1985 300TD SERIOUS front oil leak and smoking underneath air filter housing - PeachParts Mercedes-Benz Forum

tomas_maly · #1 12-22-2011, 09:31 AM

Just noticed a major oil leak at the front of my engine, directly above my oil pan. I thought it was the oil pan gasket, but I changed that.

While running, it drips a 4 inch puddle of oil in a matter of 30 seconds. And noticed the oil was real low the other day (after changing it maybe 6 months ago). I also notice that the oil pressure is really low at idle, maybe 1.25 .

Is it fairly safe to say that it's probably the front crank seal leaking? I'm wondering if that's a do-able job, and how long that typically takes. This is a W123, so it's a bit less room than the W126, so maybe there are some tips to make it easier to get to, even if I have to take more stuff apart.

I also notice that there's an incredible amount of grease all over the passenger underside of the engine, but NOT the drivers side - so I'm wondering maybe as it's leaking, the fan (since it rotates clockwise, toward the passenger side) may be blowing the oil toward that side.

Possibly a separate note, that I'm noticing all of the sudden some smoke coming from underneath the air filter housing. I sprayed the throttle linkage with some heat-resistant WD40 (and may have leaked some fluid over the passenger edge of the engine block), but I doubt it's that. The smoke seems to get worse as I drive more, ie perhaps as more oil gets on the side of the engine. It's not any thicker/darker smoke than would come out of the valve cover into the air filter housing, anyway.

Perhaps I'll put the car on ramps and take a peak from underneath to see exactly where the smoke is coming from.

Stretch · #2 12-22-2011, 09:44 AM

Quote:

Originally Posted by tomas_maly

...

Perhaps I'll put the car on ramps and take a peak from underneath to see exactly where the smoke is coming from.

Well it could be the front crankshaft seal - it could be the rocker cover seal too.

I think the last thing you wrote is the best thing to do though.

It is always good to take a look yourself.

andrewjtx · #3 12-22-2011, 09:55 AM

I'd put money that you took the air cleaner off recently? If so, I'd also venture to say that the drain tube for crankcase vent system did not get seated into the metal tube. That would be dripping oil down on the turbo/exhaust system and get oil all down the passenger side of the engine.

vstech · #4 12-22-2011, 10:19 AM

also the tube connects to the top of the oil pan right behind the alternator. there is also the turbo oil return line there...

tomas_maly · #5 12-22-2011, 11:33 AM

Rocker cover seal? You mean the valve cover gasket? (google seems to suggest they are equivalent terms for the same thing). The valve cover gasket was changed quite recently. I don't see any oil leaking from the top of the engine. Looking into the pulley area, I don't see any oil at all, so I suspect it's coming from the underside of the crankshaft. From underneath, it seems to be coming from above the oil pan gasket. It's all so close together, so it's hard to see exactly.

As for my smoking issue, is there a problem with taking the oil filter housing OFF, while running, so I can get a better look at the source?

Stretch · #6 12-22-2011, 01:49 PM

Quote:

Originally Posted by tomas_maly

Rocker cover seal? You mean the valve cover gasket? (google seems to suggest they are equivalent terms for the same thing). The valve cover gasket was changed quite recently. I don't see any oil leaking from the top of the engine. Looking into the pulley area, I don't see any oil at all, so I suspect it's coming from the underside of the crankshaft. From underneath, it seems to be coming from above the oil pan gasket. It's all so close together, so it's hard to see exactly.

As for my smoking issue, is there a problem with taking the oil filter housing OFF, while running, so I can get a better look at the source?

Rocker cover seal - yeah sorry I'm trying to fit in with American terms - valve cover gasket is what I meant.

I wouldn't remove the top of the oil filter housing with the engine running - you might get more oil shooting out the top of it making your investigations all the more tricky. Which oil was leaking? Which oil was just spewed out?

For the amounts of oil you mention I would expect it to be obvious - try the places suggested above. If you're not sure what people mean - ask!

If you are really stuck - and you can't figure it out - try positioning toilet paper in key positions - run the engine and then check them to see if they are sodden. This works best for small leaks. With big leaks you should be able to see it dripping.

Whilst you are doing all of this investigative work - don't forget to top up the engine oil - don't let it run too low.

whunter · #7 12-22-2011, 02:07 PM

Quote:

Originally Posted by tomas_maly

Just noticed a major oil leak at the front of my engine, directly above my oil pan. I thought it was the oil pan gasket, but I changed that.

