Transmission tunnel getting hot

[ranger]

Has anyone ever encountered this problem.
I have a 960 2.5 manual transmission and when driving the car solo it's OK. When I tow the caravan the transmission tunnel and drivers seat get very hot to the point where it caused the hand brake to seize which freed up again when the car cooled down. I notice the cat is under the drivers seat and understand they do caues a lot of heat. Has anyone any ideas if this is the cause of the heat problem or could it be something else. I have already fitted a new clutch and release bearing and the gearbox has 80/90 grade oil and is filled
to the right level. Any help or ideas would be gratefully received thank you for your time

[Peter Milnes]

The gearbox should be filled with fully synthetic ATF type F or G (1.75 Litres), although it is a manual box. 80/90 grade gear oil increases the internal friction of the gearbox to the point where it's efficiency begins to suffer.

It may be that the heatshield between, the cat, the underbody and gearbox, has come adrift causing an overheating condition to arise. If the cat has become partially blocked it will retain more heat than if it was flowing freely. Any increased rolling friction will make the engine work harder which results in more heat being generated. This is the reason why many towing experts advocate the need for a gearbox oil cooler when towing.

Another point to check ios that the caravan brakes are not binding and that the caravan is properly loaded and having the correct noseweight, approximately 75kg max. It also helps if the outfit tows level throughout or slightly caravan nose down, car level.

I hope I have been of help, but let me know if there is anything more I can help with.

All the best, Peter

[ranger]

Thank you Peter for your advice. I will change the oil to ATF.
i had 80/90 oil in the box to help with a noisy first gear bearing which has not made that much difference. I thought it would help an old worn gearbox. Is there any way to tell if your cat's partially blocked and can you do anything to un block it. The heat shield is in place but I do think it could be made bigger which I shall have a look at this week end. thank you again.

[keith.talbot]

When towing with my 960/S90 Auto it gets hot around the transmission tunnel, and also in the boot above the exhaust, but not THAT hot.

Ranger ? not a Bailey Ranger caravan ?

(Another) Keith

[Peter Milnes]

It might be a good idea to check the airflow through the coolant radiator as if that becomes partially blocked it may well cope with solo driving but not be able to keep the engine cool enough whilst towing. The trouble withthe coolant temperature gauge is that it does not register much of a change around it's mid-point, giving an average temp rather than actual temp. This is how it has been designed and the actual temp may change by as much as 15-20°C before the needle registers a temp change. Do you have the two-speed electric fan fitted to your car or is it a mechanical one? If you have air-conditioning you should have the electric fan. This can also lead to less airflow through the radiator as the condenser is fitted in front of the coolant radiator.

The only way to check for blockage of a cat is to take it to an exhaust specialist who can measure the temperature of the cat and possibly the resultant airflow through the cat. If it is getting blocked there will be a bigger pressure drop across the cat than normal.

Keep me informed of your progress, please Keith.

All the best, Peter

[ranger]

Thank you again for your advice. Yes I do have the electric fan and air-conditioning.am i correct in thinking there is no cooler for a manual box. Do you think it would be OK to wrap the cat in heatproof material to keep the heat down and I was also going to design a better heat shield. And yes it is a bailey ranger Caravan. I have also considered fitting air vents in the bonnet to help push air under the car. Let me know if you think these ideas will help thanks again .

[Peter Milnes]

The electric fan has four vents with rubber flaps on them to the passenger side of the fan cowling/housing. Make sure that they are still flexible enough not to cause blockage when under way. These flaps allow air to bypass the fan and increase cooling when moving. The air-con condenser can become blocked with flies/road dirt etc and restrict the flow through the radiator. Someone was experimenting with the vertical angle at which the condensor was installed with respect to the radiator. I think the details may be in the archives of this forum.

No, there is no seperate gearbox cooler for the manual installation.

Wrapping the cat will only increase the heat of the cat and cause more problems. It would be much better to arrange for the airflow around the cat to be as clean and straight as possible so that it can contribute to keeping the heat within normal operating range. Perhaps a double walled heat shield which allows air to circulate between the two walls would be the best solution if/when the cat is OK.

All the best, Peter