I have searched and read that Dex-cool turns brown if air is in the system , about 300 miles ago I changed my coolant 1 gallon straight Dex-cool 1 gallon distilled water and 1 bottle of water wetter ... Now 300 miles later brown again.... my quesstion is where is the best place to start looking for the air getting in the system ? also the car is getting to about 221 temp in stop and go traffic but runs at 174/172 on the high way. both top and bottom radiator hoses are getting really hard at temp and I have a 160 T/stat fans are adjusted to come on earlier, and the radiator is unblocked. Thanks in advance for any and all help you can offer.

Phil

 

I doesn't sound like you have actually flushed the system, just changed what drains from the radiator.

 

Whats the proper way to flush the system? also what is the dex-cool brown ?

 

Hopefully NOT because there is oil in it. What color is your oil?

Just the first thing I would check if you haven't already.

 

oils fine changed it today a little dark but no coolant in it at all . also checked the valve cover cap nice and clean no tan foaming. is it normal for the hoses to get hard at temp ? I still can squeez them just feel hard to me they do get soft after I relive the pressure at the coolant tank.

 

Yes, the hoses will get hard. The system pressurizes to around 13 psi under normal operating conditions. When I flushed my system, I drained and filled, drained and filled with straight distilled water until the water ran CLEAR. Then I drained it out and filled it with straight dexcool. The dilution was close to 50/50.

Once you do that, it will stay nice and pink.

BC

 

The cooling system holds 12.6 quarts of coolant. If you want to get darn close to a 50/50 mix of Dexcool and water ... follow Bill Curlee's advice to the point where the water coming from the engine is clean.

Button everything up and add 6.3 quarts (6 will be fine ... that's 1.5 gallons) of Dexcool and then top up with water from there. The running engine will mix the coolant, even into the reservoir, so don't worry that the reservoir is just water at first ... unless you park the car in freezing temperatures .....

 

The procedure (from the Service Manual) for flushing the coolant system ....

1) run engine until the thermostat opens (on unmodified systems this would be 190 degrees .... do not let the coolant rise past 212)

2) Stop engine and ensure vehicle will not move (in PARK, parking brake set, etc.)

3) Remove surge tank cap (BE CAREFUL - coolant over 212 degrees may surge out of the tank and burn you - release pressure slowly)

4) Open drain **** located on radiator (passenger side) - You only need to turn it 90 degrees - pull GENTLY outwards if it doesn't pop out by itself and start draining coolant .... WARNING the coolant will be HOT ... don't splash it on yourself.

5) Close the drain ****

6) Put clean water (distilled if you want) into the reservoir until the sytem is full

7) Start the engine and add clean water as air bubbles from the system

8) Allow coolant temp to rise above 190 degrees

9) Shut off engine

10) Repeat steps 4 through 9 until the coolant draining is clean water

11) With clean water draining from the system, allow the system to drain as much as possible.

12) Close drain ****

13) Add 1.5 gallons of Dexcool through the reservoir

14) Add water, as needed (approx 1.5 gallons) to fill system

15) Start engine and let run for about 1 minute - you may need to add more water during this time to keep the fluid level at the HOT mark.

16) Place pressure cap on reservoir

17) Raise engine RPM from idle to 3000 RPM over about a 30 second period, and after letting it drop to idle, slowly raise it again to 3000 RPM. Continue to do this until the coolant is at about 200 degrees.

18) Shut off engine

19) CAREFULLY remove the reservoir pressure cap IF YOU NEED to add more water. Bring the reservoir level to the HOT level.

20) Replace pressure cap

21) Go have a beer (or two) ... you're done

WATCH the coolant level over the next few days. There may still be minor air bubbles in the system that will flush out and lower the reservoir level. Adding clean water to bring it up to the corect mark is fine at this time. In the future, say weeks or months later, if you add coolant - add a pre-blended 50/50 mix of Dexcool and clean water.

 

I followed this procedure on my old C4 but I let it cool between draining and filling so I wasn't dumping cold water into a hot motor. Took me three days

 

Thanks guys any Idea where the air might be getting in ? also how come there is such a big variance in temp now ? I understand it will get hotter from stop and go traffic but I dont feel it should get this hot, the temp has been in the 20's and 30's here ... do you think the brown coolant will cause this problem or do you feel some thing else is happening ? Iam not losing any coolant.

 

If you're not losing coolant, and the reservoir is remaining filled to the correct level, then you're NOT getting air in the system. For air to get in, coolant would have to leak out.

