Other Clues to low compression ,heres my story - Page 2 - PeachParts Mercedes-Benz Forum

pawoSD · #16 04-21-2007, 09:21 AM

The manual that comes with our vehicles specifies "L" and a speed of 15-20mph.

t walgamuth · #17 04-21-2007, 10:17 AM

that is probably safer.

tom w

Astroman · #18 04-21-2007, 04:28 PM

So has it started yet?

chasinthesun · #19 04-23-2007, 11:03 AM

to soak the rings ,I just slightly bumped the starter to get some oil around the rings .Guru had soaked his for 10 days then attempted a start with no luck .His next attempt was a success with a repeat soaking and several other listed new items before success,I believe those were a new starter ,injectors and a hot battery.Im going to clean my injectors ,my battery and starter are ok and hope for the best this coming Saturday.Ill report a compression reading and a hopefully a start.Guru had impressive higher numbers on his 2nd compression check ,the only thing I havent done to copy his path is he had his block heater plugged in all the time ,mine needs rewiring ,I hope to get that working tonite.

chasinthesun · #20 04-30-2007, 10:06 AM

Had no time to recheck my compression with the mmo soak down.Ill have something on wed to post ,had a full weekend of things to do ,this one was at the end of the list.I hope its a good result.

chasinthesun · #21 05-02-2007, 12:15 PM

orig wet numbers / mmo soak for 8 days
1) 170 / 1) 240
2) 60 / 2) 100
3) 220 / 3) 325
4) 90 / 4)0 120
5) 180 / 5) 280
Some cylinders have had big improvements ,others not so good ,ill continue soaking another week with some added heat from the block heater.If it is gummed up rings , hopefully the 2 low holes will come up.

Stevo · #22 05-02-2007, 02:54 PM

Good show, what are you soaking them in?

t walgamuth · #23 05-02-2007, 05:40 PM

mmo= marvel mystery oil.

i would expect the rings will get a lot better after you get it running and take it on a good long trip.

i would pull it if necessary to get it started then drive it good and hard on the highway providing your other systems like brakes and cooling are in good op condition.

tom w

barry123400 · #24 05-02-2007, 11:35 PM

One more week of soaking with the block heater on to aid chemical action should still improve it. If you got this far with less than 70 degree constant temperatures there is still real hope. For practical purposes chemical action almost ceases below 70 degrees. Or is extremely slow. It does appear the rings are starting to loosen up.
With a little luck it may self start then if the numbers keep coming up. Make sure to replenish the marvel oil especially on the lower compression cylinders. This approach of ring soaking on these engines is still too new yet to form any solid conclusions. It will take awhile and a few more engines done to understand what is really possible.
You have a couple of cylinders at about three hundred pounds. That at least indicates the engine was just not totally worn out. Also that the rings were not overheated to the point of being soft.
Once running replacing one quart of oil in the base with marvel mystery oil in my opinion is a good ideal. Purging the pump and injectors with marvel mystery oil may clean out any residue in the pre chambers as well. Hope it all works out well.

arew264 · #25 05-02-2007, 11:46 PM

Wow, this thread is really cool, can't wait for you to post back.

t walgamuth · #26 05-03-2007, 05:38 AM

although i have done it myself, my favorite machinist is against putting any mmo in the crankcase.

he does approve of lucas oil treatment though.

tom w

lonewolftek · #27 05-03-2007, 09:17 AM

Let us know if you get it fired up. I'm following this saga closely, hoping to bring back my other 300SD from two years of non-running limbo.

barry123400 · #28 05-04-2007, 01:56 AM

I did a little checking on marvel mystery oil. It appears we are not doing anything really new with it. Marvel claims it has been used as a soak for many many years to free up stuck rings and to unseize pistons. .
Our initial interest or mine at least was to see if rings carbonized in place with burnt vegatable oil or even carbonized diesel oil residue might respond to it. I believe they do to some meaningful extent.
The major concern in application of the oil was to make certain the block is at least 70 degrees to ensure reasonable chemical action. This is very important as below that temperature chemical reactions are virtually nil in comparison.
We will all be watching. All those cheap veg burners out there that have lost there compression and ability to run may no longer be feared and should remain cheap but recoverable aquisitions. In fact engines we consider to have slightly low general compression may have partially carbonized rings instead of worn bores and rings. Or if you find you have a cylinder with a bad injector streaming instead of misting with seemingly low compression. Perhaps a soak of that cylinder should be done before it is assumed to have a major issue. .
My guess is marvel mystery oil may not attack the aluminium oxide on piston grooves that have been sitting for long periods of time. That oxide is very hard and tenatious compared to the base aluminium piston material. Instead it is more likely it dissolves the iron oxide that builds up on rusting rings. They are prime candidates because the higher tempered metals like to oxidize easily in comparison to milder steels and alloys.
Towing and starting one of these engines allows the thermal expansion and contraction to break up the oxides a little and release the rings. There is a chance in my opinion that an engine sitting for years in a damp location will have so much aluminium oxide in the ring area there will be no simple way to get those rings moving. I cannot see the marvel oil directly attacking the aluminium oxide without attacking the base piston material. Perhaps someone with more metal properties knowledge could mention a lot I might be missing here.
Another area where my thoughs have been taking me is could this soak be benificial to certain engines we consider normal to clean out the rings? Especially the lands etc.
Originally I asked the typical amount of carbon deposit in the ring grooves on those 123 engines people have taken apart to rebuild. If a substantial deposit was noticed in the majority we may be able to help raise an average running engines compressions simply by soaking from time to time. I hope a few people will respond with their existing knowledge. There is a possibility here that should be examined in my opinion. Talk about skating on the edge of an oil thread.

t walgamuth · #29 05-04-2007, 05:54 AM

mmo has been around seemingly forever. but apparently it is a new product to some of us. it really does work, i don't know how, perhaps it is a secret combination of seven herbs and spices!

it is imho, helpful in engines as barry has described, which have been run on the wvo and on engines which simply have not had good oil changing or have simply stuck from sitting.

mercedes engines which are allowed to sit after having a non starting episode in which the fuel washes the oil film off the cylinder walls will stick in an alarmingly short time.

the tolerances on a decent engine are much tighter than many other cars and a bit of rust or oxidation will really tighten them up.

tom w

chasinthesun · #30 05-09-2007, 07:21 AM

The New #s on the 300cd have not netted any great news but still holding compression close to its original improvement.#1 200,#2 100,#3 320,#4 100,#5 280
no heat was added to the motor like I originlly was set to do,the repair on the block heater needed a cord end so it was left out of the test.My shop does get up to 90 degrees during the day time so I wasnt to worried about adding the heat.
Ive got an idea on this mmo soak down ,I might be adding the mmo to the cylinders but on the low holes ,it might be passing by the rings and not letting a soak happen .Since this car is not a priority for transportation Ive decided on one more 8 day soak down but with the block heater on at all time and a daily dose of a 1/2 cup of mmo per cylinder .Ill really give the mmo a chance to do its thing and hopefully get the most out of the product.
By the way ,if this works Ill use this same test on a 78 300cd with a no start issue and post a trial and error gain on its beginning to end progress ,probably on this same post.The real answer on the 84 will come when I pull start it at the end of May, at that time hopefully all this will have been worth it.