I have a 1997 F150 4.2 SPI w/ 110,000 miles and sometimes when I start it, especially in the morning it runs rough almost dieseling for about 10 seconds and then it runs great after that ? Any ideas ? I replaced the MAF and the PCV valve.

Thanks, Ron

 

Have you had to add coolant? Check it to make sure it is not low.If you are losing coolant then you have one of two or both gasket problems.If the lower intake gaskets leak the coolant goes into a cylinder or cylinders and thats why your truck might be running rough at start up,burning it off.If they get bad enough the cylinder or cylinders fill with coolant and it hydro-locks.

The other gasket is the timing cover gasket.If it leaks internally it will wipe out your bearings.The 97 and some 98 4.2s are known for these bad gaskets.

If the gaskets are not your problem try changing your fuel filter.Or,your plugs and/or wires need to be replaced.

Keep us posted!

 

Ditto the above.
Check your coolant level first.
Also, possible vacuum leak, IAC problem ro plugs and/or wires.

Welcome to FTE! Hope we can help you fix your problem.

 

Well the coolant was down about 1 quart. I have not checked it in over 3-4 months. I guess it may be time to replace those dreaded gaskets and at t eh sametime, plugs ?

I'll update when I get this thing apart in a month or two.

Thanks

 

You're gambling by letting it go that long.Each time you start it then shut it off the next start up could be the hydro-lock start! I've had to have mine replaced,twice!The first time Ford did it they botched the job.They replaced them again,but at a much lower rate!
I've seen several 4.2s hydro-lock and its not a pretty thing, esp. when I told the person to get them replaced ASAP!

 

Yep, then you get a bent/broken rod and a new shortblock is needed as well.