Rick's Free Auto Repair Advice

GM engine leaks and DexCool

GM engine leaks and DexCool

There are loads of websites that rant about the evils of GM’s DexCool coolant and how it destroys engines. There was even a class action lawsuit over DexCool. GM settled without admitting fault. But history has proven that the actual problem was NOT caused by DexCool but by faulty gasket design. In fact, GM has revised the intake manifold gaskets for the 3.1L and 3.4L engines several times to correct the problem. If the problem was solely the result of DexCool, the revised gaskets would not have failed when the engine was refilled with other types of coolants. But they CONTINUED to fail, proving that DexCool was not the cause. Bottom line, it was lousy gasket design.

Read this clip from a 2013 article from Engine Builder magazine about GM engine issues:
Common Problems of the 3.1L
• Leaky Intake Manifold Gaskets. This is the most common problem on these engines.
Some have blamed the problem on GM’s Dex-Cool antifreeze, but the real problem has been the intake manifold gaskets. The original equipment gaskets have a plastic carrier and soft sealing beads around the coolant and intake ports.

dexcool, intake gasket

The hole in this gasket was NOT caused by DexCool. It’s a faulty design.

Over time, the plastic carrier and seals soften and deform, causing the gasket to lose its seal. Coolant then starts to leak down into the lifter galley and crankcase. Eventually, the loss of coolant causes the engine to overheat, which may cause additional damage such as a cracked cylinder head or crushed head gasket.

The leakage problem can occur in as little as 60,000 miles on some engines. The higher the mileage, the more likely the intake manifold gaskets are leaking coolant.

Coolant leakage can be diagnosed by checking the oil dipstick (if the oil looks milky or foamy it probably has coolant in it) or by pressure-testing the cooling system. If an internal coolant leak is indicated, the fix is to pull the intake manifold and replace both intake manifold gaskets.

Several aftermarket gaskets offer design and material improvements over the OEM gasket to provide a longer lasting trouble-free seal.

Replacing the old intake manifold bolts with new ones is also recommended.

If you have a GM 3.1L or 3.4L engine and have had to replace the intake manifold gaskets, heed this warning: Do NOT use any coolant other than DexCool. Both GM and major engine rebuilders have discovered chemistry incompatibilities between the new gaskets and non DexCool coolants. By substituting your judgment or that of some fly-by-night seat-of-the-pants opinions regarding different coolants from someone on the Internet, you may actually cause more damage to your engine.

Coolant does far more than transfer heat from the engine to the radiator. It contains anti-corrosive additives that prevent electrolysis. And with all the different metals used in engines, water pumps, heater cores, steel tubing, transmission coolers and radiators, you’re just begging for really expensive trouble if you go with anything other than GM recommendations.

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© 2012 Rick Muscoplat

Posted on by Rick Muscoplat

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