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Automotive/1997 Blazer overheating/4X4 blows fuses

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Expert: - 7/24/2007


Question
My 1997 Blazer tends to overheat after driving for about 40 minutes in 80-90 degree weather.  Mechanics checked it out and were not able to find a problem.  Best recommendation was a radiator flush.  I flushed the radiator three years ago for basic maintenence and did a partial flush two years ago when I added a transimition oil cooler.  I've heard the GM coolent chrystalizes and may reduce flow through radiator, is another flush my best option?
On a seperate note, my electronic 4X4 blows fuses, but only after the vehicle warms up.  Again, mechanic was unable to find an electrical short or even recreate the problem yet it happens to me every time I need to pull the boat out of the water.  What could be heat sensitive and blow fuses?

Answer
Good preventative maintenance practice would suggest a proactive approach carried out on a regular periodic basis.  A good program for the cooling system would be one whereby one completely flushes the system, replaces the thermostat, inspects the balance of the the system and replaces any any soft hoses or frayed belts and repairs any core leaks if needed, and finishes with the installation of new antifreeze and waterpump lube / rust inhibitor.  I have followed a two-year cycle for this work on all my vehicles, and have had NO problems with overheating or failures for years, even though all my vehicles are over twenty years old.  I recommend this approach!

Pulling a boat out of the water?  Are we using a winch, which may be creating an overload for which the fuse protection is not properly coordinated.  Or are we using the vehicle itself, and perhaps backing into salt water?  You speak of fuses in the plural, which suggests that more information is needed here to fully understand and assess the problem, however, I would suggest that you might review your operating manual and, better yet, your shop manual to trace out the affected circuit(s) and see if the protection is correctly sized.  Fuses themselves are heat sensitive devices (the inverse-time characteristic is based on the thermodynamics of heat energy as a function of power and time), and a fuse subject to a high ambient temperature will require less energy to melt at a given current than will the same fuse subject to the same current under cooler conditions.  The temperature dependency suggests more of an overload condition than a fault, as it appears the melt threshold is being reached when the weather is warm.

Carry on and good luck ... EGK  

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Ernest (Ernie) Kenward

Expertise

The challenges I most enjoy are thoughtful technical questions of a trouble-shooting nature in both electrical, power electronic and mechanical systems, mainly automotive but also machine control and small-machine PLC applications. Please note, however, that I am NOT a walking shop manual! I DO, however, make it a point to have those manuals and other service literature for those vehicles I DO own, and highly recommend that anyone serious about maintenance or modification of their vehicles do the same; MOST of your answers WILL be found there. For that matter, I do NOT go out of my way to acquire shop manuals for any vehicle I do NOT own! That being the case, any general query to me along the lines of "What is the meaning of this code read from the ECU of my 2015 XYZ?" or "Where is the fuse for the windshield washer pump found?" (try your car's electrical distribution panel for a start!) will not go far. What I do offer is a pretty good collection of literature, insights and hands-on experience with 1950s to 1980's Ford products (plus a developing database of information and practice with the Mercedes diesel cars), along with an engineering perspective and the ability to design and implement custom control, electrical and mechanical subsystems for vehicles. For that reason, I am happy to make my thoughts and efforts available to those who are of like mind and/or are seriously making a point of learning about their vehicles. Use the Opportunity to Learn!

Experience

A key skill in my work and hobby pursuits both is STRATEGIC TROUBLESHOOTING. I am a senior instructor in Electrical Engineering Technology at a leading Canadian polytechnic, my areas being Electrical Power and Industrial Control, electrical and electronics design and manufacturing, and AutoCAD and related CAD/CAE software - plus equipment problem-solving and new equipment design and prototyping. Hobby-wise, I have 30-plus years of experience in auto restoration, mostly in electrical and mechanical systems. Ongoing projects include a 1959 Edsel Corsair, my 1978 Ford E250 class-B motorhome conversion, and the care and upkeep of my Mercedes 300CD. My vehicles become engineering test beds for electrical and mechanical upgrades as ideas present themselves. This includes the design and production of circuit boards to restore or enhance features for which no OEM replacement parts are obtainable, or where better specifications or reliability can be had via newer concepts. Regarding the E250 RV conversion, I designed and continue to revise a custom power distribution system, managed by a Programmable Controller (PLC); this has made most revisions as easy as uploading new firmware as I develop it. The "mini" PLC is a powerful device for custom automotive control systems. One good example (there are many) would be the Moeller "Easy Relay"; these offer a wealth of control, monitoring and variable-and-status display options for such projects. A good example project which has worked well is that one for my RV noted above, which has been on the job - revised in firmware only - for a decade now. It is a load management and charging control system to avoid the sulfation-induced early failure that often befalls deep-cycle batteries used in RV power applications. The battery installed in 2003 lasted long enough to more tnan pay for the PLC that contributed to its longer life ... and the PLC will be there for the next battery as well!

Organizations
IEEE - senior member ... past WCC Student Activities; SME - senior member ... past chair, greater Vancouver chapter chair 318; Edsel Owners' Club - have served in various capacities on chapter executive during seventies; have been Power and Driveline resource on the Edsel Owners' Club "E-team" for more than a decade.

Education/Credentials
Graduate of UBC

Awards and Honors
Certificates of appreciation from IEEE and SME for work in student and chapter activities

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