Question about 2004 Pontiac Grand Prix

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Noticed it was overheating, let it cool, removed radiator cap, saw this brownish substance all over the inside of cap and in radiator. What is it and what should I do?

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The brownish is oil/the head gasket busted threw letting in oil to the water pull the dipstick and see if there is any moisture or milky looking substance if so look for another motor or have the heads magnafluxed for cracks

Posted on Mar 24, 2011


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I have a 99 pontiac grand prix SE overheating,no service lights on, never overheated before.

Coolant level full ? Cooling fans come on ? Ever have the thermostat changed ? Pull the radiator cap an look inside the radiator , is it caked with a substance that looks like redish mud . Is it actually over heating or is the gauge in the insturment cluster bad.

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If you have overheated your car recently, then you possibly have a blown head gasket. Take off your oil fill cap (with engine off) and inspect to see if there is a milky substance underneath the cap. If so, bad news- head gasket. You can also check the oil dipstick for the same substance to verify bad head gasket, but usually it has to be pretty bad (gasket) or driven for a while before exhibiting any signs. The oil fill cap is a pretty good indicator. With the car cool, you can open the radiator cap and look and smell for anything other than coolant (fuel smell or oil slick). If so, probable head gasket.

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I have a Monterey sport latest model which i drove recently on a tour then suddenly on my way there were white smoke coming out of the radiator cap after that we took it to the montero service station and...

are you sure it was smoke and not steam? without seeing this substance myself, I am thinking it could POSSIBLY be oil in your cooling system. Didnt the mechanic tell you? It would mean a serious problem. This "waxy" substance is what happens when oil mixes with water. It might mean your car overheated and cracked the block. I hope this isnt true. Ihave seen this before. Take off the radiator cap. Roll up a piece of white paper and slip it down into the radiator. When you bring it out, it should not have anything but water/antifreeze on it. If there is any black substance, thats oil.It got into the cooling system. Now check the oil dipstick. If it looks greyish, it means water/antifreeze got into the oil system. I'm not an expert and this is just my personal opinion. Check your radiator fluid.first. Dont drive the car if you find "oil in the water." It will cause further damage and if you plan on having the car fixed, dont take that chance.

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Did you 'burp' the cooling system and get all the air out? It sounds like it has an airlock.

Turn the heating to FULL (very important). Remove the radiator cap, (as opposed to the reservoir cap, but remove that too). Start the engine, and keep topping it up. When the thermostat opens, there will be a surge or drop in level. Continue to top up. Check the temperature gauge in the car to make sure you are at full operating temperature. Turn the engine off, top up to the brim one last time, put the radiator cap on. Top up the reservoir, and put the cap on that.

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What you see is a mixture of water, oil and fuel, Unfortunately you car has a blown head gasket or cracked head, you need to get a mechanic to completely diagnose it as the engine will sustain more damage if you continue to use it.

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Ok, g35 coupe 06,52k miles Had over heating problem in april 2010,replaced thermostat, all's well. Now Jan 2011 overheating again, noticed upper & lower radiator hoses collapse, changed thermostat...

Heres a couple of things you can check. Start your car and remove the radiator cap,(before it gets hot mind you) when it reaches norm operating temp, look inside radiator to see if water is circulating. If its not moving, its a bad water pump. Also, youre hoses should never collapse, if they collapse when they get hot maybe you need new hoses? Finally, if those dont work, flush out your radiator. Open the bottom cockpit and use a garden hose and let it flush out the system while the car is running, about 10 mins should do the trick. If the radiator looks clean inside then it doesnt need flushed.

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Car is running hot and the heater quit working. i have a thick oily substance in my radiator resservoir. this car is a 1999 Saturn sl. in the radiator reservoir it has a brownish thick liquid and when the...

Sounds like a head gasket, the oily substance is actually oil. Do not drive the vehicle, at some point a $1000 repair will into $3000 repair when the engine seizes.

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cool air and overheating point to low coolant level. Do you have a bleeder valve near the thermostat? You may have air trapped in the system. If no air trapped, the radiator may be plugged up not allowing proper circulation of coolant.

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Hi my name is Allen!
The first thing you need to do is check for coolant leaks, I suggest this because you seen steam coming from under the hood. Various places to check would be the radiator, hoses, water pump, heater core, head gaskets, freeze-plugs. Check the level of coolant in the radiator, but only after the engine has had time to cool-down because you could be seriously burnt by removing the cap if it has not cooled.

If the radiator is full then other causes could be; the radiator fan not working properly, the thermostat could be sticking closed, the system could be restricted not allowing coolant flow unless driving vehicle, and the water pump could be defective. These are just a few possible causes!

If you need further asistance you may contact me through FixYa!

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