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Registered User
Join Date: Mar 2002
Posts: 3,563
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Is it normal for these older generation engines to generate a subtle rattle when cold, which dissipates away as the engine warms up?
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Merv '89 911 Turbo Cab Protomotive MAP ECU, Twin Plugged Heads, GT2-EVO CAMs, 3.3L fully finned P&C's, ARP fasteners, C2T head gaskets, Titanium Retainers, Turbo spec valves, springs & guides, 964 splash valves, GT35R BB turbo, GSF Stainless Headers, Magnaflow Exhaust, Full bay Intercooler, TiAL 46mm w/gate, TiAL 50mm BOV, Apexi AVC-R EBC, SPEC Stage3+ Clutch kit, Crane CDI Ignition ![]() |
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7.0:1 > 11.3:1
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Is the noise new, or has it always been there?
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Registered User
Join Date: Mar 2002
Posts: 3,563
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hmmm, kind of new I guess. Been there for the last 2-3 months I'd say.
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Merv '89 911 Turbo Cab Protomotive MAP ECU, Twin Plugged Heads, GT2-EVO CAMs, 3.3L fully finned P&C's, ARP fasteners, C2T head gaskets, Titanium Retainers, Turbo spec valves, springs & guides, 964 splash valves, GT35R BB turbo, GSF Stainless Headers, Magnaflow Exhaust, Full bay Intercooler, TiAL 46mm w/gate, TiAL 50mm BOV, Apexi AVC-R EBC, SPEC Stage3+ Clutch kit, Crane CDI Ignition ![]() |
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7.0:1 > 11.3:1
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Presuming you have lots of cycles on the engine in the last couple months and the noise has not changed (worsened) it's likely not an issue. A few things that come to mind however is valve train, piston/cylinder clearance, and tensioners. These items do have differences when cold versus warm which could make various sounds.
Sometimes exhaust systems can have loose or rubbing components which rattle a little when cold or warm due to expansion. Think - heat exchanger boxes on the headers. Tough to be of much help without being there to listen with a stethoscope, but if the noise is minor, consistent, and dissipates, then it's probably a non issue. Jim |
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Registered User
Join Date: Mar 2002
Posts: 3,563
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Thanks. I'll take closer notice if it dissipates fully or not once fully warmed. I'm a little worried cause it's more prevalent now, than before. Hope it's not a spun bearing or something. Doubt it though. Full engine rebuild wasn't done THAT long ago, but who knows if it was done properly or not
![]() Unlikey it's a heat exchanger rattle. I'm running heaterless headers.
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Merv '89 911 Turbo Cab Protomotive MAP ECU, Twin Plugged Heads, GT2-EVO CAMs, 3.3L fully finned P&C's, ARP fasteners, C2T head gaskets, Titanium Retainers, Turbo spec valves, springs & guides, 964 splash valves, GT35R BB turbo, GSF Stainless Headers, Magnaflow Exhaust, Full bay Intercooler, TiAL 46mm w/gate, TiAL 50mm BOV, Apexi AVC-R EBC, SPEC Stage3+ Clutch kit, Crane CDI Ignition ![]() |
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Join Date: Dec 2006
Posts: 63
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Maybe a screw was dropped somewhere? Licence Plate could rattle! A barrel nut that has come undone can shake up inside a valve cover! The boxed tin located just above each oil return line under the engine sometimes get flimsy! I'd get a long screwdriver and poke at them while the engine runs! I'm not really sure what they are for though. I guess they help in guiding air between the cylinders. Get a long rubber hose and try scoping that noise out.
Last edited by madkow; 01-08-2007 at 09:25 PM.. |
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A fellow Pelacanite
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Buy a stethoscope and see what you can find.
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1981 UK 930. G50/01 shortened, 964 3.8RS Fibreglass Body Kit, 18" Alloys 8.5" F & 10" R, 225's F & 285's R, Special Colour Metallic Blue Paint, FIA Sparco Evo's, A/C and Air Pump removed, Electronic Boost Controller, GHL Headers, Tial46 WG. Fitting - New service kit. Needs Fitting - Innovate XD-16 Kit, Kokeln IC. Stephen's K27 HFS, EVO Intake Assy & his Modded USA Fuel Head. 1983 UK 911 3.2 Carrera Sport Coupe. Black, Black Leather with Red Piping, Black Alloy Gear Knob, K&N Air Filter Element, Turbo Tie rods. Needs Fitting - K&N CO Sensor, Round A/F Dial Gauge, Factory Short Shift Kit. http://www.danasoft.com/sig/Iamnotanumber.jpg |
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Registered
Join Date: Jul 2002
Location: IL
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Merv, I call it, the Turbo rattle.
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Forced Induction Junkie
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Maybe the tensioners are not extending properly till the oil is warmed up? Were the tensioners bled before they were installed from the last build?
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Dave '85 930 Factory Special Wishes Flachbau Werk I Zuffenhausen 3.3l/330BHP Engine with Sonderwunsch Cams, FabSpeed Headers, Kokeln IC, Twin Plugged Electromotive Crankfire, Tial Wastegate(0.8 Bar), K27 Hybrid Turbo, Ruf Twin-tip Muffler, Fikse FM-5's 8&10x17, 8:41 R&P |
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Registered User
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Quote:
As for the tensioners, I don't know the specifics of what was done during the full rebuild. I'm going to keep a close ear on this one and see how it goes over the next couple weeks.
