ReRinging Pistons, Head On

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IDave

IDave

Joined
Jan 3, 2003
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McCall, ID
I think I've seen this come up before, but I want to ask before I go ahead:

I will have the oil pan off to regasket on my F engine in an upcoming project. I don't want to rebuild the engine at this point, and the head was redone in August. I am pretty sure the rings are worn (compression test).

So, can I reasonably get to and rering the pistons from underneath? I know it isn't ideal to do it this way, but if it isn't too hard, I want to try.
 
David-


It is going to be difficult to keep the rings from catching on the uneven bottom end of the cylinder block, and to get them back in without damaging them...


If you are set on doing an inframe....Take the extra hour, and remove the head, and DO IT RIGHT!


:)


Good luck!


-Steve
 
Thanks, Steve. The more I stare at it, the more I realize its probably really stupid to even think about not removing the head.
 
It is not difficult. It is impossible. The pistons will not come out the bottom.


Mark...
 
Yup, I see that now. But it is possible to do in-frame, right?
 
IDave said:
Yup, I see that now. But it is possible to do in-frame, right?
Click to expand...

Yah, it's possible to re-ring in frame with both the pan and head off, but re-ringing may not solve your problem. The cylinders wear along with the rings, and so do the pistons. So you'd want to measure the roundness and taper of the cylinders and the piston clearances in each bore unless you want to go to the trouble risking ending up right where you started.

There is also the camshaft to consider. The bearing clearances do change with wear, the alignment of the bearing bores changes with time, heating, cooling, and wear. Many engines have been "rebuilt" in frame only to have the cam break soon afterwards.

In the old days there were people who could come to a vehicle and bore the cylinders of an engine in frame but I haven't even heard of that in years.

OTOH, sometimes it works. You play craps?
 
honk said:
You play craps?
Click to expand...

I do hear what you're saying. Perhaps it is the better part of valor to just rebuild the engine with the spun bearings sitting loose in the shop, and limp along with the one on board until I can switch them out. I just wanted to see if I could get a little more time out of the "replacement" engine.
 
Maybe I'm off here... But, wouldnt it take way more time to remove the tranny and rebuild this engine "in frame", then it would to just pull the damn motor? Plus, the awkward angles and limit of access.. Leave the tranny, unbolt the motor, and pull it out... Engine stands are cheap, and cherry pickers can be rented... I dont see the benefit otherwise...
 
I will openly admit my naevity in this job, but my minimalist approach plan was to undo the two bolts on each of the connecting rods ends at the crank and remove the pistons from the cylinders, reringing them and replacing them one-by-one. I could check the rings for size in the cylinders as I went along (a job made easier by removing the head). I was hoping then not to have to remove the tranny/trans at all, or the crank, camshaft, whatever.

I should say that the reason I was considering doing this is that am burning oil, despite my excellent compression numbers and an otherwise excellently running engine. My theory is that one or more of the oil rings were burned, crudded up, warped or whatever at the time the head gasket burned through last summer. At the time, what I could see of the cylinder walls looked fine, and I wasn't bothered until I replaced the gasket and reassembled the head and ran it and I realized I would be down a quart in 1000 miles.

There is also some leakage from the oil pan gasket, and maybe timing cover gasket, so I intend to replace those two. These leaks are newer than the burning issue, separate in time, and I blame them in part, anyway, on my use of Marvel Mystery Oil in the cleanup.
 
Dave, you should hone the cylinders while the piston is out. There is usually a glaze on the walls and the rings will not seat right if it is not removed. Did you try disconnecting the PCV valve to see if it affects your oilburning issue? I had an MGB that all of a sudden started to use oil and it ended up being a "gulp" valve.
GL

Ed
 
Dave,
You said that the head was redone in August. Was that a professionally done valve job? If not do you know if the valve seals were changed -(these are small rubber or plastic seals that ride around the valve stem inside the valve spring) and the valve guides inspected/renewed?

I think that valve seals account for about as many cases of oil burning as piston rings do - it's a split. Even money.

BTW, you can't remove the engine leaving the trans. The trans would be floating in mid air :) as it has no mounts of it's own. Take the whole powerpack at one time - engine, trans, transfercase. Ain't hard to do.
 
