Rust in coolant.

[94Sierra4x4]

Not sure how I never posted this on here.. I've done several basic rad flushes to no avail, the coolant turns back to a solid brown within a day. Any ideas where rust might be hiding? Any additives that help remove rust while flushing, i don't know. Really bugs me to think that rust is circulating around in there -.- although its been there for years.. :/

 

[Horns]

What kind of coolant are you using?

 

[Chris.G.Jr.]

if you've flushed the radiator multiple times try replacing the radiator or pull it out and run a water hose through it and see if the water changes from clear to brown, if so get a new radiator, if not then start looking at parts on the motor, maybe pull the manifold and check where the coolant comes in at. just check everywhere the coolant goes and you'll find your answer,

are there pieces of rusted metal coming out as well or just discolored coolant?

the fitting on the back of the manifold (passenger side back by firewall on manifold) sometimes that fitting gets really corroded, its happened to mine (the corrosion) its some type of bs quick connect or quick disconnect fitting gm installed when in reality theres nothing quick about it cept quick to break. Most say its a pita to replace but mine was simple after i got the right fitting and just bought a hose and ran it from there to the heater core inlet on firewall.

sorry that last part is just a tip

 

[94Sierra4x4]

What kind of coolant are you using?

I'd have to check the jug.. just some lordco brand stuff I believe it is..

if you've flushed the radiator multiple times try replacing the radiator or pull it out and run a water hose through it and see if the water changes from clear to brown, if so get a new radiator, if not then start looking at parts on the motor, maybe pull the manifold and check where the coolant comes in at. just check everywhere the coolant goes and you'll find your answer,

are there pieces of rusted metal coming out as well or just discolored coolant?

the fitting on the back of the manifold (passenger side back by firewall on manifold) sometimes that fitting gets really corroded, its happened to mine (the corrosion) its some type of bs quick connect or quick disconnect fitting gm installed when in reality theres nothing quick about it cept quick to break. Most say its a pita to replace but mine was simple after i got the right fitting and just bought a hose and ran it from there to the heater core inlet on firewall.

sorry that last part is just a tip

I had a hose runnin in the rad and truck running for like an hour one day. It was clear water coming out. So i filled it up and put plug back in. Next day it was brown.
No metal chunks that I saw.

Unfortunately I'm not about to pull the intake manifold to look for rust.
(Time is a factor, and confidence in engine-work is lacking, hah, for now. 2 more weeks of work then laid off till Feb.. will get a bit more involved when I know I don't need the truck the next day)

I'll check the fitting on the back, does it get rusted solid in there?

 

[JollyGreen]

Does the truck run above normal operating temp? Mine had this problem after I bought it. A family friend who is a mechanic back in Illinois told me it was the same "quick disconnect" that Chris mentioned. It's probably a 5/8" or so internal diameter and mine was corroded so bad it was probably half that size. The truck was running warm, and that was the cause.

I doubt this is what's causing the color of the coolant to turn brown since that piece I referred to is aluminum and not steel.

 

[Chris.G.Jr.]

I'd have to check the jug.. just some lordco brand stuff I believe it is..



I had a hose runnin in the rad and truck running for like an hour one day. It was clear water coming out. So i filled it up and put plug back in. Next day it was brown.
No metal chunks that I saw.

Unfortunately I'm not about to pull the intake manifold to look for rust.
(Time is a factor, and confidence in engine-work is lacking, hah, for now. 2 more weeks of work then laid off till Feb.. will get a bit more involved when I know I don't need the truck the next day)

I'll check the fitting on the back, does it get rusted solid in there?

nah the fitting doesnt get rusted it just gets badly corroded ill attach a pic of how mine was i was lucky enough to get it out without breaking it surprisingly with my impatients, but ya i understand bout not messing with it if ya need it the next day, im the same way, ended up having to walk to the parts store when i replaced the fitting and the guys gave me the wrong parts so i had to go back later and actually talked to a guy who knew and understood what i was trying to do and set me up!!

if you ran water through the radiator and it came out clear id conclude the radiator shouldnt be the prob (dont quote me) so since you had it running then you say it got brown id say its gotta be coming from somewhere inside the motor when its circulating.

when you ran water through it did you have the bottom hose connected?

trying to think....all im coming up with is if you ran water through the radiator with hoses off and drain plug open and it was all good its gotta be coming from the motor or somewhere where the coolant/water circulates to.

well the pics were removed i guess...

hopefully this will embed took it off gmfs

got the fitting and hose off without breaking the fitting :success: had to use a razor blade to cut into the hose a bit for it to slide off easy but got it done now just gotta get a new fitting and hose and put it on and top of the fluid :yeah:

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final

yes i know its dirty under the hood i realize that

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2 foot of hose worked perfectly

 

[Tempted]

Are you 100% sure its rust?

Most of the time if the truck was ran without antifreeze for a long period of time the rust will take a long time to remove. I've always used Prestone cooling system flush and it works pretty well. Just follow the directions. Some people use CLR with great results as well. Take *some* caution when flushing out old, high mileage motors though. Sometimes the rust/corrosion/sludge is whats keeping it from leaking. When you are flushing it, the truck is running, correct?

 

[Horns]

I had a problem with my quick disconnect leaking, A quick o ring replacement fixed that.

I would make sure it actually is rust you are seeing. If it is, flush the system until clean water starts pumping through.

 

[TylerZ281500]

my 88 had the same discoloring issue. the truck ran water a mojoority of its life, hes the coolants passages are hurt but as long as you arent burning coolant id say your fine. what i did on mine was flushed it after checking the radiator and replaced it with 3/5 coolant, and 2/5 water. drove it for about the time of an oil change and a half and changed it and it was nasty, murky brown, no transparancy what soever and thicker. ran warm water through the hole system for about an hour. schools auto shop had heated water all the time for some reason. after that and filling it back up i neve had an issue. it just needed time to clean out all that nasty stuff.

if you did that then my next guess is that it may be hiding in your water pump or by the rear manifold passage that gets blocked off due to the gasket. thats what happened to my camaro after it sat for 4 years.

 

[Chris.G.Jr.]

I had a problem with my quick disconnect leaking, A quick o ring replacement fixed that.

I would make sure it actually is rust you are seeing. If it is, flush the system until clean water starts pumping through.

mine wasnt leaking just badly corroded and figured its only gonna get worse might as well swap it out for a better fitting and hose