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2000 Grand Prix possibly blown head gasket?
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USMC1st
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May 31, 2011, 3:44 PM
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2000 Grand Prix possibly blown head gasket?
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I have a 2000 pontiac Grand Prix GTP with the Supercharged 3.8 V6. Its an automatic and has about 174k miles on it. When I bought it the man told me that now and again the car would stall or sometimes act like its losing power due to a Crank sensor. However, not even two days after I purchased the car when the RPM reached 4K or higher I could hear a metallic rap in the motor as if it was failing. As I was driving home it continued to worsen and the noise would occur at lower RPM's until I had to baby it around 2K before it ceased. The CheckEngine light came on and flashed a bit before staying permanently. The car now is gutless and sounds like its dumping fuel. The Supercharger is giving full boost at only 2K RPM and it takes forever to get to speed. The coolant levels were really low and only down a quart on oil so I thought it might be a blown head gasket because it explains the loss of power if compression is gone. I removed the cover over the supercharger and noticed a little oil sitting on top of the intake manifold just under the front of the supercharger. When I checked the codes It read a cylinder 6 misfire so I checked the plug. It was completely burnt out. It crumbled in my hand when I touched it. What might cause that to happen?
-James
(.. no outside links please)
(This post was edited by zmame on May 31, 2011, 3:54 PM)
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zmame
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May 31, 2011, 3:53 PM
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Re: 2000 Grand Prix possibly blown head gasket?
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regardless if it is a headgasket or not the engine has to come apart if there is no compression. Once you take apart the engine you will know what it is. If there was knocking I would suspect mechanical failure, but you won't know for sure untill you inspect.
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USMC1st
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May 31, 2011, 3:59 PM
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Re: 2000 Grand Prix possibly blown head gasket?
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But what would cause a spark plug to literally catch on fire? The rubber was charred white and black.
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Mr.scotty
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May 31, 2011, 4:01 PM
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Re: 2000 Grand Prix possibly blown head gasket?
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Sounds like the whole engine will need a rebuild or just get another engine.
With a 174k miles I'd just get another engine..
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USMC1st
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May 31, 2011, 4:10 PM
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Re: 2000 Grand Prix possibly blown head gasket?
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Another thing I had noticed before when I had pulled over was that in Park it would Rev and sound perfectly fine only in motion did it act up. I cant afford a new motor. I want to fix the spark plugs first so I can hear it on all cylinders
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zmame
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May 31, 2011, 4:15 PM
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Pices of rubber??.. good possibility the supercharger might of piled up and sent stuff into the combustion chamber.. I would check that..
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zmame
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May 31, 2011, 4:17 PM
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Re: 2000 Grand Prix possibly blown head gasket?
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Did you actually do a compression test yet? or do you think there is no compression?
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Hammer Time
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May 31, 2011, 4:27 PM
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You really want to do a compression test as Z suggested and a coolant system pressure test. Another problem that is very common to this engine is deterioration of the plastic intake manifold near a water port which fill the vacuum vallly with coolant and eventually sucks it into the cylinders. There is a TSB on the problem also.
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We offer help in answering questions, clarifying things or giving advice but we are not a substitute for an on-site inspection by a professional.
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USMC1st
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May 31, 2011, 4:36 PM
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Re: 2000 Grand Prix possibly blown head gasket?
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Do you know if the problem was fixed after 1998? This is slightly newer. I have yet to perform a compression test but where Im noticing the oil ontop of the intake manifold is possibly either from the actual seal with the supercharger or the front valve cover due to the location. Im going to grab a Spark plug wire set and then perform the test tomorrow hopefully
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USMC1st
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May 31, 2011, 5:14 PM
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Re: 2000 Grand Prix possibly blown head gasket?
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Thanks for your help by the way. I just looked into recalls on this vehicle and there is a compartment fire recall that applies to this exact problem. Maybe they will fix it for me haha
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Mr.scotty
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May 31, 2011, 6:15 PM
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Oh.., so maybe it can be saved after all.
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Tom Greenleaf
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Jun 1, 2011, 1:12 AM
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Re: 2000 Grand Prix possibly blown head gasket?
