Mobile mechanic or someone able to help re-ring 4.0l?

Hey there,

In the midst of a head gasket job and I'm seeing a cylinder has a worn ring (did not retain the 2 cycle oil I covered it with). I'm assuming I need to re-ring it, which is beyond my ability. However, it's torn apart in my garage. So...

Any suggestions on a great mobile mechanic or know of a 4.0l guru willing to make some extra $$ helping my pull the pan, pistons, hone, re-ring, and I'm sure some other stuff while it's open?

How long does it take to seep past? If it sits long enough it will move past the rings, I wouldn't have that be your sole reason for condemning the rings

I agree. Turn the motor over till that piston is at the bottom and check your ring ridge and whether you can see the crosshatch anymore. Won't tell you if the ring is worn out, but even on abused engines I've torn down the bores wore first.

If the rings are perhaps stuck, you could try some seafoam poured into the cylinder in question to free it up.

trippled said:

How long does it take to seep past? If it sits long enough it will move past the rings, I wouldn't have that be your sole reason for condemning the rings

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It was less than 24hrs. My concern was the other 5 are still holding back the oil poured in 5 days later.

kastein said:

I agree. Turn the motor over till that piston is at the bottom and check your ring ridge and whether you can see the crosshatch anymore. Won't tell you if the ring is worn out, but even on abused engines I've torn down the bores wore first.

If the rings are perhaps stuck, you could try some seafoam poured into the cylinder in question to free it up.

Click to expand...

Are you thinking this cylinder just happened to have the rings stick to where the ring gasps line up?

linksvu said:

Are you thinking this cylinder just happened to have the rings stick to where the ring gasps line up?

Click to expand...

Either that, or one of your valve seals was leaking more than the rest causing that cylinder to burn more oil, which will gunk up the slots the rings sit in more. At that point the rings can get stuck compressed more than they should instead of being able to slide outward and press on the cylinder walls, which will result in a leakier ring seal than normal. I'm banking on seafoam or something else that will dissolve oil varnish and carbon buildup cleaning it out enough that the rings can slide back out and seal against the cylinder properly again.

Shouldn't be more than a few bucks to try it, so it's worth doing before you take more drastic measures. If you have the oil pan off, you could always pull that rod bearing cap and lift the piston and rod out (put small pieces of rubber hose over the rod bolts/studs to prevent dinging up the crank journal during removal and reinstallation!) and see if the rings are stuck, if they are, soak it in a bucket of solvent for a while and get them freed back up and put it back in.

If you do an in-frame hone and re-ring, make sure you very, very, very carefully clean all surfaces the dust could possibly get on in the process before reassembly. The last thing you want is extremely fine metal dust and abrasive dust from the hone sitting in your oil, it can and will chew up all your bearings very quickly if you leave any residue in the crankcase and it circulates through the oil system after putting it back together.

I’m liking this idea. Happen to know any local CO contacts willing to help with this? I’m feeling it’s beyond my ability but the jeep is turn apart in my garage.

Re-ringing and re-honing the cylinder walls is pretty easy if you removed the engine from the jeep.

With the pan off remove the rod caps, silde the piston out the top or bottom, soak the pistons in a bucket of carb/choke cleaner to dissolve the carbon overnight.

I use a flex hone to rehone cylinder walls, its fairly cheap and seems to work well:
https://youtu.be/iIkmHu_EaP8

Make sure to clean all the oily gritt stuff off after you hone the walls, make sure to put the pistons back in the same order they came out.

With new rings and de carboned piston ring grooves, and rehoned walls your block compression should be excellent. You could spend a little time and lap the valves in the head while it was apart. This wouldn't be completely rebuilding an engine, but would refresh the critical components for compression nicely.

I have some one helping me replace this #2 piston and hone the cylinder. I feel everything else looks good. I also had the head cleaned up and valves checked at a head shop.

I’ll update the thread after this next stage

Well, I decided to take the slight additional costs and replace all the pistons. Only the one was truly bad but it was only $100 or so more to replace all 6.

So... I pulled all the pistons, marked the bearings and rod, had a shop press the new pistons on the rods, and I’m going to hone and clean the cylinders. Then I’ll re-set the pistons and finish what was suppose to just be a head gasket job.