Long story but here it goes:
After owning this car 6 years with nearly no trouble I gave it to my daughter to drive as her daily. She is a very careful driver, and one night she called, said the car had died, and that the flashers wouldn't even come on. So I grabbed my jump pack and headed out. It did restart, so the next day I replace the battery with a new Interstate. However, as I drove it home I noticed that if I tried to use the "kickdown" function it would really mess with the drivability. Missing, lack of power, etc. The more I pushed it the worse it got until I was literally idling the last few blocks home. At this point I checked the alternator output and found it putting out 18.5 volts. This was confirmed on Napa's tester as well. I replaced the alternator. It ran great for a couple days but as before I slowly started to loose the kickdown function and it would only hold top speed. I replaced the tank strainer and fuel filter a and inspected the ignition system. I'm not sure where to go from here. I'm thinking that between my daughter not opening it up much, and it sitting a lot it may have a pressure issue. Suggestions?

Confirm/compare that your voltmeter is accurate with another meter if you can and then re-check the voltage output, it should be approx 13.8-14.2 VDC with a fully charged good battery. The replacement alternator may be bad.

Good luck!!!

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"Rudeness is a weak man's imitation of strength" - Eric Hoffer

At this age you need to make sure your electrical ground points, cable connections, and the cables themselves are all solid and uncorroded. I have had plus cables corrode on the inside - given the low costs, often best to replace pre-emptively.

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Prost!

standard125r, when the car died on your daughter it was likely due to worn voltage regulator brushes resulting in the alternator not fully recharging the battery. A new voltage regulator costs around $15 and is an easy DIY repair. 2 screws secure the voltage regulator to the back of the alternator. Your old voltage regulator is probably long gone, but I would attempt to retrieve it and check the condition of the voltage regulator brushes. If they are worn to short nubs, then a new voltage regulator should fix your initial problem.

The 18.5 volt output of the new alternator may have fried the overload protection relay which is likely behind the removable black plastic piece behind the battery (I am not familiar with the under-hood arrangement of the 190 vehicles), or blown the 10-amp fuse. The overload protection relay is shiny aluminum about 1 1/4" square and 2 1/2" tall with a red plastic top holding a 10-amp fuse. With the engine running you may hear a clicking sound coming from the overload protection relay. Regardless, remove the battery and the black plastic piece to access the overload protection relay. Remove the relay and shake it lightly. If you hear something loose inside, buy a new overload protection relay [Kaehler (KAE)] around $50 online.

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Fred Hoelzle

Agree on replacing the OVP relay, its likely destroyed if the alternator was churning out 18.5+ volts.

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-diesel is not just a fuel, its a way of life-
'15 GLK250 Bluetec 118k - mine - (OC-123,800)
'17 Metris(VITO!) - 37k - wifes (OC-41k)
'09 Sprinter 3500 Winnebago View - 62k (OC - 67k)
'13 ML350 Bluetec - 95k - dad's (OC-98k)
'01 SL500 - 103k(km) - dad's (OC-110,000km)
'16 E400 4matic Sedan - 148k - Brothers (OC-155k)

The fuse is irrelevant. If the OVP is toast, the issue will be the zener diode. Best to replace it. If it's not the problem, it's good to have a spare because you'll have problems with it sooner or later.


I't located behind the battery. You need to pull up the weather stripping and remove the thin plastic splash shield.