Anyone ever use Bon Ami to seat rings? - PeachParts Mercedes-Benz Forum

otto huber · #1 05-26-2009, 11:16 PM

A friend of mine said that he has used Bon Ami to seat the rings on his old Detroit diesel engine. I did a google search and found that this technique was also used on old Chevy's.
I have a rebuilt engine with 30,000 miles on it. I acquired it with 16,000. I have paper work to verify the mileage and installation of the MB factory rebuilt engine into the car which was later totaled. It has consistently burned a quart of oil every 1500 miles for the past year. My only guess is that the original owner didn't break the engine in properly. The engine has enough blow-by to rattle the oil cap pretty good.
I've been happy with the performance of the engine other than the oil consumption, and will probably just keep adding oil once a month, but I'm curious to see what responses I get from the members on this.

RUN-EM · #2 05-27-2009, 05:08 AM

This was the GM approved break-in by the dealers back in 1955 for the new v8. They had nigh nickel content in the first engine blocks (super hard) and a chrome vanadium piston ring and too fine a cross hatch hone pattern that was not productive in achieving a proper ring seal. The cure was to run the engines at a fast idle---1500 to 1800 or so and let the engine inhale (with the oil bath air cleaner off) the powder off of a tablespoonfull or so of the powder thru the two barrel carb into the engine. Took about 30 minutes or so. Then run the car hard on a test drive, warm the oil good and change it. Return to customer. Seems Chevy did not want their new high reving v-8 to get a bad rep from the start and had thrown a goodly amount of heavy duty parts into the engines from the get-go.....forged cranks, rods, chrome-vanadium rings, oil filters, good high tensile valve springs, etc. on their Ford beater. At 265 cu.in. and 165 horsepower rating, it was a world beater....and the rest is history. And imagine, a car factory going to all that trouble to achieve customer satisfaction on new car introduction. My how times have changed. Now they throw them together before introduction, and only fix anything that they can't get away with.

Regards,

Run-Em

#3 05-27-2009, 05:16 AM

If the engine is burning that much oil, which is within MB's normal limits BTW, then the damage is already done.

leathermang · #4 05-27-2009, 09:17 AM

Quote:

Originally Posted by ForcedInduction

.... which is within MB's normal limits BTW,

Thank You. This needs to be said more often.

awsrock · #5 05-27-2009, 09:21 AM

"And they used Bon Ami!!"

...anybody?? (Hint: Don Knotts)

Diesel911 · #6 05-27-2009, 05:44 PM

Due to the Blow-By I would be curious enough the check the compression (if it were mine).

Any possibility that if the Engine sat somewhere for a long time that you have some sticking rings?

Round up your heavist Friends and fill the seats in your Car and maybe 100 pounds of something in the trunk with a full Fuel Tank and take the Car for a hard drive where there are some hills. Increasing the load on the Engine will increase the pressure/heat inside of the Cylinders and more pressure on the Piston Rings against the Cylinder Walls. Hopefully to seat and unstick them. Sort of like the "Italian Tune-up" but instead of speed you are using weight to increase the load on the Engine.

leathermang · #7 05-27-2009, 06:24 PM

I really don't think that ' more of the same' has much chance of helping stuck rings...

However, if you have the time pulling the precombustion chambers and putting one ounce of some thin oil like Marvel Mystery Oil on top of the piston... several days in a row...Then changing the crankcase oil and turning the engine over several turns by hand... then putting it back together and taking it for a spin might make a difference...

If it is simply worn due to age this will not help it... but would be cheap to try and would not hurt it either...

leathermang · #8 05-27-2009, 06:28 PM

Quote:

Originally Posted by RUN-EM

And imagine, a car factory going to all that trouble to achieve customer satisfaction on new car introduction.

I have a completely different take on this...
This means the R and D department did not do their job.
This flaw in the ability of the engine to seat the rings through regular use should have been corrected before it got out the door.

screwnail · #9 05-27-2009, 08:01 PM

Your problem might be that you are keeping the oil level too high. You should keep it below the top line and above the bottom line. If it is at or above the top line the engine will burn it according to MB.

JonL · #10 05-27-2009, 11:05 PM

I vote for stuck rings. Very common on diesels that sit for long periods.

otto huber · #11 05-28-2009, 12:20 AM

This engine did sit for about 7 or 8 months before I installed it. I never have the oil above full. I let it burn from full to 1/4 full and then add around 3/4 of a quart.
I once tried dropping marvel mystery oil into the cylinders through the glow plug holes and let it sit overnight, turned the engine over a couple of times to prevent hydro-lock, ran it out on the highway and it didn't seat the rings, but the engine felt good with oil in there.

JonL · #12 05-28-2009, 12:32 AM

I don't think ring "seating" is the issue. They're either stuck or they're worn out. I think they're stuck. You can try solvents, I'd go for something more aggressive than MMO. I've never been successful with solvents. You might need to use one of those "engine flush" oil additives and drive around for a while to free the rings. Use synthetic oil for a while, also might help.

jt20 · #13 05-28-2009, 12:37 AM

I am no expert, but this does not belong in your engine.

MMO is 30 weight oil and mineral spirits.

jt20 · #14 05-28-2009, 12:41 AM

JonL, any recommendations for flush additives?

jt20 · #15 05-28-2009, 01:38 AM

after reading a little, it appears this has been documented to work on CARBURETOR engines.

That means: it is mixing and diluting in GAS fuel before being injected into the cylinder. Do not pour powder in your cylinders!