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91 420 SEL
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209 Posts
Discussion Starter #1
With the turn to cooler temperatures, two problems have cropped up with Grumpy. The first is a starting issue; the colder the temp on the first start of the day the longer it takes to get started. There is definitely a correlation between ambient temp, time since shut down, and follow on start duration. Once she does catch, it’s a real rumble-y affair for several seconds, then everything cleans right up. Over the summer, and now on warm afternoons, Grumpy fires right up. I suspect cold start valve. How would I test this?
The second problem is my ABS is cycling on the first 3 or 4 stops of the day. It seems to be getting progressively worse. If I get after it hard, the ABS doesn’t cycle (you can feel it in the pedal, and hear a sort of buzzing, bong, bong, bong). If I’m gentle with the brakes, like sliding up to a stop sign, the system cycles from about 25 to 5 MPH. Brake fluid level is fine, and I do occasionally get an ABS light, but I can clear this by turning the car off.
Suggestions?
 

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91 420 SEL
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209 Posts
Discussion Starter #2
OPR vs. CTS

After surfing the forum for an hour or so, it seems I may have some leads to my cold weather hard starting problem; Overload Protection Relay and/or Coolant Temp Switch (for CIS and Radiator Fans). I have had some problems over the summer with one of the fans not coming on, which would suggest the CTS, on the other hand, it seems that the cold start valve (controlled by the CTS) only fires at 10F and below (and it hasn’t been that cold yet). This would suggest the OPR. Hmmmm....would the OPR have some bearing on the weird ABS issues I'm having? Vote OPR vs. CTS.
 

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'88 560sec (180k mi.), '82 380sec (236k mi.), '86 560sec (?miles)
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273 Posts
I would say 99% sure it's your OVP relay. From my experience.
 

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Two '87 570SECs, one '87 560SEL
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4,467 Posts
My ABS was kicking in the first one or two stops each day until I pulled each ABS sensor out of the hole and cleaned it. The sensing ends were covered with metal particles (worn off the disc?) and then blasted the brake rotor ABS sensing slots with 90 psi air. End of problem.
 
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