stripped spark plug
#16
03-26-2011, 11:34 AM
Got the lower intake off. Those metal bits turned out to be pieces of spark plug electrode, one of them is large enough to still have the curve in it and they are all magnetic. More in a couple days once I get the exhaust manifold off and unbolt the head.
Does the front cover have to be removed to pull the head, or is it possible to slide the head up enough to clear the locating pins on the deck without unbolting the chain cover from the block?
Also is it best to unbolt the exhaust manifold from the head, or to unbolt it from the downpipe?
Thanks,
JB
Does the front cover have to be removed to pull the head, or is it possible to slide the head up enough to clear the locating pins on the deck without unbolting the chain cover from the block?
Also is it best to unbolt the exhaust manifold from the head, or to unbolt it from the downpipe?
Thanks,
JB
#17
05-25-2011, 03:36 PM
The saga continues. After having the head rebuilt and putting the truck back together, going through all that noise with plugs, coils, injectors, pump, FPR and such, the truck seemed to be running OK but was getting about 11 mpg. The cowl shake was gone though which was a good thing so I set out for a visit to Tennesee. Halfway there the missfire and cowl shake came back.
I have just finished another round of working on it and I think I finally have an approach which stands a good chance of ultimately resolving these issues, but first this is what I found. #6 spark plug had once again been severely damaged, but this time it seemed clear that the cause of the damage was most likely a lean misfire condition, as the ground electrode was partially missing and the center electrode was burned away to a depth of about a quarter inch. So what could cause such a problem that had not already been eliminated? I began to start thinking in terms of preventative maintenance items. In the military, Because the taxpayers are footing the bill and because you do not have the luxury of unscheduled down time, items are replaced on the basis of their expected service life. So what items on the Lincoln Blackwood have a service life in the range of about 100K miles or less? It turns out they are many. Coils, injectors, sensors, and a myriad of other components, in fact just about everything that runs the engine except the ECM and the wiring.
Next question, which of these items could fail in such a way as to cause a lean misfire? MAF (cleaned previously), TB (ditto), TPS, O2 sensors, maybe a few others. BINGO! The light bulb went on. So, new plugs, new O2 sensors all around (4 of them) and a new TPS. The truck fired up and ran smoothly at last but mileage does not seem to be improved. So the next step is to visit Scotty at the parts store and see which components for these trucks and similar ones he sells the most of and schedule them for replacement also. By going into preventative maintenance mode it is hoped that soon the marginal component or components that are responsible for the decrease in mileage will soon find their way into the garbage can.
This appears to be the only prudent approach for this vehicle, as failures can easily cascade into more expensive repairs, and it certainly is less expensive than a replacement engine, even assuming that would be an effective remedy, an assumption that is wholly unjustified.
JB
I have just finished another round of working on it and I think I finally have an approach which stands a good chance of ultimately resolving these issues, but first this is what I found. #6 spark plug had once again been severely damaged, but this time it seemed clear that the cause of the damage was most likely a lean misfire condition, as the ground electrode was partially missing and the center electrode was burned away to a depth of about a quarter inch. So what could cause such a problem that had not already been eliminated? I began to start thinking in terms of preventative maintenance items. In the military, Because the taxpayers are footing the bill and because you do not have the luxury of unscheduled down time, items are replaced on the basis of their expected service life. So what items on the Lincoln Blackwood have a service life in the range of about 100K miles or less? It turns out they are many. Coils, injectors, sensors, and a myriad of other components, in fact just about everything that runs the engine except the ECM and the wiring.
Next question, which of these items could fail in such a way as to cause a lean misfire? MAF (cleaned previously), TB (ditto), TPS, O2 sensors, maybe a few others. BINGO! The light bulb went on. So, new plugs, new O2 sensors all around (4 of them) and a new TPS. The truck fired up and ran smoothly at last but mileage does not seem to be improved. So the next step is to visit Scotty at the parts store and see which components for these trucks and similar ones he sells the most of and schedule them for replacement also. By going into preventative maintenance mode it is hoped that soon the marginal component or components that are responsible for the decrease in mileage will soon find their way into the garbage can.
This appears to be the only prudent approach for this vehicle, as failures can easily cascade into more expensive repairs, and it certainly is less expensive than a replacement engine, even assuming that would be an effective remedy, an assumption that is wholly unjustified.
JB