smoke

Paul (MN)

Hi,

My 200T burns about 1 litre of oil every 1250miles approx. Which is OK I guess. When I first got it it was quite smokey but I think my daily driving cleaned it up a bit as I never notice much smoke and I haven't noticed much smoke from it for a while.

Today, I was commuting to work and was late and pretty much managed to do 60-70mph for 30 mins solid. As I eased off the power to leave the motorway a huge plum of smoke came up from behind, and continued for a while as I put more power on. Also, when stopped at lights the smoke would appear as I revved. After a few mins it disappeared. I'm sure there is always a little bit of smoke from it, but I can never notice it out the back window.

My question is... what causes it to smoke as I ease off the power? Is there some builded up oil leakage that gets burned off at that point? Why then?

It's a white/blue smoke. I did notice that for the last 2 weeks it didn't use up any oil at all, which I was surprised at. Could it be storing it somewhere ready to burn!!??

Ta.

kyote00

you could try to take out the plugs and see what you find. They should be a light brownish colour. If not then it could be a mixture problem (too rich but thats normally black sooty smoke....)

Not sure if the car has a open or closed crankcase ventilation but its also working checking that. In open systems, they can get blocked over the years.

Of course, it could also be a sign of piston rings about to go.....do a compression test on the engine to check this. If one cylinder is down on compression, squirt in a little oil to the cylinder and quickly retest, the normal pressure should return for a few seconds....

lomb

Paul (MN) wrote:

Hi,


My question is... what causes it to smoke as I ease off the power?
Ta.

negative pressure when u release the throttle sucks any oil in the crankcase past the (well worn) piston rings into the combustion chamber and out thru the valves.

so basically ur piston rings are worn. negative pressure in the combustion chamber is normal on throttle release its only the worn rings that allow the oil underneath to pass them.

oh the longish journey at a constant rpm would have caused oil to leak into the crankcase and build up and when u released it it was sucked into the chamber and all over the valves etc so toot a minute to burn off.

Paul (MN)

ok, so worn piston rings means.......
I'm looking for a damage assessment here! (damage to my wallet!)

lomb

Paul (MN) wrote:

ok, so worn piston rings means.......
I'm looking for a damage assessment here! (damage to my wallet!)

the damage would be HUGH.how much is the car worth? to rebuild the motor, the rings, valves, and cylinder liners would have to be changed, merc parts are mega bucks. labour would be 1000+euro, parts 1.5-2 grand?
maybe best leave it and drive it till it dies. do u have to pass an nct? has it passed recently the emissions end of it?

Paul (MN)

The car is in great nick considering it's 21 years old! A few small spots of rust, nothing major. Very clean inside.

I bought 8 months ago with a full NCT. It passed the emissions easily.

I guess all I can ask you is if you had a car that was generally great, no NCT problems and it was using 1litre every 1250 miles (there is also a small oil leak from the rocker cover) how long would you expect it to last?

It's got an easy life. I do do about 12k/year in it, but it's most cruising at 60 on the motorway.

Would changing to a thicker oil help prevent further wear?

lomb

Paul (MN) wrote:

The car is in great nick considering it's 21 years old! A few small spots of rust, nothing major. Very clean inside.

I bought 8 months ago with a full NCT. It passed the emissions easily.

I guess all I can ask you is if you had a car that was generally great, no NCT problems and it was using 1litre every 1250 miles (there is also a small oil leak from the rocker cover) how long would you expect it to last?

It's got an easy life. I do do about 12k/year in it, but it's most cruising at 60 on the motorway.

Would changing to a thicker oil help prevent further wear?

it probably does need a rebuild if its never been done. a thicker oil will help to reduce the losses certainly but doubt it would reduce wear, it would probably increase wear as it would be a mineral oil. funny though i dont think thin synt oil is recommended on high mile engines, so u can shift to a quality thicker mineral oil like mobil super.

as regards the nct, i think emmisions is lenient on older cars do u have the print out they gave u, what is the hydrocarbon emmisions?

if the smoke has got worse, one of the rings/cylinder liner may be damaged now, or one of the valves may be damaged also. u could do a cylinder compresion check on it if one of the cylinders is now damaged a compression test will show it clearly. u can buy the tester tool for 50 euro , insert in the cylinder after removing a spark plug and crank it to see what the reading is. then compare it to the other cylinders.


also the 'smoke' may not be oil at all but water if the head gasket has gone kaput.

rooferPete

Hi Paul,

Is the engine in your 200T the same or similar to a 124 series 200 ?

I have a 1986 200E gas converted parked up, it was running ok before being lent out and is sitting in a shed dying slowly.

I had the 123 series 300D auto (with all bells and whistles) when they popular in my opinion one of the best mercs built.

A replacement for a 123 series engine should be easy enough to source and probably cheaper than a re-build.

Regards,

Peter.

lomb

Paul (MN) wrote:

Would changing to a thicker oil help prevent further wear?

f its using a litre every 1000 miles i wouldnt be woried about further wear but when u would get the motor rebuilt. its sad but true

Paul (MN)

Thanks.

I haven't noticed it getting any worse lately. I'm just going to keep driving it. It's not worth spending that kind of money on. It's not even a real classic.

