brown coolant

[Grovebaby]

I have a coolant question. We've had quite a temperature drop around the northeast lately, so I decided to check the antifreeze on the 91 4.0l that I just bought. when I opened the radiator it was low so I added about a half gallon of antifreeze. When the level reached the top, I could see that the coolant looks like chocolate milk. I checked the oil and it looks ok. Does this just need a flush or is it indicating something else?

 

[aldive]

How long has the coolant been in the system?

I would drain and flush the cooling system and then refill with new coolant.

Good luck ....

 

[JStrider]

looks like chocolate milk!!

thats definently not right... maybe its got a bunch of rust in it...

but it does need a good flush and refill

 

[Crankcase]

Definitley flush it and refill.....But be aware, the rad might be shot and the sediment at the bottom might come out and unplug any pinholes.

 

[Grovebaby]

I just hope it's not oil. I won't power flush it. Maybe just drain and refill or a can of flush stuff at the most.

 

[Ford_Racing_Guy]

its probably just old coolant.


maybe not power flush it, but back-flushing the system with a Plastic Tee kit and garden hose wouldn't be out of the question

this is one of the best ways because it gets ALL of the old coolant out.

 

[Grovebaby]

Found out something else. What color do you get when you mix red (texaco) antifreeze with green?

 

[Tony H]

It can also be that the previous owner tried to mask the notorious Intake Manifold leak with some BARRS STOP LEAK. That will absolutely make chocolate milk out of Green Anti freeze.

You said your coolant level was down a bit. Do you get a sweet smell of Abtifreeze when you get out of your car? Keep an eye and a nose out for signs of a leak, especially now that you added more antifreeze.

 

[Grovebaby]

The previous owner was my brother in law's father and I'm pretty sure he didn't have a clue about anything like that. I have not heard of the notorious intake leak. It was down on coolant and I here a whistle when accelerating from the left side engine compartment. Could this be it? What's the deal with the leak, is it a big thing?

 

[Tony H]

You can probably do a search on Intake Manifold and here much tearing about anti freeze dripping down front of engine. on these First Gen 4.0's.

The design of this engine has a weakpoint ( in my opinion) when it comes to the Bolting down of the Intake Manifold by the Water Jackets. They should have straddles the Water Jacket with Bolts but did not.
A common failure is for the Manifold gasket to give out in the front of the engine very close to the Temp Sensor, just to the left of where the Thermostat is. It is sometimes mistaken for a Waterpump leak sinse it weeps down the front of the engine that is buried behind the Alternator and Upper Radiator hose. You see the wepping antifreeze as it runs down the Water pump area. If/when you have this leak , it is a no fun. many parts have to come off to get down to it. Valve Covers , Electronic distributor, Upper Plenum ( upper manifold), Fuel Rail, All injector wiring Harness, Many Vacuum lines. You will need ne w gaskets for te Intake manifold and the Valve Covers. Very time consuming.

 

[Grovebaby]

Is this something that they all will do eventually.

 

[Tony H]

In my opinion....Yes

Just like GM 3.8 you don't need an odometer, 'cause every 50000 miles, they need an Intake manifold gasket.
Chevy 4.0's every 90000 they need a new Fuel regulator/injector set.

to me, it's designed in failures. It keeps the Service Dept. busy and profittable.

 

[aldive]

Is this something that they all will do eventually.

No.

 

[IAmTodd]

I had the same thing. More of an orange for me. Drained everything, refilled, it came back, I said oh well.

 

[Grovebaby]

What do you guys get for mileage with the 4.0's ? I'm getting 14.7. I hope that can be improved.

 

[aldive]

What do you guys get for mileage with the 4.0's ? I'm getting 14.7. I hope that can be improved.

It can be improved.