I'm getting a rebuilt engine for my 300D because I got a fantastic deal and because the old one has developed severe blow-by even though the compression numbers are OK (weak but OK). It also burns a lot of oil. I plan on a very conservative break-in period using B20 until the rings have seated but don't know when it's safe to start using WVO again. How will I know and what should I look for to determine that the break-in period has ended?

I don't attribute the blow-by to me using WVO for the last year but rather it was a worn engine when I bought the car. It has been burning oil from day one and I have been changing the oil at 2K intervals since the conversion because of the blow-by.

This message has been edited. Last edited by: hheynow,

If it were up to me I would talk to the rebuild mechanic and find out what, how, and how long it takes to properly break in that particular engine. I would also talk to a Mercedes dealer and independent specialized mechanic and ask the same. From all that gathered information, make a decision on the break in. I would then add a bit more time and mileage before introducing the WVO. My 2 cents.

quote:

Originally posted by hheynow:
I'm getting a rebuilt engine for my 300D because I got a fantastic deal and because the old one has developed severe blow-by even though the compression numbers are OK (weak but OK). It also burns a lot of oil. I plan on a very conservative break-in period using B20 until the rings have seated but don't know when it's safe to start using WVO again. How will I know and what should I look for to determine that the break-in period has ended?

I would suggest considering using B5 or even strait petrodiesel at least until the rings seat fully. The "engine manufactuers group" has determined that blowby that contains biodiesel can cause the same lube oil polymerization that VO does and have expressed concern that B20 might be too high a blend for optimum engine life due to this. At the very least keep an eye out for lube oil polymerization..and if you decide to use B20 change the oil a bit more often than reccomended for break in.

I really want the rings to properly seat so I have no problem using B5 for the break-in period. But my question is how will I know when the break-in period is completed so I can safely use WVO again?

I don't understand the need to wait till the engine is broken in before using WVO.
The fuel won't effect the break in as it is not what lubes the bores and the rings will seal perfectly well from the get go.

Normally brakin is a specified mileage so look at your owners manual and observe the break in procedure as far as varying speed and load, keeping the speed down and the other usual break in procedures.
I also change the oil the first time on a new or rebuilt engine after a very short time, like 500KM because if one looks at the amount of metal particles that will be in the oil after only those few miles, you know why it's worth doing.

I would be putting a Water injection system on the engine to keep it clean of any buildup from the veg or that even occurs from straight Diesel over time.

quote:

Originally posted by hheynow:
I really want the rings to properly seat so I have no problem using B5 for the break-in period. But my question is how will I know when the break-in period is completed so I can safely use WVO again?

Two measures of ring seating are lack of lube oil useage and maximum compression values.

If you care to take compression tests every 1000 miles you should see a leveling off as the rings fully seat. Similarly if you see lube oil consumption drop to zero the rings have probably seated fully.

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Originally posted by danalinscott:

quote:

Originally posted by hheynow:
I'm getting a rebuilt engine for my 300D because I got a fantastic deal and because the old one has developed severe blow-by even though the compression numbers are OK (weak but OK). It also burns a lot of oil. I plan on a very conservative break-in period using B20 until the rings have seated but don't know when it's safe to start using WVO again. How will I know and what should I look for to determine that the break-in period has ended?

I would suggest considering using B5 or even strait petrodiesel at least until the rings seat fully. The "engine manufactuers group" has determined that blowby that contains biodiesel can cause the same lube oil polymerization that VO does and have expressed concern that B20 might be too high a blend for optimum engine life due to this. At the very least keep an eye out for lube oil polymerization..and if you decide to use B20 change the oil a bit more often than reccomended for break in.

What's the issue with biodiesel ?? Does it polymerize?

quote:

Originally posted by DCS:


Normally brakin is a specified mileage so look at your owners manual and observe the break in procedure as far as varying speed and load, keeping the speed down and the other usual break in procedures.

Never though of looking there because my owner's manual is in German. But with the help of an internet translator the code is deciphered. Yes mine is a Euro thus the German manual.

"The more cautiously you treat your engine during the break-in period, the more satisfied you will be with its performance later on. Therefore, drive your vehicle during the first 1500km [1000 miles] at moderate vehicle and engine speeds. During this period, avoid heavy loads (full throttle driving) and high RPMs (no more than 2/3 of maximum permissible speed in each gear) and do not force the engine to labor at low engine speed. Shift down in good time! On vehicles with automatic transmissions avoid accelerating by kick-down. It is not recommended to brake the vehicle by means of manually shifting to a lower gear. We recommend to select positions "S" or "L" only at moderate speeds (for hill driving). After 1500km [1000 miles], speeds may gradually be increased to the permissible maximum."

quote:

Originally posted by danalinscott:

Two measures of ring seating are lack of lube oil useage and maximum compression values.

