960 getting hot (still)

[rogerthechorister]

AFAIK it's standard Volvo rad for a B6304, all of which were petrol and all of which had aircon.

I don't see how it could be running weak, the mixture is controlled by the ECU which I think is LH 2.4 - and she does about 20 mpg when not towing.

But keep the theories flowing.

[Skavac]

Hi Roger the Chorister,

I have had problems similar to yours, but my S90 LWB's temperature has been a bit high when I bought it, turns out the thermostat was of the wrong rating, and it cured it when driving on level ground. But the car does get hot to the point where the orange warning on the dash lit up when driving up long mountain gradients in tropical heat. The cure for me was an OEM Volvo ATF cooler. It was installed by my Volvo mechanic, I am not sure how it is mounted, but the cooler in the radiator was blanked off, and the ATF fluid lines are directly connected to the ATF cooler, bypassing the radiator completely.

I suggest you do it this way, a friend of mine has his radiator leak internally, causing coolant to mix with ATF, and the rest, is history

And check your cooling fan, my old 960 has its second speed wire broken off..

Hope you find your fix soon,
Skavac

P.S: I think 96- 960s are controlled by Motronic 4.4 ECUs. I am pretty sure LH 2.4 are for 940s...

[rogerthechorister]

Thanks Skavac. I'll check out whether the official ATF cooler is still available.

[rogerthechorister]

PS - a nice neat mounting is important to me though...

[jor]

Not going to solve the problem - but you might consider Evans coolant, which not being water based will at least be kinder on the hoses

jor

[rogerthechorister]

The official ATF cooler for the Mark 2 960 is NLA. An official one for the mark 1 is nearly 400 squid. Braydons say they cannot tell the difference.

I'm going to go with an aftermarket one that does NOT retain the internal ATF cooler within the rad - it leaves that out of the loop. Apparently this is a very common mod. From my perspective it will stop the ATF putting extra heat into the rad - which I suspect is behind the rise in temperature. If it is common it should also be enough to keep the ATF cool enough.

I absolutely hate the idea that it's hung on the front of the rad with (basically) cable ties though. That's asking for holes in te rad - but apparently it does not happen.

The standard rad in the mark 2 960 is (I can confirm, having inspected) MAHUSIVE - and it sticks out so far sideways that the space where a 760T ATF cooler sits is 100% occupied by rad, so where the standard Volvo ATF cooler would go I do not know. It would be vulnerable in front of the aircon condenser, being so low.

[alfadave11]

Originally Posted by rogerthechorister

AFAIK it's standard Volvo rad for a B6304, all of which were petrol and all of which had aircon.

I don't see how it could be running weak, the mixture is controlled by the ECU which I think is LH 2.4 - and she does about 20 mpg when not towing.

But keep the theories flowing.

low height is a more efficient radiator at dispersing heat and is easily recognized by fins being very close together
also running a lower temp thermostat will let engine run cooler initially but its down to radiator to disperse heat effectively once its open
an engine that's running lean even controlled by ecu can eat the juice .removal of a spark plug to check insulator and burn ring will confirm this

[rogerthechorister]

I'll try to put a picture up when it's light.

[AndysR]

Originally Posted by rogerthechorister

The standard 960 ATF cooler is inside the radiator. It's a heat exchanger - the autobox fluid is cooled by the radiator water. It's quite interesting to note from that link to the manual on the AW30 box that the limit temperatures of the autobox fluid are within about 10 degrees of the boiling point of the pressurised radiator water (115 degrees plus or minus a few depending on exact 960 model, if the pressure cap is perfect).

My 760 T also has an external cooler for the ATF.

Since, however, the air temperature will always be a lot less than 115 degrees, it seems to me that although the amount of heat that a given airflow could transfer is low, with a big enough ATF cooler you could get the ATF fluid a fair bit cooler than simply using the one inside the rad.

Yeah that sounds the same as the 760 and 850 standard coolers, they're built into one of the end tanks of the engine coolant radiator. I guess the harder the engine is working the hotter the rad will get, which will also transfer heat into the autobox oil and reduce the oil coolers effective operation at the same time.

Both the 850 and 760's auxillary oil coolers sit in front of the rad, on the 760 it sits between the condensor and the rad and on the 850 it sits right up front due to the a/c condensor, intercooler and then radiator rad pack not allowing the room for it to sit in the same position as the 760's.

[rogerthechorister]

Well, you will not believe this but I nearly boiled the 960 towing up from the Medway bridge to the top of Bluebell hill yesterday evening.

However the gearbox seemed fine with that atf cooler in - my friends were most admiring of it. I think the exact quote was "***x me that's the biggest one I've ever seen".

So, not urgent (my next tow, in a fortnight, has no long steep hill like that in it) but important -

1. Re-check that all fan speeds are working: tricky as she will not get hot enough ticking over on the drive. Maybe try a bypass switch so that I can manually turn on the fan to top speed. This has to be carefully planned because I am pretty sure that the ECU controls the radiator fans and we do NOT want to blow up the ECU.

2. Try towing with the aircon off - but I don't think it will be that as the condenser does not rely on the main radiator to cool it.

3. Check whether the undertray bits might direct air up onto the radiator - it might just be an airflow issue.

4. Try it with no radiator grille.

5. And the nuclear option - might it be the ATF cooler obstructing the airflow - change atf cooler for a smaller one!!?