morriss

I recently replaced quite a few things on the '92 after it was down for about a month with a no-start issue caused by a faulty main ground cable. I fired it up today to take it for a drive and it was spewing white smoke out of the tailpipe and from the passenger side exhaust where the manifold meets the y-pipe, and there was a strong smell of gasoline. I turned the truck off after about a minute. About 30 minutes later I started it again so I could move it around to the back of the house and noticed the same things, plus it started shuttering when I put it in drive. After I moved it and put into Park I crawled underneath to check for the source of the smoke from the manifold / y-pipe and noticed oil dripping from one of the exhaust flange bolts - as it burned off it was smoking.


I immediately Googled causes of oil in the exhaust and of course got worried at what I read. Wanted to check with y'all first to know where to start troubleshooting after sharing what parts I replaced, HOPING that something I did is the cause of the oil in the exhaust. This is something new, it wasn't happening before I replaced things. Here's a quick video of the truck idling and the smoke coming from the tailpipe -

Here's what I recently replaced:-New exhaust manifolds and manifold gaskets

-New rear crossover pipe and large metal check valve

-New valve cover gaskets

-New fuel injectors

-New intake plenum gasket

-New air temp sensor

-New EGR tube

-New EGR gasket

-New throttle body gasket

-New spark plugs
Any ideas?

raski

Since the oil is at the top, I would suspect a valve cover gasket leaking. The oil is not going to go against gravity. As far the rough running, I suspect a misfire with one of your cylinders. After sitting so long, oil can work its way past worn valve seals and foul out a plug. I would remove each plug and check for that.
Burning oil will produce blue smoke not white.

morriss

I checked all around the valve covers yesterday, looking for leaks, and did not see anything. From what I can tell, the oil is seeping from the joint where the manifold meets the exhaust y-pipe, and then running down the flange bolt. I'll try to get some pictures of the valve cover area and the manifold joint today.
Th plugs are brand new, they had seen zero use until I started the truck for the first time after replacing the negative ground cable. I also double-checked the plug wire routing: I pulled each wire from the plug and then reset them, making sure they were on snuggly, and made sure 3 & 4 and 7 & 8 were not touching anywhere.
I will also get a better pic of the smoke coming from the tailpipes.

morriss

I'll get a compression gauge today, and when I pull each plug to examine them, I'll check each cylinder.

morriss

Completed compression test on all eight cylinders today, and they all held, no leak down. The results are below.

I'm confident the oil is not coming from the passenger side valve cover. I looked from both up top and from underneath with a bright light and a mirror and confirmed there is no oil dripping down onto the exhaust manifold. Since all cylinders held pressure, that rules out piston rings and head gasket, right?




I replaced the PCV valve recently - if it was faulty it would fault to the closed position, right? I'm trying to rule it out as the source of the oil coming out of the manifold / exhaust pipe connection.

Most of the plugs looked clean, as would be expected since they only have about 10 minutes of runtime on them, but two of them were a little black / brown. Cylinder #2's plug was bright shiny clean and smelled like gasoline. In fact, when I went to test cylinder three, the gauge showed 0 psi, I think because it had sucked in some gas. I took the gauge apart and blew through it, and it smelled of gas. After hooking it back up again, it worked fine. I'm wondering if the #2 injector is bad and is dumping extra fuel into the engine. Would that explain the white smoke coming from the tailpipes? I did not get a chance to get a good picture of the smoke before it got dark today, I will do that in the morning and also shoot video of the oil dripping off the flange bolt.



#1 – 110 psi, no leak down, plug was sooty


#2 – 127 psi, no leak down, plug was shiny and smelled of gasoline

#3 – 109 psi, no leak down, plug was sooty


#4 – 120 psi, no leak down, plug was clean

#5 – 119 psi, no leak down, plug was clean

#6 – 119 psi, no leak down, plug was clean

#7 – 109 psi, no leak down, plug was clean

#8 – 115 psi, no leak down, plug was clean

raski

For a rebuilt engine those compression readings are very low. There is more than 10% difference between the highest and lowest cylinder. Not good if you want a smooth running engine. I would expect around 150. I think your valve timing is off.

morriss

The engine is original and has never been rebuilt, and has over 250,000 miles on it.

I THINK I have two different issues going on here, and could use y'all's help to confirm / deny that.
1) White smoke from exhaust that has a very strong gas smell to it. This was not happening prior to me changing the parts I listed up above in my original post. My theory is that one of the fuel injectors I replaced is bad and is dumping extra fuel into the cylinder.
Would that cause the white smoke with strong gas smell?

2) Oil dripping from exhaust flange bolt. I did not notice this prior to me changing the parts I listed up above in my original post, notably the exhaust manifolds (the driver side had a small crack in it, which is what prompted me to replace them). I am certain oil is not dripping down from the valve cover, or anywhere else externally on the engine - the oil has to be coming from inside the engine and making its way out of the exhaust port on the block. The drip is pretty significant, as can be seen in the video, so the engine must have a pretty big leak somewhere.

What do y'all think? Do I have 2 separate issues, or do you think they are related to the same cause?
For the white smoke, if you think it is too much fuel, I will pull the injectors and blow into them to see if any are bad. Unless you suggest something different.
For the oil in the exhaust, do I start at the valves, and if so, where? Their gaskets? Valve timing? Of the two issues, this is the one I could use the most help with as I have never worked on valves before. I'm willing to try, and learn, though.

raski

Check your fuel pressure regulator for fuel in its vacuum line which could be allowing excess fuel into the intake. With your fuel pressure gauge, see if the pressure holds after engine shutdown which could indicate a leaky injector. In my opinion, youi are dealing with a worn out engine with low and uneven compression. Don't expect miracles from it.

morriss

Checked the FPR vacuum hose and it is dry as a bone.
Gotta run back to the parts store for a new fuel rail Schrader valve, and to borrow the gauge again.
I fully realize the engine is old and tired, but was hoping to get a few more years use out of it, to last my son through college.

raski

A few more years? Good luck with that.