starter won't spin the engine with all spark plugs

Asked by Jan 11, 2017 at 09:32 PM about the 1979 Ford Mustang Base

Question type: Maintenance & Repair

I've got a kit car that uses a Ford 302 V-8, and it has sat for a couple of years and now won't start.  I know the battery is bad, but with jumper cables I turn the key and the engine only turns over about a "little"  (which I define as the fan only turns about a quarter or half a revolution-- about 1 to 2 seconds of cranking and it stops, even though I'm still trying to crank with the key).  I remove all the spark plugs, and try again, and now the engine cranks and seems to spin just fine.... I've cranked it as much as 15-20 seconds continuously.    So then I tried putting half of the spark plugs back in (all of the plugs on the left side), and added a little starting spray in the carb, and low and behold the engine started and ran on just those 4 of 8 plugs.  But I put in the ones on the right side (all 8 installed) and the same problem.  The engine only turns over about a half of a turn on the fan.    Any ideas what could be the problem, or what the next diagnostic step is?  

4 Answers

79,555

Your fuel system is probably clogged up from old gas. Check for spark and make sure the timing is correct.

102,085

Remove the valve cover on that side, I think you have some stuck valves in one or more cylinders and possibly even bent push rods. If the valves are stuck you will have to pull the head and have them redone and it just might be wise to do the other side as well.

tennisshoes, This was my thought as well. I removed the valve covers (both sides), and the rockers are all moving... can't see the valves themselves, but it looks like they are moving also. The rods don't appear to be visibly bent or broken, but I'm just eye-balling them. Full_of_regrets, I expect that the fuel system may be clogged.. but would that cause a lack of rotation? Also, I had the engine fully running (i.e. combusting gas and drivable, as opposed to just cranking) with just 4 of the 8 sparkplugs installed, but not with all 8 installed. For those reasons, I don't really suspect fuel as the issue. Or at least not the primary issue.

102,085

Then run a compression test on those cylinders on the suspect head, if one or more are high then the head will have to come off to find out why.

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