Hi fellows - me again.
Yesterday, I changed the oil in my sister's truck. 2003 Chevy Silverado half ton, 5.3 V-8, (Mobile 1 10W30).
While pouring in the last quart, I asked her if she had ever flushed her cooling system. She said she didn't know they needed flushing. The radiator on this truck does not have a cap on the rad, but instead has an overflow tank where you add fluid. I took the cap off that and looked inside. The sides of this tank is covered with these little bumps, (like pimples). The coolant itself is very dark and looks like syrup. It's the original factory fill, (this truck belonged to my Dad and he gave it to my sister - so I know if she never changed it, it's never been changed as my Dad never changed it). The truck has 167,000 miles on it.
Additionally, I took a white paper towel shop rag and wiped the inside of the oil cap and inside the filler tube on the engine, the residue on the white paper towel was a dark red/brown-red color.
She got the truck with 120,000 miles on it and has always used Mobile 1 10W30 with every change, changing oil every 6,000 miles, (I changed it for her yesterday as money is tight for her and she was worried because she was at 6,800 miles on current change).
When my Dad bought the truck new in '03, part of the deal was a free lifetime oil change every 3,000 miles which he faithfully did. I'm sure they used a conventional motor oil, but oil and filter was changed every 3,000 like clockwork from 0 miles to 120,000 miles. Since 120,000 miles, she has changed the oil every 6,000 miles with Mobile 1 like clockwork.
So okay, here are my questions:
1. The dex cool is obviously bad - past time on both miles and age. It appears to be turning into the famous dex cool sludge. Currently, she has no cooling issues. Should I flush or should I leave well enough alone? I fear if I get to cleaning, it might break something loose inside and then she'll have cooling problems. I was tempted to try the TSP cleaning yesterday but was fearful this might clog the system AND I'm only in her neck of the woods once a week and she would have to drive the truck a full week with the TSP in her cooling system. Is that too long to do this?
2. What is this redish/brown red coating inside her motor? Is that from the dexcool? Is this an indication coolant is starting to leak into her motor? Is this the beginning of a head gasket issue?
This vehicle is her only ride and she doesn't have the money for a trade. I'm fearful of doing something that will really mess up her truck. On the one hand, I want to help her maintain her truck but on the other, I don't want ot leave her stranded with some bone head move on my part.
What say you guys? Any advice and guidance will be most helpful and welcomed.
Thanks - Glenn.
2003 Chevy Half ton truck - dex cool funky
- Thread starter GreeCguy
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One more thing, I live in Central Florida as does my sister. So running without antifreeze for a period of time will not be an issue.
Seems to me that a good idea for the coolant would be to simply drain the radiator and refill...and do that a few times over the period of a few weeks. That would slowly introduce new coolant into the system without a big "chemical shock". When the radiator is drained down the first time, I'd probably remove the expansion tank and thoroughly clean that. I'm not sure I'd be concerned with anything in the cooling system "clogging". But I would likely take a close look at the various coolant hoses to assess their condition.
If it were me, I'd probably change the oil every 5k miles and just monitor that. The engine's probably fine inside, especially with the good lubrication maintenance it has received to date. The residue on the filler tube may simply be varnish/condensation from a relatively cool part of the engine. As I recall, Dodge 4.7L V-8 engines got that as well in the filler tube. My old Oldsmobile 5.0L V-8 would as well...it had a long filler tube in the front of the engine.
I would not judge the condition of the coolant by the overflow container. Drain the radiator and replace it with 50/50 Dex and distilled water. See how the stuff draining out looks. Do a few drain & fills.
If its not a big deal, remove the overflow container and clean it with Joy and hot water and shaking.
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Originally Posted By: Donald
I would not judge the condition of the coolant by the overflow container. Drain the radiator and replace it with 50/50 Dex and distilled water. See how the stuff draining out looks. Do a few drain & fills.
If its not a big deal, remove the overflow container and clean it with Joy and hot water and shaking.
The red/ brown mud is rust from the iron block. Definitely overdue for a flush and new coolant.
Age and neglect are no reason to indict Dex, this poor vehicle has been ignored for a LONG time to be in that shape.
You'll need the whole house cleaning, one of the important aspects is a COMPLETE drain of all coolant. That can be challenging!
Drain all coolant, remove the rad hose and flush the system with a garden hose. Put the rad hose bad, add water, and add a coolant system flush additive. Drain that stuff out, and fill the cooling system with a 50/50 ratio of distilled water and Dexcool or equivalent.
I have a similar truck and get the reddish brown crud on the oil fill cap too. Its just that the fill tube is long and junk accumulates there. This is with an aluminum block and pristine Dex cooling system so I don't think its rust.
Certainly get new coolant in there though.
Obviously concentrate on the coolant issues as the engine maintenance sounds quite adequate with the "ole skool" 3K mile OCI's and 6K mile synthetic OCI's. Maybe think about replacing the PCV valve if you have the time.
Drain the coolant, flush the system, clean reservoir, and refill with coolant according to the owners and/or service manuals. Have her monitor the reservoir in your absence and closely monitor engine temperature on the dash gage.
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