Dist Cap and Rotor replacement
11-20-2002, 02:13 PM
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Dist Cap and Rotor replacement
I'm sure that some of you will think I am thick for asking this, but hey, we all have to start somewhere! 
My garage have found out that the upper distributor is not working, which may be a problem with the cap/rotor, or with the coil. They have left the non-functioning cap unplugged for the time being, and the car is far from smooth!
I want to replace both caps and rotors, as I have no paperwork showing when they were last done.
Is there an "easy" way to do this without getting in a terrible muddle?
If I also need to then replace the coil for the upper distributor, how easy is this to do?
My garage have found out that the upper distributor is not working, which may be a problem with the cap/rotor, or with the coil. They have left the non-functioning cap unplugged for the time being, and the car is far from smooth!
I want to replace both caps and rotors, as I have no paperwork showing when they were last done.
Is there an "easy" way to do this without getting in a terrible muddle?
If I also need to then replace the coil for the upper distributor, how easy is this to do?
11-20-2002, 03:16 PM
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Yes, this is easy to do. Just make sure not to lose track of which wire goes in which hole, otherwise it makes it tough to run the engine 
If you need to, use tape on each wire and write down a sequencing or cylinder number.
If you need to, use tape on each wire and write down a sequencing or cylinder number.
11-20-2002, 04:24 PM
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I wouldn't recommend it, unless you pull the rotor on the bad distributor and I'd probably also pull the coil cable to the bad distributor too.
11-20-2002, 05:33 PM
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The mechanic pulled the main "plug" that goes into the coil, but I will pull the lead from the top of the cap before I drive it.
Silly question - is there a trick to accessing the coils to replace them?
Silly question - is there a trick to accessing the coils to replace them?
11-20-2002, 05:56 PM
#6
Firstly, if the engine is not running properly, why are you driving it?
Pulling the amplifier plug off disables the coil so there is no need to disconnect anything else.
You need to find out exactly what the fault is before replacing any parts. Obviously correct maintenance should be done at the same time.
We have replaced several coils due to intermittent and total failure, always replace both coils at the same time.
Pulling the amplifier plug off disables the coil so there is no need to disconnect anything else.
You need to find out exactly what the fault is before replacing any parts. Obviously correct maintenance should be done at the same time.
We have replaced several coils due to intermittent and total failure, always replace both coils at the same time.
11-20-2002, 06:06 PM
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Brad,
I just changed both distributor caps and rotors on mine. The secondary distributor’s lower screw is hard to get at so make sure you don’t round it off. You will have to take off the rubber duct from the heater blower to get at this one. I used a small screwdriver on it and used a good bit of pressure. <a href="http://www.vertexauto.com" target="_blank">www.vertexauto.com</a> has the best deal on the 4-piece set for about $120. It’s really hard to move the wires over one at a time so just label them clearly and take all the ones off for one cap at a time.
The Bentley book has an easy way to check the resistance on them to verify what is actually bad. In short this is what the values are. Center to tip of rotor = 1k, inside contact to cap tower is 1k. Both of my rotors and each of the 6 contacts inside were very pitted.
While you have it off, check the belt by making sure the secondary rotor doesn’t spin freely. It should be fine if you have the mains center coil wire off and it runs.
As far as the coil. Resistance from primary winding (1 and 15) should be .4 to .6 ohms and secondary windings (15 and 4) should be 5k to 7.2 k ohms. Good luck, Mark
I just changed both distributor caps and rotors on mine. The secondary distributor’s lower screw is hard to get at so make sure you don’t round it off. You will have to take off the rubber duct from the heater blower to get at this one. I used a small screwdriver on it and used a good bit of pressure. <a href="http://www.vertexauto.com" target="_blank">www.vertexauto.com</a> has the best deal on the 4-piece set for about $120. It’s really hard to move the wires over one at a time so just label them clearly and take all the ones off for one cap at a time.
