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Discussion Starter · #1 ·
I acquired a leak in my radiator, but the car would only overheat on the highway if I pushed it past 75 for a prolonged period of time. The overflow tank would also boil.

Out of nowhere, the overheating issue expanded to casual driving, so I changed the radiator. The car didn't overheat immediately, but once I started to drive, it began overheating again.

The thermostat is only a few months old, but could this be the culprit?
 

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The overflow tank would boil? Would have been good at the time to feel how hot the overflow tank was. I suspect the overflow tank was cool - the bubbling you were seeing was exhaust gas being pushed into the cooling system from a bad headgasket or a cracked head.

I would recommend you have your coolant tested for exhaust gases in it. Many shops have the equipment to perform this test. Hopefully the test is negative. If it is, perhaps your water pump impellers have broken and you aren't flowing coolant very well. But getting what looks to be boiling in the overflow tank has the feel of an exhaust leak into the cooling system.

Does your coolant level go down over time? Are you getting and creamy brown look under the radiator cap?
 

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Discussion Starter · #3 ·
Yes the coolant level did go down overtime, but this was because of a leak in the radiator which I fixed yesterday. But the car went from overheating at excessive highway speeds to overheating in general, before and after the radiator change.

Currently the level appears to be normal
 

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the radiator is full of oil*

Sorry I didn't really think about what I was saying.

I changed the radiator out, then the head blew after overheating again.
No idea why.
No idea why? Wait a moment. You had a radiator that was leaking while you were having an engine running hot when at highway speeds. You saw bubbles in the overflow bottle. You changed the radiator, no change in the other symptoms, but it got worse in that your engine temperature was near or at hot while driving in town. Then you saw oil in your radiator.

What you have to understand is the bubbles in the overflow bottle you saw was exhaust gases being pumped into your cooling system (not bubbles from boiling, as that would have condensed back to liquid once it would have cooled off below the boiling level for antfifreeze (about 245 deg F). The exhaust gases were likely being pump into the cooling system due to a blown head gasket. You may have run your engine long enough to cause so many hot/cold cycles (and much hotter on the hot cycles than the engine was designed to withstand), and you may have cracked your head as a result (or you may have only increased the magnitude of the leak from the blown headgasket, if you are lucky).

If you want to try to salvage the engine, the head has to come off and needs to be pressure checked for cracks/internal damage. If none, it will need to be checked for warpage at the headgasket sealing surface (I'm sure it is warped) and will need to be machined flat again. Good time to have the valve seals changed and the valves lapped. Then put on a new headgasket, along with all the other seals you are affecting while having the head off (and consider a new timing belt and seals in the block side too).

Or find a suitable salvage engine. Or find a replacement vehicle.
 

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Discussion Starter · #9 ·
Ok here's the final synopsis; it's transmission fluid that's inside the radiator. There is nothing in the engine oil, besides oil. Now I'm going to have to flush the coolant system and change the radiator, or vice versa.

Any other recommendations?
 

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Transmission fluid? Are you sure? Only way that could get in the radiator is if the new rad has a leak internally from the transmission lines running thru it. This has an automatic trans, right? Manual wouldn't have the lines going into the rad.
 

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Transmission fluid? Are you sure? Only way that could get in the radiator is if the new rad has a leak internally from the transmission lines running thru it. This has an automatic trans, right? Manual wouldn't have the lines going into the rad.
Agreed. And, if the cooling system holds pressure, when the engine is turned off and the transmission drops all fluid pressure, the cooling system would be putting coolant into the transmission fluid lines, so there will have to be coolant in the transmission fluid. Is there? If not, then I don't understand how it is possible to only have transmission fluid in the coolant. A leak within the new radiator wouldn't have a single direction leak.
 

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Discussion Starter · #13 ·
You guys were right. There was also coolant in the transmission. After several flushes on both the trans and the radiator, there is still some of each stuck inside and mixing with one another :/
 

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You guys were right. There was also coolant in the transmission. After several flushes on both the trans and the radiator, there is still some of each stuck inside and mixing with one another :/
OK, glad you confirmed this before the transmission sustained any serious damage (I hope the transmission is still OK).

Why are you trying to clean the transmission fluid residue from the radiator? You aren't planning to continue using it, are you? Get the proper replacement radiator for it. And clean out your transmission fluid with a full flush the best you can.
 

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Discussion Starter · #15 ·
Why are you trying to clean the transmission fluid residue from the radiator? You aren't planning to continue using it, are you? Get the proper replacement radiator for it. And clean out your transmission fluid with a full flush the best you can.
Was cleaning the transmission fluid residue from the cooling system. This took 4-5 different flushes as trans fluid got all inside the heater core and the system in general. Coolant and water also got in the transmission. Flushed that as well, but there are still minor traces of mixed fluids in each.

And the radiator was replaced with a brand new one.
 
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