I have a 78 F-150 with the original 351M. It has 241,000 mi and always ran great for me. Then one day while driving it started running rough and I lost a whole bunch of power. Well, after trying to figure out forever what was wrong with it, I did a compression test and found out my #5 cylinder has no compression. I'm wondering if there is anything I can do to get this enginge back to running right on all 8 cyl. for cheap. I'm basically broke but I cant stand not driving my truck! I havent tore it down yet so I dont know whats going on with it. What could it be? Thanks for any help.

 

Before you tear the engine down take the valve cover off that side and look for a broken spring, retainer or bent push rod. If you don't see anything you could go ahead and pull that head. You might get lucky and just replace a valve.

1977 Ford F-100
400m/c6/4:11/Gear Vender O.D.
Crane hydralic roller, forged, ported polished,Deamon,Edlebrock, yada, yada, yada
280,000 miles
Stock on the outside
modified/rebuilt everything

 

beartracks, thanks for answering. I just pulled the valve cover and everything looks fine. I guess I'll just go ahead and start disassembling the engine. I really dont have a lot of experience with motor internals. Is it going to be possible for someone thats never taken apart an engine to do it and put it back together, or am I going to need some special tools too? What all should I be looking for? I did a compression test again and it shows no compression in cylinder #5. Excuse my ignorance, but I just want to get all the info so I dont get in way over my head. I'd appreciate everyones comments.

 

Besides time, space, and willingness to get dirty - you will need some specific tools. You will of course need a decent socket set, ratchet, extensions, and possibly a breaker bar. Before removing any of the larger bolts (head, intake, exhaust, water pump, etc) get some type of penetrating fluid on them a day or two in advance - a few applications. Non-exposed (head) bolts should not be as much of a problem. You are trying to avoid the pains of a broken bolt. The way I handled this recently was to have my 13-year-old son do the wrenching - figuring that if one was too tight for him - then it needed more attention to avoid breakage.

When you re-assemble, go to the expense of new bolts (and new gaskets of course) and apply some anti-sieze compound to bolts. You should also have a repair manual that tells you the proper torque sequence (a set of bolts are tightened in steps, in a particular order, to a specific tightness). I suggest a good torque wrench, such as one of the Craftsman 'click stop' type - about $60 or so. Lastly, proceed slowly, ask for help when you are unsure (or look it up), and know your limitations. For instance, I suspect that you would want to take the head someplace for the machine work.

Keep as much debris out of the engine as possible, and plan to change the oil soon after re-assembly. Keep copious notes when you disassemble as some brackets and such may not be shown in a shop manual. When I disassemble, I put parts in ziplock freezer bags and label them with a sharpie - makes re-assembly much easier and reduces clutter. Good luck!

Tom