I have the water pump off, and it looks like there is white sand inside. Is this corrosion from the aluminum block? How much is acceptable?

 

Hard to gauge the extent from a brief text description, but I have pulled many aluminumwater pumps over the years that exhibited corrosion ranging from spotless, to a few pits, to significant aluminum oxide coverage on the surfaces.

How much corrosion haseverything to do with how well the cooling system has been maintained. Regular coolant flushes (at least every 2 years or 30K) are essential because the additives in the coolant are consumed over time and when they're gone, corrosion happens rapidly.

Chances are if the aluminum oxide coverage is extensive, your cooling system has probablynot been well maintained and there is likely corrosion in the radiator. Corrosion in the engine cooling jacket is usually nota problem unless it gets to the point of being scaly. The radiator is the most sensitive due to its thin passages which can be easily clogged or eaten through entirely.

Dave

 

Also when using hard water will cause corrosion just like a hot water heater without a water softener. Change your coolant on a regular basis and it shouldn`t happen no matter what kind of water you use.

 

This is a good indicator that a radiator rod out is in order. Stuff like what you are describing is what causes the majority of radiators to loose flow and allow the engine to run hot. Consider paying a visit to your local radiator shop for a test and possible rodding.

 

X2 on that. Sounds like your radiator is heavily corroding. It is the most corrosive component in your cooling system, the heater core not far behind.

 

Im planning on a new radiator (aftermarket) this month so I probably wont drive it until that gets in. Ill take a picture after work today to show you what Im talking about, looks just like wet beach sand and I hope thats what it is not.

 

Why replace the radiator, how many miles on your truck?

 

This is an excellent point. I only use distilled water (available at the grocery store) in my cooling systems, for that reason.

Dave

 

133k, was a rental in NV, CA, and HI most of its life so who knows what kind of abuse its seen.

 

Same here, only distilled but lately Ive been buying the 50/50 mixed stuff that says not to add water.