1997 Mercedes C250TD Mark 1 Oil Rings. Some good advice needed.

[Futureoils.com]

Hi,

I just got my 97 C250TD back after 2 weeks in the garage after having the turbo, exhaust manifold seals and main engine rocker gasket seal replaced in a number of attempts to stop the engine consuming oil at a rate of 1.5 litres every 300 miles. The exhaust smoke is clear at low revs but the mechanic has told me that there is excessive amounts of oil being ejected after he pulled off the breather at higher revs. The engine seems to run fine when it has reached normal operating temperature but occasionally the power seems strangled for the first few minutes when driving from a cold start and this is accompanied by a slightly blue puff of smoke from the exhaust. (When this happens I get a slight smell of smoking rubber coming into the car if the dashboard fan is switched on) He seems to think the oil ring seals are gone which is quite shocking for a car that has supposedly covered only 70,000 miles low city mileage. (HPI checked) I purchased the car 2 years ago with 52,000 on the clock and have been running it on rapeseed oil (with a coolant heat exchanger) ever since regularly changing the engine oil and filters every 6000 miles. My mechanic is now convinced the only way to stop this oil leak is to take out and strip down the engine. (which I am prepared to do if this is the only option) He has advised me to drop the car back to him next week so he can take out the engine for further investigation. He informed me that it looks like I will have to get a new head gasket set and might as well replace the valve stem seals as there is back pressure blowing the oil dip stick up out of the engine putting the new alternator at risk of one again being covered in oil.

Any advice on how I can finally resolve this 6 month ongoing problem would be greatly appreciated. From what he is telling me it's looking like a 1500 euro job to put right. I was half thinking of trying a litre of Ametech Engine Restore Oil in the next oil change. Has anyone else tried this or is it better to swallow the cost of the engine overhaul longterm?

Does anyone know the cheapest place to buy the full head gasket set and valve stem seals?

Many thanks,

Dylan

 

[BlackC55]

Get the HG kit from MB ONLY.

It looks like your engine is "breathing heavily" in which case the rings will need replacing. You may find this premeture wear is due to the engine being starved of oil at some point in its life or crappy oil being used for excessive miles.

have you tried using mineral oil for a few thousand miles?

 

[Futureoils.com]

Thanks Black C55, Up until recently I was using a German 10W-40 semi synthetic oil Liquid Moly MB approved. Then I bought a 25 litre drum of Duckhams 10W-40 synthetic oil when the engine started to burn oil (which I've only just found out is crap oil) I. It was recently recommended that I use Mobil 10W-40 Turbo Diesel Oil by a local MB mechanic. I have been using the Duckhams oil for the last 12,000 miles and have noticed the problem getting slightly worse since then but I think it's got to the stage now where there is no point in splashing out on the high quality engine oil until after the rings are replaced next week?

 

[grober]

I would be inclined to get an appropriate compression test done just confirm the nature and extent of the problem before taking things to bits. Assuming you want to keep the car long term I would also look at the economies of a complete recon engine (with warranty) versus a partial rebuild. e.g what if the bores are worn as well as the rings and the timing gear is also feeling its age a bit? Just something to consider.
Do the sums carefully.

 

[bolide]

Have you had a leakdown test and a compression test done on the engine?

Now the turbo seals are done, if it's burning oil I'd think there's some significant wear in the engine

A customer of mine works for a major oil company in their biofuels division. He told me that vegetable oils have much lower lubricity than diesel and, as a result, you get a lot more wear in the injection pump & other areas that are lubricated by the fuel

Nick Froome

 

[Number_Cruncher]

I suspect the crappy oil was not that poured into the oil filler, but, that poured into the fuel tank. I suspect the piston rings will have gummed up as a result of the use of comedy fuel, and the blowby is a result of this false economy.

 

[Futureoils.com]

The fresh rapeseed oil I'm currently using has been refined to the German internationally recognised: Quality Standard for Vehicle Grade Rapeseed Oil:


Quality Standard for Rapeseed Oil as a Fuel (RK-Qualitätsstandard) Properties /Contents Unit Limiting Value Testing Method min. max. Characteristic properties for Rapeseed 0il Density (15ºC) kg/m3 900 930 DIN EN ISO 3675
DIN EN ISO 12185 Flash Point
by P.-M. ºC 220 - DIN EN 22719 Calorific Value kJ/kg 35000 - DIN 51900-3 Kinematic Viscosity (40ºC) mm2/S - 38 DIN EN ISO 3104 Low Temperature Behaviour - - - Rotational Viscometer (testing conditions will be developed) Cetane Number - - - Testing method will be reviewed Carbon Residue Mass-% - 0.40 DIN EN ISO 10370 Iodine Number g/100 g 100 120 DIN 53241-1 Sulphur Content mg/kg - 20 ASTM D5453-93 Variable properties Contamination mg/kg - 25 DIN EN 12662 Acid Value mg KOH/g - 2.0 DIN EN ISO 660 Oxidation Stability (110ºC) h 5.0 - IS0 6886 Phosphorus Content mg/kg - 15 ASTM D3231-99 Ash Content Mass-% - 0.01 DIN EN ISO 6245 Water Content Mass-% - 0.075 pr EN ISO 12937[FONT=Times New Roman,Georgia,Times][FONT=Times New Roman,Georgia,Times]