The Bentley book has an easy way to check the resistance on them to verify what is actually bad. In short this is what the values are. Center to tip of rotor = 1k, inside contact to cap tower is 1k. Both of my rotors and each of the 6 contacts inside were very pitted.
While you have it off, check the belt by making sure the secondary rotor doesn’t spin freely. It should be fine if you have the mains center coil wire off and it runs.
As far as the coil. Resistance from primary winding (1 and 15) should be .4 to .6 ohms and secondary windings (15 and 4) should be 5k to 7.2 k ohms. Good luck, Mark
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11-21-2002, 02:11 AM
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Brad,
I also just went through all of this stuff with my 89 C4. I sent my distributor to Rennsport and $170 bucks later and 1 week had it back, nes belt and all. Steve Weiner gives excellent service and is always there to answer questions.
As far as replacing the coils it's easy. You'll see a couple of allen screws used to hold the coils in the bracket. These can be reached by a long allen key that pokes through access holes in the mount itself. You don't have to totally remove them, just loosen them up and with a little wiggle the coil will come out the top.
As far as checking the coils by just checking the resistance, I also asked this question and was told by Adrian that these numbers mean nothing. 964 coils are all together a different animal and passive resistance checking is useless. It's just something needed by DOT as a legality or something to that affect. See if you have a bud in the neighborhood who will let you swap out coils. I found a Rennlist guy who turns out to live 4 blocks away from me. Good luck!!
Drew
89 C4 (axle should be here tomorrow)
86 930
I also just went through all of this stuff with my 89 C4. I sent my distributor to Rennsport and $170 bucks later and 1 week had it back, nes belt and all. Steve Weiner gives excellent service and is always there to answer questions.
As far as replacing the coils it's easy. You'll see a couple of allen screws used to hold the coils in the bracket. These can be reached by a long allen key that pokes through access holes in the mount itself. You don't have to totally remove them, just loosen them up and with a little wiggle the coil will come out the top.
As far as checking the coils by just checking the resistance, I also asked this question and was told by Adrian that these numbers mean nothing. 964 coils are all together a different animal and passive resistance checking is useless. It's just something needed by DOT as a legality or something to that affect. See if you have a bud in the neighborhood who will let you swap out coils. I found a Rennlist guy who turns out to live 4 blocks away from me. Good luck!!
Drew
89 C4 (axle should be here tomorrow)
86 930
11-21-2002, 08:24 AM
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[quote]Originally posted by GMS:
<strong>Firstly, if the engine is not running properly, why are you driving it?</strong><hr></blockquote>
I'm only driving it to a mate's house (with nice warm dry garage) to do the work in comfort, out of the London rain and cold!
Just on this question: Am I right in thinking that the double dist was added in order to counter uneven valve wear? Do the plugs spark at the top and bottom of the stroke, thereby equalising the pressure on the piston?
<strong>Firstly, if the engine is not running properly, why are you driving it?</strong><hr></blockquote>
I'm only driving it to a mate's house (with nice warm dry garage) to do the work in comfort, out of the London rain and cold!
Just on this question: Am I right in thinking that the double dist was added in order to counter uneven valve wear? Do the plugs spark at the top and bottom of the stroke, thereby equalising the pressure on the piston?
11-21-2002, 08:31 AM
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[quote]<strong>964 coils are all together a different animal </strong><hr></blockquote>
Interesting that the coils are a 944 numbered part!
Interesting that the coils are a 944 numbered part!
11-21-2002, 10:38 AM
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Steve -
Fantastic!!!!
Thanks for your clear explanation - makes me much more confident!
BTW, ordered the parts from Type-911.co.uk - comparable cost - a few pounds in it.
Fantastic!!!!
Thanks for your clear explanation - makes me much more confident!
BTW, ordered the parts from Type-911.co.uk - comparable cost - a few pounds in it.
11-21-2002, 04:47 PM
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I am now planning on taking the car home (170 miles) to get it fixed with a mate who knows what he is doing!
Anyone see any problems with driving that far on just one coil and therefore one distributor?
Anyone see any problems with driving that far on just one coil and therefore one distributor?
