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Head off, replace rings while exposed?

linksvu

NAXJA Forum User
Location
Littleton, CO
Suggestions on (what I assume) to be shot rings on #3 piston...

Situation: Picked up a '98 4.0l 180k with a blown head gasket. I have the head off and it's out getting cleaned, but found the #3 cylinder drained all the 2-cycle oil I poured on the pistons to cover/coat it while cleaning the surface for the soon-to-be cleaned head and new gasket. I have to assume this means the rings are shot. Would you agree? Anything else I should be looking for? The others appear to be holding the oil back well.

I had a shop drop the oil pan and they said the rod bearings looked good; they didn't say they found any parts in the pan.

So, thoughts on replacing just one piston's rings? Should I replace them all since there? Should I be concerned or looking for anything else? Etc....
 
Well, your facts make no sense. There's no way to detect bearing damage from removing the oil pan. If you need ring's, you probably need the cylinders honed?
 
I'm not a mechanic, but all I've read is the bearing can be checked (and replaced) when the pan removed.

My non-expert eyes like how the cylinder walls appear. Do they need to be honed if the ring(s) are just worn?
 
The honing needs to happen so the rings can break in properly.

Given what you have described, if the head is off and the pan is off, I would say you have nothing to lose.

A cylinder hone on a drill should be adequate.

Since the 4.0L doesn't have shared journals it should be no problem to keep things clean below and confirm they are clean afterwards.

I would recommend getting the help of someone with some experience for the reinstalling of the piston with the new rings on it. There are a number of details to screw up in that process, and if you are not a mechanic it may be easy to find more than one pitfall.
 
Well, the pan was put back on. So, do you think it is worth pulling again to hone the cylinders?

To confirm, am I correct in my assumption the rings are worn since it did not hold back the oil poured in?
 
You would be replacing the rings from the bottom. I'd recommend putting it together and do a proper compression test. Oil draining past the rings on a cold engine doesn't necessarily mean bad or broken rings. As stated above, there are many things that could go wrong with the ring replacement so why risk it if you're not sure you have an issue.
 
You would be replacing the rings from the bottom. I'd recommend putting it together and do a proper compression test. Oil draining past the rings on a cold engine doesn't necessarily mean bad or broken rings. As stated above, there are many things that could go wrong with the ring replacement so why risk it if you're not sure you have an issue.

Forum is not letting me edit my post. You would be replacing the ring from the top, but I'd still recommend putting the head back on and perform a compression test first.
 
That is an interesting thought... you think it better to put it all back together, test it to see what/if I have noticeable compression loss?
 
Your taking a pretty big chance on something you have no background on and died from a over-heating problem! But if your that close?
 
I'm more interested in doing what's right while I have it open then creating more work.

Are you thinking re-ringing it is not worth the hassle at this point?
 
At this point it would be most cost effective to replace all 6 sets of rings. The pan isn't rocket science to remove (if not already done). And the head already being off makes the effort almost negligible. In for a penny, in for a pound.

As for necessary...without disassembly and inspection by a knowledgeable repair person, its anyone's guess. A couple rules of thumb:

Deep scratches in an updown direction are not a good sign.
Keep pistons, rod caps, and rod bearings together and oriented so as to be reinstalled in the same bore, direction, and position.
Take lots of pictures before and during disassembly.
Rent (or invest in) a good piston ring compressor!
 
Last edited:
As mentioned earlier.

Oil draining past the rings on a cold engine doesn't necessarily mean bad or broken rings.



I'm thinking that time and budget are the more deciding factors.
 
As mentioned earlier.





I'm thinking that time and budget are the more deciding factors.

Yes, though time over money on this senerio. The last think I want is to put it all back together only to find the compression is out of spec.

To confirm, I can re-ring without having to pull the block?
 
Not properly, you should have the block completely checked over before proceeding on anything. The includes align bore, cylinder bores, and the deck surface. Same would apply the crank and rods, pistons you won't know about until they check the block!
 
What have you done to inspect the head?
 
I only pulled the head; I had the head checked and cleaned by a local head shop. I’m comfortable with the head. Is there something I should be looking for beyond their work?
 
To confirm, I can re-ring without having to pull the block?


Sure it's doable, just not as easy if the block were on a stand. I replaced a piston and re-rings all the pistons after one had a rod bearing seize in a 2.5l wrangler. Amusing to discover that half the rings were upside down from the factory. Plenty of room to work on that one as I could stand between the engine and the rad. It was still running great when I sold it 30k miles later.



As mentioned, keep everything in order and orientation (front-back on the pistons too). You'll need a few specialty tools like a ring compressor and hone. Did you ever figure out why it had a bad head gasket?
 
For a ring compressor, you are most likely to get the best results if you spend the money to get one of this sort:

https://arp-bolts.com/kits/ARPkit-detail.php?RecordID=4663

That will help remove one major potential error and make your life easier.

