Friend loaned a '94 S500 (which for some reason has years 95, 96 and 2001 associated with it's records). I am using it while traveling for business and pleasure instead of renting a car since the car was available, local and supposed to be better than any rental for free minus gas.
Car almost has 200k miles and was missing a slight bit at idle, but seemed to be running well on the road and do well at a mechanic checkup so decided I'd take the loaner. Auto. Supposedly recently had rebuilt head/valvetrain and trans.
It now sounds and feels like it is running on 2-4 cylinders. Horrible. Dist Cap, Coil, Plugs, Wires, Motor Mounts, other? Any way to pinpoint/eliminate possible problems with code reading the wiring harness .... maybe jumping something with a paper clip or getting the codes to read on the dash etc?
Here's what happened: Hadn't driven the car for a week, so decided to punch it from a stop. Did a bit of a brake stand - only to about 2500-3k rpms, then off the brake and floored the throttle simultaneously.
Result=
Took off slower than typical smooth acceleration. Engine noticeably stuttered and I was hoping it was pulling timing for slip control. Car runs really rough, park it a few blocks later, almost stalls out. Starts smoking from the engine bay - out the vents, under the car etc. Blue smoke. Let it idle, thinking maybe somehow oil leaked into plug valleys and maybe it will burn and drain and smooth out. After 5-10 minutes of idle engine stalls out. Let it sit for 4 hours. Start it up .... seems to have same old miss at idle ... no smoke after 30+ minutes idling. Take it for a drive .... is as initially described.
Zero acceleration from start till maybe 3rd gear - as if only running on 2 cylinders, rich/rotten egg smell sometimes. Maybe when kicks into 3rd gear it actually has decent acceleration but sounds and feels like a 4 cylinder. Was able to drive it like this for a few miles, parked it and idled it and no smoke this time.
Really want to get all 8 firing for cheap without friend knowing, tell him about the problem but don't return it with it. He knows it an old pos and doesn't want to put much money in it - never drives it for 2 years roughly, I just want to return it firing on all 8 and actually make use of it for some meetings asap without worry in a busy busy town where a car is very necessary.
Looked at partsamerica.com for some prices. Sheesh. $300-$600 wire set, coil/caps $200 each need 2 each, rotor button $70 need 2, engine mounts 200 each need 2. Plugs only $2 each need 8.
Benz mechanic near. Parts store near. Figured could start with plugs and have the mechanic give opinion after tearing things down a bit. Hoping just flooded spark plug valleys.
Any help?
Last edited by S500Travel; 11-02-2008 at 03:25 PM.
Oil Dipstick shows full and clean. Not overfilled or underfilled - right on the money.
Coolant reservoir full and clean.
Engine oil cap inspection shows no coolant mixed with the oil.
Full oil pressure.
No overheating noticed, but did not see temp when car stalled out on it's own initially after idling. Did not overheat when idling for 30+ minutes after restart/drive 4 hours later.
Just major missing now, all an immediate consequence of the rather moderate brake stand combined with pre-existing issues.
Don't mean to be bumping too much. Just adding notes as I quickly try to rectify and forget this ever happened.
No Check Engine light. I guess that rules out the code pulling idea.
I'm not sure if the engine light came on at any other time. I just know it isn't on now that I just went to fire up the engine a second ago.
I don't think the motor mounts have anything to do with it. I just mentioned it because it seems to be a common problem and a benz mechanic who only watched the engine idle mentioned it. Just throwing thoughts out rapidly.
When I did the brake stand. The auto trans was manually selected for 1st. Trans may now shift harder than before, or its just the rapid change in acceleration when it finally gets to a certain speed/rpm - around 3rd gear maybe - that causes the gear change and makes it seem violent.
Car shifted a bit firm/tricky before. Likely trans not at all the issue, but maybe.
Wouldn't it be nice if this was all a fuse or vacuum line? Wishful thinking?
Last edited by S500Travel; 11-02-2008 at 03:17 PM.
Take it to an MB mechanic imo, should be under $100 to get it all checked out.
Thanks.
I know of 2 local non-dealer Benz shops and 1 local dealer. Friend uses 1 of the non dealer and the same 1 dealer, so they would probably let him know and that might be an issue at this point. Dealer is usually less flexible and more expensive. Dealer and non-dealer used by friend is quite a drive.
Luckily, other non-dealer Benz place is in view of where the car is parked - within 100 yards. Met the mechanic today as he was just stopping by the shop on his off day. He figured coils or cap. He only watched it idle, though, and didn't get the latest perspective on driving characteristics.
Everything seems like it may be out of my travel budget, but if I could be certain about the problem I might be willing to push it. Maybe I can talk the shop manager into cheap labor to new plugs and cleaning/dielectric grease. Wires, coils, dist cap set etc x 2 all high without labor. No tools or time to work myself. Mechanic seems cool but nobody wants to work on the side these days. I'm a bit worried about being overcharged for inspection with no real work done. I figure I might be able to pull of a "free inspection" while negotiating cheap plug change, though.
When traveling there is no money coming in. Been traveling for a year. Meetings to make cash from, though, but could really use/should really have car to get there because public transportation is too unreliable and time consuming for where I need to go on what schedule.
