2007 V6 Oil Issue

I have a 2007 4.0L with 278k miles on it and I checked my oil today and it’s black and smells burnt. I change it every 3-5k miles and I drive it a lot but the last time I changed it (only around 2k miles ago) it was perfectly golden with 5k miles on it. There’s no smoke coming from the exhaust, just vapor on start up and on cold mornings, and it’s not low on oil either. It is holding oil fine, no blow by, just black and smells burnt on the dipstick. I need help please

 

Possible overheating? Check your coolant system first. Does it have the correct amount of coolant? Does the coolant look clean? (It should not be milky or rusty-looking.)

How about the water pump -- does it make any weird sounds when the engine is idling, like gravel rocks rolling around, or turkey-gobbling noises? Any signs of pink/red coolant crust anywhere around the water pump?

Feel free to post pics & video of the oil, the coolant, sound of the engine when it's idling, etc.

 

Are you changing it yourself or having it done?
If your having it done maybe it didn't get done last time...

Only other thing I can think of is a PCV valve that isn't working properly.

 

Possibly also a failed or failing coolant thermostat valve? If it doesn't open correctly when the engine warms up, coolant will not be pumped through the radiator and engine temps will rapidly climb above normal operating range.

 

If the engine would be overheating to the point that the oil is getting cooked I would think it would be fried by now.

 

Not a mechanic here, just a DIY guy -- is it possible for thermostats to fail part-way, so they don't fully open? Leading to chronic increased running temperatures but not outright overheating?

 

Theoretically it could I guess but engine oil temp would have the be exceeding 250F or more for extended periods for it to start degrading the oil that quickly from heat.

 

I change my oil myself. It has some lifter tick, I feel it has been getting worse lately. Coolant is fairly low, I’ll run and get some at some point this week. Have never had any form of overheating issue.

 

May want to send an oil sample in to get analyzed to see whats going on.

 

If it was overheating wouldn't you see it in the temp gauge? I forget where the coolant temp is measured relative to the thermostat.... so I could be off base.

Also could monitor engine temperatures with an OBD reader or scangage on your next trip.

 

If your coolant is low, it wouldn't be a bad idea to replace your radiator cap when you top it off.

 

Dark oil is not a sign of anything wrong that is what it is supposed to do. Lubricate and capture combustion contaminates and carry them to the filter for removal.

The smell on the other hand could be an issue of a larger issue. I would take Dm93's advise and have it checked with an oil sample the next time you change the oil.

Oh just want to add that the 4.0 liter engine doesn't have lifters so you couldn't have lifter tick...

 

When my dad (RIP) was in a pinch schedule wise, he'd get his oil changed at a nearby service station. He began to doubt their service so he marked the filter. He later checked the filter and saw his mark. So at the age of 12, I started changing the oil.

Thanks for the memory.

 

oil can normally turn dark quickly.

what oil are you using

if it leaks up past the piston rings it gets combusted through the tailpipe

if fuel leaks past the rings into the oil then the oil and filter smell like gas

this tends to happen more on other vehicles designed with caca pattern piston rings, DI fueling with HPFPs that fail and leak down, etc

 

+1

oil starts to degrade around 260 and won’t really have a burned smell until around 300. Have to get well above that to turn black. VERYYY hard to get oil to those temps on a modern liquid cooled engine, even with the coolant overheating. My first guess is that you cracked a compression ring. This will turn oil very black, very fast. Compression test will confirm or eliminate that theory.

 

While lifter is not the purely correct term, there are definitely caps on the valve stems that the cam lobe acts upon and they ride in a bore in the head (these are solid, not hydraulic and they make about 25 variants with different depth stems in order to set correct lash or clearance). They have a specified dry clearance and if you get wear on them, increasing that clearance, they will tick just like an old school mechanical lifter with too loose of a lash. Because they are mechanical and not hydraulic, there is never 0 lash, so they will always tick, but softly when the clearance is right.

 

The 4.0 has a bucket-and-shim lifter setup, not hydraulic followers, so they make some ticking noise even from the factory.

 

VSV tick makes tick. And stops altering doing VSV tick fix.

 

Had to quote this for posterity.

 

Yeah. I know... It's a Bucket Cap (No Shims) even though they call it a lifter.

And the 2TR-FE has Hydraulic Lifters...