M103 still burning oil...Need advice - Page 2 - PeachParts Mercedes-Benz Forum

ps2cho · #16 01-08-2010, 10:45 PM

I was about to report back...I agree I think its not burning it, but it is leaking out somewhere. Problem is that there are NO drips on the ground at all! I smelt the exhaust and it doesn't smell like its burning anything either.

Visually I don't see anywhere. If the filter gasket was the location of problem, there would be drips on the ground (my 300TE had same issue recently). How can I find this elusive leak leaving no traces on the ground?

pberku · #17 01-09-2010, 12:37 AM

Quote:

Originally Posted by ps2cho

I was about to report back...I agree I think its not burning it, but it is leaking out somewhere. Problem is that there are NO drips on the ground at all! I smelt the exhaust and it doesn't smell like its burning anything either.

Visually I don't see anywhere. If the filter gasket was the location of problem, there would be drips on the ground (my 300TE had same issue recently). How can I find this elusive leak leaving no traces on the ground?

You can get some UV dye leak detector that is specifically made to detect oil leaks. Just add to the oil, drive the car for a few days, and than using a UV light, (a UV light bulb, or a UV flashlight) look around for the source of the leak. Its best to do in in the dark, as its much easier to see.

The source of the oil leak will become very evident.

You can buy UV dye (for Oil Leaks) at almost any auto part store. Should be less than $5.00.

Phil

long-gone · #18 01-09-2010, 12:49 AM

Hope it isn't showing up in your coolant. If it is, it will make it to the highest spot it can get to pretty quickly, which is your coolant tank. But you know that from your head gasket experience.

Do you still have the plastic pan or cover under your motor? If you do you've obviously dropped the cover and saw no oil drips there?

If you're pretty certain it is leaking externally, and not showing up as drips, that usually means it only leaks while being driven (under a load, that is) and possibly also that wherever the source is, it's finding it's way to a very low point and dripping into the airstream as you drive.
If you have one, it should still show up in that bottom cover though, unless it's the rear main seal (or the back of the valve cover) and it's finding its way down through the trans bell housing cover and out into the airstream that way.

A leak like that might indicate the source could require pressure as in crankcase or oil pressure that rises with RPM (and also really gets the oil splashing around), which might give you clues as to where to look. But there's only so many oil sealing places on a motor, so that just gives some first ideas where to look.
There's a few obscure locations I can think of on your M103, like the inboard bolt on the belt tensioner bracket, the bolt hole of which goes though the timing cover and is an oil bearing passage. This bolt hole must be sealed with an o-ring as well as sealant when being reassembled from an affected repair (like your head gasket job).
The oil stand gasket is in a fairly hard spot to see (and oil filters have certainly been found to be leaking).
The oil level sender mounted trough the side of the oil pan is the point of a rather common leak. It can leak not only from the o-ring that seals it, but more commonly though a failure at the aging plastic housing where the electrical lead is plugged. That by the way is a good example of a leak that not only might occur when the car is under a load, but also one that has the opportunity to find it's way quickly to the lowest point (bottom of the oil pan). I've had this particular leak and it tends to seep in a very thin, broad film across the pan as it makes it's way to the back pan corners. But if you have an under-engine cover it would drip there to be seen and not enter the air stream.

If the oil isn't finding it's way to a point low enough to get in the airstream then there would be a trail of dark/wet streams down the underside.
If it's burning off on hot exhaust or engine parts you'd almost certainly smell it when you get out of the car, maybe even see some smoke rising from under it.
If your burning it, you'd likely see smoke when you get on it, particulaly at night when the lights behind you illuminate the smoke. But not necessarily.
You can also lose what might be a significant amount of oil as excessive oil vapor through your crankcase breathing system. A symptom of blow-by. Look for oil puddling in your air cleaner (it also gathers in the bottom of your intake under the throttle but that's kinda hard to see).

The UV dye is a very good suggestion!

