What the hell is going on here? An '04 with 220k on it. I did the headgaskets 50k and 5 years ago. Never overheated, in fact 212°F is the highest I ever saw and only once about about 2 years ago, and never run above 4.5k RPM under my watch. Pretty clearly the cooling system is somehow venting into the oil passages (uhhh HG, prob) but has anyone seen this before? No milkshake under the cap or on the disptick but there is a coolant smell on startup and she took a cup or so of Dexron last week, and the level is down to about 1" up from the lowest part of the reservoir again. In an effort to perhaps save some troubleshooting time I'm interested in others thoughts here.

It just occurred to me that I got two separate misfire codes about two weeks ago. I was running on fumes and went around a decreasing radius exit ramp when I assume I starved the pump and it started bucking and CEL'd. The bucking cleared up in a quarter mile or so and I pulled into a gas station within another quarter mile. I cleared the #5 misfire and drove on. About 15 miles later I was pulling away from a light onto a divided highway and needed to get over a lane so I took each gear up to about 4k to get around the guy next to me, and at around 75mph #3 misfired. I cleared it and it's actually running completely normally. I've had no issues for 100+ miles after that day. Apart from coolant escaping from my valve cover of course... although I'm not certain those incidents are related. I just wanted to add them to the story. Otherwise I pretty much drive this thing like an old lady.

 

Dripping from heater hose?

 

UV dye in the coolant tank and UV flashlight, you will find the leak quick and easy.

 

Yeah, are you sure it's not leaking down from somewhere? The valve cover looks to be wet above gasket area, coolant normally doesn't flow upward...unless manipulated by fan or airflow...and in those cases usually has more of a sprayed/spreadout appearance.

 

Great suggestions. I should have clarified that this in on the driver's side back at the firewall so there's really no reason for coolant to be over there. My immediate thought was something to do with the valley pan gasket but once I looked a picture I'm struggling with how that could be the culprit. A leak from somewhere else external is starting to make sense. I'll check around for other leaks. Maybe pressurizing the system parked over cardboard will reveal something. Thanks for the help. More to come.

 

Could it be from the intake heater lines? They are pretty famous for leaking.

 

@ahab Throttle body heater or the hoses for it, coolant from leaks hits the valve cover and travels back.

 

You guys are good. There was no visual evidence of a leak under the throttle body heater but when I stuck a paper towel up against the underside of the hoses it came up wet. Further investigation revealed a slightly loose clamp on one of the TBH hoses and a REALLY loose clamp on the other. No clue how that happened. I haven’t touched them in months. As suggested, it’s probably been running down and around the valve cover and collecting on the edge.

Anyway, I sprayed the valve cover edges with brake cleaner and cleaned them all up. I had to leave town for a couple days but when I get back I’ll refill the overflow snd monitor the situation over the weekend.

Thanks for all the suggestions and common sense! Hopefully this is as simple as it appears.

 

A little easier than HG’s!

 

After replacing that TBH plate/gasket for the fifth time, I finally took the system out. If you live in a non-freezing climate, it might be something to consider doing but obvi a personal decision given the potential safety implications.