Hey gang,

1976 Cherokee / Rebuilt 401 with about 90K miles on it. Once it warmed up, it started idling really rough, especially in gear. I did my normal checks and couldn't figure it out so I took it in. The mechanic (trustworthy) said that 2 cylinders came back with low compression, he did a leak check and said it read below the pistons. I limped it home and started planning for new engine.

The next day, it miraculously revived and is running normal again. I called him and he said it is likely that those piston rings were just getting stuck in gunk and that I should try some fuel additives to clear it out. Its been about 4 years since I changed the plugs/wires (not sure if that will help give the pistons more 'umph' so I will change those out this weekend when they come in.

Any other advise or guidance? I would prefer to keep this engine alive if possible, obviously.

Thank you in advance!

 

It does sound like rings are sticking perhaps from carbon build up. Add a can of SeaFoam to a full tank of gas. You can also add SeaFoam down the throat of the carb to help clean out any carbon buildup.

 

Thanks, Steve. I did add some fuel additive in yesterday and also threw a can of "Restore" into the oil for kicks and giggles. Might just make a habit of that for a while and see if that helps the old gal out. I also cleaned the carb, but might take your suggestion of putting something down the throat too.

I saw somewhere it was recommended to put some deep clean into the spark plug ports. Anyone have any experience with that?

 

There's quite a few anectdotal reports of throwing everything in there from ATF to PB.

And Seafoam:

 

So basically, try anything.

 

Thank you for your kind replies and help on this.

I have already:

1. Added Techron treatment to fuel
2. Added Restore to oil

This weekend I will:

1. Spray a can of Seaform into carburetor throat
2. Add Seafoam into each cylinder via sparkplug ports
3. Replace spark plugs
4. Replace wires

Next week I will:

1. Change oil
2. Add another can of Seafoam to oil
3. Add Seafoam to fuel when I refill the tank

Following week:

1. Change oil
2. Add Lucas Oil additive
3. Spray can of Seafoam into carburator
4. Add Seafoam to fuel when I refill tank

I would think with all that, I will have done all I can to clean the engine out. Then maybe just continue to add Seafoam to the fuel once a month maybe and see what happens?

 

IIWM, I'd just load the cylinders up with Seafoam or ATF and let it sit for a few days, turning the crank just a tad every now and then.

In all those other applications, your solvent concentration has dropped down to just a few % with no guarantee that ANY of it gets to the rings.