I own a 71 Ford F100 custom with a 4 speed 360. It have very low miles, 22k, and has been garaged since I have owned it. I took it out for it's first drive this spring and about 10 minutes into the drive I began to hear a loud tapping noise. I drove it right home and checked the oil, and it was low. My fear is that I pulled some sludge up into the engine causing a stuck lifter?

I have read other forum posts and they suggest using Marvelous Mystery Oil. I purchased a quart and have driven it for only about 10 miles so far.

1. How far do you think I need to drive it for the detergents to work?
2. Can I cause damage driving it in this condition?
3. Any other ideas before ripping into the engine?
4. If you do have to take the engine apart, what are we talking about in terms of cost and time?

Thanks for any help!

 

Mark, I would pull the valve cover and check if all the push rods are in there correct location.

I think the oil flows through the rocker assembly down the push rods and to the lifters...
thats a long way for gunk to travel to get to the lifter if you ask me.

How low was the oil?

 

Some quick answers:

Yes, you probably have a stuck lifter. It could be something more serious, but stuck lifters are very common on engines that aren't driven regularly. It's caused by a gradual buildup of varnish and gunk inside the lifters over time. It's not likely to have been caused by one incident of being low on oil. I'm assuming that you still had oil pressure, right?

The Marvel Mystery Oil trick may work, or it may not. There's no guarantee. When my '90 460 engine in my van got a stuck lifter last fall, it worked and solved it. I put in a quart of MMO, and within 5 miles it unstuck. I drove it about 25 miles with the heavy MMO dose, and then changed the oil & filter. If you just put in a pint of MMO, it may not have an immediate effect. The heavy dose of MMO is a risk, but it may solve it.

Yes, driving it for a while with that bad tap may do more serious damage to the engine, particularly if you rev it up high. On a nice old low mileage engine, you really don't want to risk mechanical damage.

The correct repair, if the MMO trick doesn't work, involves pulling off the valve covers and taking the whole intake manifold off. Some grunt work, but nothing difficult. Then you remove the pushrods and pull out the lifters. You can disassemble them and clean out the gunk, or buy a new set. It's not a lot of money in parts, mostly just the labor.

 

I'd pull the valve cover on the side with the tap to be sure nothing more serious is going on. With the VC off , lay rags across the rockers and start the engine. (The oil actually flows up through the lifter to the rockers and will spray all over without the rags) Then grab each lifter with rour hand untill you find the noisy one. Inspect that valve/rocker closely.

 

Tinfoil works good inplace of using a rag.

 

My 71 with a 360 had a tap when I bought it. It turned out to be 2 bolts in the rocker arm shaft had been stripped and the shaft was flopping up and down rather than opening some valves. I doubt that is terribly common, just thought I'd throw it out there!
But yeah, I agree. Take the valve covers off and see what you can see.

 

Thanks for all the advice. Looks like I'll be pulling the valve cover next weekend!

 

I've heard oldtimers running Atf(automatic tranny fluid). Put it in the oil. Don"t know how much(whatever you fill comfortable with). It has alot of detergent in it. Run for about 5 miles than change the oil and filter. If it were mine i would change the oil after another 50 miles or so.