My theory on coil packs cracking. Whadayathink?
01-07-2009, 11:39 AM
#1
Race Car
Thread Starter
My theory on coil packs cracking. Whadayathink?
Engine is hot, coils are hot.
Then, you pass over water puddles and cold water splashes in between the heat shields and onto the hot coil cracking the plastic.
The coil packs is really susceptible to water exposure due to being close to the ground unlike "V" and "inline" engines.
Discuss.
Then, you pass over water puddles and cold water splashes in between the heat shields and onto the hot coil cracking the plastic.
The coil packs is really susceptible to water exposure due to being close to the ground unlike "V" and "inline" engines.
Discuss.
01-07-2009, 11:51 AM
#2
Rennlist Member
Yes, although I think the majority of coil pack damage is simply from the heating and cooling cycles. Porsche is not the only one. My mom's Jag and Mercedes both had the same problem. The newest version for the Cayenne (they all fail on the Cayenne's on a V) has some sort of silicone rather than plastic. I assume it's to help with expansion / contraction.
01-07-2009, 11:53 AM
#3
Race Car
Thread Starter
Yes, although I think the majority of coil pack damage is simply from the heating and cooling cycles. Porsche is not the only one. My mom's Jag and Mercedes both had the same problem. The newest version for the Cayenne (they all fail on the Cayenne's on a V) has some sort of silicone rather than plastic. I assume it's to help with expansion / contraction.
01-07-2009, 11:57 AM
#4
Parts Specialist
Rennlist Member
Rennlist Member
I am not an engineer....
however there are many types of plastics and I am sure that knowing what type of plastic is being used would help diagnos this thought. If the plastic is fragile (like polycarbonite) then perhaps but if it is more ductile (like some nylon base) then I dont think so. Many plastics are thermally more stable than metals and have lover TCE's (thermal coefficient of expansion).... SO perhaps the metal expands more than the plastic housing and there inlies the trouble if there is not enough room for it to expand... it CRACKS...might not show up when new because when the plastic is heat cycled/ and over time it might become more brittle....
my $0.02
however there are many types of plastics and I am sure that knowing what type of plastic is being used would help diagnos this thought. If the plastic is fragile (like polycarbonite) then perhaps but if it is more ductile (like some nylon base) then I dont think so. Many plastics are thermally more stable than metals and have lover TCE's (thermal coefficient of expansion).... SO perhaps the metal expands more than the plastic housing and there inlies the trouble if there is not enough room for it to expand... it CRACKS...might not show up when new because when the plastic is heat cycled/ and over time it might become more brittle....
my $0.02
01-07-2009, 12:01 PM
#5
Race Car
Thread Starter
I am not an engineer....
however there are many types of plastics and I am sure that knowing what type of plastic is being used would help diagnos this thought. If the plastic is fragile (like polycarbonite) then perhaps but if it is more ductile (like some nylon base) then I dont think so. Many plastics are thermally more stable than metals and have lover TCE's (thermal coefficient of expansion).... SO perhaps the metal expands more than the plastic housing and there inlies the trouble if there is not enough room for it to expand... it CRACKS...might not show up when new because when the plastic is heat cycled/ and over time it might become more brittle....
my $0.02
however there are many types of plastics and I am sure that knowing what type of plastic is being used would help diagnos this thought. If the plastic is fragile (like polycarbonite) then perhaps but if it is more ductile (like some nylon base) then I dont think so. Many plastics are thermally more stable than metals and have lover TCE's (thermal coefficient of expansion).... SO perhaps the metal expands more than the plastic housing and there inlies the trouble if there is not enough room for it to expand... it CRACKS...might not show up when new because when the plastic is heat cycled/ and over time it might become more brittle....
my $0.02
Aluminum expands a lot while plastic not so much at the same temp.
01-07-2009, 12:10 PM
#6
Race Car
I never understood why people replace their coils when they can be perminently sealed in so many ways, whether it is by spraying a flexable coating on them or installing a thin protective film on them or even coating them with a vinyl protectant. This is standrad practice for electrical cables and wires, distributers, etc, so why not the packs?
01-07-2009, 12:12 PM
#7
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01-07-2009, 12:16 PM
#9
Race Car
Thread Starter
I never understood why people replace their coils when they can be perminently sealed in so many ways, whether it is by spraying a flexable coating on them or installing a thin protective film on them or even coating them with a vinyl protectant. This is standrad practice for electrical cables and wires, distributers, etc, so why not the packs?
01-07-2009, 12:18 PM
#10
Race Car
Thread Starter
01-07-2009, 12:26 PM
#12
Race Car
As far as the heat effect....the packs don't get very hot to begin with. You can remove the packs with your bare hands even after the cars has been run all day long. Also make sure the connector boot is good and installed properly.
01-07-2009, 12:31 PM
#13
Race Car
Thread Starter
01-07-2009, 12:37 PM
#14
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Lifetime Rennlist
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Torque value on the retaining bolts of the coil packs is only
84 IN-Lbs or 7 ft-lbs. or 9.6 Nm
I would put a light coat of hi-temp thread lock to ensure they dont back off from vibration from all of you hi-rpm drivers
