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'05 montero limited - an engine light came on while driving on the highway, then turck died 2 km later at about 2500 RPM and when it was restarted there was an engine knock that was VERY loud. Towed to dealer - the codes came up as #2 cylinder mis-fire and engine failure.

Turns out the knock was the spark plug in #2 has stripped it's threads in the head and was bouncing up and down between the head and the spark coil on the valve cover - and the 3 inch connector between the plug and coil was missing.

The plug literally looks like it has been beaten with a hammer, the gromet on the bottom of the coil is chewed up, threads in the head are completely stripped. The tube (plug boot) going from the coil to the plug is no where to be found. Dealer tech has no idea how this could happen. Engine would always have been knocking without the connector yet it happened very suddenly. Hood hasn't been openned in 4000km, since oil change and it has been runnung great on several long drives. Thoughts

Submitted: 127 days and 16 hours ago.

Category: Car

Value: $23

Status: CLOSED

Year: 2005
Make: Mitsubishi
Model: Montero Limited
Engine: 3.8L V6

Already Tried:
Dealer. They are completely confussed and are trying to decide if they tap the threads on the head or replace the block.

Posted by Cardoctor74 127 days and 16 hours ago.

Info Request

Was here any repairs doen prior to this happening?

127 days and 16 hours ago.

Reply

No. All tune ups have been doen by the same dealer. Hood literally has not been openned for 3-4000 km since last oil change (by brand name chain). Even teh tech said he had to "crack" the nuts to take the coil off and that they had not been off recently.

Just before the engine light came on I could feel a wheel bounce from the rear right wheel like it threw a wheel weight - assuming that was the engine unbalance from the mis-fire coming through the drive train. Take your foot off the gas and it mostly went away then came back with throttle. Then light came on..engine got rough then cut out.

Posted by Cardoctor74 127 days and 15 hours ago.

Answer

Ok this is most likely caused by a bad casting at the factory and over time the plug started walking itself out ive seen this a few times before and alot of times it could be from the piston actually became loose and actually knocked the plug right out of the head so before they make any decesions they need to look at the top of that piston because if they decide to helicoil in the plug which i dont agree they should it can be that that motor is damaged and will happen again also call the corperate office and let them know what happend either way im sure they will cover the repair

127 days and 15 hours ago.

Reply

any ideas where the platic boot from the coil to the plug could have gone? The spark wouldn't jump that gap and would arc off the side metal tube I would assume.

If it walked itself out would that have stripped the threads? Although the first thread could likely just be damaged by the plug firing up and down in there I would guess.

Tapping the threads would not be an option correct? I would assume it would leave filings in the cylinder head which woudln't be condusive to long engine life

Accepted Answer

YEs definately do not want to tap it will contaminate the cylinder with metal shavings ,the plastic boot most likely broke when the spark plug came out of the head and is either laying in the frame of teh motor or fell to the ground

Accepts:
Expert:	Cardoctor74
Pos. Feedback:	98.4 %
Answered:	7/17/2009

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Optional Information

Year: 2005
Make: Mitsubishi
Model: Montero Limited
Engine: 3.8L V6

Already Tried:
Dealer. They are completely confussed and are trying to decide if they tap the threads on the head or replace the block.

Info Request

Was here any repairs doen prior to this happening?

Reply

Answer

Reply

Accepted Answer

YEs definately do not want to tap it will contaminate the cylinder with metal shavings ,the plastic boot most likely broke when the spark plug came out of the head and is either laying in the frame of teh motor or fell to the ground

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Question

Optional Information

Year: 2005Make: MitsubishiModel: Montero LimitedEngine: 3.8L V6 Already Tried: Dealer. They are completely confussed and are trying to decide if they tap the threads on the head or replace the block.

Info Request

Was here any repairs doen prior to this happening?

Reply

Answer

Reply

Accepted Answer

YEs definately do not want to tap it will contaminate the cylinder with metal shavings ,the plastic boot most likely broke when the spark plug came out of the head and is either laying in the frame of teh motor or fell to the ground

Related Car Questions

Year: 2005
Make: Mitsubishi
Model: Montero Limited
Engine: 3.8L V6

Already Tried:
Dealer. They are completely confussed and are trying to decide if they tap the threads on the head or replace the block.