400Eric · #19 01-09-2010, 01:30 AM

I've noticed that if I keep my oil on the "full" mark, my oil consumption goes way up. I'm pretty sure this is because the M103, unlike the M104, doesn't have a windage tray and the oil gets thrown back up on the cylinder walls and overwhelms the oil control rings. This windage problem is less severe when you keep the oil level down a bit. I keep my oil at the middle of the marks and only add a half quart at a time when it gets to the "add" mark. My car's oil light is always on anyway, always crying "wolf" even when the oil is at the middle between "add" and "full"

BTW, I want to go on record and say that was pretty rotten of M.B. to scrimp on this, especially on a $36,000-$40,000 car (80s dollars mind you). Even a cheap 340 Dart in 1968 had a windage tray! It was also proven to be worth 15 horsepower on said engine at 5,000 RPM. How much more would it be worth on a longer 6 cylinder crankshaft at 6,000 RPM? Like it would really have killed them to put a cheap piece of sheet metal down there. We know it was beneficial because they did do it even on the later M104s which weren't as "revvy" as the early engines were.

Also, these engines were known to be oil burners even when new! I have a Consumers Reports article from 86 or 87 and high oil consumption was one of only two complaints they had about the car. The other was that it was way overpriced!

Sorry if these have already been touched upon but I don't have time to read all the posts in this thread right now. I will later though.
Regards, Eric

long-gone · #20 01-09-2010, 02:34 AM

400eric, if your oil light is on when your oil level is okay that's generally your oil level sender going bad. As mentioned this is a common replacement item on these models.
An oil leak through the plastic housing on the electrical terminal of the oil sender is common also, as well as being somewhat hard to detect.

The senders are about $50 online and require two o-rings.

400Eric · #21 01-09-2010, 04:11 AM

Thanks, I already knew that it's just one of those things I can't find time for right now. I just live with it. Not good I know because the boy that cries "wolf" all the time gets ignored and when it really is a wolf I'll be ignoring the warning but again, no time, too many other even more pressing fires to put out.
Regards, Eric

samiam44 · #22 01-09-2010, 09:33 AM

Just a comment which might help.

In the rings, the compression rings appear to be good if your @ 180 psi. If you have too much variation, that could be an issue. Since you know it has seldom oil changes, it is possible that the oil rings are stuck. This could cause oil consumption.
You could add something like Kroil (sp?), or switch over to an oil with a more aggressive cleaning package. Maybe Mobil-1 diesel 5W-40 would be good. Go through several changes- 1k, 3k, 5k and then see where things are at. Pulling the head you could see/measure cylinder wall wear-but will never be able to inspect stuck rings. These M103's are quite common- you can find a good used engine cheap.
The early cars are known for valve guide wear. And you could have a loose valve guide too.

You stated it's not dripping any oil? Have you removed the lower engine shroud, washed the block, driven and inspected or are you simply stating there is no puddles under the car????
I ask this as I've seen 300E's where the taillights were oily from a bad head gasket and they left no puddles under the car.

M

ps2cho · #23 01-09-2010, 10:22 AM

Thanks for all the advice guys. Much appreciated.

I think I will go wash the block and add some dye in. There is no compartment tray. I also have some Delo 400 15-40 diesel oil ready to go in today.

pawoSD · #24 01-09-2010, 10:28 AM

Quote:

Originally Posted by 400Eric

Also, these engines were known to be oil burners even when new! I have a Consumers Reports article from 86 or 87 and high oil consumption was one of only two complaints they had about the car. The other was that it was way overpriced!

Since when? My 300E burns virtually no oil. I had the valve stem seals replaced last July, and did an oil change the same day. It has been 4000+ miles since then, and the level has barely moved on the stick. It went from a quart per 500 miles easy to virtually nothing in 4k. Essentially, if the engine is in good shape, it will burn next to nothing.

400Eric · #25 01-10-2010, 02:38 AM

They did mention that the oil consumption was much greater when the car was driven in a spirited fashion. Does your 300E get driven in a "spirited" fashion?

I think there are way more M103s that use oil than not. And I think it's a scandal how early in their lives these things need valve stem seals. My 88 300E got them at 5 years of age and 100,000 miles (before I got it but I have the documentation) and now at 195,000 it needs them again.

Sorry, my 89's being a brat right now (perhaps you saw the thread?) and I'm sure you remember my misery with my 88 about a year ago. I'm just down on M103s right now.....hopefully it will pass.

I wanna be like you and be a diesel man..... I'm looking for a good deal on a good W124 diesel! Know of any? My 304,000 mile Volvo diesel is just so rough now that my wife won't ride in it anymore....She won't let me take the kids in it either! (Maybe she's affraid she'll never see them again!)
Regards, Eric

Thread Tools
Show Printable Version Email this Page
Display Modes
Linear Mode Switch to Hybrid Mode Switch to Threaded Mode