[/FONT][/FONT]so I'm not so sure it's down to the fuel. I bought the car in the outskirts of West London off a woman who was only using it for commuting around the suburbs after work and at the weekends. Hence the low mileage. The mechanic told me the compression seems good and that the cold stop start style of city driving may have added a lot more frictional wear and hours to the engine as the miles clock only works when the car is moving. He also told me the veg oil works to loosen and strip down any carbon deposits in the engine which may explain why the oil rings are now on the leaky side. I chose this Merc engine specifically for running on veg oil as I was advised the old Merc Bosch in-line mechanical fuel pump engines are the most suited to running on veg oil and I have found this to be true having run a 2 litre 92 Merc 190D on veg oil for many years with minimum engine oil consumption. I would have considered turbo charging the 190D until I decided to buy the C250TD for £2900 2 years ago in London. It looked like a similar engine to me apart from the extra cylinder and turbo. The engine still goes quite well once it has warmed up but it's not like the old days when I first bought the car it went like a rocket compared to the 190D. [FONT=Times New Roman,Georgia,Times][FONT=Times New Roman,Georgia,Times]
[/FONT][/FONT]

 

[johnsco]

I'm sorry to say I agree with Number Cruncher.
If the oil dip-stick is blowing out of the engine, this is probably a result of blow-by.
This will likely be caused by the piston rings being worn or stuck in their grooves.
If that's the case, the cylinder bores may also be worn unevenly.
So - Replacing the piston rings without a rebore is probably a waste of time.
Whichever combination of these problems it is, you are looking at some heavy-weight money.
A recon engine is probably your safest bet, assuming you want to keep the car.
I would then seriously consider running it on the diesel fuel it was designed for, rather than the stuff that has probably caused the problem in the first place.

Sorry to be so down-beat, but it's very easy in these situations to carry on throwing money down a black hole.

Johnsco

 

[Number_Cruncher]

>>so I'm not so sure it's down to the fuel.

While your fuel has been made to *a* standard, this wasn't *the* standard for the fuel which was used when the engine was designed and developed, i.e., pump fuel compliant with the relevant standard as written in your owners manual.

You mentioned that it sounded like poor compressions higher up, and then that your mechanic thinks the compressions "seem" to be good. What were the actual compression pressures?

We've seen evidence that these engines gum up their piston rings when run on false economy fuels, and that your fuel injection pump is OK is the least of your problems.

>>veg oil works to loosen and strip down any carbon deposits in the engine

It can also gum them up - in a serious way, leading to excessive blow by, and loading of the oil, leading to complete oil failure.

Check your compression pressures properly, and go from there.

 

[spock500]

Have you done any mods to the car, ie twin tank, fphe ect..?

I would switch to premium diesel straight away and go for a long hard run which stands a good chance of freeing up the rings if they are stuck.

I can probably help with OEM parts as I have just rebuilt mine http://www.peachparts.com/shopforum/showthread.php?t=248826

 

[Futureoils.com]

Thanks David,

I'll certainly try a full tank of diesel in the mean time before getting the compression test done. It's a shame if the ring gumming problem can't be rectified. I never had this problem with the 190D unless the C250TD I bought was clocked but I did HPI check it before and the exhaust was very clean even reving up to 3000rpm in neutral.

According to Elsbett.com These engines are suited to a single tank SVO conversion. They come with 10mm fuel lines as standard and I've installed a new set of Bosch Duraterm Chromium glow plugs along with a stainless steel in line coolant heat exchanger which gets the veg oil up to around 80 degrees C once the engine warms up. The exact fuel mix I have been using is 45 litres SVO 3 litres of diesel and 2 litres of petrol to slightly reduce the viscosity of the fuel on the cold start. I just want to know why I never had this problem with the 190D? I think I might try to buy it back from the woman who bought it as it's still running well according to her.

Just one other question to the number cruncher. (I get the impression you have seen a lot of these engines)

Have you seen this kind of ring gumming on the 190D 2 litre engine and is it only a problem in C250 engines which have high mileage, worn rings (before the use of veg oil) or that were poorly maintained?

Thanks again to all who posted.