If the engine does go I suspect a "new" engine would be the easiest route alright. Although I doubt it will be me that does it. I would more likely change to a different car.

I've never done a compression test. Might give it a go.

I had the full NCT report posted up on MotorNet when it was alive. I'll try to remember to search for it tonight.

Head gasket.... I check the water/coolant every week and haven't noticed anything. I'm supposed to be looking there right!??

I also check the oil every week or two. Never noticed nothin.

528i

Can i make a suggestion ?

Paul (MN)

rooferPete,

Mines a 4cyl carb. I suspect yours has fuel injection.

Paul (MN)

I suspect it's got a couple of years left in it. I did the same run this morning and there was no signs of smoke at all.

lomb

Paul (MN) wrote:

I suspect it's got a couple of years left in it. I did the same run this morning and there was no signs of smoke at all.

thats why i would drive it till it dies. not worth spending the money, no classic is really worth spending cas on, they are all money pits i tells ya they are though.

think is u can buy a good 500sec coupe 1982 in the uk with a sheaf of mots, and history for 3000 euros, so dont worry about it, enjoy the car for as long as it goes for, it doesnt owe u anything.

Dades

Does it overheat at all when it smokes?

Paul (MN)

no overheating.

The only time I have ever had smoke out the back (apart from when I eat too much chinese) is

- after pushing the engine hard for a while (i.e. do a mile or so at 75mph ish to overtake a long line of slowish cars. again as I ease off up went the smoke
- as described above
- when I first got the car, if I was stuck in a traffic jam it woudl sometimes smoke as I drove, after being stationary for a couple of mins.

It's probably not as bad as I describe here.

Dades

I had blue/white smoke a with head gasket issue, but it was always accompanied by overheating. Had to sell in the end.

But I agree that your issue don't sound that terminal.

MercMad

I think you'll find those are the classic symptoms of valve stem oil seals. This isn't a huge job and can be done without removing the cylinder head. You can buy a set of sealsfor about €25 and fitting would take about 3-4 hours roughly.

It'll soldier on forever in this condition without doing any harm at all ............except to your pride !

rooferPete

Hi Paul,

The 124 came as a 200 and 200E, the 200E was fuel injected mine 200 is a carbuwhatsit

That is why it was converted to gas, the 200's ran well except for the carbs when they gave trouble it was big money and even the experts couldn't guarantee them.

Feel free to take a look and see if it suits you.

lomb

MercMad wrote:

I think you'll find those are the classic symptoms of valve stem oil seals. This isn't a huge job and can be done without removing the cylinder head. You can buy a set of sealsfor about €25 and fitting would take about 3-4 hours roughly.

It'll soldier on forever in this condition without doing any harm at all ............except to your pride !

nah the releasing of the throttle and a HUGH puff of smoke is classic piston bore wear. a constant blue haze is valve stem wear, and i am almost sure this involves valve replacement as the valve seats are much harder than the valves and the valves would wear first.
but u are correct no harm(except environmental) in continuing to drive the car, as long as it keeps passing the nct, and the cars oil level is topped up.

Paul (MN)

rooferPete,

Thanks but not in the market at the moment!

The carb had work done on it (or replaced, dunno) within the last 5-6 years so I guess it's OK.

It's running fine. I'm getting a steady 28mpg from it on the commute and am hitting 32/33 on longer journeys.

Paul (MN)

"500sec coupe 1982 in the uk with a sheaf of mots, and history for 3000 euros,"

and how do you think I would explain me buying a Merc 500 to my wife!!!!!

rooferPete

Hi Paul,

That is a bargain, I wonder what our revenue friends would say about VRT ?

I think they have to be thirty years old to be exempt as classic but I'm not sure, a car like that well looked after has a lot of life left in it.

green-blood

STATISTICAL CODE: 40389917
MAKE: MERCEDES-BENZ
MODEL: 500SEC
VERSION: COUPE 2DR A / SPORTS COUPE (NON-CONVERTIBLE) / AUTOMATIC / PETROL ONLY /
MILEAGE: 150000 MILES

---

The information requested in respect of the vehicle shown is indicated below.
DATE OF FIRST REGISTRATION(MM/YY): AUGUST 1982
OPEN MARKET SELLING PRICE:
(applicable on enquiry date) €3963
RATE OF TAX: 30.0%
VEHICLE REGISTRATION TAX:
(payable on enquiry date) €1188

huh!!!!!!!!1

rooferPete

Gulp !!!!!!!!

She has gone from €3,000.00 to €4,200.00 plus collection €800.00 ? insurance and road tax ?

Hmmmmmmmmmmm

As Dr. Phil would say "That Dog Just Won't Hunt Here"

As tempting as that piece of luxury is "She Who Must Be Obeyed" would probably ask me to check out if the car has sleeping arrangements.........For Me

MercMad

nah the releasing of the throttle and a HUGH puff of smoke is classic piston bore wear. a constant blue haze is valve stem wear, and i am almost sure this involves valve replacement as the valve seats are much harder than the valves and the valves would wear first.

........a cylinder leak down test is the only way to find out for sure !

If it was my car I'd do the valve stem seals, it's bound to improve things either way as they've most likely never been done before !