Ummm, I just read this part:
"and I wasn't bothered until I replaced the gasket and reassembled the head and ran it and I realized I would be down a quart in 1000 miles"
Click to expand...

Does this engine smoke?? If not I wouldn't think that a quart in 1000 miles is excessive - these ain't Honda Accords, ya' know!
 
Honk, no, it doesn't smoke at all. But I can smell oil in the exhaust, and that only intermittantly.

The valve seal question is a good one. The rebuild was done by a guy recommended by my mechanic friend, who I trust, but the fellow was new to the area, so who knows.

As for the tranny/trans, again, I want to change the rings without removing the block from the engine bay, or the crank from the block. I should be able to do that, si?

Ed, the PVC valve rattles nicely. What else can I check?
 
Dave, have you ever heard the maxim "If it works, don't fix it" ?
 
Dave,
It seems that the whole world, except the US manufacturers, knows that it is simpler, easier, and more cost effective to re-ring than bore the holes and get new pistons and rings. I've had a couple of BMW's re-ringed in the car.
You can check the bores, but with the compression you have, I doubt there is any serious wear, so if you are of a mind, just put new rings in it. BUT....a quart/1K miles??????? I'm with Honk, don do nothing. I think that a quart per 1000 miles is "within normal limits".

Ed
 
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Well, I gotta tear things down to a point, anyway, to work on the water jacket crack, and I have to pull the oil pan to replace the leaky gasket. It just seemed like one more step while things are apart....(and it didn't burn 1 quart/1000 miles before!)...would be worth a bit of effort.

I'm glad to hear what you're saying, Ed. I'll just have to see.
 
IDave,

I am rebuilding(partially- Hone,rings,RV cam,cut the valve seats,valve stem seals,main bearings,rod bearings,new gaskets,front crank seal,timing cover gasket,timing back plate gasket, new lifters,shaved head approx .040) my 2F in the vehicle and this post has me concerned with terms like "You Play Craps". Things I didn't/couldn't do while engine in vehicle - cam bearings("Playing craps"), rear main seal (have to separate the trans- I hope it's not leaking). did nothing to the crank.

This was/is my 1st engine rebuild. If you are thinking about replacing the crank bearings you may have trouble removing the cap on the front most bearing due to the camshaft backing plate gasket bonding. If you have to replace the gasket you'll have to remove the whole front to (crank pulley, timing gears , etc.- not too bad once you get in there) You weren't talking about bearings but I thought I would ramble while I had something to contribute to this fine Forum. I still have not completed putting the bad boy back together and will be sweating the day I turn that key

Good luck and keep us posted

John
 
IDave said:
Well, I gotta tear things down to a point, anyway, to work on the water jacket crack, and I have to pull the oil pan to replace the leaky gasket. It just seemed like one more step while things are apart....(and it didn't burn 1 quart/1000 miles before!)...would be worth a bit of effort.

I'm glad to hear what you're saying, Ed. I'll just have to see.
Click to expand...

Oh, now the block is cracked.

I'm fully aware of the benefits of in-frame engine repairs but I think that a person who contemplates such a thing ought to go at it with a clear understanding of what is involved and eyes open to all of the possibilities for disapointment. Frankly Dave, a person who could ask about the feasability of changing rings without removing the cylinder head could not lay claim to either.

May I suggest that your claim that "didn't burn 1 quart/1000 miles before!" could be born of your never before paying such close attention to what rate of oil consumption there was? Clearly, it isn't a problem, then or now.

Now what about this crack?
 
Honk, the crack in the water jacket has been discussed elsewhere, I only brought it up to fill you in. It became apparent only after I replaced the head gasket when that blew last summer. The plan is to have an expert welder friend do a muggy-weld job on it once the ambient outdoor temperatures reach 70 degrees, and I have the FJ45 in shape to drive when the FJ40 is torn down. I humbly admit my ignorance in this whole area, and I realize that it may go wrong in a number of ways, and thus my reason for asking is to try to anticipate problems.

On the other hand, Ed has offered me his spare F and 1/2, so I have a plan B should it be necessary.

As for the oil burning, I drive a pretty consistant 1000 miles/month. Thus, the change in the oil use was easily noticable. What can I say?

I really appreciate your suggestions! Thanks! :)
 
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