Stupid question: Sticky Piston Rings

[whiz05403]

Can any of you fellow Pelicans explain to me what exactly is happenening when people say that they have sticky rings.

Products like Rislone or MM say they free up stuck or sticky rings.

Not sure I understand what a stuck or sticky piston ring really is.

Thanks in advance.

Mike

[James Brown]

crud, carbon, gunky overheated oil, get collected in the piston lands and trap the piston rings mostly in the compressed state allowing gas to leak past the rings reducing performance and compression. Some additives or "motor in a can" use strong solvents to try to melt that crud out from the inside. Guess what that stuff is doing to the seals and small leaks that have plugged themselves up over the years. Of course the best thing is disassembling and cleaning, using good oil, checking wear specs, etc. Most miracle fixes don't.

[HawgRyder]

Old trick to decarbon an engine....dribble some water into the intake when the engine is nice and hot...keep it reved up a bit...and as you pour in the water...don't let it stall.
It will spit out all sorts of junk...maybe even plug up the exhaust a bit...so be advised.
Don't stand in front of the exhaust outlet when you do this!!!
Pieces of cabon are very hard...and can hurt you!!
Up to you...difficult to do in a flat 6...but it might be a cheap fix.
Bob

[911pcars]

Is that a theoretical question or are you asking for your engine? Why do you think it could be stuck rings? Low compression? If so, wet test? Just one cylinder? Leakage test?

Whatever, do all the prelim. tests first, followed by all the suggested remedies. When you decide it's purely mechanical wear, breakage or stoppage, look at the various rebuilding options.

Sherwood

[Peter Zimmermann]

We discovered, at my shop, many many years ago that "stuck rings" were almost always caused by the long term use of Castrol or Pennzoil motor oils. A secondary cause was leaving the oil go for extended periods between changes, such as 7,500+ miles instead of 3,000 miles. We knew that the detergent action of those two oils was very poor, and using them really required change intervals of only 1500 miles. Our solution was to learn how many miles the above oils were used in a particular car; if it was more than 50K miles we suggested a shorter change interval, but not a change to different oil. If it was less than 30K miles, we suggested a change to either Kendall or Valvoline, with a follow-up oil change in about 1,000 miles. We also cleaned the oil sump screen on those cars. The cars between 30K and 50K miles we judged on a case by case basis.

I remember one customer in particular, who wanted to drive to Las Vegas from L.A. We knew he had a high-mileage Castrol engine, and he was eager to do an experiment. We changed his oil, to Kendall, and filter, put ten extra quarts in his trunk, and sent him off with an instruction that he must stop in Palm Springs (it might have been Barstow - this was twenty-five years ago!) and check his oil (he was well-schooled so we trusted him to do that right). He called later in the day, and told me he had to add three quarts. I told him that he had to stop in Baker, and check the oil again.

Later, he called from Baker, and told me he had to add two more quarts. By this time I knew that the Kendall had cleaned away a large amount of built-up crud on the rings, but the jury was still out as to whether his rings would be able to expand and re-seat in the cylinders. I asked our customer to stop at State Line and check the oil again. You could almost hear the joy in his voice when he told me the car was only a half quart low.

The car used only a half quart more on the drive into Vegas, and back to State Line a couple of days later. The car used no oil on the return trip back into L.A. We changed the oil a couple days after that, it was positively black, and the sump screen was loaded with particles of carbon and crud. The rings got un-stuck, the car ran really well, and for all I know it's still running.

So, yes, rings can become inefficient, call them "stuck." In some cases they can be fixed without dis-assembly, but it takes great care, a bit of luck, and a set of good circumstances. The above story illustrates a point, but it's one that I've seen repeated about a half dozen times during my career.

I have been away from Red Line Service since 1999, so I can not state that Castrol and Pennzoil still turn out low detergent products. I can offer that my 2002 BMW 325 had been run exclusively on Castrol, sold by BMW of Bakersfield, since it was new. I bought the car with 50K miles on it, and changed the oil shortly after purchase. I bought the oil & filter from the dealer, and when they put Castrol GTX on the counter, I asked the clerk, "Are you kidding?" He assured me that Castrol is what BMW recommended, so I took it home.

In my garage, I removed the oil filler cap, and gazed down into the blackest mess that I'd ever seen. Keep in mind; Castrol since new, changed by the dealer every 5K miles. In 2005 Castrol had not improved. Is it better today? I don't know.

[manbridge 74]

Sticky rings are a conundrum indeed.

Think about it:

If rings/bore are worn some carbon buildup might be beneficial.

If buildup is so much it inhibits ring seal you've a different problem.