So, after some free way driving in my 88 Dakota one day I noticed my exhaust header on the driver's side was glowing red at a gas stop. I gently drove it home and took an exit on a highway. I figured it was an exhaust leak related issued due to a broken bolt and I removed the manifold and cut it at the Y and drilled and tapped the broken bolt and replaced the gaskets and went on my merry way. Today I took it out and I immediately noticed a rattling and discovered a mild exhaust leak in a spot I had missed and again, only one side was glowing, the driver's side with the exhaust heat valve. Any ideas to what it could be? Vacuum leak? I've replaced the O2, EGR, and recently replaced the head gasket, intake gasket, and a plethora of other things. New plugs, new wires, new coolant sensor.

 

I also forgot to mention that on occasion it will die when I let my foot off the gas in particularly cold weather.

 

did you check the exhaust heat valve if it moves freely?

 

It rotates freely and smoothly by hand, although I haven't examined it closely while the truck is running. The spring appears intact. I assume the issue is related to the pre O2 exhaust leak and the momentary siphon is tripping the motor out and causing a pig rich condition and the leak allows enough oxygen in for the fumes to actually combust in the side with the leak causing the heat, but I'd like a second opinion from someone more knowledgable than myself.

 

Here are a couple of thoughts:

• It could be out of time (retarded) to the point that the exhaust valve is still open momentarily when combustion takes place. This would allow the combustion to expand to the manifold, making it glow. This phenomenon is not uncommon in the jeeping world where it's fairly easy to re-install the distributor "one tooth out" in the inline engines, giving that retarded timing issue. If you had this problem, it would affect both manifolds, so from your description of having the glow on only 1 side, I'd tend to discount this.
• You could have a leaky exhaust valve that would give a localized symptom of a retarded condition. Have you preformed a compression test recently? Cylinder pressure leakdown test?

 

Well, I checked the timing and adjusted it with a light to 10* btc like on the emissions label. I welded up the exhaust leak and checked both the O2 and other sensors and then checked for vacuum leaks with a propane torch and a bit of heater hose and all was well and the issue disappeared and the truck ran better than it ever has, lots of power, good drivability, better mileage.. Then one morning it refused to start and started puffing exhaust out of the throttle body, so.. I'm concerned the timing chain has jumped or broken completely and, not being clearance engine, it's toast. I am currently on my campus and can't check, I can't pull the dizzy and see if the rotor spins, and I've been worrying the whole time. If the valves are bent and the piston crowns messed up I'm just going to have to scrap the whole motor because I don't have the time nor money nor resources to do that job.. ugh.

 

I would turn the motor over by hand and feel for any binding(if its still there you would feel it) and listen for any unusual ticks from the valves.

 

Finally got back to where my truck was, and took enough medication to feel like messing with it (got some kind of bug) and unhooked the battery and coil and turned it over by hand and there was no binding or strange noises and everything seemed peachy and so I took off the breather and the distributor cap and lo and behold it turned exactly like it was supposed to and lined up right, so I touched the rotor and it spun freely.. which was a little.. odd.. so I took the distributor out and it turns out that the distributor shaft broke up inside the distributor's main body and it came apart in a clean half. You can see the grain structure of the steel in a clean break. Metal fatigue I guess? But, I get the feeling this could be the source of all of my problems, there are some subtle signs of twisting from where the shaft began to break and this could cause an uneven rotation which would affect the fuel air mixture on one side of the cap (I imagine, anyway, this is just guess work based on my limited mechanical understanding) which would affect one of the two banks in the throttle body injection and cause one side to run a bit richer or leaner than the other and then it finally fully broke the night it acted so bad and the friction bond held it together long enough for me to limp it home. I got lucky, I guess.. But, I'll drop in a new distributor over the holiday and let everyone know.

 

I've never seen a distributor shaft break, but that certainly could have been your problem if it had twisted somewhat before breaking - this could have given you the retarded timing condition. While you're checking things out, have a look at the dynamic balancer, the rubber connection between the outside of the pulley and the inside can break, allowing the outside to shift position. This will also change your ignition timing.

 

So, here's a few quick photos of the dizzy.
As I first took it out:


After I sat it down and began looking at it:


The break fits back together like a puzzle piece.