I just took a 360 mile trip (each way) in my 1986 way up north of NYC near Canada for Thanksgiving. (1) It was cold, my gauge read a solid 70 all the way and cold air came from the vents except at a stop or slower speeds. (2) The car was not quick going up hills, the tach was only reading 21,000 rpms and would not go faster than 40-50mph! and (3)The scariest thing was the cruise control seamed to get stuck in accel and would not disengage by braking or decel on the wand, I had a small panic attack, put it in neutral, the tach flipped and in finally disengaged (whew). Any similar experiences? solutions?

Thanks

I have had a similar problem once. My cruise stuck and I had to throw it into neutral and pull it off the road. I waited a few minutes and started it again. It immediately redlined so I shut it down again. I couldn't imagine what was wrong. Eventualy I reached down ad grabbed the gas pedal. It had stuck to the floor. It came up no problem and after that everything was fine. My mechanic said it was the linkage and he lubed it or something. Hasn't happened again. (This happened while accelerating (resume) on cruise). Haven't experienced the other problems.

Can't comment on the cold running or cold air problems.

JP Toronto

PS I think you meant 2500rpm not 25,000rpm

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Jason Priest
1999 E430
1995 E420 - retired
1986 420SEL - retired

Jason,

Thanks, I'll lube it! I am looking into the thermostat being the culprit for the temp problem. As far as the acceleration up hill, I'm still lost.

How steep a hill was it? If the tach was only showing 2500 at 45-50 mph then I assume you were in 4th gear. To accelerate a car as heavy as a 420SEL going up a steep hill you'd have to get into the higher RPMs. Get a second opinion on this as I am no expert, but it sounds like it just didn't downshift for you. Try it again and step on the gas hard and fast. Either that or manually downshift into third.

JP

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Jason Priest
1999 E430
1995 E420 - retired
1986 420SEL - retired

Dave, check two things, first, attached to the throttle linkage is a downshift cable that somehow actuates the transmission in relation to throttle pressure (your foot). This may need to be adjusted, easily done by loosening a threaded nut on the end of the linkage. Secondly, the downshift button located beneath the gas pedal may be bad and in need of replacing, its electrical I believe. I had a similar problem on my 89 420 and it was easily corrected. Good luck...

Thanks Hunter! I'll check both of those possibles this weekend, sounds likely it's one or the other. Do you remember the cost of the switch?

If you still have the problem, consider a plugged catalytic converter.

Yes a plugged cat can be a cause of slowness.

My bro's 85 190e had a clogged cat, in neutral it would rev fine, in gear you put your foot down and car would go maybe 10-20 mph.

After that was fixed, car ran fine.

Alon

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'92 300CE - Sold
2004 C240 - 744 - C7 Wheels - Android Radio
2002 C320 - 816 - Sport Wagon

Your lack of heat is 95% caused by the monovalve diaphragm being broken, you buy it as a kit and it's very easy to replace but messy. PN for my 420sel 88 is 000 835 06 44. Symptoms on my car were the same as yours.

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Mihai

1988 420sel
1973 porsche 914 2.0 (Deceased)