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Draft—DEX-COOL 2007, Part 1a: 5.7L V8 Engine Sludge and Gasket Change
by John R. Hess with additions from Mole Snoopster
To appear in March 2007 Cool Profit$ Magazine
© 2007 All Rights Reserved
We're all aware of the problems with the 3.1, 3.4 and 4.3L IMGs (Intake Manifold Gaskets), what about with the less noticed 5.7L Vortec V8? Did it suffer when GM switched over to DEX? California's John B believes that it did. He became a believer while performing a gasket changeover. Below are the photos. At 100,000 miles, clearly something was not working well inside the engine of his 1999 Chevrolet Suburban K1500.
Below: While the photos are a little out of focus, the contaminant-sludge in the coolant channels is still recognizable. Plus, it looks like the gaskets had indeed been leaking coolant at certain points around the port.

To lay the groundwork, John stated: "I'm the original owner and did all cooling maintenance myself. I flushed and replaced the DEX-COOL twice since new (about 3 year intervals). I mixed 50/50 with distilled water and never added any other product except Bars Leaks factory sealer (gold powder). The orange sludge is about 1/4 inch thick."

John believes the sludge above came either from the DEX-COOL itself or from other components that were broken down by the antifreeze. He's convinced that this sludge interfered with the cooling of the cylinder heads, causing excessive heat and leading to detonation. The detonation problems occurred mostly in hot weather.

John says: "It's also possible the cheesy plastic intake manifold gasket developed slight air leaks over the years causing the fuel/air mixture to run too lean." He adds, "now when I periodically check under the radiator cap, the coolant level is never low. Fel-Pro actually told me about the special gasket they make called the Problem Solver."

What caused John to finally undertake the arduous repair is when the IMG eventually failed to the point where "coolant was shooting out of top of the engine like a geyser."

Above: Some type of sludge has coated the radiator hoses. If anyone has analyzed this contamination and KNOWS exactly what it is, please call us at 800-883-8929. Or use this email link: Click to email imcool.com.


Above: The "Problem Solver" Fel-Pro PermaDryPlus® gasket that John Bell chose to replace his original part. As seen, this gasket is built around a metal carrier versus nylon used in the original model.

Truly concerned about the future of his "Burb," and wanting it fixed right, John had called me last summer looking for a true expert to guide him through a quality repair. I pointed out several DEX experienced shops who I knew would lead him correctly. John chose to work with Bruce Balfour, owner of Mac's Radiator and Air Conditioning (562-920-1871), Bellflower, California. Bruce provided the Fel-Pro gaskets.

If you have similar stories but maybe with differing details and outcomes, and would like to share them with Cool Profit$ Magazine's readers, please call me at 800-883-8929. Click here to email your story.   $$$

Return to DEX-COOL 2007, Part 1
Return to DEX-COOL 2007, Part 2
Return to DEX-COOL 2007, Part 3
© 2007 All Rights Reserved