HEEEEEEELP!!!!! i have an 89 F-150... tuned it up.. ran like a kitten... the problem... drove it for a week... then dropped a cylinder.. i don't know why.. i pulled the plug.. looked nice and tan.. but was covered in gas... ran a compression check and it read about 10 way way low...... i figured a broken spring ? i drove it a little more.. my brother seemed to think that it may have a carbon build up.. for the last few months it sat most of the time and was just recently ran everyday.... he seemed to think that there was something holding a valve open... sooooo... i get the additives for the gas tank.. and the oil... put it in with a good tank of gas... ran about half a tank out.. now i'm hearing ticking in the valvetrain.. approximatly where the dead cylinder is.... now... for the next problem... the pressure guage is running right where it should be as i am driving or when i give her a little gas... but as soon as i come off the throttle... it dropps way down to nothing... the engine light comes on..no valve tap mind you.. just a drop in pressure signaled by the guage.. i touch the gas.. the pressure comes back up and off it goes... 7 cylinders.. no less but it goes.....it this thing ready go blow? my thoughts are that there may be a ton of sludge in the oil ..( from the cleaning additives that i put in..) the filter is really cloggged ( possiblely even the oil pump pick up)..... and my ticking in the valvetrain is because of the the original idea of a broken valve spring.. or there is just not enough oil getting up there ( also.. i do not hear a low end knock like a rod bearing ) any help? hunting season is here and i need to either fix her up... or dump her and get something else... any help from any of you would be greatly appreciated...

 

first off, the oil gauge in the dash is not reliable and does not indicate any semblance of pressure. basically its an idiot light that will read somewhere in the normal range if there is any pressure at all, but again, these are know to have many problems. Try cleaning the connection on the sensor usually near the oil filter.

Second, pull the codes. Autozone will pull them for free as will manyother places or you can get them yourself. See fordfuelinjection.com for instructions. I'm guessing you'd set a code if the exhaust were stuck open, probably the computer detecting rich and unable to adjust properly with the cyclinder being down ...

definitely change the oil & filter asap. It does sound like a broken spring.

Popa Tim

 

thank you popatim... if there were codes in the computer.. wouldn't the engine light come on and stay on..? or am i mistaken in that ? the only time i see the engine light is when that guage bottoms out. and it goes off again as soon as i bumpup the rps a bit.... I do know that those guages are pretty useless.. knowing myself that if there is no oil pressure at all .. things will be knocking all over the place....