How does the "Italian tuneup" work exactly?

I am talking about the method of leaving a car in a low gear, running the engine up near redline, and then letting off, letting it engine brake and slow down. This seems to have relatively good success of freeing stuck piston rings that allow for oil burning. I have done this on several engines with about 50% success rates. Some are too far gone while it works wonders on others. The two most recent I can think of where it worked was a Cadillac Northstar 4.6 that had been run WAY beyond when it should have been changed on cheap oil and putted around town. I understand these engines are known for and almost designed to burn some oil so the rate went down by about 75%. It didn’t stop using oil but was at least tolerable.

The second one I recently did was another 1.0L 3 cylinder Geo Metro. It had been sitting for 6 or more months and it was obvious that the previous owners have not given the engine the TLC I would have. The oil I drained out was filthy and I basically replaced every seal and gasket in the engine with the exception of the head gasket. I could see sludge in the recesses of the engine and under the valve cover although the engine ran fine. I changed the oil after like 500 miles and this change looked dirtier than a lot of oil left in for 3000-4000 miles.

The main problem was oil consumption. There were no external leaks since all of that was taken care of and I double checked. No oil is leaking. There is also no smoke that I can see but about 1 quart of oil was disappearing every 1000 miles. I did about 6 cycles of “Italian tuneup” after making sure the oil was full. The car has been driven over 500 miles since with much of that being high speed interstate driving since then and the drop in oil level has been imperceptible.

So, how does this work exactly? I have heard that the engine vacuum under heavy closed throttle deceleration loads the piston rings differently and unsticks them if they aren’t too stuck. Also, if the engines treated this way are maintained better in the future with good oil and frequent changes, how much of a chance do the sticky rings have of returning?

What the heck, you might as well load it up with Sea-Foam while you are at it…

I don t know either.

when I got my current 75 ford, it had sat for long periods. it was basically only used for hauling firewood out of the woods one week a year.

after I got it, whenever I stepped on the gas , clouds of black smoke would come out of the tail pipe.

this was handy when I was being tailgated.

but after a couple months, and a few episodes of me really getting on it, this problem went away and never returned. its now 5 yrs later. the truck runs great now and no longer burns oil.

I wonder if stuck rings was the problem.

I also changed the oil numerous times at first, always when hot

Sounds like you took advantage of this phenomenon. I think a lot of it is just sitting. I assume the nasty deposits form a hardened mass and lock the rings where they are as the engine sits. Some engines just start burning oil from sticking rings as they are being driven, especially when neglected.

I once knew a guy who had a van like this. This was an older Chrysler van which were notorious for burning oil anyway. It burned oil so he never changed the oil. He figured just adding oil was good enough as the old oil was just getting burned. This thing was nasty. Clouds of blue smoke just poured out the back and you could see it a mile away. This was a clunker, gross polluter, or whatever else you might want to cal it. His son got ahold of it and changed the oil. The old oil was like tar and the oil filter was completely plugged off and bypassing. IT weighed like 10 lbs. They kept it running a little while longer but I think it finally got traded in for something different.

I used to run Seafoam in the crankcase right before an oil change but have heard that engines with a lot of neglect may release lots of crud all at once and do more hard than good. I have been told that engines with good care won’t be harmed but you are basically pouring in snake oil that isn’t needed. I know the Geo Metro like the one I have can be killed by using Seafoam in the crankcase. Marvel Mystery Oil seems like a gentler alternative and I did use some of that too.

In days of old
when knights were bold
we all had carburators.

They looked real purty
but sure ran dirty
and thus we had carbon gators.

Seriously, carburetors ran very dirty, leaving carbon deposits in engines. “Dirty” from a combustion standpoint means that after the combustion stroke much of the carbon in the hydrocarbon molecules (gasoline) was left over as carbon monoxide, unburned hydrocarbons, and carbon. Carbon sticks to carbon very well (hence the strength of carbon fibers), and it would build up inside the engine. That presented two problems. (1) carbon retains heat, great for charcoal briquettes but not so great for cylinders, and (2) it could build up to where it would increase the engine’s combustion pressures. Both of these problems could cause preignition. In addition, it could build up on and foul sparkplugs.

The “Italian tuneup” was an attempt to get the cylinder temps high enough and long enough to burn out the carbon deposits.

Modern engines are far, far better at metering the fuel, and far, far better at vaporizing the fuel. These two abilities of modern fuel systems means that very little of the hydrocarbon molecules (gasoline) remains unburned as carbon monoxide and carbon. Today’s engines run very, very clean. “Italian tuneups” are no longer necessary, and in fact are totally useless.

If you’d like, simply ask and I’ll be very happy to explain the difference between how carburators work and how modern fuel injected systems work and why carburetors ran dirty and modern systems are so much cleaner. But in the interest of brevity, I’ll ask you to trust me. {:slight_smile:

I understand how a modern engine and fuel management system works with fuel injectors, throttle position sensors, oxygen sensors, and the like works. Instead of a one size fits all approach, a nearly optimum amount of fuel is injected for constantly varying conditions. This is better for the engine, fuel economy, and emissions.