Just still wondering if anyone has a sure way to narrow things down or has an epiphany about the exact problem from experience.
Last edited by S500Travel; 11-02-2008 at 04:12 PM.
Re: Just still wondering if anyone has a sure way to narrow things down or has an epiphany about the exact problem from experience.
I thought I'd clarify.
It seems to me that the combination of misfire + oil burn from the engine bay (not out the tail pipe) + rich/rotten egg smell = combination of no spark igniting fuel + spark igniting oil. Then, later when no oil burning from engine bay, still rich smell and no spark = oil drained from plug valleys but permanently fouled the plugs.
That's why I theorize plugs fouled from oil.
What would be good about that is that would be the cheapest fix.
What would be bad about that is I'd have some manner of luck in them not getting fouled again. Maybe if I just go easy it won't flood the valleys, though.
In this scenario, the only thing I'm not sure of is how the moderate "brake stand" caused oil to flood the plug valleys. I suppose the pressure would build up higher and a bad valve stem seal/plug seal with little load on the engine ... but I'm still unsure about it.
In theory, the flooded plug valleys seems to be it. Then the engine smoke could also possibly be related to oil dripping from the cam cover area onto the exhaust.
But, if oil was being sparked in the plug valley, then why would the smoke appear underneath/around the engine bay instead of out the tail pipe? Did I just rule out the plug scenario altogether? Nah, more like I ruled out bad rings.
Please, share your thoughts regarding this attempt to narrow things down. If it is not what I theorize, what else could cause both the oil burn from the engine bay and misfiring? Do bad coils/dist caps/wires cause this?
Wires can cause misfire but not oil burning (maybe a bit from spark between wire and plug in flooded valley ... but that's not wires themselves). It would seem to be the same for the coils and dist cap ... not at all possible to have anything to do with the oil burn. No?
Last edited by S500Travel; 11-02-2008 at 05:06 PM.
Thinking a bit more clearly, spark is always exposed to the piston chamber. If the rings are good then the oil shouldn't flood the spark (the rings seem good otherwise I'd have tones of smoke out the tail pipe and I don't seem to have anything coming out the pipe except a rich smell and missing noise.)
However, if the plug valley is filled with oil then the plug connection to the wire is fouled. The spark there is less exposed, but could still cause smoke via igniting oil. For the amount of smoke I was seeing, though, I would think it would be oil dripping on the exhaust. But, the engine oil level is not low or dirty. I didn't check the trans fluid yet though.
Hmm, then when I think of trans fluid, it seems to initially make sense because it seemed the smoke was coming from the rear and lower part of the engine .... just guessing. However, the trans shouldn't have anything to do with the extent of the missing(rich smell too)/bogging/underpowering/ I would think. I mean, sure, acceleration is largely tied to gearing ... but the acceleration problem seems to all be spark.
The smoke was a very considerable/visible amount .... for about 10 minutes ... under the engine - especially immediately to the rear of the front tires ... and when popped the hood seemed to come from rear of engine but don't remember exactly - might have come from the sides too. This was only immediately after the brake stand before the car finally stalled out.
The smoke didn't seem to come back in the slightest during the drive after starting it 4 hours later. I let the car idle for 30+ minutes, drove a few miles, floored the throttle a few times and let the car idle for about 10 minutes before shutting it off myself ... no stalling. No brake stand. Hood was open for constant observation during all idling. Did smell bad, though, but more like rich/rotten egg than burnt oil.
I don't see how fuel is a problem.
Vacuum seems unlikely, but possible. Fuse seems more possible, but no clue how it ties into the oil and no clue how the Benz fuses are set up. I know there is a fuse problem with the trunk, but all I know for sure regarding the fuses.
Last edited by S500Travel; 11-02-2008 at 05:11 PM.
Don't mean to be bumping too much. Just adding notes as I quickly try to rectify and forget this ever happened.
No Check Engine light. I guess that rules out the code pulling idea.
I'm not sure if the engine light came on at any other time. I just know it isn't on now that I just went to fire up the engine a second ago.
Just because CEL is not on does not mean that reading the codes would not be useful so it would seem prudent diagnostically to do that as one of the first steps. Detected fault codes can be stored even though the CEL is not turned on. Has your friend ever had similar issues with the car? Maybe that's why he let it sit for a couple of years....
Just because CEL is not on does not mean that reading the codes would not be useful so it would seem prudent diagnostically to do that as one of the first steps. Detected fault codes can be stored even though the CEL is not turned on. Has your friend ever had similar issues with the car? Maybe that's why he let it sit for a couple of years....
Thanks.
Hmm. Is it easy to pull CEL codes? I loved doing it on saturns - jumper with paper clip plus turn ignition and count blinks. Link while I'm searching?
I have no clue what the true history of the car is. Weird. Different year associations. Stories. Alleged top end rebuild/valve rebuild 10k miles ago - no paperwork I've seen. Guy is a distant friend .... a lot of history ... very rocky due to me calling him out on crap .... big gap from old friendship to little present and future.... he provides the car to try to make up for it. It's complicated. He is loyal but he lies a lot. He would lie about work done/needed for the car to seem like he has his life together. I really don't want to deal with him for many reasons right now, but I want to use the car.
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