Getting hot when towing

I'm sure this has been asked before but I pulled a swift twin axle yesterday with my '95 4.6 and it was fine until I got to a hill. Then the temp gauge got to the last white speck on the gauge and had to put the heaters on full to cool it down again as I didn't want to risk reaching the red.
Anyone have any idea what might be causing this. I'm thinking radiator as it's had a new water pump and the viscosity fan can be heard coming in and out.

As I run on LPG 100% of the time I was considering ditching the viscous and fittin twin thermostatic fans to keep the temperature down further. Any thoughts?

Thanks in advance!

Worth checking the serpentine belt.

customknight said:

I'm sure this has been asked before but I pulled a swift twin axle yesterday with my '95 4.6 and it was fine until I got to a hill. Then the temp gauge got to the last white speck on the gauge and had to put the heaters on full to cool it down again as I didn't want to risk reaching the red.
Anyone have any idea what might be causing this. I'm thinking radiator as it's had a new water pump and the viscosity fan can be heard coming in and out.

As I run on LPG 100% of the time I was considering ditching the viscous and fittin twin thermostatic fans to keep the temperature down further. Any thoughts?

Thanks in advance!

Click to expand...

You can use the aircon fans to supliment the viscous, cheap and simple to do. Twin aftermarket fans are unlikely to cope without the viscous present.

customknight said:

I'm sure this has been asked before but I pulled a swift twin axle yesterday with my '95 4.6 and it was fine until I got to a hill. Then the temp gauge got to the last white speck on the gauge and had to put the heaters on full to cool it down again as I didn't want to risk reaching the red.
Anyone have any idea what might be causing this. I'm thinking radiator as it's had a new water pump and the viscosity fan can be heard coming in and out.

As I run on LPG 100% of the time I was considering ditching the viscous and fittin twin thermostatic fans to keep the temperature down further. Any thoughts?

Thanks in advance!

Click to expand...

Don't they run hotter on LPG?

Not that much hotter.. it points to a problem with the fan viscous coupling, water pump ,radiator and or thermostat.... not in any particular order.. My radiator was 50% blocked with mud in the cooling fins.

So the twin fans are a no then?!! Right the problem with the air on fans is that my AC doesn't work at all. Do they cut in as soon as you engage the AC? Or do you mean wire them as a manual set of addition fans?

With regard to the other bits, the thermostat is an unknown but seems to be working ok. The coupling I think is working as I can hear it change speed. The water pump is new and the radiator I have flushed to death during the block sealing exercise. So it could be bunged up outside, I haven't looked.

Check radiator get equally hot all over as well

So how am I supposed to do that when the fan is spinning?!!

customknight said:

So how am I supposed to do that when the fan is spinning?!!

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Get it warmed up, turn off engine, check rad

Also check pulley belt tensioner. As these wear and allow the belt to slip

blue beasty said:

Get it warmed up, turn off engine, check rad

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If you had a brain you would be dangerous

Grit Valve said:

If you had a brain you would be dangerous

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A solid metal fan on a perkins lump took half me thumb off once...

I's a fast learnerer

Jesus guys!, thumbs, fans, checking with the engine running. There's gonna be blood everywhere.
It's overheating under load; so check/renew the serpentine belt. Check/ flush out the radiator. Bleed the system properly to get rid of air.
Are you losing water from the expansion tank, and is the system overpressurising?
If the entire cooling system has been renewed then your looking at something a bit more serious (headgasket, slipped liners).
I'm sure I've seen some info from datatek re the air con fan mod, but can't see it in the how to section. But this mod won't help if there is a problem with the cooling system or engine.

The engine has been rebuilt so no headgasket problems or lack of coolant.

Quick question. When you press the AIR CON OFF button and the light is on, is the air con on or off. When my light is off the engine revs increase but when the light is on the engine revs drop dramatically as if the ac compressor is engaged.
I'm only asking because I think I'm driving around with the air con on all the time which may have added to the load on the engine, hence the heat.

customknight said:

The engine has been rebuilt so no headgasket problems or lack of coolant.

Quick question. When you press the AIR CON OFF button and the light is on, is the air con on or off. When my light is off the engine revs increase but when the light is on the engine revs drop dramatically as if the ac compressor is engaged.
I'm only asking because I think I'm driving around with the air con on all the time which may have added to the load on the engine, hence the heat.

Click to expand...

When you press the AIR CON OFF button (light on) the air con is off. Does exactly what it says on the tin.
So when the engine overheats, your not losing any coolant from the expansion tank overflow, and the system isn't overpressurising??

You're reading too far ahead I'm afraid! I didn allow it to actually overheat due to having rebuilt the engine twice already this year.
It reached the last white line on the temp gauge and I turned on the heaters to prevent overheating.
There is no coolant loss AT ALL. No over pressurising and as I've said the engine has been rebuilt twice so two new heads!!
And new water pump, and fan is fine!!

Either your rad is sludged up, flushing will not clear it, or the viscous is not working properly, assuming the stat and water pump are OK after your rebuild. My air con fans mod is fully automatic but not suitable for trying to mask a problem.

customknight said:

You're reading too far ahead I'm afraid! I didn allow it to actually overheat due to having rebuilt the engine twice already this year.
It reached the last white line on the temp gauge and I turned on the heaters to prevent overheating.
There is no coolant loss AT ALL. No over pressurising and as I've said the engine has been rebuilt twice so two new heads!!
And new water pump, and fan is fine!!

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see post #7

Rad and or stat

Right I will check the rad next week and the stat.

With regard to the mod, I've tested the fans and one is knackered and the other doesn't spin so well, so I'm going to get some replacements.
Could you please give me the info for the mod as I'd like to do all of it at the same time if possible.

customknight said:

Right I will check the rad next week and the stat.

With regard to the mod, I've tested the fans and one is knackered and the other doesn't spin so well, so I'm going to get some replacements.
Could you please give me the info for the mod as I'd like to do all of it at the same time if possible.

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Fix the overheating problem and I'll send you the mod.
If the aircon fans do not work that could be part of the problem if you were using aircon. Are you sure the fans are duff and it's not one of the 3 relays involved? The fans can run at half or full speed according to need.