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Merv '89 911 Turbo Cab Protomotive MAP ECU, Twin Plugged Heads, GT2-EVO CAMs, 3.3L fully finned P&C's, ARP fasteners, C2T head gaskets, Titanium Retainers, Turbo spec valves, springs & guides, 964 splash valves, GT35R BB turbo, GSF Stainless Headers, Magnaflow Exhaust, Full bay Intercooler, TiAL 46mm w/gate, TiAL 50mm BOV, Apexi AVC-R EBC, SPEC Stage3+ Clutch kit, Crane CDI Ignition ![]() |
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A fellow Pelacanite
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Quote:
I didn't do any special venting on my pressure fed ones...
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1981 UK 930. G50/01 shortened, 964 3.8RS Fibreglass Body Kit, 18" Alloys 8.5" F & 10" R, 225's F & 285's R, Special Colour Metallic Blue Paint, FIA Sparco Evo's, A/C and Air Pump removed, Electronic Boost Controller, GHL Headers, Tial46 WG. Fitting - New service kit. Needs Fitting - Innovate XD-16 Kit, Kokeln IC. Stephen's K27 HFS, EVO Intake Assy & his Modded USA Fuel Head. 1983 UK 911 3.2 Carrera Sport Coupe. Black, Black Leather with Red Piping, Black Alloy Gear Knob, K&N Air Filter Element, Turbo Tie rods. Needs Fitting - K&N CO Sensor, Round A/F Dial Gauge, Factory Short Shift Kit. http://www.danasoft.com/sig/Iamnotanumber.jpg |
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AircooledB4itwascool
Join Date: Jan 2006
Location: Barrington Hills, IL
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Piston Expansion?
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AircooledB4itwascool
Join Date: Jan 2006
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He did mention that it goes away when the engine warms up, Possibly the piston ring tolerances are a tad loose.
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Registered User
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Quote:
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Merv '89 911 Turbo Cab Protomotive MAP ECU, Twin Plugged Heads, GT2-EVO CAMs, 3.3L fully finned P&C's, ARP fasteners, C2T head gaskets, Titanium Retainers, Turbo spec valves, springs & guides, 964 splash valves, GT35R BB turbo, GSF Stainless Headers, Magnaflow Exhaust, Full bay Intercooler, TiAL 46mm w/gate, TiAL 50mm BOV, Apexi AVC-R EBC, SPEC Stage3+ Clutch kit, Crane CDI Ignition ![]() |
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AircooledB4itwascool
Join Date: Jan 2006
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Nothing to fix, thats completely normal. When you first start the engine, the pistons and rings are cold. When the pistons and rings are cold, the metal is contracted. As you progressively warm up the motor, the pistons and rings will expand, and then the noise goes away. Most people refer to this as piston slap, im guessing that this is the rattle that your speaking of.
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Quote:
Mind you, *IF* I ever have to replace the P&C's, I think I'd opt for some nice 3.4 P&C's next ![]()
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Merv '89 911 Turbo Cab Protomotive MAP ECU, Twin Plugged Heads, GT2-EVO CAMs, 3.3L fully finned P&C's, ARP fasteners, C2T head gaskets, Titanium Retainers, Turbo spec valves, springs & guides, 964 splash valves, GT35R BB turbo, GSF Stainless Headers, Magnaflow Exhaust, Full bay Intercooler, TiAL 46mm w/gate, TiAL 50mm BOV, Apexi AVC-R EBC, SPEC Stage3+ Clutch kit, Crane CDI Ignition ![]() |
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AircooledB4itwascool
Join Date: Jan 2006
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Merv,
No problem. I know Yermancars motor started to do that after they built the motor to a 3.3 Its very common with high performance rebuilt motors.
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Frank, have you heard of people "gapping the rings" for such high HP setups? I believe my engine builder just used OEM 930 rings, but I've heard that for such big HP applications, these rings need to be gapped appropriately to accommodate ring expansion in big power motors?
I guess this only relates to track cars tho, right?
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Merv '89 911 Turbo Cab Protomotive MAP ECU, Twin Plugged Heads, GT2-EVO CAMs, 3.3L fully finned P&C's, ARP fasteners, C2T head gaskets, Titanium Retainers, Turbo spec valves, springs & guides, 964 splash valves, GT35R BB turbo, GSF Stainless Headers, Magnaflow Exhaust, Full bay Intercooler, TiAL 46mm w/gate, TiAL 50mm BOV, Apexi AVC-R EBC, SPEC Stage3+ Clutch kit, Crane CDI Ignition ![]() |
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AircooledB4itwascool
Join Date: Jan 2006
Location: Barrington Hills, IL
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Merv,
No mater if the rings are OEM or after market, the way the rings are gapped are all dependent on the engine builder. During the build process the builder will file gap the rings to what his personal preference is. Some builders will gap tighter, while others gap looser. However, if the motor is being built for a high boost application, an engine builder will usually gap the rings to a larger tolerance like you mentioned.
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Thanks for clarifying... makes sense
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Merv '89 911 Turbo Cab Protomotive MAP ECU, Twin Plugged Heads, GT2-EVO CAMs, 3.3L fully finned P&C's, ARP fasteners, C2T head gaskets, Titanium Retainers, Turbo spec valves, springs & guides, 964 splash valves, GT35R BB turbo, GSF Stainless Headers, Magnaflow Exhaust, Full bay Intercooler, TiAL 46mm w/gate, TiAL 50mm BOV, Apexi AVC-R EBC, SPEC Stage3+ Clutch kit, Crane CDI Ignition ![]() |
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