Auxiliary fan - purpose.

[98chevy2500SS]

I believe the auxiliary fans only came on 8600-up GVWR trucks. Mainly seen them on one tons. My dad's dually has the aux fan, trans cooler, and power steering cooler (I think that's what it is? I could be wrong). Like others have said, I would assume it's to cool things down when you are towing something for long periods of time.

 

[Supercharged111]

Trans fluid should hit the main radiator first, then the external cooler. They don't sell those zip tie cooler mounts on that side of the pond?

https://www.amazon.com/Cooling-Fan-Zip-Tie-Mounting/dp/B008YGC7GC

 

[someotherguy]

I hear what you're saying but I'm just not for tracing leaks. I want a simple dependable truck. I'll focus on sorting the heating out. The immediate benefit is decluttering the engine bay. Easier access makes for better maintenance. I already have a heap of LPG (propane) stuff in there.

A/C leak on 1996-up almost always the compressor. The seal between the case halves fails and the tell-tale sign is greasy residue all around the compressor body, as the refrigerant and oil escape. There are better compressors (Sanden) that can be adapted.

*Sometimes* the leak is as simple as one of the service port valves.

Richard

 

[Pinger]

They don't sell those zip tie cooler mounts on that side of the pond?

https://www.amazon.com/Cooling-Fan-Zip-Tie-Mounting/dp/B008YGC7GC

Not to 'my region' from that link.
Moot anyway as the rad won't be flush against the main rad as its pipes dont reach. I'll mount it to the body instead.

Trans fluid should hit the main radiator first, then the external cooler.

That confuses me further!
I have to imagine that something went wrong with the main rad part before it was isolated out of the system. I just assumed the rad replaced it. Are there any known problems with the cooler in the main rad (eg, the Valeo rads on MBs that leak and contaminate the trans with glycol)? If that has happened though, the engine coolant would be leaking. The pipes are still there, cut, and left open ie, unplugged.

I'm not losing much warming (from cold) though if after warming in the main rad the trans fluid then goes through its rad cooler - yes?

 

[someotherguy]

Transmission line pressure is much higher than engine cooling system so generally you'd see transmission fluid mixed with the coolant, in the event of failure in the radiator of the transmission cooler.

The reason for running the transmission lines into the radiator cooler is indeed to help get it up to temperature first, as too cold is not good.

Sometimes people eliminate the factory transmission cooler from the radiator because it was leaking, or they incorrectly think that it's not needed if they have an auxiliary air-to-air cooler.

Richard

 

[Pinger]

A/C leak on 1996-up almost always the compressor. The seal between the case halves fails and the tell-tale sign is greasy residue all around the compressor body, as the refrigerant and oil escape. There are better compressors (Sanden) that can be adapted.

*Sometimes* the leak is as simple as one of the service port valves.

Richard

I hear what you're saying.... but its out and not going back - in for now at least.
No residue on the compressor, it's dry as bone. When I bought it I asked the previous owners if the air con worked and they both shook their heads as if they'd tried and failed. I see so many posts on internet threads about AC leaks I just don't want to be there.
There's still a lot of work to do just to get the heating working properly and I'm a bit freaked after reading some of the horror stories of burst pipes to the rear heater core dumping all the coolant and frying the engine or stranding me, that I'll put my efforts into attending to that.

 

[Pinger]

Transmission line pressure is much higher than engine cooling system so generally you'd see transmission fluid mixed with the coolant, in the event of failure in the radiator of the transmission cooler.

I think what happens with the Valeo rads is that they leak coolant into the trans on shutdown when the trans pressure is gone but the coolant is still at pressure. It was definitely a big problem for some MBs as it trashed the trans.

The reason for running the transmission lines into the radiator cooler is indeed to help get it up to temperature first, as too cold is not good.

Agreed, And I can see that even if it does subsequently pass through the air cooler, it at least picked up some heat.
I am always very gentle during warm up (and when lockdown is over) tend to do longish trips where everything is right up to temp and stays there for most of the day. But......

Sometimes people eliminate the factory transmission cooler from the radiator because it was leaking, or they incorrectly think that it's not needed if they have an auxiliary air-to-air cooler.

Richard

..... do you think I should try and reinstate the main rad part of the cooling circuit? (I intend changing the trans fluid later this year and that would be the time to do it if it's to be done). Or will gentle warm up suffice?

 

[Supercharged111]

I would put it back the way GM intended, but the open lines would concern me as dirt has likely found its way into the thing now.

 

[PlayingWithTBI]

the open lines would concern me as dirt has likely found its way into the thing now.

You can flush the system with something like this stuff.

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[HotWheelsBurban]

Knock on wood, I haven't had issues on my Burb with the rear heater lines--except for the little plastic Y under the hood and the plastic heater control valve. I'm sure after 21 years of underhood heat it's probably gotten cooked pretty good which is never a good thing for plastic! Also where they are, they are prone to getting whacked when doing repairs on that side of the engine. If you have to replace the spark plugs or wires it'll help you a lot to move the air cleaner box, makes it lots easier to get to the right bank of the engine!