The one linked might be close enough to be the right size, but you should confirm the size and check to make sure you get the best size possible: https://arp-bolts.com/kits/product.php?PL=47

That is just one source. A sales person at Summit or Jegs could probably offer more sources/options.

Getting things just right with a band type compressor is an iffy proposition for someone without experience or an experienced guide.
 
I'll say double to that, I have dozens of band type compressors but since losing the use of my right arm I had to buy the new style so I could get the job done this time!
P1080510_zpszrlfib5k.jpg
 
I agree with RCP Phx about having the entire block checked, at a block shop. To do that correctly, imho, there will be some tear down, and restoration of stuff by that shop, and the extra cost. This is so done in order to best to determine that you have not obtained a mystery engine with issues exacerbated by the conditions causing the blown head gasket in the first place, etc. Such a shop will insure all oil/coolant passage ways will be clear, and line-bore checked, etc.

1) Are you physically able?
2) Are you working indoors, or outdoors?
3) Do you have a good selection of mechanic tools?
4) Have time, and sufficient dinero?
I am not so perfectly able, and have replaced heads indoors, and out, i.e. of a few.., once in a blizzard, under a makeshift piece of tarp. Indoors is best, lol.

Typically one purchases a package of Plasti-gauge in order to check the rod bearings. Ask your shop what they did to check your rod bearings. Answer that for us. Details, details, details.

That said, many of us just go 'fer it. The job you are looking at is not too difficult, but you have to do everything correctly. Suggest you get a repair book. The common ones will share how to correctly cross-hatch the cylinder in question, (any cyl.), and how to ridge ream the top of it in order to send a rod/piston down into the hole. The problem with your #3 is that after miles the walls become glazed, but to expert, or non-expert eyes the glaze is there never-the-less. You must remove the glaze to ensure that the new rings marry the cylinder walls. As ANAK said; you can get that tool to utilize in a common electric hand drill. Follow the directions in a manual.., easyish. Thanks ANAK for the link!!!!!!

In replacing the rings to your rod/piston, just take it to a shop, along with the rod bearing cap, and let them do it. There are different ring sizes, blah, blah, and without special measuring tools it can be a bit confusing for most. However there are simple clues as to that subject, (like breaking rings to use as tools to clean out same channels as the old rings came from), but since you are not a mechanic, let a mechanic do it, i.e., to clean out the piston ring channels with proper tools, and to determine the correct size of a replacement set of rings for that piston, and their positioning for you. You can then install the completed unit. Be sure to protect crank shaft bearing surfaces with a rag when you knock down the rod/piston towards positioning, i.e., pull out the rag from below, pull the rod/piston down over surface, and install bearing rod cap. The bearing in the cap may be good, or not. Ask a mechanic what he/she thinks. Sorry, I digress, as a manual for your engine should explain all of that.

sflier is correct, but to qualify his statement a compression check is always mandatory. It appears you did not do that, and you can only do that once it's all together. But he, like many of us just go for it, but the major downside is if the check is bad, then sheesh you gotta do it all over. I think your draining of the oil test sez something. I'd be hard pressed to ignore that. Could be a 50/50 thing, but I'd make sure that that #3 is correct, hence a bit of a tear down.

I agree with four_shot, just do all the cylinders, that way everything will be balanced as best as possible, i.e., your final compression check should all be tightly together from one to the next, etc. His suggestion to keep parts in order is most useful. I have fount empty egg cartons are part of that triage. Anyway the idea is to have all pistons to compress the same pressures, thusly minimizing any overheating of any overworked one, so as to wear bearings evenly. All pistons/rods are at the shop, being reworked, whilst you are busy de-glazing piston cylinders, and such.

Hey RCP Phx, nice looking engine so far.

linksvu: Be absolutely sure you obtain brand spanking non-chinese head bolts. USE THAT LINK. I hope others will remind us which head bolts need to utilize some waterproof, and/or glued use.., I can't remember at the moment, lol. Your old bolts will have stretched, and are maybe useful in putting together parts of a back yard wood project. Secondly, after a few hundred miles you MUST do an in-service head bolt re-torque procedure, meaning you remove the valve cover, loosen the bolts a bit, and re-tighten to spec. You have a quality torque wrench.., right?

Also I wonder if the shop planed the mating surface of the head. One way to check is to get a can of WD-30, and a sheet of glass that will easily fit the entire head, (have a glass shop fab one for you). Flip the head so as to present the mating surface up to the sky. Use a level, and some shims in order to get that head sea-level. Spray the mating surfaces with the can getting the surfaces evenly well wetted. Place the glass onto that mating surface. The pattern you will see will indicate areas that are more, or less even in appearances. Think gasket. You should see an even display of oil between the head, and glass showing mostly exactly the same size/shape of a replacement gasket. If so, you are good to go with such a non warped head.
 
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