While running, it drips a 4 inch puddle of oil in a matter of 30 seconds. And noticed the oil was real low the other day (after changing it maybe 6 months ago). I also notice that the oil pressure is really low at idle, maybe 1.25 .

Is it fairly safe to say that it's probably the front crank seal leaking? I'm wondering if that's a do-able job, and how long that typically takes. This is a W123, so it's a bit less room than the W126, so maybe there are some tips to make it easier to get to, even if I have to take more stuff apart.

I also notice that there's an incredible amount of grease all over the passenger underside of the engine, but NOT the drivers side - so I'm wondering maybe as it's leaking, the fan (since it rotates clockwise, toward the passenger side) may be blowing the oil toward that side.

Possibly a separate note, that I'm noticing all of the sudden some smoke coming from underneath the air filter housing. I sprayed the throttle linkage with some heat-resistant WD40 (and may have leaked some fluid over the passenger edge of the engine block), but I doubt it's that. The smoke seems to get worse as I drive more, ie perhaps as more oil gets on the side of the engine. It's not any thicker/darker smoke than would come out of the valve cover into the air filter housing, anyway.

Perhaps I'll put the car on ramps and take a peak from underneath to see exactly where the smoke is coming from.

It sounds like the front crank seal is gone.
You will need to make this special tool to install a new one.

PeachPartsWiki: Replacing Front Crankshaft Seal with "Special Tool"

.

tomas_maly · #8 12-22-2011, 08:35 PM

How much time is involved, on the smaller W123 chassis? The FSM says to remove the 'cooler and fan'. By 'cooler' does that mean the entire radiator? Ie so I can just work straight through the front.

Price-wise, I seem to be finding about $30 for the seal and the spacer ring. Does that sound about right? Anything objectionable about the brands Febi/Elring? There were some cheaper seals, but they seemed like they were less durable materials.

I see a 'kit' and instructions from Mercedes Source for $75 total, and that seems a bit outrageous. Especially when I have the FSM (and these forums).

thatguy · #9 12-22-2011, 08:48 PM

Febi has been building some suspension parts in China lately, so take that as a bit of a warning about buying anything from them. I'd buck up for the OEM stuff in this case, would rather not have to do the job over again for the sake of less than $50.

whunter · #10 12-22-2011, 11:24 PM

Quote:

Originally Posted by tomas_maly

How much time is involved, on the smaller W123 chassis? The FSM says to remove the 'cooler and fan'. By 'cooler' does that mean the entire radiator? Ie so I can just work straight through the front.

Price-wise, I seem to be finding about $30 for the seal and the spacer ring. Does that sound about right? Anything objectionable about the brands Febi/Elring? There were some cheaper seals, but they seemed like they were less durable materials.

About four hours for me.
Average first time DIY is one day.

Main seal front/rear and harmonic balancer + Pulley

I generally use the "FEBI"
Spacer Ring, for Front Crankshaft Seal
MB# 615 031 00 51

I like the Victor "Reinz" Front Crankshaft Seal, but use the "Elring" almost as often.
MB# 011 997 22 47

I always insist upon using six NEW cap screws for the pulley.
MB# 000912008203

.

vstech · #11 12-22-2011, 11:26 PM

but be SURE it's the front seal before you disassemble the car!

Zacharias · #12 12-23-2011, 01:37 AM

Thomas, may I ask where you got these two cars?

At the rate you are going, you should be able to write an entire new DIY series for us pretty soon.

I have never seen anyone work through so many issues in such a short time. Well not on a Benz... maybe when I was on the Jaguar list. I had an awful 300sd, years ago, that drove me nuts for the first few months I had it on the road. But it was child's play compared to the work you've done since I've seen you posting here.

By any chance had one or both of these cars sat unused for an extended period, before you acquired them?

I am really curious, as I have seen people melt down in frustration over less, in such a short time span....

Cheers

tomas_maly · #13 12-23-2011, 07:56 AM

Zacharias,

Well, my 300SD seems to be in quite good condition in the sense that it was taken care of well, but a lot of the things are still original. Rubber goes bad and electrical wires short, etc. I think the previous owner must've been the original owner - the original Benz manual was in the dash, and everything was just kept totally clean. They were even in the middle of replacing the wood paneling! Nobody in their right mind would take that good care of a car unless they spent $40k on it, or whatever it cost originally.

