When the Viscous Mechanical fan on my PRV engine failed in 2011, I locked the fan to the water pump pulley since I couldn't get a good used or new one. I stupidly thought I was smarter than Peugeot until I embarked on a road trip days later. The faster I pushed the car, the lower the coolant temperature dropped. By the time I got to Ajaokuta, the temperature gauge remained under 30° Celsius, even though the engine had a good working stock thermostat at 79°C opening temperature and weather was extremely hot that day. It dawned on me that my engine was doomed if I maintained that crappy abused modification on the engine cooling system for long. As soon as I got back from the trip, I converted the fan to Electric, modifying the fan to be triggered at around 87°C. Something interesting happened as soon as I started the engine without the locked mechanical fan. The engine immediately started hunting at idle, terribly. The symptom refused to go away until after about 50 km drive (the next day), and the car suddenly became quicker at much lower rpm (as soon as the engine hunt reduced). It was not only the first time I experienced the engine ECU adaptation process, but also confirmed firsthand how badly locked mechanical fans restrict/reduce engine power to the wheels. I was too delusional not to think of the consequences of what I was doing to the engine lifespan, fuel economy, and engine performance when I locked the fan blades to the Viscous coupling. I was able to save myself early, but what about all the thousands or hundreds of thousands (if not millions) of 504 sold and used in Nigeria with mechanical locked fans on the water pump pulleys?

If I am not mistaken, all 504s sold new in Nigeria had the locked mechanical fans as standard, while the 504s sold in Europe and other first world countries had the temperature controlled fans, similar to what we have in modern cars. Aside from the higher fuel consumption that the locked fans ensured on these Nigerian 504s, the rapid engine wear it contributed was too enormous that it was accepted as normal or an expected cost of owning a 504 in Nigeria. The funny part was that it wasn't limited to only 504s in Nigeria (other countries in Africa were victims, too). The scary part was the absence of engine cooling system thermostat in these engines, even with the fan permanently locked to the water pump, pushing off whatever little warm temperature engine could get at cold start as acceleration increased. Obviously, is probably the reason why the majority of 504s assembled in Nigeria didn't have a coolant temperature gauge since there was no need to be staring at a gauge that won't make any movement upward anyway. As an Australian stated a few years ago on Aussiefrogs that the mechanical fans reduce approximately 10hp on 504s, as engine speed increases. The 1.6 - 2.0 Carburettor engines in 504 didn't have impressive power figures, yet the little they had were ridiculously reduced by these fans. As indestructible as those engines were, it might be hard to find a user in Nigeria in that era that didn't rebuild his/her engine once, twice or more within 100,000 - 200,000 km mileage, when the story is different in other climes. Some have argued that the locked fan makes the engine sound more aggressive. I would tell you, at lower rpm, they all sound the same (with or without the fan), especially on the carb 4-cylinder engines. The ones with locked fans only become coarse or harsh when the rpm climbs over 4,000. But then, none of the Nigerian assembled 504s had a Tachometer anyway.

There have been debates among 504 users on the need to retain or maintain the coolant/water lines or hoses attached to Carburettors in a temperate or hot environment like Nigeria. Some claimed they only served the atomization purpose or prevent icing of the carburettors, which are not experienced in hotter environments or regions. One thing is clear, the coolant or water does no harm to the Carburettors, at least, the ones I have used on a 504. There is one major advantage water has on a Carburettor (some models, though), which makes the engine perform efficiently and economically, and that is choke plate control. The choke on some Carburettors models are manually controlled via cable, while some are temperature controlled via water/coolant. Cold engines require the choke plates to be closed, in order to let more fuel in. As engine starts and water temperature increases, the thermistor-like part of the Carburettor inside will gradually open the choke plate to reduce the fueling into the manifold until it stays fully open (fuel reduction). It's basically the same setup with the modern EFI cars in controlling fuel consumption at cold start and at optimal engine temperature via the CTS (Coolant Temperature Sensor). But the majority (like 97% of 504 users in the past) yanked out their water lines to their Carburettors (irrespective of the carburettor models), likewise the current 504 users. Not only that, the cables have also been cut-off (intentionally, sometimes), and choke plates are fixed permanently either closed, half open or fully open, as they expect abused Carburettors to manage the engine properly. The worst of it is the disconnections or blockages of the water or coolant lines on the Intake manifold Carb engines in 504s. The temperature of the intake manifolds needed to be regulated for better engine performance and fuel economy, yet almost every user here disconnected or blocked theirs when the water passing through the intake did no harm to these 504s. You might disconnect coolant lines on the carburettor because your choke plate is manually controlled via cable (still doesn't make sense to me), but doing same on the intake manifold is the worst

In the '90s, I passionately became obsessed with knowing how a clutch kit inside the bellhousing actually works. The fork and release bearing were easier to understand than troubling anyone with questions, but I wanted to understand how the friction and pressure plate work together on the flywheel and input spline. No mechanic I asked gave me any explanation that made sense. All their explanations or descriptions didn't match reality, looking at those 2 components, until I ignored every answer i got externally and figured it out myself (Internet wasn't a thing at the time). Maybe, that could be the reason I have never had clutch kit (release bearing, friction plate and pressure plate) failed on me ever since I started driving on the public roads in the early '90s. By understanding how clutch works, I subconsciously avoid the DON'Ts with the clutch pedals, which elongated the lifespan of all the clutch kits in cars I have used, owned and currently own. If the majority of Nigerian 504 users had understood their engine cooling systems and how their Carburettors work, most of them probably wouldn't have messed with them or continue to do so by the current users. I am not a Carburettor expert, but with the understanding of the 3 Carburettors I have used so far on Peugeots (Solex 34 BISCA 3, Solex 32-35 MIMSA, and Solex 34-34 Z1), I can authoritatively tell you that it's probably to average 40 mpg on a 504 with Carburettor engine on highway (not more than 100 km/h), even here in Nigeria and other African countries. Otherwise, be man enough to stare down under the hood of yours, admit to yourself why your 504 sucks. That realisation will not profer solutions but also lead to a different chapter of 504 ownership for you.

Lion-King Monk