Rough idle

parkbro · Post by **parkbro** » 06 Jul 2011, 17:37

I have a 1996 Volvo 850 (non-turbo) 172000 miles, all maintenance schedules maintained. Recent Oil/Filter, all fluids topped.
While driving 65-70 MPH on the Interstate, in the mountains, the Check Engine Light came on. Pulled over and noticed a rough idle, all systems fine (oil level, coolant, etc) Took to local Volvo Dealership and left for evaluation. According to the Technician I had a burnt valve. (Supposedly a Wet and Dry Compression test was performed)
I had it towed home and had a Volvo Guy check it out. It also had a ticking noise (lifter) along with the rough idle. My Guy wanted to think it was a stuck lifter.(After having Oil analysis, it shows high concentration of fiber....possible Oil Filter Failure?) He ran a Quart of Marvel Mystery Oil in it and the lifter quieted down and apparently the rough idle went away . He drained the Marvel Oil and replaced with Standard Oil only for the tick and rough idle to return. I have received further advice that the lifter isn't completely cleaned and was advised to add another treatment of Marvel Mystery Oil and Drive for several miles to throughly clean the lifter(s). If I add the Marvel Mystery Oil and the rough idle/lifter noise goes away, I'm thinking I will invest in having the lifter(s) replaced. But my question, is it possible for a sticking lifter to cause a rough idle? Could Volvo dealership Compression test mis-diagnosed a lifter issue as a burnt valve.

Post by **Ozark Lee** » 06 Jul 2011, 18:07

I have no experience with Marvel Mystery Oil but if that temporarily solved the problem then that tends to rule out a burned valve in my mind and it would point to a lifter problem.

Do you have any compression numbers from the shop?

Stuff like Marvel Mystery Oil or Seafoam in the crankcase is a heck of a lot cheaper than replacing the head so, while it may not fix the problem, it is certainly cheap enough to try in comparison to the alternative.

I occasionally (very occasionally) get really surprised by the "miracle in a can" products. Some ATF stop leak fixed a real nasty leak in my power steering rack.

...Lee

parkbro · Post by **parkbro** » 06 Jul 2011, 18:13

I do not have any compression numbers. I too am not fond of additives. I am familiar enough with Marvel Mystery Oil and have used it occasionally during my lifetime. But being faced with the possibility to remove the Head from my Volvo or possibly unsticking a valve I chose to try the MM Oil...which has to be akin to ATF.....it look and fills of the same viscosity. Thank you for your response.

Post by **bigdaddylee82** » 06 Jul 2011, 20:15

With MMO, you can use it in your oil continuously, you don't have to drain it and replace it after a certain time/mileage interval like you do with a lot of other additives. It smells good, like peppermint schnapps, but I wouldn't recommend tasting it.

MMO wrote:Marvel should be added to your engine oil at every oil change. In a traditional automobile engine with a 5 quart oil capacity, simply replace one of the engine oil quarts with a quart of Marvel. For your convenience, MM13R is the quart size of Marvel Mystery Oil® and can be found at most automotive parts and supply retailers and mass merchants. Marvel is also safe and effective to use with synthetic and synthetic-blend motor oils.

When added to engine oil, Marvel reduces and prevents valve sticking and clatter by breaking down harmful deposits of carbon and sludge. Oftentimes, valve sticking can be identified by a "ticking" sound coming from the engine compartment when the engine is running. This ticking sound will increase and decrease with the speed of the engine.
Marvel fortifies the properties of motor oil, both traditional and synthetic. Marvel prevents oil breakdown caused by extreme temperatures. In addition, Marvel promotes easier cold weather starting with its extremely low pour point of (-65) Fahrenheit and ability to eliminate oil's tendency to congeal at low temperatures.

Sludge build-up in newer and older engines can result in lower performance and life expectancy. Marvel will prevent sludge build-up from occurring in new engines and removes sludge from older engines. In newer engines, Marvel protects against scoring or seizing and creates a highly polished, wear resistant finish on engine surfaces. Your new engine will remain clean and your older engine will thank you for cleaning the insides.

I've did an AMSOIL Engine Flush treatment on an engine of relatively unknown history, and have substituted 1 Qt. of MMO in both of the last 2 oil changes (full synthetic) I've done since getting it running. Running like a top. If it's quieting everything down, and there are no other serious issues, maybe just leave it in there?

- Lee

parkbro · Post by **parkbro** » 09 Jul 2011, 12:58

BTW....as I have been advised to drive the vehicle for several miles in hopes of freeing the stuck lifter.......what kind of damage could I been doing to the catalyst converter......with a valve stuck open/or burnt valve?