Help finding source of excessive smoking

F150 302 1986 bullnose

Ok so my poor truck has been sitting for the better part of 2-3 years. The main culprit was excessive smoking from an indeterminate area under the hood. Coupled with gas prices and living in an apartment i just didnt have enough incentive or area to work on it. I keep the battery charged and start it up (not often enough) and run it for a bit until the smoke becomes too much. I am now in a house with a large area to work on my truck.

I have a general to advance level of ability. I can change oil, brakes etc. I upgraded alternator and rebuilt the entire cooling system. With proper direction i can do slightly more advance stuff but am limited in both time and budget.

I understand that in general a truck sitting may seep oil and that can contribute to the issue. But it was being driven regularly before the problem started. There are no obvious puddles or drips. Oil seems to be relatively at a stable level. Cooling system was overhauled a while before the smoking issues and levels are/were also stable.
Smoke does not have a paticular smell. It eminates from all over under the hood as well as out exhaust (though exhaust i would guess comes from sitting)

My thoughts: replace whatever seals i can access without removing engine (recommendations?). Wash down everthing with dawn and elbow grease, clean/replace injectors, fresh fuel, oil change.

What should i be looking for or what possibilities are there for the source of this excessive smoke. If i had to give a color it is pretty light, not black at all. Please help with any advice you can, i want my truck to see the open road again.

If I couldn't determine where the smoke is coming from I think I'd wash the engine down to get it as clean as I could, and then start it and watch for leaks.

But the areas I'd concentrate on would be around the valve covers, both on the outside near the exhaust manifolds, and on the inside near the intake.  The exhausts obviously get very hot and will create smoke quickly, but the heat riser passage in the intake manifold get hot as well.  So you need that area very clean.

one of the points that you brought up was the smoke from exhaust. out the pipes or off the manifolds? how many miles? What engine? etc.
are you sure that its smoke and not steam? after sitting a while ,espcially fall-winter, there is going to be a steaming that happens as the engine warms up but should go away after a couple moments. if it seems to get worse as it runs and gets warmed up it may be a symptom of a failed head gasket allowing coolant/water to get steamed off as it is getting pushed into a cylinder. not a small repair and NOT one to ignore. this is not a diagnosis just something to check or have checked.

mat in tn wrote

one of the points that you brought up was the smoke from exhaust. out the pipes or off the manifolds? how many miles? What engine? etc.
are you sure that its smoke and not steam? after sitting a while ,espcially fall-winter, there is going to be a steaming that happens as the engine warms up but should go away after a couple moments. if it seems to get worse as it runs and gets warmed up it may be a symptom of a failed head gasket allowing coolant/water to get steamed off as it is getting pushed into a cylinder. not a small repair and NOT one to ignore. this is not a diagnosis just something to check or have checked.

If it is out the tail pipe and dose not go away after it warms up and gets worst it could be a head gasket as Matt said.
Thing is if you have anti freeze in it the smoke out the tail pipe will have a sweet smell to it and the smoke kind of hangs around.

Pulling plugs can tell you what hole the gasket is bad at as the plug would be clean.
Dave ----

Yeah... so i got water somewhere it isnt supposed to be. I though i was decently careful, had battery away from truck until i thought things were dry. Its been a week and either i fried something or theres still water somewhere. Things apear normal, lights etc work fine until i turn the key to try and start it. Theres a power drain when/while i turn the key, an electric hum for a second then nothing. I would assume this indicates there is water shorting something when the key is engaged; maybe the starter is wet? Any other ideas?

I would expect the starter to be drained if not dry by now.

a humm for a couple seconds and stopping could be deceptive. this happens every time with efi trucks. the ecu triggers the fuel pump relay for two, three seconds to regain static fuel pressure to help the engine start. does the starter attempt to start the engine?

It does not attempt to start the engine. If i leave the key in accessory mode there is significant dimming of the lights indicating a power drain somewhere. Attempting to start there is electric noise but no attempt to turn the engine over.

prove battery voltage and clean connections. try a jump or different battery if you can. just eliminate a weak power source as the cause before going too deep.

I truly appreciate all the help here. I admit i am not any kind of expert but learn quickly. These old trucks this is really the best source of info!

I missed this reply but it turned out to be a very bad connection to the starter solenoid made worse by the washing. This bum connection was causeing all kinds of electrical readings and i spent a good deal of time trying to get consistent readings haha. Cleaned up and reconnected also sloved the trouble starting i was having that i thought was from sitting for so long.

Finally got it started and running for a while. It looks like all of yhe exhaust manifold gaskets are bad/loose. On both sides of the engine both against the engine and between the manifold and tail pipe.

Is this a job that can be done without removing the engine? (Looks like theres enough room, not counting all the work its going to take...). Other work/jobs i should consider during this process?

It does not smell sweet (just like nomrmal old truck exhuast) and coolant level remains steady. There is significant oil coating the engine but none on the ground, i am hoping its just seepage from sitting. Time will tell.

this sounds as if it is neglect accumulated over time. on the efi engines it is necessary to remove the upper intake in order to remove the passenger side valve cover. however, I would consider doing this as a step towards having a reliable, drivable, and enjoyable truck. it's pretty strait forward although a bit clumsy assembly except for the "blind bolt". this is a single torx drive bolt in center of the intake under the curve, accessible through a cleared narrow slot in the center. torx 45 on a long 1/4"extension will get it. as far as the exhaust manifolds go. broken bolts are common. NO FUN! get a can of "free all" not a sponsor but no other brand has worked any better for me. soak all bolts threads and nuts. let this soak a few while you get tools ready.

For reference. A pretty decently put together video on replacing/upgrading the exhaust manifolds.

https://youtu.be/Lal04GJ4H94

Reference: Tips on not breaking bolts

https://youtu.be/9PKNCVXvZ6w

That went way too easy.
It's a '90's truck with at least a decade less corrosion and abuse.

Around here you're lucky if there's even a hex left to get a wrench on.  
But I recently did my leaking drivers side manifold and wouldn't even have attempted it without an acetylene torch to get the bolts /studs cherry red. (and I have stainless bolts with almost no corrosion from when I installed a new engine in 2008)


Hopefully your bolts and studs are in better shape and are already all oily already from the leaking valve covers.

very nice bronco. obviously not driven on salt for 40 years. also, the exhaust had been previously replaced. but in general, a good demo.

I will add a couple of items.

First while you have the intake plenum (top part) off, carefully examine the injection wiring harness, these trucks are very prone to crumbling insulation.

Second, exhaust manifolds, the passenger side is a unique to 1985-86 302 EFI engines so be very careful with it. The O2 sensor can be a real pain to get out if it needs replacing.

Is replacing the injectors something i should consider at this time? I have not had any problems i can think of. Id rather not get into the fuel system if i can help it but i also would rather do mork work now than have to take things back apart again later.

If everything is functional now, leave it alone.
You're going to open a can of worms.

I would stay focused on the exhaust. it's true that you would need to remove the upper in order to do a fuel injector service but just consider this experience. if you get the exhaust completed easily enough then take it from there.