Hey all,

I'm new to the old F150 scene, so I'm not entirely sure what should be expected in terms of vibrations and idling with this older truck. I've been looking for some info on it but have had no luck, so I figured I'd come to you fine folks. I bought it used and the original owner doesn't have anything written down in terms of maintenance. I know the oil has been changed regularly and I think the transmission was flushed once, but that's about it.

The RPMs when idle seem to be right and I don't have any real concerns there, but the cab of this truck is *bumpy* when I'm just sitting still. I feel like I'm rattling around when sitting idle. The engine definitely shakes a bit, but it's not bouncing around everywhere. It thuds a bit when shifting between 2nd and 3rd, but I've seen some folks mention that that's normal.

I guess I'm trying to figure out if I should go ahead and check out the engine mounts, spark plugs, etc. I'm not sure of the history around those components and I don't have a record of whether any of it has ever been replaced. Looking for some thoughts from you all on where you might start, or if I should just accept it as part of driving an older truck.

 

I don't remember my 1993 302 rattling me around in the cab while at idle.
Probably a good idea to perform a mild tuneup if parts don't appear to be fresh.

You could remove and clean the contacts on the distributor cap and the rotor inside the cap. The metal gets burnt.... you can scrape the terminals 'cleaner' and scrape clean the rotor. It should be obvious when you look at it, the leading edge of the rotor will be course with deposits. Look at a picture of a new one, you will see it is smooth and shiny.

Find documentation for the firing order and make sure the spark plug wires are routed to the correct cylinder.

For peace of mind, just replace the plugs, distributor cap, rotor and plug wires. No need to get fancy parts, just get the stuff form your local parts store. I've had a variation of plugs in mine back in the day. Today it's recommended to stick with motorcraft parts, not sure if I was just young and dumb back then or if it was less important.

If the 'tune up' doesn't give you a smooth result, dig deeper to motor mounts, etc. Consider a compression test. If you do change plugs, could be a good time to do a compression test while your're changing them out. Check each cylinder before replacing with a new plug. Take good notes with the value at each cylinder, and I suggest calling the cylinder numbers the correct number in case you need to troubleshoot in the future. A post saying "The 3rd one on the right" gets confusing because there are 2 rights! One is wrong. haha

Consider changing the fuel filter as well, they are serviceable and located on the left (driver) frame rail.

The only reason the "older truck" should have that vibration is if something is wrong like internal motor concerns (worn out, etc) or a motor mount or improperly tuned (bad plugs/wires as mentioned above).


I don't have any comment about the shifting aside from inspecting the universal joint in the driveshaft. Could just be play/sloppy at that connection. Otherwise, I can't speak to a harsh shift experience.

 

Thanks so much for the info! That's what I was looking for. I'm a newbie at all this and I'm enjoying fiddling and learning all of it. I didn't think about cleaning the distributor cap so I'll go there first, like you said. I have a repair manual so I have the firing order and all so I can check that too.

I might go ahead and just do the plugs and wires to remove that possibility. I have no record of them ever being changed out and it was mostly used as a "work truck" in its later years.

Thanks for the tips! Just glad to know that it *should* be smoother than it is. I'll get to poking around on it.

 

If you have a spray bottle.... use plain water in the bottle and spray a mist over the plug wires at dark. If the wires are leaking you'll see sparks from the wires trying to mate with the water.

Note: If you suspect any fuel leaks you may reconsider my thought.
Declaimer: You cannot sue me if you cause damage to your vehicle or to yourself or surrounding people. Kidding, it's funny how we on the internet feel compelled to provide this little note. haha

Good luck though! Hopefully there is a good resolution.
There could be additional possibilities but none I can personally think of (just because I don't know everything).