Can't diagnose smoke after valve cover replacement

L

lexus4nxtc

New member
OK so my husband is at his wit's end with this thing so I'm hoping you guys can help us out. I have searched, and searched for an answer to this problem, but all of the suggested fixes have not worked for us.

A few weeks ago we were doing some DIY maintenance to include replacing the valve cover gasket, spark plugs, etc. We were not having any mechanical issues, but it was due for a tune up and noticed oil on the back of the engine so wanted to replace the passenger side VCG as well. When he pulled the valve cover off, he noticed a small crack in the corner so we ordered a new one online. After everything (new cover, new gaskets, new spark plugs) was installed and we started it, the exhaust smoked like crazy.

Have been troubleshooting for weeks now. Oil and coolant levels are steady, replaced the PCV valve, triple checked all connections and nothing is loose or leaking that we can see. Pulled the spark plugs and there was no coolant. Changed the oil and didn't notice anything off about it. The smoke has been odorless, white and only at cold start. Thought we had finally fixed it when it didn't smoke the past 3 days (no driving, just starting/looking for smoke). Then after a short drive today, it randomly smoked after pulling away at a stop light. After we got it home today and let it sit, it smoked again at start but now it smells like burning and some black residue was on the tail pipe, which we haven't seen before.

We also replaced the battery today because the voltage was low and oddly enough, we found something online that said that could cause the smoking as well. This did not fix it either. :/.

Truck has 125K, all routine maintenance done (including timing belt at 100K). Just had tranny rebuilt about 2K miles ago. Injen intake and Vortex muffler installed months ago with no problems.

My biggest fear is a blown head gasket but it's actually running fine, with no coolant in the oil, and it's not overheating so pleeeeeasse tell me it's something else!!! Is it worth doing a compression test? Is it possible this valve cover we bought could be bad?? As with most people troubleshooting, we are both getting very frustrated so any help is much appreciated!
 
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What does the smoke smell like? Fuel, burned oil or musty sweet? Was everything apart while you waited for the new valve cover to come in? Any water or other liquid get down the spark plug tubes?

Do you have a check engine light on? How does it run, any misfiring?
 
i guess there's some small chance that coolant is making it into the t-body via the coolant line running to it. it would have to be cracked or something but there's a chance??? or is it possible that you hooked the coolant line to a vacuum port? it sounds like you know whats what so no offense, I wouldn't ask if i hadn't done 100 things like that myself.
 
Sorry for the slow response guys, I am 2 weeks away from separating from the military, so things have been a little hectic lately! Turns out we are going to have to drive both our vehicles (I'd really hoped they were going to ship them!!) so it's imperitive we get this fixed.

kball-- the smoke really doesn't smell like anything, but it's definately smoke and not just vapor. It was just that once that it smelled like burning (that line always makes me think of Ralph Wiggins from Simpsons!!!) but even then, it was so quick I couldn't say for sure what was burning... didn't smell like oil to me. And no, it was all put back together while we waited so no chance something could've snuck in there. No CEL and the truck is running absolutely fine (minus the embarrassing cloud of smoke), which is why it's so confusing!!

Whitson-- i will have my husband double check everything again, but I know he has been under there so many times triple checking all the lines... I don't see how we could've missed it, but maybe after not looking at it for a week or so, he can put some fresh eyes on it. :)

Do you guys think it's possible that this valve cover is just no good? I am to the point where I'm ready to just pull one from a junkyard and see if that fixes it. If we do that, do we have to replace the VCG again or can we use the old (new) one? Thanks so much for all your help!!!
 
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If the valve cover was bad, you'd see smoke from where it was leaking, not out if the exhaust.

The symptoms you're describing to me sounds like a bad valve seal. If its not running hot and you're not noticing any substantial loss of oil, don't worry about it.
 
Having the same exact problem except it doesnt smoke at startup, only when i punch it from a light or merging on the highway. for me, my friend says it looks like im rolling coal but in a gasser. coolant is at the brim every time i check. wtf toyota
 
If it was coolant you'd know it. It has a very distinct sweet smell.

Both of you, pull the rubber intake tube off and clean it up. Pull the throttle body of and clean the piss out of it. Run a can of Seafoam through the PCV hose. Let it suck in a whole can, shit it off for 20 minutes. Then start it back up, let it run for a while, it'll smoke like hell. Take it for a drive (highway if you can, really open it up), them come back, shut it down and let it cool off.

If you still have the same issue, it's most likely a valve seal. And doing what I just outlined is good maintenance so nothing lost.
 
You mentioned it's white, could it have a bluish tint to it? If it is only at start, I would have to agree with PitbullRescuer... Bad valve seals, the oil will leak through when the engine is off and build up (not much, just enough to smoke at start) then you might get a small dribble while it's running, but not enough to smoke. A compression test would not be helpful in identifying this problem, only tell you that it's not the gasket, valves, rings....
 
Just another thought. if you have a diagnostic reader to tell you if the engine is running rich, it could be a sign of a touch of oil in the mix, either way, you can still drive it without too much concern. Though it would be best to change the seals when you reach your destination.
 
Ill try the throttle body trick. Between screwing with with my cai and taking the intake manifold apart for valve cover gaskets, I wouldn't be surprised if I swapped something. Not sure if it's bluish since I've only seen mine at night in other people's headlights. If its running rich with just petro would there be smoke? I have noticed a massive decrease in mpgs. New air fuel sensor coming in the mail. I guess ill just have to wait for that. But I dont get any smoke when I crank it up, only at WOT so im thinking

bigger tires+CAI+bad a/f sensor= smoke?
 
Generally....

White=coolant/water
Blue/bluish=oil
Grey/blackish=poor burn or rich

These of course are general/simplistic diagnosis to start from, and does not indicate every possible solution....

Hope you get it worked out!
 
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