I have the overflow/surge tank on the fire wall. Where exactly would the sensor on the manifold be for the solenoid? I was told it was at the very rear, and replaced that one with no luck. Strangely enought this all happened at the same time, blew the manifold hose and saturated engine compartment and been having both problems since. My fan takes air to engage it and thats the problem with the fan not getting power to open solinoid. I'm goning to replace the water level sensor just to be able and rule it out on the Engine shutdown and Electrical Malfunction ligts. Mine has the E7-427 and she'll pull around my JD 750C II Dozer like it isn't even back there.
The second best was a 1996 with a E-7 454hp it was awesome as well.
Is your metal radiator cap on the radiator itself or on an overflow/surge tank in the fire wall? Forgot to mention, love your truck, Alxe forward CH's are my faavorite! One of the best ones I ever drove was a 1990 with a E-7 400hp manual fuel pump, the old man that taught me all about Macks cranked the rpms and fuel to it and it was a screamer. Which light is coming on red shutdown or yellow electronic malfunction? If it's both it's the low water sensor or wiring to the sensor or really has low coolant. Both systems still used the same fan clutch and solinoid. The dealer could also raise and lower the engagement temp with a prolink computer. It used the existing temp sensor for the ECM to decide when to turn on the fan. When VMAC2 came out, it controlled the fan on/off. VMAC1 had nothing to do with engine fan control, the fan control was kinda added on and not really part of the VMAC system.It had it's own 2 prong sending unit ontop of the water manifold, the degrees stamped on the sensor tells what temp it will engage(usually around 205).
Your year model is tricky because it could be either a VMAC1 or VMAC2 (engine electronics), all fuses and ECM's are in the cab on both models( unlike the ETECH style engine). Anyone have any input on this? Always appreciated. So, I got on BMT and found a similar topic with fan failure and someone said that the sensor was part of the fan operation and was know to go bad. I did put a wire tracer on solenoid hook up and ended up at a air conditioner line on the oposite side of the radiator and another sensor. Ok, I've checked for any fuses for the fan soleniod in the engine compartment, results-negative(not to say there isn't).