90 mercedez 500 sl help - PeachParts Mercedes-Benz Forum

mercedez500sl · #1 08-07-2007, 03:13 AM

hey guys
my 90
500sl
when warm, and you step on the accelator it hasitates a bit?????//
any suguestions????
also the temperature reches over the line obove the 80 on the gage when hot is that normal?????
thanks

Mike Miller · #2 08-07-2007, 01:59 PM

What kind of fuel are you using? I don't mean what octane. I know that has to be 91+. I mean what brand. Mine hates Arco (too much ethenal). I use Chevron or 76 and it runs fine. If this is not the issue, you may need a tune-up. When was the last time it got new rotors and caps?

My '92 runs well above 80 C. More like 90-95 C. I was worried at first that I was going to need a new water pump or radiator. Three years later, it is still 90-95 C and no problems. It just likes to run there.

patbianchi · #3 08-07-2007, 06:09 PM

My 91 was to rich turned down the adjustment on the injectors down 1/16-1/8 turn problem solved??

mercedez500sl · #4 08-11-2007, 06:44 PM

ok cool thanks guys.................

Doctor2687 · #5 08-20-2007, 09:52 PM

Had same issue last year.

Ended up changing plugs, running injector cleaner though, changed wires, and distributor caps. Last one finally cured it..

Matt

Barefooter6 · #6 08-27-2007, 09:54 PM

I've got a 1992 500 SL. The temp runs from 90 up to almost 110 and falls back to 90. The fans are working. any clues?

aam · #7 08-27-2007, 11:02 PM

Quote:

Originally Posted by Barefooter6

I've got a 1992 500 SL. The temp runs from 90 up to almost 110 and falls back to 90. The fans are working. any clues?

Need more details, like where are you.
Whats the outside temperature?
A/C on or off?
If its hot with A/C on it is a little on the hi side but still normal.
If A/C is off Check fan clutch.

Barefooter6 · #8 08-28-2007, 04:25 PM

The can be idling in 100 degree heat with the a/c on and the needle will stay at 90. While driving it will creep up close to the 110 mark and suddenly fall instantly back to 90. The fans are working and I really can't say the engine seems any hotter.

Mike Miller · #9 08-28-2007, 05:19 PM

I tend to agree with the theory that it is a bad gage.

I don't want to lead you off in the wrong direction, but I did have a "similar" situation with my '92 500 SL some time ago. It seemed to run OK and stay around 90, but hard running in heat on the freeway would cause it to rise up to 110. If I let my foot off the gas abd ciasted at speed, it would come back down pretty fast. I wouldn't do it instantly, but quickly. I found out that I had a couple bad rotor caps that would start arking in heat under load. New caps, rotors and a tune up and all returned to normal. Don't go spending the money for caps, rotors and a tune up until you check the gage and sensing system.

aam · #10 08-28-2007, 08:10 PM

Quote:

Originally Posted by Barefooter6

The can be idling in 100 degree heat with the a/c on and the needle will stay at 90. While driving it will creep up close to the 110 mark and suddenly fall instantly back to 90. The fans are working and I really can't say the engine seems any hotter.

First check your coolant level.
How old is your thermostat?
Looks that the therm. gets hang up and then it gets loose.
Unless you are driving fast or going up hill.
My car in California with A/C on 82" to 95"

Barefooter6 · #11 08-30-2007, 06:29 PM

Thanks for the info. Mike. The engine is has 6,000 miles on it. A factory re man. Everything was replaced, complete ing. system, thermosthat etc. The coolant is full and the fans work. At 65 it starts to creep up to the 110 mark. If you run 85 it drops back to 80 deg. I've got a new thermosthat and will put it in tommorow.

Barefooter6 · #12 09-04-2007, 09:10 PM

Wasn't the thermosthat, it was the sending unit. Replaced it and everything is back to normal.