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Quote">>Maybe they will fix it for me haha "<<
11 years and 174,000 miles - don't hold your breath for a freebee for this,
T
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USMC1st
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Jun 1, 2011, 5:38 AM
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Compartment fire recall. The valve covers leak oil on to the intake manifold which under heavy braking or acceleration drops it down onto the exhaust manifold and the spark plug wires catching them on fire. Now I know why it burnt out. I changed the plug wires last night and started it up. From the cold air intake I could hear an almost shearing metal sound but it vanished after a little time at idle. I test drove it and it seemed fine at first but as I came back up a hill it bogged down and the engine again couldnt keep above 2K RPM's and was obnoxiously loud. Now the Supercharger didnt kick in like before but I think its only because its running on all cylinders now. When the car was running fine the supercharger would only engage around 3500 to 4000 RPM. I can't even get it to that point to see if it works normally. When I parked it and throttled it a little I could hear what sounded like a miss but only when the RPM came down.
I called Pontiac and that recall is active and has never been performed on this vehicle.
(This post was edited by USMC1st on Jun 1, 2011, 5:38 AM)
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speed
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Jun 1, 2011, 9:31 AM
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Re: 2000 Grand Prix possibly blown head gasket?
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see if they will perform the recall for you, i woudlnt be usrprised if you spun the bearing for the supercharger also, just a guess as to why it doesnt kick in anymore, considering youve been hearing a metal on metal grinding noise.
GM ASEP 26 SCC Milford ASE certified in Brakes and Electrical on Thursday April 5th 2012
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USMC1st
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Jun 1, 2011, 9:58 AM
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Yeah the dealership is going to fix the valve covers and re-route the plug wires tomorrow morning but I don't know if they will fix anything that happens as a result of a fault in the vehicle. I called the parts department just to price the supercharger coupling and they claim GM only sells the entire Supercharger....yeah as if Im paying 1000 for that. Im sure there must be a kit. It's an Eaton M90 charger.
I don't know if the boost meter in the cab is dead on either, I just wish I could get it up to those RPM's in motion to see if the supercharger is working. Or I can take the belt off it and try to turn it with my hands to check.
(This post was edited by USMC1st on Jun 1, 2011, 10:00 AM)
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USMC1st
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Jun 4, 2011, 1:16 PM
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Alright a little update here. We thought the noise may be attributed to the coupler in the supercharger and now have it apart however there is no give in the coupler and it seems fine. The pulley doesnt rattle and seems solid enough but when I spin it the bearings inside sound almost like the noise I heard through the cold air intake. Could crapped out bearings really cause the motor to stay in the low RPM's? Going up hill its almost like driving a manual and not down shifting when you should; it has no balls whatsoever. I need help guys and thanks for everything you have suggested thus far.
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Mr.scotty
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Jun 4, 2011, 1:44 PM
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Re: 2000 Grand Prix possibly blown head gasket?
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If the bearings are making funny sounds and feel worn they are.
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Your only as good as your tools!
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USMC1st
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Jun 4, 2011, 1:53 PM
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But I don't see how bearings that still turn and spin fine would cause it to lose all that RPM. My other thought was if my cat convertor is junk. It over-heated only once to the point where smoke came up through the shifter and burnt out one of the spark plug wires(Cylinder 6)... It makes sense :/ If the exhaust cant escape then the airflow is screwed and I would have no power right? The only thing is the guy before me had it inspected two months ago and it passed emissions, could it really plug that fast? Or maybe something crawled in there and made a home haha
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zmame
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Jun 4, 2011, 7:41 PM
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Re: 2000 Grand Prix possibly blown head gasket?
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Reason you would have no power is because you had one cylinder not firing(because of damaged wire). If you suspect a plugged cat you can get a back pressure test done on it. Megnaflow direct bolt cats free up few hp and are relitivly cheap. There is a way to check for backpressure with vacuum gauge, but since it's supercharged the boost will mess up your readings. I don't know under what conditions the supercharger makes boost.
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USMC1st
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Jun 4, 2011, 9:26 PM
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I figured that was it zmame but we replaced all the wires and plugs and its still gutless and all cylinders are firing :/
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zmame
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Jun 4, 2011, 9:38 PM
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Re: 2000 Grand Prix possibly blown head gasket?
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test for backpressure, after that is verified make sure supercharger ismaking boost..
if you have been driving with a dead cylinder for a while the cat is probably damaged
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USMC1st
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Jun 14, 2011, 7:58 PM
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Re: 2000 Grand Prix possibly blown head gasket?
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Thank you all for your help. We were right on about the Cat convertor. It was completely blocked. We first removed it from the manifold and drove it and it ran fine. Just installed a new one tonight and it runs better than ever. Again thank you all for your advice :)
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