91 white gmc blowing alot of white smoke when reving in neutral. Doesn't do it going down the road. Over 15 it blows a lot and skips a little. It's a 350 air to air 3406b.
Does it use coolant ? What's the history? Get it acting up and crack injectors one at a time watch for changes. Also check fuel injection pump timing.
No doesn't use coolant. Had a leak at main line to pick up pump tightened it no change. Has a leak right at pump where injector line is screwed in but that's pressure side it can't be sucking air through there can it?
Oh and it's a 4mg motor 350. Has no blow by and I have no clue how many miles are on it. Guy I bought it from only had it a short time and bought it from an auction
Install a clear hose where the shunt line runs from thermostat housing to top radiator tank to check for bubbles in coolant system. The bonnet seals on the individual pumps at injector pump are probably what your seeing for a leak. Also like said above, check the pin timing on pump. That advance unit on the front of injector pump located in the front structure on 4MG's were problematic, more than likely though someone has tack welded it. Which is ok too. Truck Shop
Ok it started rattling turned out it was coming from cone. I pulled it and a fly weight was laying in it. So that's apparently my problem. Can I replace weights and all like it sits or do you have to pin motor and pump?
That's the advance unit for the injector pump. You could try to source a used one but I would recommend a new one. And yes there is a procedure for replacing the advance and pin timing the pump. When correct the pin should fall into place on the pump a split second before the one on the flywheel falls into place. It's easier to have an extra pair of hands when doing this. Truck Shop
You need to strip and rebuild the advance unit. All parts should be available and it's not hard to do. You will see a large adjustment screw with a smaller one up the middle in the centre of the unit. Do not disturb these. They set the speed at which timing advance starts and ends and they can only be set dynamically. You were lucky by the way. A lot of the times when a flyweight breaks loose, it will fall into the timing gears, break the oil pump mounting lugs off and smoke the engine.
I figured I got pretty lucky, it did it when I went out to warm it up, so I heard it instantly. I can take the outer cage off and replace weights and carrier and spool without messing with timing can't i?
No, you've got to pin the flywheel and pump and take it off the engine, reason being that the bolts that hold the cover on go in from the back. Also even if you could get the cover off you would be fighting gravity against the weights, pins, screws, thrust washers and other little bits and pieces. You would need about six hands!
Very good point. Some years back had one in the shop that was just re-timed they forgot or didn't get get the bolts tight on the advance. Fortunately nothing fell into the gear train. Truck Shop