If you care to take compression tests every 1000 miles you should see a leveling off as the rings fully seat. Similarly if you see lube oil consumption drop to zero the rings have probably seated fully.

Correct answers are still free.
I have the compression tester kit.

This message has been edited. Last edited by: hheynow,

If your lube oil consumption drops to zero, it's probably because your engine isn't running any more.

Again, have a look and translate your owners manual at the part oil consumption is specified. These are fairly thirsty engines oil wise and have a good rate of oil consumption when in good operating condition. If you wait for the oil consumption to stop all together, you could be waiting till the engine needs another rebuild.

On the page before the break in procedure in my Merc owners manual, ( pg 48) the stated Max oil consumption is 250Ml per 100 KM. That is a lot of oil but the manual also says that much depends on driving style and the RPM used as Higher revs will also use more oil.

There are very few engines that use no oil ( especially diesels designed 30 years ago) as most rely on an amount of oil being consumed as part of reaching certain components in order to properly lubricate them. If you look at most engine service manuals or parts catalogs, the bottom set of rings are called " Oil control rings" . Their job is not to wipe all the oil off the bores but in fact to leave the right amount there. Obviously some is going to be burnt if it is left on the cylinder walls and if no oil was there in the first place, the pistons would sieze.

The same is applicable for other parts of the engine as well such as valves and the most obvious one is the Crankcase ventilation system which is very evident on the Merc's as it sits on the top of the engine and feeds oil mist back to the engine intake. Even new engines have some mist coming out of there ( as you will soon see) and obviously some oil is being lost and burnt in the engine from this process.

If an engine appears to be using no oil it's most likely because the oil that is being used is being replaced with condensation or fuel. This would make an engine that appears to use no oil a far less attractive proposition than one that uses the amount it is designed to.

I would recommend you verify any advise given as some of it is plainly just wrong and put forward by people whom have no clue what they are talking about.
Best to do your own research and find out for yourself which is right and which is rubbish.

"Engine oil consumption can only be determined after a certain mileage has been covered. During the break-in period, higher oil consumption may be noticed and is normal. Frequent high engine speed operation will also cause increased oil consumption"

That's it. No mention of ml/km oil consumption figures like you stated in my manual. My Benz mechanic told me that >1qt/1000 miles (.95 liter/1600 km)is excessive but under a quart is acceptable.

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My Benz mechanic told me that >1qt/1000 miles (.95 liter/1600 km)is excessive but under a quart is acceptable.

I guess that I would interpret that to mean that at 1qt./1000 miles it is time to rebuild.

I would watch for lube oil polymerization (especially in cold climates) with the level of blowby that probably exists with rings that worn.

quote:

I have the compression tester kit.

You are all set then. When compression values level go flat your rings are seated.

No doubt a different manual Version for a different market and your car is also some years later than mine.

The important thing is that they do indicate there IS going to be some oil consumption under normal operation when the engine is broken in and you would be misguided waiting for there to be NO oil consumption.

As I said, I think what is in my manual is a lot of oil but even what your mechanic indicates as ok is a significant amount of oil that can expected to be used between oil change intervals and it would need to be kept an eye on certainly until a normal consumption pattern can be established.

I would expect an engine of this type to take anywhere from 10 to 20,000km to be fully broken in and you may be able to feel when it has properly loosened up by the difference in power and response leveling out. I wouldn't think there was any need to avoid WVO during this time though, quite the opposite in fact.

I remember the difference in engine performance on my Harley was huge between the time it was tight and when it finally loosened right up 18,000 Km later. As you get up around the 3000 km mark, don't be afraid to give the engine a rev and the occasional squirt of full throttle. I like to hold the gears at moderate throttle settings and let the engine climb gradually up to full revs. There is a difference in Full power and full revs which can easily be achieved at moderate throttle. It is important to give the engine a wide range of speeds after the initial break in as the internal forces and tolerances change at different speeds so you effectively have to break it in for all RPM and loads.

The best people to talk to about the break in would be the people who rebuilt the engines as different builders have different ways of setting the engines up depending on how particular they are and how much pride they take in their work. I wouldn't go mentioning anything about Bio or veg though because you just know if there are any issues it will be because of the fuel and they will try to reneg on their warranty liability.