Here's what I'd do ....

1) Replace thermostat with stock 190 degree ... your engine is running WAY to cold if it's running 174/172 (from your OP) on the highway. The engine should run about 195 on the highway. You are causing excessive engine wear (the oil is not hot enough) and are hurting your gas mileage and performance with the engine that cold. You are also stressing the engine thermally, the reported temperature is at the head, just as the coolant is leaving the engine .... the coolant coming in at the bottom is MUCH colder than that ..... not good.

2) Re-program the fans to stock settings - from the Service Manual ...

The low speed cooling fans are commanded on when the coolant temperature reaches 108°C (226°F). It is turned off if the coolant temperature lowers to 104°C (219°F). The high speed cooling fans are commanded on when the coolant temperature reaches 113°C (235°F). It is turned off if the coolant temperature lowers to 108°C (226°F).

3) Flush the coolant system as described in my previous post. Be sure that you get as clean a flush as you can - the Dexcool may be being contaminated by older Dexcool (from your description you only cleared 2 gallons of fluid from the system ... it holds over 3). Fill with a good 50/50 coolant mix.

4) Watch your reservoir over the next few weeks. If the level is going down slowly, and/or the Dexcool is changing color again, I'd suspect that exhaust gases are contaminating the coolant ... you MAY have a blown head gasket, or similar such problem.

Good luck,

 

whats the best way to test for head gaskets just do a leak down test ? I looked at the bottom of the water pump and noticed very slight weeping a few small drops of coolant on it could the pump be failing causeing this as well ?

 

If you have water weeping from the water pump .... that is 98 percent chance the source of the problem. The water pump needs to be replaced. It will only get worse, until you are at the point the engine will start overheating. That could also explain the large swings in temperature you report you are seeing.

So, replace water pump and thermostat, re-program the fans, flush/replace coolant ... you should be fine.

IF the Dexcool then continues to change color, then I'd pull the spark plugs and look at them. If you have a leaking headgasket one plug will look radically different in color/texture from the others. Then you'll have an indication of the problem, and on which side of the engine it is. But I wouldn't worry about that yet, get the cooling system working properly and I'll bet everything will be fine after that.

 

is it ok to use a graden hose to flush the system with ? than fill it with dex cool and distilled water ? I wiil also flush the bock out while the pump is off.

 

Sure, a garden hose will work, remove the lower radiator hose and be sure to run plenty of fresh water through the radiator also to be sure that is clean. Remember, if you have pets, the Dexcool has ethylene glycol in it, which tastes sweet, but is also poisonous, so be sure not to leave any puddles of coolant on the ground, wash it away carefully.

Once you've flushed the block and radiator as well as you can, some water will remain in them. That's OK. After you close everything up, fill with the 1.5 gallons of Dexcool first, and then add either tap water (some of which will still be in the system) or distilled water. Chevy recommends "drinkable water", so in most places tap water is fine .... that's what the car had from the factory. Some people, like Bill Curlee are more "cautious" and use only distilled water. Your call, if your water source is high in mineral content, then I'd top it off with distilled, I wouldn't worry about the small amount of tap water left in the system ... it isn't enough to worry about.

 

Good deal brother off to do the pump I'll let you know how it turns out Thank you for the help....

Phil

 

As we say in CA, Da nada ....

Might consider (since it will be off) replacing serpentine belt, and since it is easy to get to with the serpentine off, the A/C belt.

Good luck, let us know how it goes.

 

BlackZ06 you are the man switched out the pump , upper & lower hoses as well as the Belts. flushed the **** out of the block and rad. got all the air out of the system and took a nice long test drive right at rush hour bumper to bumper for a good 1/2 hour (I was already up to temp before the traffic .. It never went over 182 . And out on the highway it stayed at 178 ran great. but took a while to do it beings I had to pull the Procharger off to remove the water pump. but all is good Thanks alot Bro.

Phil

 

Fwiw. I had the brown gooey dexcool in my GMC Jimmy several years ago. I took it to the dealer and it turned out it was a known issue with those vehicles. They had no explanation for it. They flushed it out under warranty with whatever equipment they use. A year later when the warranty had expired, it was brown again. This time they wanted to replace my radiator at my expense. I said no f'n way, just flush it real good, it can't possibly be that clogged. So they did and it was fine for 3 more years till I sold it.

So the best I can figure is that it takes a couple of good flushes to get it clean.