About 3 weeks ago i pull out of a gas staion and here the engine making a loud metal on metal (clang clang clang, real fast) tapping noise that increased with the speed of the engine as white smoke appeared to pour out of the tail pipe. Problem went away when I really reduced acceleration stress on the engine and babied it. The problem just happened again today for about five minutes in stop and go traffic. Once i was able to slowly get to a smooth speed things seemed normal again. Made it home with no overheats and engine seemed to run normal at that point. A headgasket getting ready to fail for good? Wondering if anyone has any ideas on this, as I am trying to plan my next strategy. I am certain whatever it is will only get worse and more frequent instead of it going away. Thanks for any advice. 1998 R/T 5-speedMT Hooyer

 

Just some more info it has 180000 miles on the engine. Started to do a compression check today and had 135 on number 1, then lost the o-ring to my gauge so i couldn't check the other cylinders. Will remedy the o-ring dilemma and get other readings tomorrow. head gasket has never been changed. I did the timing belt pulleys and tensioners and water pump, for the second time at 166000 miles. The check engine light reads only 55 for codes and the engine has lived it's life with proper oil chage intervals using mobil synthetic. I am not one of those people that think you can go longer between oil changes just because you use synthetic. Airfilters every 10 to 15k and plugs around every 20k. Overall the maintenance has been kept up good on this car. The rattle and smoke combination have me perplexed, especially because i can go easy on the engine and problem goes away.

 

Here is my compression test data on the engine after it has been ran for awhile and off for about 15 minutes:
1 180
2 172
3 153
4 138

Also the ceramic white of the spark plug for number 3 was mildly browned and for number 4 it was quite browned at the base. The ceramic of number 1 and 2 was white like normal, if this helps. I am just perplexed as to why, on a couple instances I here clanging steel and smoke pours out of the exhaust, then all seems well. In my past engine disasters it was always sudden and no turning back to normal operation, none of this intermittent stuff. Any theory's out there? I am at least going to attack this with pulling the head and replacing the gasket and checking out the head itself, or maybe just buy another head, as well as new water pump and timing belt hardware again since it's there. Is there any hint with the compressions getting lower from 1 to 4? Does that mean anything? I rebuilt the engine on my old Omni GLH Turbo a couple times but am somewhat fearing this project. If my work was good on the Omni do i have any worries here? I am not a pro but am very meticulous about doing things clean and right according to the specs.