Thread: Overheating when towing

LPG generally likes a reasonable amount of advance. Retard the timing and watch temps rise.

Are you sure the viscous fan is OK ?
A lot of TD Patrols (in particular) and some TLC's overheat under high load conditions, and after fitting larger radiators, etc without improvement, a band aid is slightly overfilling the viscous clutch to lock it up more and bring the fan in more often. (I'm doing this mod on a Patrol in the next week) Usually problem solved. I also remember one of the Aussies on one of the Pommy forums a few years back having overheating problems with his Tdi Defender on hills, etc. Apparently the viscous fan checked out OK in static tests, but the overheating was 'cured' after trying a new fan clutch. It appears the airflow through the engine bay on our beloved 4x4's is pretty crook. Ram air isn't enough, they need some supplementary help.

Thanks Rick,
Worth a second look, it is fairly new, but may have gone thru one too many water crossings.
One other thing that made me think it was mixture was that, thru N.S.W. ( Armidale to Narrandera) we filled up on Gogas three times and the temp needle sat right in the middle on the flat(ish) runs. We then could only get Mobil or BP and it then went up to 3/4 or a bit under on the guage under similar runs
Hills made it get up to the red in both brands.. Weird...
Maybe Gogas was straight propane out there, but I know they only do a servo run, so it is more likely all were propane/butane blend.
David

to test your viscous fan coupling, with the engine off) grab it and try to turn it while its cold, it should turn with just a modicom of force applied (one finger should be enough), then grab your 1500w hot air gun and heat up the center of the fan while you try to turn it, it should get harder and harder to turn. If you experience little difference and have gotten the center of the fan hot enough to be uncomfortable to touch its cactus and theres no point in trying to do a dynamic test on the fan.

a mate of mine that was in the radiator buisness once said to me any speed over 50k,s your fan is useless so keep that in mind you might have other dramas

Originally Posted by rangieman

a mate of mine that was in the radiator buisness once said to me any speed over 50k,s your fan is useless so keep that in mind you might have other dramas

not so it appears on most 4wd's. I always assumed this, but have found that the airflow through the engine bay on Defenders and Patrols is bad. The air appears to 'pack up' in the engine bay as it appears not to be able to exit efficiently, it becomes a high pressure zone, and as air will only flow from a region of (relatively) higher pressure to a relatively lower pressure region it ends up relying on the fan to force the air out of the underbonnet area.

The bloke that had the overheating problems with his Defender only had the problems over 80km/h. I actually said it wouldn't be the fan, that ram air would be sufficient, but it was the viscous coupling, even though it felt OK by hand.

This is also a known problem with Patrols, which I have first hand experience with. Unfortunately SWMBO won't let me hack a big hole in her GU bonnet, so I'm going to refill the viscous fan clutch.
And before anyone suggests lifting the rear of the bonnet to let the air out, unfortunately that doesn't work. The base of the windscreen is a high pressure zone (think of where most cars have the ventilation intake and A9X Torana's had the bonnet scoop opening) which I've proven with wool tufts to check air flow. When I raised the rear of the bonnet 40mm on a Patrol, every wool tuft right along the back edge was forced back under the bonnet into the engine bay above around 50km/h. A bonnet opening to vent radiator air has to be quite forward, ideally just rear of the radiator. Have a look where Mitsubishi Evo's have their radiator bonnet opening.

Originally Posted by rick130

not so it appears on most 4wd's. I always assumed this, but have found that the airflow through the engine bay on Defenders and Patrols is bad. The air appears to 'pack up' in the engine bay as it appears not to be able to exit efficiently, it becomes a high pressure zone, and as air will only flow from a region of (relatively) higher pressure to a relatively lower pressure region it ends up relying on the fan to force the air out of the underbonnet area.

The bloke that had the overheating problems with his Defender only had the problems over 80km/h. I actually said it wouldn't be the fan, that ram air would be sufficient, but it was the viscous coupling, even though it felt OK by hand.

This is also a known problem with Patrols, which I have first hand experience with. Unfortunately SWMBO won't let me hack a big hole in her GU bonnet, so I'm going to refill the viscous fan clutch.
And before anyone suggests lifting the rear of the bonnet to let the air out, unfortunately that doesn't work. The base of the windscreen is a high pressure zone (think of where most cars have the ventilation intake and A9X Torana's had the bonnet scoop opening) which I've proven with wool tufts to check air flow. When I raised the rear of the bonnet 40mm on a Patrol, every wool tuft right along the back edge was forced back under the bonnet into the engine bay above around 50km/h. A bonnet opening to vent radiator air has to be quite forward, ideally just rear of the radiator. Have a look where Mitsubishi Evo's have their radiator bonnet opening.

thats strange but who am i to know any better when i have,nt had that problem

Originally Posted by rick130

not so it appears on most 4wd's. I always assumed this, but have found that the airflow through the engine bay on Defenders and Patrols is bad. The air appears to 'pack up' in the engine bay as it appears not to be able to exit efficiently, it becomes a high pressure zone, and as air will only flow from a region of (relatively) higher pressure to a relatively lower pressure region it ends up relying on the fan to force the air out of the underbonnet area.

The bloke that had the overheating problems with his Defender only had the problems over 80km/h. I actually said it wouldn't be the fan, that ram air would be sufficient, but it was the viscous coupling, even though it felt OK by hand.

This is also a known problem with Patrols, which I have first hand experience with. Unfortunately SWMBO won't let me hack a big hole in her GU bonnet, so I'm going to refill the viscous fan clutch.
And before anyone suggests lifting the rear of the bonnet to let the air out, unfortunately that doesn't work. The base of the windscreen is a high pressure zone (think of where most cars have the ventilation intake and A9X Torana's had the bonnet scoop opening) which I've proven with wool tufts to check air flow. When I raised the rear of the bonnet 40mm on a Patrol, every wool tuft right along the back edge was forced back under the bonnet into the engine bay above around 50km/h. A bonnet opening to vent radiator air has to be quite forward, ideally just rear of the radiator. Have a look where Mitsubishi Evo's have their radiator bonnet opening.

You are definitely correct about the base of the windscreen being a high pressure zone. What about finding a metal worker who will put a heap of louvres in the bonnet, or a couple of NASA ducts, available from hot rod/street machine shops. Better still, find out why it is getting hot in the first place. Does it get hot on petrol under the same circumstances, with the spark advance set correctly for petrol? I think it most likely that you have a problem with the tuning of your gas conversion.

I had a similar problem with my Rangy once..it ended up being 1/3rd of the radiator was blocked with sludge..around town it was normal but towing it just kept getting hotter