler water but just enough to keep the temperature at or near stat temperature, rad is only hot at the top, now you start climbing a long hill while towing, the stat opens wide the viscous fan cuts in and the rad is flooded with 90 c water but the bottom should always be below 70c or it cannot supply cool enough water to take the heat away, hope that helps, have kept it short as there is a lot more than that goes on in a cooling system, Rick

 

[Madmark]

Thanks rick. Last month I fitted new Nissan's rad new water pump and thermostat as when we did laning day as you knowy electric fan was crap. So got home didn't mess about and ordered the lot. But have noticed when doing 60mph ish. When I stamp on pedal to climb hill the return water from rad the temp goes on up to at least 60-70 degrees but drops rapidly on the flat etc

 

[Madmark]

The new rad is Nissens not nissans

 

[Banshee]

I'd change the rad mate, seems like you've always got overheating issues, or at least flush it through?

 

[Madmark]

It is a brand spanking new rad. Can you get a flush out for the water system

 

[solarman216]

Just cos it is new does not mean it meats the correct spec, but on the other hand not many people monitor the return temp bear in mind that at higher temperatures heat transfer is much quicker so you may be fine at 70 as long as it is stable, you need a good hard hill while towing to test it, Rick

 

[Madmark]

Cheers rick. I bought a good quality rad etc as don't belive in cheap. But I've also got a new rad from an older terrano which the cap is on a tilt which I put in a few month's a go which worked spot on so thinking I'll stick that back in and make brackets to fit as the bottom fits perfect but the top is different. Also this seem to be a thicker rad. I took it out as wasn't the right rad and bought the proper one but like you say it just might not be up to the job in the first place. But now I've another problem as when I removed thermostat house the long bolt picked up on it's threads so looks like partial strip to helicoil a new thread back in. Oh the joys!!