Ring Job

[cseger1]

Can rings be changed with the motor in the truck?

[philip]

Yes an "in-frame" re-ring job can be done but ... WHY would you want to when the job is better executed OUT of the truck?

[asavage]

The oil pan has to come off. I think you can do that if you remove the crossmember (it does unbolt).

You'll have to ream the ridge, always risky if you're going to re-ring and not rebore. It takes practice to ream so that the cutter does not end up damaging an area where the new ring will have to seal. I know from experience. I sold my ridge reamer: I'm never going to re-ring again.

Generally, if the rings are worn so is the bore. Out of round is how cylinders wear, because the major thrust load is to one side. And bore taper is a problem as well.

[cseger1]

I need to do it quick. I rely on the truck heavily. When you say you'll never re ring again do you mean never again without a re-bore or never again.

[philip]

I need to do it quick. I rely on the truck heavily. When you say you'll never re ring again do you mean never again without a re-bore or never again.

What discovery makes you think just a re-ring is imminent?

BTW, in spite of aftermarket oversize pistons, these engines are repaired by replacing the cylinder liner / piston / rings as a kit.

"There's never enough time to do it right the first time but ... you'll find the time to do it over"

[cseger1]

I don't know that I need a ring job, the PO threw them in and I am just doing some research. Sounds like its not a good idea.

[asavage]

I need to do it quick. I rely on the truck heavily. When you say you'll never re ring again do you mean never again without a re-bore or never again.

Due to the way cylinders wear (egg-shaped and tapered), by the time an engine that I plan to keep needs rings, it'll need a rebore as well.

I have seen successful re-ring jobs; the ones that worked best were ones that didn't need the rings replaced!

Round (new) rings will not work well in an egg-shaped bore. And it takes a looong time for a round ring to wear oval.

You can't (in general) use a hone to turn an oval, tapered bore into a silk purse.

One good reason to re-ring is if you have a broken ring. But if you have that, you probably have bore damage as well.

For those reasons, I eBay'd my Ammco ridge reamer and hone in 1999, knowing that I wouldn't use them. And I never sell my tools.

I've kept my ring compressors though. Still useful.

[cseger1]

Good info. Thanks.

[redmondjp]

It can be done but I agree with what has been said above.

I did it in my '81 Rabbit diesel when I first bought it--it had stuck rings in one cylinder. We popped all four pistons out, removed and discarded old rings, cleaned ring grooves and pistons, installed new rings, and lightly honed all four cylinders.

The engine had just over 100K miles on it at the time and I did measure the cylinder bores for wear--three cylinders were pretty good (only a couple of thousandths over) and the one with the stuck rings was worse, as the piston was wearing directly on the cylinder wall. It took about 10K miles of driving before the rings on that extra-worn cylinder fully broke in. It runs fine now, ZERO oil consumption, but there is no guarantee that it will continue this way for very long. We were taking a chance and we knew it. So far, so good, 30K miles later . . .

How far worn the cylinder is really determines if you can get away with this or not. I bought another Rabbit diesel parts car that had almost 200K miles and the head had already been removed due to the engine no longer starting (low compression--empty ether cans scattered all over the car). For kicks and grins, I measured the cylinder bore wear--the cylinders were WORN 0.017" oversize in one direction and you could rock the pistons back and forth with your fingers--it was amazing to me. On this engine, boring the cylinders and installing oversize pistons/rings would be the only way to get it running again--no way in the world that you could hone and re-ring an engine with this much wear on it. Well, you COULD do it, but it would be a huge waste of time and money, as you'd soon discover.

I took the new windshield, injection pump, starter, door handles, and a few other items off of that car and it went to the boneyard!

[asavage]

For kicks and grins, I measured the cylinder bore wear--the cylinders were WORN 0.017" oversize in one direction and you could rock the pistons back and forth with your fingers--it was amazing to me.

True story:

I bought an extremely clean, one-owner '80 Rabbit 2dr base model for $600 in Portland, Ore. for $600 in about 1992, with about 102k showing. It was a very nice car, a 4-spd so it had to rev on the highway, but had all the usual benefits of that vintage VW diesel.

At 112k it was getting so it was hard to start. Eventually I tore it down and measured -- get this -- .030" bore taper. That is a truly unbelievable number, and I dont' expect anyone to believe it, but I know what I measured.

How it ran to that state, I have no idea.

I priced out repairing or replacing that engine, ended up selling the car to someone who said he was going to put a gasser in it. I was sorry to see it go, and a couple of years later I bought an '82 2-dr deluxe (twin outside mirrors, rear wiper, carpet!) and ran that one out of engine too, but that's a much longer story.

[philip]

SNIP- For kicks and grins, I measured the cylinder bore wear--the cylinders were WORN 0.017" oversize in one direction and you could rock the pistons back and forth with your fingers--it was amazing to me. -SNIP

SNIP- Eventually I tore it down and measured -- get this -- .030" bore taper. That is a truly unbelievable number, and I dont' expect anyone to believe it, but I know what I measured. -SNIP

Finding such extreme cylinder wear suggests to me more than just infrequent oil changes or a long history of injested dirt; perhaps soft cast iron. Solution would be fitment of PRESS-FIT dry sleeves and better filtration both oil and air.