coolant gunk and leak at manifold

[pboling]

I have a 96 regal and I have recently discovered that a bunch of brown gunk has built up inside the radiator and underneath the cap. I want to go about flushing it even though the engine does not overheat or shown any other signs of a bad cooling system. when researching online I have noticed a lot of controversy over the recommended dexcool and saw that this tends to happen in older gm cars that use dexcool when unwanted air is finding its way into the cooling system it gunks up and blocks up the passageways. After i found this out i inspected more and saw that i have puddles of what looks to be orange dexcool seeping from underneath the plenum. My question is do i need a new radiator or can I just flush the system? I think I caught it pretty early considering I couldn't tell it was bad until I opened the radiator cap. also what should I go about fixing first? and should should I upgrade to the aluminum plenum? I believe they updated the 3800s with the aluminum one after 2002 due to this same issue but I may be wrong.

 

[-Regal-]

How long have you owned the car? Do you know its maintenance history?

If someone used GM coolant pellets in the past for example, it would be that color. Otherwise I'm not sure what Dexcool would look like if it were too old but apparently something similar is a fairly common issue with it. When I had a car that came with it factory I just completely removed it and started using regular antifreeze, but this was when I was also replacing the rad and surrounding hoses etc. Upper intake manifold gaskets commonly need to be replaced on the 3800.

 

[pboling]

How long have you owned the car? Do you know its maintenance history?

If someone used GM coolant pellets in the past for example, it would be that color. Otherwise I'm not sure what Dexcool would look like if it were too old but apparently something similar is a fairly common issue with it. When I had a car that came with it factory I just completely removed it and started using regular antifreeze, but this was when I was also replacing the rad and surrounding hoses etc. Upper intake manifold gaskets commonly need to be replaced on the 3800.

I've had it for just over a month but when i initially tried to open the cap it was tough to get off so I had decided to just recently check the coolant and from what i can tell it doesn't look like the previous owner had touched it either. I already planned on at the very least doing a complete flush and switching to the green stuff but i don't want to replace the rad and all the hoses unless i have to. Should I worry about the intake manifold gasket immediately? what other problems can this cause?

 

[2007LucerneCXL]

Your post said you saw coolant on the intake manifold which may require the repair of the upper plenum and lower intake manifold, also the plastic elbows should be done with metal ones and thermostat.

No mileage is mentioned or changes on when the coolant so that is a factor, so assume it needs at least a full flush, hoses if soft or OEM. There's probably a need to do both upper and lower intake, but should be inspected if that's the leak first.

 

[pboling]

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[pboling]

Your post said you saw coolant on the intake manifold which may require the repair of the upper plenum and lower intake manifold, also the plastic elbows should be done with metal ones and thermostat.

No mileage is mentioned or changes on when the coolant so that is a factor, so assume it needs at least a full flush, hoses if soft or OEM. There's probably a need to do both upper and lower intake, but should be inspected if that's the leak first.

car has 80k on it and from what i can tell no maintenance on the coolant. the hoses are fine and all i can see is a small leak on the front right corner of the plenum making a puddle of coolant on the lower intake manifold.

 

[2007LucerneCXL]

Assume it's time that the plenum needs to be replaced with a updated version and lower intake manifold needs gaskets replacement. As mentioned coolant elbows replacement with metal and thermostat while doing the other repairs. These are common problems on the series adding age and maintenance into the mix.

While it's apart it's a good time to flush the heater core, block and radiator watching what comes out as that may just be the old coolant that has been aged or possibly someone may have used a "stop leak" product in the past but you should see if it's flowing good.