The only thing that makes me nervous about the sedan is the rear suspension, which I think the shocks are shot. Going over any bump, I hear a grinding metal noise (it has a 'push/pull' sound to it, ie two equal sounds with a slight pause in between, not just a thud, so I am guessing shocks) as the rear of the car bounces. Different from a creaking noise, which my understanding would be the springs. I'm a bit nervous since there is some rust back there, I'm worried there's some rust I haven't noticed and then the car would need some serious body/frame work. =( There is rust on the driver's trailing arm, which actually prevents the shock from being bolted on with two bolts. Which may be why they never changed the shocks. Probably said the trailing arm would be $2000 parts and labor, etc and better to get rid of the car. Luckily I have a parts car (another blessing that makes my work on my cars possible and not so frustrating) so it would only cost me a few days work - but not the easiest to balance with 3 kids and a job that's 45 miles away. Waiting for that home business to pull through. If I change the shocks now I risk breaking the trailing arm (since it has rust) and then I'd have to depend on the wagon which has it's own problems.

My 300TD however must've sat around for YEARS. So many things neglected. I think it's one of those perpetual project cars. I'll probably never really have it in 'excellent' shape, not unless I throw another $3000 in parts at it. Right now I'm a bit pissed off at the triple square bolts on the rear door struts. I have the sockets but they strip the bolt too easily. Probably never changed (factory tight). I'm thinking of just drilling them out and putting normal hex bolts in. I thought the car was going to be junk since when I first got it, I couldn't keep the battery charged. Kinda frustrating on the first drive to have it die on the way home. Turns out some dummy (previous owner) left the alternator belt loose (or maybe put on the wrong belt altogether). After trying to fit in a W126 alternator and W126 alternator belt into my W123, spending maybe 6 hours since replacing the alternator is a PITA and the belts were just too short (had to improvise with just one and then drive to the parts store to get the other). The engines on the W123 and W126 are identical but some things are different to fit the chassis better. Like the alternator belts (yes, they are different by about an inch) or the transmission line to the radiator (on the W126 its about an inch too short).

Either way, I only can manage because I have two of them (the POS wagon was $500 and the sedan was $1000). I would burn out if I only had one. Usually there is one at a time that has certain problems that prevent me from driving it. So I have the other car, which makes it less of a big deal and so I can handle the work better.

It's somewhat obsessive lately (I just wish I had a reliable car that I didn't have to worry about), but ultimately a fun learning experience, seeing what I'm capable of doing with the right resources (FSM, ambition and these forums). Eventually I'd like to know enough about these cars that I can extend that mechanical knowledge to other areas like DIY off-grid power generators, ie biodiesel generators, solar power, wind turbines, etc - for that quiet cabin in the woods someday.

Other positive thing is that maybe in a few years I could make some extra money fixing these cars up, either reselling them, or repairing them. I do quite like the 81-85 W123/W126's, though. After that, it just starts getting complicated with all the modern 'features'.

tomas_maly · #14 12-23-2011, 08:04 AM

Quote:

Originally Posted by vstech

but be SURE it's the front seal before you disassemble the car!

It's definitely a massive amount of oil dripping, from above the oil pan (already changed the gasket). I can't see any oil from looking inside the engine from above. So I'm fairly sure it's the crankshaft seal, although I can't know for sure until I take the radiator/fan/belts off.

Is there anything else it can possible come from? I'm 99.9% sure it's coming from around the inside of the lower (crankshaft) pulley.

Even if it's not for some weird reason, I'll at least get a better look as to where it's coming from and then be preventative with the front seal anyway. Car was neglected enough anyway.

tomas_maly · #15 12-23-2011, 08:28 AM

This may be totally different, but after repairing my steering box on the wagon, the steering is nice and tight/stable, but depending on my speed or whether I just start the car, or are moving from a stopsign, etc it seems the tension radically changes, almost like the power steering gives out (about 75% off, still moves ok, but feels much tighter).

I'm wondering if since the steering pump uses a belt attached to the crankshaft pulley, if this is being all affected (ie loosening tension randomly) because the crankshaft seal is giving out?

When I replaced the steering box, I just left the steering pump as is. I pre-filled the box with fluid, bolted it on, and then ran the steering wheel back and forth probably 50 times. I'm fairly sure I purged all air, but wasn't sure if I needed to turn the steering wheel with either of the pump tubes off the box or the pump (ie return line loose sticking into the pump top so air gets out better).

But I drove it for maybe a week, and was fine, didn't notice a thing wrong with the tension, until just now as I'm noticing this major oil leak from the crankshaft seal.

I changed my alternator maybe 6 months ago and tightened it back up (never having the steering lock/tighten up until just now), new fluid (no leaking), etc. Will check tension on belt, but seems a bit odd since it comes and goes, like either the belt is at the end of it's life or something else is moving around.