The deal I am discussing is a neglected engine where the rings are stuck and no longer seated properly, allowing for oil burning and/or blowby. Maybe this creates intense stresses that bust them loose if they aren’t too far gone??? This must also work in these situations as I have seen it work several times myself and heard other success stories. I have also seen it fail to do anything or make the situation worse but these engines were so far gone there was nothing to lose.

A couple of the engines that got worse seemed like the old cruddy oil was holding them together. The oil change seemed to make them worse if that tells you how far gone they were. The old oil looked like tar.

Rings work by combustion pressure pushing them out against the cylinder walls, so the high rpm of an ‘Italian tuneup’ would do that more.

Combustion pressure pushes the combustion rings against the cylinder walls, but not the oil rings. Oil rings are pushed against the walls by spring tension. The oil rings are not intended to contain combustion pressures, only to wipe the walls down to where a residue of oil remains in the honing and/or cavities in the cylinder walls sufficient for the combustion rings to slide on, but not enough to allow oil burning. Wiping the oil down via the rings also removes heat from the walls, carried down by the oil being wiped off the walls.

Oil rings and cylinder walls do not get hot enough via combustion temperatures to burn away carbon deposit or to burn away coked oil. Italian tuneups do not and never did have any effect on oil rings or cylinder walls. An Italian tuneup MIGHT, however, burn carbon off of a caked up valve, allowing better operation… in old carbureted engines. It’s useless in a modern engine. The root source of all that carbon, the limitations of carburators to vaporize fuel well, is gone now.

I thought he said the important part was the letting off the gas in a low gear high rpm situaion

He simply described the process of forcing the engine to run at high load and RPMs than letting it slow via the compression. That MIGHT, I emphasize MIGHT, in some cases, if you’ve been really good and the almighty likes you, free a stuck oil ring, but it doesn’t describe what’s commonly called an “Italian tuneup”. At least not in my neighborhood.

your kinda grouchy tonight, need a hug?

It was explained to me that high engine vacuum of slowing down in gear had something to do with the process. I would say this was a bunch of bunk but have seen it work myself so know it isn’t just nothing. I usually drive them like they are stolen. 100% on then 100% off during the slowdown. I don’t know if the high loads or the high vacuum situations do most of the work.

Not really, wes, but there is this gorgeous blond… I could use a hug from her, grumpy or not…
Sorry, couldn’t resist. Bad form, slap my hand.

Mountain, when you close the throttle at high RPM there is no compression…The engine will be pulling a high vacuum…This is pulling the rings in the opposite direction then what occurs under WOT conditions. Sort of like whiplash for the compression rings…That could possibly break a stuck ring loose…

Yes, sounds like the high vacuum created by closing the throttle at high RPM is the key. Normally on the piston intake downstroke, with throttle open, there is some vacuum pulling the rings up, along with a bit of inertia and friction. But with the throttle closed at high RPM the vacuum force is greatly increased on the rings. And keeping it in gear prolongs the high revs/high vacuum condition. Since most engines aren’t ever subjected to that regimen, I can imagine it breaking some stuck rings loose.

I understand, caddyman.
But the original question is “how does an Italian tuneup work”. In my hometown, an “Italian tuneup” was the act of pushing the engine beyond its normal operating environment for the purpose of blowing out carbon. I concede that the original posting went more in the direction of stuck rings and oil consumption, a whole different question based on my hometown’s definition of an Italian tuneup.

I will also add that the vacuum-to-pressure variations of going from WOT to closed throttle don’t have the effect on the oil rings that they do on the compression rings. The effect of the cylinder friction causing quick changes in the loads on the oil rings due to quick changes in the direction of the pistons at high RPMs has much more impact. Remember that the oil rings are protected by the compression rings from the changes from the high top-loading created by high cylinder pressures to high bottom loading caused by the high vacuum of decelerating with a closed throttle. High amplitude, fast pressure changes from positive to negative cylinder pressures do not affect the oil rings… but wall friction and inertial forces do.

The exercise described by the OP MIGHT free some stuck oil rings, but not from pressure to vacuum changes in the cylinder.

I remember Italian tuneups from yesteryear. In today’s engines, I can’t help but wonder if the placebo effect is playing a role.

As for the high vacuum when the throttle is released at high rpm, the difference in pressure below the rings and above them will still not exceed 14.7 psi.

IMHO, an Eye-talian Toon up is a lazy man’s way of avoiding hard work. If it works, GREAT! If it doesn’t, then you still have the same amount of work to do.

The only downside is if it causes additional problems. In general, it might be worth the risk.

Sorry for the newbie question here but, why are piston rings supposed to move? I mean when we say stuck it clearly doesn’t mean stuck to the wall of the cylinder or the engine wouldn’t run at all. So the ring is in the groove of the perimeter of the piston. What exactly does it get stuck to? I didn’t think it was supposed to move at all.