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Registered
Join Date: Feb 2006
Location: The former Republic of Texas
Posts: 47
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DME Relay, why not one?
ANOTHER DME relay thread! Sorry.
After, too many hours searching for someone else that tried this I have given up and started a new thread. The short end of the story: My '86 911 (generally stock) sat for a couple years (4+?) while I gathered the courage to rebuild the transmission. Now that she is all better I had a tremendous time getting it started (i.e. might be replacing the starter soon) once started it only, well never mind, the point is I replaced the DME relay and she came alive! No sweat! Drove the piss out of the car for a couple days, (the more I drove it the more everything seemed to start working again, lights, gauges, funky smells dissipating, etc.) Then one day... no start, suspecting my URO (Chinese) relay; I got another one with the same result, ran like a champ for a few days then no start. (specifically, no spark, especially in the AM when it is a bit colder) So my question is why are there two relays in one? Why not just fabricate a single relay? Once this ice storm from hell clears out and I can get to my garage I intend to make a jumper wire (harness) to bypass the relay (for the time when the DME relay fails somewhere other than my house), but I intend to put a switch on it, and if I have a switch on it why not a relay? OH! To make sure my car isn't killing the chinese I was going to stick my ammeter on the jumper wires to determine the load of each system(Sears sells a fantastic DC clamp ammeter for ~$50). Anyone else done that? Any ideas what each load should draw? Thanks for all the advice! Andrew
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86 911 Carrera |
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02-01-2011, 02:30 PM
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Make Bruins Great Again
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Sounds like you are frying your relay. Maybe someone can chime in with what to test. If nothing else, if you know someone close by that has a 911, put your "bad" relay in their car and see if it starts. That would mean you have an intermittent problem rather than bad relays.
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-------------------------------------- Joe See Porsche run. Run, Porsche, Run: `87 911 Carrera |
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02-01-2011, 02:53 PM
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On that thought I pulled the relay then I pulled the guts.
 It is a known fact that I am pretty horrible at soldering, however this job is pretty despicable None of the terminals look like they got hot and I wish I knew what this white powdery stuff is. HA! It appears that one of the arms for the contacts is pretty badly bent....
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86 911 Carrera |
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02-01-2011, 03:52 PM
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Wash. State
Join Date: Jun 2006
Posts: 3,569
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Not that it will solve the problem, but the OEM relays are rated at 15 or 20 amps I beleive. I bought mine (2 in fact) rated at 30 amps; tougher, no doubt.
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02-01-2011, 04:16 PM
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Registered
Join Date: Feb 2006
Location: The former Republic of Texas
Posts: 47
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Sucess!
Turns out the arm that that makes the contact was bent so the electromagnet was engaging but not turning the circuit on.
so what did we learn? Lesson 1: Don't buy crappy parts Lesson 2: Don't buy crappy Chinese parts Lesson 3: Don't buy crappy Chinese parts even if they are supposed to work with your car. nesslar, so you are using two relays?
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86 911 Carrera |
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02-01-2011, 04:41 PM
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Wash. State
Join Date: Jun 2006
Posts: 3,569
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Quote:
 
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02-01-2011, 04:42 PM
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muck-raker
Join Date: Jan 2009
Location: Coastal PNW
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I've never had good luck with URO parts....on my P-car or my Land Rover. Pure caca.
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STONE '88 Cabriolet, using EP Slick 20w50 partial synthetic Snake Oil...just as Rommel intended.  Deny Everything; Admit Nothing; and Always Make Counter-accusations 
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02-01-2011, 06:29 PM
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Member 911 Anonymous
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From memory, as I understand it the DME relay's terminals tend to fracture over time and use causing non-continuity.
I heard and seen people re-flow the terminals/contacts. Question is with the non-continuity will that cause the relay to over heat, the usual symptoms of a failing relay. over,
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'85 Carrera Targa Factory Marble Grey/Black * Turbo Tail * 930 Steering Wheel* Sport Seats * 17" Fuchs (r) * 3.4 * 964 Cams * 915 * LSD * Factory SS * Turbo Tie Rods * Bilsteins * Euro Pre-Muff * SW Chip on 4K DME * NGK * Sienes GSK * Targa Body Brace PCA/POC |
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02-01-2011, 09:37 PM
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Registered
Join Date: Aug 2002
Location: Galivants Ferry, SC
Posts: 10,550
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yes...the soldered contacts break easily over time due to age and vibration....MADE WORSE by Porsche's idiotic design of the terminals being oriented to plug-in sideways....leaving the relay BODY hanging in space ! ( picture in post #3, here, with the relay cover off). Therefore, there is a tremendous moment-arm leveraging of the circuit board.
Solution?....( or at least, "big-help"?)--> place a rubber block under the unsupported relay body such that you take the bending stress ( gravity) off the body and its plug-in connection.
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Wil Ferch 85 Carrera ( gone, but not forgotten ) Last edited by Wil Ferch; 02-02-2011 at 11:00 AM.. |
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02-02-2011, 10:57 AM
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Registered
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Quote:
My DME Relay is changed out before it fails. Doyle
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Recording Engineer, Administrator and Entrepeneur Designer of Fine Studios, Tube Amplifier Guru 1989 Porsche 911 Carrera Coupe 25th Anniversary Special Edition Middle Georgia |
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02-02-2011, 01:44 PM
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Wash. State
Join Date: Jun 2006
Posts: 3,569
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Beautiful. That's really good stuff right there. Maybe add a little electrical tape to hold everything in place. For you, Wil and Doyle:
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02-02-2011, 02:09 PM
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| dme , dme load , dme one relay , dme relay |
Max
Marble Grey