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how will I know when the break-in period is completed

During break in oil consumption will be noticeable; when it decreases to a constant low amount then break-in is complete. For aircraft engines it's recommended to use non-detergent single viscosity oil for break in and to change it at half the normal interval or more frequently.

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Originally posted by john galt:
For aircraft engines it's recommended to use non-detergent single viscosity oil for break in and to change it at half the normal interval or more frequently.

Yup, an aircraft engine in my 300D. John, I'm amazed at your clairvoyance.

John's obvious point was that oil should be changed more frequently during breakin, not that a Mercedes has an aircraft engine (despite the original source of the Mercedes emblem).

Regarding the use of non-detergent oil - that recommendation is unique to older aircooled aircraft engines. For aircraft engines with filtration systems similar to those found in a car (which category includes Mercedes, if you aren't clairvoyant), the use of detergent oil during breakin is recommended. The purpose of "detergent" is to prevent the wear products (little pieces of metal worn off of rings, cylinder walls, bearings, etc) from settling to the bottom of the oil pan as sludge. It's better that they circulate to reach the filter where they are trapped and removed.

New car engines used to come from the factory filled with a special break-in oil, to be changed very soon. There was endless speculation about the nature of the break-in oil. 1500 miles was a common first-change interval for the British cars I was trained to work on in the 1970's, but I've heard of change intervals as short as 500 miles. Please don't mistunderstand me - your Mercedes is NOT a 1970's British vehicle, to the best of my knowledge. As has been mentioned several times, find out what was recommended for YOUR vehicle when new.

I also recommend verifying that the parts used for your engine rebuild were Mercedes parts. If after-market parts were used (such as cast-iron rings, after-market pistons, or a non-factory cylinder hone pattern), then the factory recommended break-in method may not apply. Generally speaking, non-OEM parts tend to break-in faster/sooner than factory parts, especially cast iron rings. That will show up in both oil consumption, and compression tests.

SVO and biodiesel will both polymerize when added to motor oil. If there's a lot of SVO or Biodiesel in the motor oil, it will become unusually thick, decreasing it's ability to lubricate properly.

Cheers,
JohnO

quote:

If there's a lot of SVO or Biodiesel in the motor oil, it will become unusually thick, decreasing it's ability to lubricate properly.

Even worse...if enough polymerization occurs the lube oil can completely set overnight as it cools to the ambeinet temp (especially if the ambient temp is very low). This can cause oil starvation upon startup resulting in "catastrophic" engine failure as all the surfaces which require lubrication fail to receive it.

I have seen the aftermath of two such events. One engine was in a large diesel truck which had been using a primitive conversion for around 20,000 miles and the other was a large genset that had been run on homemade (possibly poorly made) "B-100".

I have also been contacted by at least half a dozen individuals that had noticed zero oil pressure upon start up and shut the engine down quickly. They all discovered to their dismay that the oil in their sumps had completely gelled.

I'd wait 20,000 miles,then switch to sync motor oil,then run wvo.With 2 tanks,and heat at the injectors,of at least 185 degrees.You will have to insulate injector lines.I use 3 wraps of aluminum foil,then aluminum tape.Keeps lines from getting sticky.

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Originally posted by Nathan:
I'd wait 20,000 miles

Nathan you're killing me.

I was thinking 15W40 dino for 500 miles then 15W40 dino again for 500 miles with a compression check at zero hours, 500 miles then at 1,000 miles. If all looks good then it's synthetic 5W40. Then maybe another compression check at 1,500 miles. Then I'll think about WVO if the break-in oil consumption has leveled off, but my first tank will be blended.

With two ILHs I'm well insulated with extra rolls of silicone tape.

Other than lawnmower and 2-stroke engines, I would not expect any engine to break-in in less than 10,000 miles. I would certainly not expect compression to level off after only 1500 miles. That's only 30 hours of 50mph operation. Maybe Mercedes are different, but I doubt it. I'm no expert, but I know of one 300-series Mercedes rebuilt engine that took well over 20,000 miles/one year, before oil consumption and smoke reduced to "normal" levels. It used all Mercedes factory parts. Hard/tough rings wear-in very slowly, but then they also wear-out very slowly too. A quart every 1000 miles for the first few thousand miles isn't unusual, in my experience.

It would still be nice to hear what the factory recommended break-in procedure is, beyond hheynow's generic quotation from his owner's manual.
Cheers,
JohnO