Hey there, first time posting here, hoping that someone might be generous enough to give me some advice.

I have a '98 Chrysler Sebring Convertible that I'm fixing up for my mother, and the main issue it has right now is a pretty big oil leak. I suspect that it's a blown head gasket, but I'm a little hesitant to just start tearing the engine apart because it doesn't have all of the symptoms that I would expect. Here's what's going on:

• Oil leaks into the coolant, creating a frothy chocolate milk looking mixture in the coolant overflow tank and radiator.
• The engine starts to overheat after idling for just 30 to 40 minutes, making it undriveable.
• Motor oil also leaks down the back of the block near the exhaust manifold. I added some UV dye to the oil and traced the leak back up the engine as far as I could but it's a bit cramped and I couldn't see past the manifold without disassembly.
• Shining the UV light around the top of the engine bay didn't reveal any oil leaks up top that I could see, it was only visible down the back of the engine underneath the vehicle.
• The oil only leaks under pressure, it doesn't just drip out while the car is sitting there with the motor off. With the motor turned on though after the oil warms up it leaks so strongly that the low oil pressure light turns on.
• The oil sending unit was also bad but I've already replaced that.

Like I said earlier though not all of the symptoms are there for a blown head gasket so I'm a little confused. Here's a list of the things that are working fine:

• The oil is clean. I've already replaced the oil and the oil filter a couple times now and I've never seen any traces of engine coolant in the oil. It isn't a frothy mess like the coolant itself is.
• There's no smoke coming from the exhaust or engine bay whatsoever.
• The engine itself still runs well and doesn't seem to suffer from signs of compression loss, it starts without hesitation, sounds normal, and seems to still have plenty of power.
• The spark plugs also aren't showing signs of coolant contamination either.
• All of the rest of the car and engine is still in really good condition. Less than 80,000 miles on it and it's spent most of its life sitting in a garage.

If anyone with more experience than myself could shed some light on this I would be very appreciative. I would hate to jump to conclusions, tear the head apart to get to the gasket, then find out the issue was something else entirely!

 

Oh also I forgot to mention, it's the Sebring JX with the 4 cylinder 2.4L engine.

 

"The oil is clean. I've already replaced the oil and the oil filter a couple times now and I've never seen any traces of engine coolant in the oil. It isn't a frothy mess like the coolant itself is."
Generally speaking, the oil pressure is going to be higher than the pressure in the cooling system, so you should expect that if there is going to be a leak between the two systems, it will go from the high pressure toward the lower pressure.

"There's no smoke coming from the exhaust or engine bay whatsoever."
If oils isn't leaking into the cylinders, or onto a hot part of the engine like an exhaust manifold, you won't get a lot of smoke.

"The engine itself still runs well and doesn't seem to suffer from signs of compression loss, it starts without hesitation, sounds normal, and seems to still have plenty of power."
"There may be no leak into a cylinder so that part of the gasket is doing its job."


"The spark plugs also aren't showing signs of coolant contamination either."
Same answer.


"All of the rest of the car and engine is still in really good condition. Less than 80,000 miles on it and it's spent most of its life sitting in a garage."
Then it's probably worth the effort to change the head gasket.

With oil in the coolant, I think you're on the right track suspecting the head gasket. Let's hope it's not a cracked block or head casting.

 

Those are some great points, dcotter. After posting this thread I started reading some articles about how a blown head gasket can show different symptoms depending on where it fails at. I'll grab a hydrocarbon test kit from the autoparts store tomorrow just to be sure before I start the long process of a head gasket replacement.

To be honest I would be really surprised if it was something like a cracked cylinder head or a cracked block. The car has pretty low mileage, has always been driven lightly, and I've heard that bad head gaskets are a somewhat common failure for this specific engine.

I really hope that's the case though, because this vehicle has a lot of sentimental value to her and I'd love to get it back on the road at some point.

 

Hey this might be a stupid question, but I was wonder if there was anything else I should be looking at while replacing the head gasket. Are there any other seals or parts that you would typically replace to be on the safe side while you have the head off anyway?

Thanks again.

 

I think I'd do the water pump while I had it all apart. And of course you'll replace the timing belt.

With the overheating at idle you described, there may be some leakage into the coolant of combustion gasses, so the hydrocarbon test will probably confirm that.

If you decide to go ahead with the project, take some pictures and post them up in an album on the forum so others can benefit from your experience.