So just bought a 1998 SL500 with 115k miles. Car can not go over 3000 rpm and has no power. The car would idle fine and be fine up to 2000 rpm can go higher than that up to 3000rpm but it will overheat. Now it does this in P, N or driving. When driving has almost no power. I did the spark plugs. It has M119 engine and the little plastic tubes by the cam that take oil to the lifter, three of them where broken so I replaced them. I haven't lost any water. The level hasn't changed. And I don't see water in oil. But I do see some smoke coming out of the oil dipstick and oil filler cap.

Also car does not blow cold (not even outside air) even when Climate control put to cold(A/C) in the interior. In the cabin it will always blow hot air. Not sure if these are related.

My guess is that I might have a badly clogged catalyc converter. This is what I did to test it since I could not remove any O2 sensors. I took out one of the spark plugs and run the engine for a few seconds. With one spark plug out the car would rev up to 4200 rpm.
So I am thinking my catalyc converter or muffler may be clogged really bad.
The check engine light is on and has cyl 2 and cyl 4 misfire code but the plugs are new from Mercedes Benz and I have switched the coils around to make sure it is not the coils. Still getting the spark plugs misfire code.

Now I do all this more as a hobby and I am not a mechanic so I wanted to ask for an experienced advice what you think? Have you seen this before?

Thank you and sorry for my English.

I only paid US $4000. Can't return it. I knew I was gambling.

If the A/C is blowing hot air all the time, it sounds like your duovalve is in need of a rebuild or replacement. Search for "duovalve" in this forum and will find lots of articles on the subject.

__________________
"It's not about how fast you can go, but how well you can go fast."

Bob in Richmond

'97 S320 (LWB), Ruby Red Metallic, 73k miles
'97 S420V, Smoke Silver Metallic, 155k miles

Good call . . when you hit the pedal, does the engine/exhaust output sound strange?? If it does, you probably nailed the problem.

__________________
Regards . . . . JimF
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'94 S500 Cpe

Visit my Mercedes Web Page

It does. Its not like the typical bad muffler sound but yes it sound kind of loud. Not sure how to describe it.

When the cats/exhaust mufflers plug, you loose the "bass" so it sounds like it's screaming . . . take it to a muffler shop to get it confirmed.

__________________
Regards . . . . JimF
-------------------
'94 S500 Cpe

Visit my Mercedes Web Page

The thing is that I just bought it. And it was acting up when I test drove it but not this bad. Then I drove it home for one and a half hour and than things got worse. But I don't exactly know how this car was supposed to sound. Either way I will take it a shop and do a back pressure test on it.

Even though the people before didn't take good care of the car, with 115k miles I still have a lot of fair in this engine. But I was aware that I was gambling my money when I bought it. $4k for the car.

Will keep updated.

Here I am replying back. Just got one of the catalyst converters replaced. One of them was completely clogged creating a back pressure of 30 psi. Max should be around 2 psi. So I took the car out of the shop got up to 50 miles about 400 yards from the shop that car turned off while driving. So I pulled over to the side and it is acting like it is a dead battery. The starter will turn the engine but only for two seconds. Tried to jump it swamped the batter from another MB but no luck. It acts like it is a dead battery but I know that is not the problem. And the car have been starting right up every time. And I tried to jump it right after it turned off. Very frustarating


When it turned off since the car was still rolling I put it neutral and tried to start the car. I wonder if I ruined the starter!

I dropped it at a mechanic. I am worried it has not messed up the engine. Well, what can I do.

BTW, the muffler guy had never seen a catalytic converter cloged that bad.

But thank you all for your advice.
I feel very disappointed and sad now.

Glad you got the cat fixed. Now you know what a plug exhaust sounds like.

Wouldn't think it's a battery . . more like an ECU failure. . . time to get the codes read.

__________________
Regards . . . . JimF
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'94 S500 Cpe

Visit my Mercedes Web Page

I hope for your pocketbooks sake this doesn't turn into one of those

'the cheapest MB's are the most expensive MB's'

So I just talked to the shop today where I dropped my car. They have been able to get it started. Now it starts fine again. I can't really explain why the car would not start yesterday even with a battery swap and trying to jump it. But if it doesn't do it anymore who care. But time will tell.

But the next problem that seems to remain is the fact that car will ide fine but if you rev up the engine and then take off the gas pedal or brake the car rpm go down and will not stay at low rpm/idle but it dies right away. Any idea on this issue? Thank you again.

. . . codes . . . . get the codes read . . . .

__________________
Regards . . . . JimF
-------------------
'94 S500 Cpe

Visit my Mercedes Web Page

I am back with news.

I just finished a HOT ENGINE compression test for a second time. After replacing the oil filter, oil, plugs, and the clogged cat converter, unlike before this time I got compression of 150-155 psi an all the cylinders. Should this be more acceptable? What are you guys getting?


Second, bad news, is that now the car revs up to red line but there is a major problem with power loss. Car idles fine and wont overheat in idle but if I setup on it and rev up the engine in about 10 min of driving it will overheat. Also tried to go up the hill car had hardly any power and died half way through. Its not the tranny I know, but the car has no power to pull and as the hill got steeper the cars rpm's got lower until death.

Now could this be still that my compression is yet too low! Or could it be some fuel issue? I know the car had been sitting for a while.....

Also, I get Check engine light, Cylinder 8 missfire, took out all the plugs, plug 8 still looks brand new and white..I might have a plugged injector there, don't you think?

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You tried Jim.