 

[spock500]

Diesels don't like idling for long periods or starting up cold for short journeys so even though low mileage it could be the rings were pretty solid before you purchased it -

Whats your location, can you get to see one of the indies on here for inspection?

 

[Futureoils.com]

Hi David,

I'm living in the deep south of Ireland. I am intrigued. What do you mean by an indie inspection and "if you drive a car fast enough it will last you a lifetime"?

 

[lynall]

Drive it to fast crash and die, hence a lifetime albeit a short one.

I am sure here was a long recent post with plenty of pics where someone had big engine troubles with a c250td, maybe be worth a search?



Lynall

 

[grober]

He seems to think the oil ring seals are gone which is quite shocking for a car that has supposedly covered only 70,000 miles low city mileage. (HPI checked) I purchased the car 2 years ago with 52,000 on the clock

Sorry mate but I think you may have bought a former taxi! Have you checked the engine number against the VIN by the way? Did the Duckhams 10W40 oil meet MB specs or did you fall foul of the "synthetic based" or "using synthetic technology" advertising speak of the jolly green giant that is BP? If the engine in the 190D was non turbo then there is world of thermal stress difference between the two engines. e.g. Most turbo engines have additional oil spray jets playing on the underside of the pistons to keep them cool. If one or more of these got blocked then the potential for overheated pistons/rings would markedly increase!

 

[Number_Cruncher]

>>there is world of thermal stress difference between the two engines.

Yes, and deposit forming processes are extremely sensitive to temperature and the chemistry of the oil and fuel, with different deposits forming at different parts of the engine which run at different temperatures.

The deposits which form on the insides of cam covers, timing covers, and the like are usually entirely harmless (although they frighten DIYers into more frequent oil change regimes than necessary), but, the deposits which form in other areas, like piston ring grooves are a) not the same deposits as found in the cooler parts of the engine (there's not necessarily a link between the two processes), and b) have much more potential for damage

 

[spock500]

Drive it to fast crash and die, hence a lifetime albeit a short one.

Spot on that man, one of the first things I was told after I passed my test


I am sure here was a long recent post with plenty of pics where someone had big engine troubles with a c250td, maybe be worth a search?

That would be me OM605/6 piston advice - PeachParts Mercedes ShopForum

It's on here as well but continued across onto the US forum

Lynall

Hi Dylan,

"indie" is short for independent garages who really know their onions -

Might be an idea to put in a request on the Mercedes specialist thread

Add a few bits into your profile/signature to speed things up, location/car ect..

 

[Futureoils.com]

Hi David,

Thanks for your all your advice. Would it have not been a lot easier for you to install a totally reconditioned engine (as recommended in a previous post by Johnsco) into your C250 or do I take it your the type of person who loves working on engines? Although I imagine the precision engineering involved in a high quality rebuild is hard to achieve in a DIY home garage. Do you think it would be better for me to fill up on premium diesel or high quality bio-diesel to free out the rings as there is a reputable supplier 20 mins drive from where I am living who produces bio-diesel for a fleet of local government vehicles which meets internationally recognised bio-diesel fuel quality standards?

 

[Futureoils.com]

Thanks John, I have three more of these cars at home as I used to sell a lot of them before the car market crashed. The best of these cars is in my garage at home and is the nicest C250TD I've ever bought. It's 1999 with a genuine 43,000 on the clock full MB service history (mobil oil changes) and fully HPI cleared. I was seriously thinking about driving this instead but it doesn't have a sunroof unlike my own car and knowing MB in Ireland they'll want the cost of a full engine rebuild to install one

 

[spock500]

Hi David,

Thanks for your all your advice. Would it have not been a lot easier for you to install a totally reconditioned engine (as recommended in a previous post by Johnsco) into your C250 or do I take it your the type of person who loves working on engines? Although I imagine the precision engineering involved in a high quality rebuild is hard to achieve in a DIY home garage. Do you think it would be better for me to fill up on premium diesel or high quality bio-diesel to free out the rings as there is a reputable supplier 20 mins drive from where I am living who produces bio-diesel for a fleet of local government vehicles which meets internationally recognised bio-diesel fuel quality standards?

n/p Dylan,

Well as with all things it wasn't as simple as that, the eventual diagnosis of stuck rings was the last thing on everyones list by which time it had a stack of reconditioned/new bit on there already.

Take a look at this thread, it's a OM606 but identical to yours with an extra pot - vegetableoildiesel.co.uk - Me rings are gummed!! Help. - Powered by XMB

I would go for premium (not standard) diesel over bio due to the additional additives in the diesel fuel.

After reading a fair bit on ring gumming issues this would be my first choice.

Btw, heres a 190D in trouble too vegetableoildiesel.co.uk - London veg expert needed! - Powered by XMB