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Help with coolant ports on intake manifold. 2001 Chevy Silverado 4.3l vortec V6 90,000 miles.

Intake manifold has started leaking on the outer seal, in the front, and back of the manifold. so I decided to go ahead and do a full intake manifold gasket replacement with the Fel-Pro kit before it started leaking on the inside. I have zero water in my oil thankfully. This is what I saw when I got the manifold off. The coolant port on the right, “drivers side” was dry with corrosion covering the entire hole. Looking at the bottom of the intake manifold I see that the other coolant port, directly across from the corroded one is blocked off. Is it suppose to blocked off? And what would have caused the corrosion build up on the right side so badly? What’s the best way to flush out the junk, can I run water down that port and drain all the junk out through the water pump lower radiator hose connection?

Also, I thought TBI ended before 2001. Could be wrong but it makes me think previous owner put an older vortec v6 in this truck. Or at least on older EFI. Thanks for any help guys

ps: truck has no engine cooling issue. It has always stayed at 185 degrees after reaching it.
 

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yes the 4.3 and the 5.7 v8 are basically the same except 2 cylinders have been removed, the 4.3 is just a v8 that was converted to a v6
 

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did you put in drinking tap water in your engines cooling system ?
after you do the work on the engine drain the coolant system complete remove the engine drain plugs flyush out your heater core . then use distilled water 40% and 60% antifreeze .
I have old engines and I have no corrosion in the coolant system.
when I purchased my 1996 Impala in nov 1995 I had to drain all that GM coolant and flushed my heater core 1 year old .
well my Impala is still running great and has no engine problems no leaks LOL...my 2000 silverado again no problems ...use distilled water .. tap water destroys the metal .
 

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Discussion Starter · #4 ·
yes the 4.3 and the 5.7 v8 are basically the same except 2 cylinders have been removed, the 4.3 is just a v8 that was converted to a v6
did you put in drinking tap water in your engines cooling system ?
after you do the work on the engine drain the coolant system complete remove the engine drain plugs flyush out your heater core . then use distilled water 40% and 60% antifreeze .
I have old engines and I have no corrosion in the coolant system.
when I purchased my 1996 Impala in nov 1995 I had to drain all that GM coolant and flushed my heater core 1 year old .
well my Impala is still running great and has no engine problems no leaks LOL...my 2000 silverado again no problems ...use distilled water .. tap water destroys the metal .
Thanks. I def am doing a full flush. Water pump is leaking also I see so that’s coming out anyway to replace it. I ran straight tap water in it for about 400 miles one time when I was stranded on the side of the road with a leaking lower radiator hose. I pulled over and turned off the engine when I noticed i was running 195 and I always normally run 185. Fixed the hose, added the water I had on me which was actually Sam’s choice purified drinking water not much better probably. Anyway I flushed it and put in 60/40 dex cool after that. Yesterday I asked the previous owner if he had run straight water he said no but did use bars radiator stop leak a couple times. Because of a leak in or near the heater core.
 

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so see how the coolant system works .. then when the vehicle runs good replace all the coolant then use distilled water 40% and 60% dexcool .. now distilled water is pure water no metal and no chlorine .. spring water has iron and other metals chemicals . because distilled water does not attack metals and dexcool will not cause the corrosion and holds up for 5 yrs ..
I have another old engine .. a boat engine merc 470 170HP has an internal coolant system .. engine is made in 1978... I bought it in 1986 and the previous owner put tap water in it .. I had to fix the water pump .. the cam shaft is connected to the water pump impeller .. I had to install a s/steel sleeve on the cam shaft ...
motor has no problems that was the only issue ..
many have plastic radiator tanks on them and over the years the plastic cracks on the high temp side.
you should also put a 15PSI cap on it .. many put a 18PSI cap ... causes damage ..
 

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the heater core will be a problem because of those nasty corroded pictures ..replacing the heater core is a lot of work .....
I do leak testing on components .. I use a air pressure gauge and put in 15 PSI of air to see if the heater core is leaking .. use a soap water spray bottle ...see if the air bubbles ....
 

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2000 Silverado Z71 4x4 5.3L 460k+ miles w/ GM rebuilt motor and trans
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Heater core job SUCKS on this model... ☹
 

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Corrosion can be caused by depressurization of the system, old coolant, and debris, I advise after draining the coolant, the system must be rinsed with distilled water, and then resort to means for flushing the engine. It is recommended to change at least two volumes in the cooling system, then fill the flush with distilled water, drain the liquid again and add fresh antifreeze, choosing the correct class. There are good options, chevy silverado radiator upgrade for good quality silverado radiators if replacement is needed.
 
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