Smoke from low front of engine. Any thoughts?

I have a 2008 Honda Odyssey. Has been a wonderful driver. It was my dad’s who passed away recently. From the day I started driving it, 1 year ago, I have smelt a burning smell after starting the van. It usually goes away. Until I’m going up a hill or driving long trips. I usually can see smoke coming from under the hood as well. Not bad but enough to make me think the engine is overheating. Yet the Guage has never gone up. I have checked multiple times and see no leaks to my knowledge. Over the past month it has gotten moderately worse to the point I’m afraid to drive it. The smoke is bad from under the hood. I can’t tell if it’s from the engine but it looks like it’s coming from underneath the engine in between the engine and the radiator. The smoke was so bad this morning it filled the inside of the van. And produces that bad burnt smell. I’ve looked and there is a bad build up of grease all over the lower portion of the engine. It’s pretty thick. I wiped it with my finger and it looks more like grease, not oil. It does not leak oil, I haven’t had to replace any. I’ve checked inside spark plugs housing and no fluids there, I’ve checked the antifreeze and no oil in antifreeze. What could this be? Is the smoke and burn smell the sludge around the engine? And if so what is the grease? Is there something that could burst grease everywhere like brake grease or gear grease? Or could it be oil? Thanks for your thoughts.

Bring it to a shop and have them look at it.

Unless the vehicle is put on a lift, it can be very hard to determine if there are any engine leaks.



It could be from a torn CV joint boot on a front axel. the grease got flung onto the exhaust causing the smoke and smell. it is the only thing i can think of that is grease and would get all over.


Thank you. I looked up signs of a bad cv joint. The car has been also making a slight clicking noise when turning and a little wobble. I’m going to take it in for service tomorrow. I was trying to avoid but it sounds like you may be right.

Sludge on the outside of an engine is from an oil leak and it has been getting
worse for a year.

Eventually it will burst into flame and you will be spared the inconvenience of actually taking your car to a mechanic.

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Sounds like valve cover seeping oil, dripping down on the exhaust manifold. Of course it could be many other things as well. My 05 Lesabre with 186k mikes has started this. Not enough to smoke yet, just enough to smell the burning oil after a decently lengthy drive.

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Engine oil is leaking onto the exhaust manifolds or exhaust pipe under the engine. If the rear main crankshaft seal is leaking the repair will be expensive.

Oil leak could be coming from a number of places, sounds bad enough a competent mechanic could find it easily. Had a 93 f250 ford pickup, debris on head gasket during manufacture caused an oil leak. No tsb, it was fine around town but highway drives were killer, maybe burning off extra oil. It did not leak enough to notice any oil loss, mechanic put on a plate to stop it from dripping on the exhaust. it does not take much oil to cause distress.

OP says it looks like grease not oil.

The right side inner CV joint can spray grease on the back side of the engine but that joint won’t make noise while turning. The outer joints will spray grease on the outer suspension parts.

It doesn’t take much oil to make a lot of smoke if it drips on a hot part, so you probably wouldn’t notice the level going down.


Oil and grease pretty much look the same if it’s coating the engine block and halfway baked on with a lot of dust/road grime stuck in it. Just saying I wouldn’t rule out oil or even power steering fluid.


I agree. when OP said it looked like grease and not oil, and it made a clicking when turning it made me think of a torn CV joint. but oil caked up is a possibility. I hope OP comes back and lets us know what it turned out to be.


Good ideas above. My guess, engine oil from a leaking valve cover is making its way to something hot, like the exhaust manifold. A little oil dripping onto the exhaust manifold will make a stink and prodigious amounts of smoke. It can be somewhat time consuming for a shop to determine where exactly an oil leak is occurring. Cleaning the entire engine then using a UV dye additive to the crankcase and a special UV inspection light is the best way. If OP feels lucky they could just have their valve cover seals replaced, since that’s a pretty common cause for this sort of problem. For a 2008, if they haven’t been replaced already the VC seals are probably nearly shot anyway, so worse case the smoke/odor problem isn’t fixed but at least you’ve got the valve cover in good shape.

I’m doubtful this is caused by a CV joint problem; however you may well have that problem based on the clicking symptoms. If so that’s a high priority repair as a failed CV joint will leave you stranded. And you know that’s going to happen late at night on the stormiest, coldest, most unpleasant of the winter.

As mentioned above, an oil leak can cause an engine fire, so don’t defer getting this solved.

BTW, don’t try to solve a VC leak by tightening the bolts that holds it on. That rarely works and often bends the VC. Then you’ll need to buy a new valve cover. Those bolts are usually spec’d at a low torque valve, just snugged up by hand.