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Spark plug replacememt.....


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brcree

During one of my visits to the local Caddy dealer I took a moment to observe one of the mechanics changing out the plugs. I asked him the same question and he informed me the rear plugs are difficult to R & R, even for the mechanics with the various extensions , lift access, etc. Small hands, and familiarity working with what you can't see are a plus. Makes one wonder how many of the plugs actually get replaced when you pay to have the job done! Gotta have faith! If it's a mechanic you've never worked with before, I'd suggest asking for return of the old parts. I'd also recommend changing the boots at the same time.

Steve M

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I have never found them difficult but being tall has an advantage. Use 1/2" drive tools, 3/8" is ok but 1/2" easier to control. Stand on the passenger side, pushing is easier than pulling. Lay into it with your left hand grabbing the area where the extension attaches to the 18 inch breaker bar. They will come out.

Pre-1995 - DTC codes OBD1  >>

1996 and newer - DTC codes OBD2 >> https://www.obd-codes.com/trouble_codes/gm/obd_codes.htm

How to check for codes Caddyinfo How To Technical Archive >> http://www.caddyinfo.com/wordpress/cadillac-how-to-faq/

Cadillac History & Specifications Year by Year  http://www.motorera.com/cadillac/index.htm

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Remove ICM

Pre-1995 - DTC codes OBD1  >>

1996 and newer - DTC codes OBD2 >> https://www.obd-codes.com/trouble_codes/gm/obd_codes.htm

How to check for codes Caddyinfo How To Technical Archive >> http://www.caddyinfo.com/wordpress/cadillac-how-to-faq/

Cadillac History & Specifications Year by Year  http://www.motorera.com/cadillac/index.htm

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Using the front 4 plugs as a guide, can you see what is blocking the access to the rear four plugs? I have not worked on a 4.9 engine before but you might need to lower the front of the subframe/engine carriage in order to tilt the engine forward to gain access to the rear plugs.

Kevin
'93 Fleetwood Brougham
'05 Deville
'04 Deville
2013 Silverado Z71

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oh i keep forgetting this is a 4.9. I laid across the engine to get to those plugs. Wear gloves there are sharp items like screws through the firewall that can cut you. I dont recall the job being hard at all using proper tools on my 91 seville

Pre-1995 - DTC codes OBD1  >>

1996 and newer - DTC codes OBD2 >> https://www.obd-codes.com/trouble_codes/gm/obd_codes.htm

How to check for codes Caddyinfo How To Technical Archive >> http://www.caddyinfo.com/wordpress/cadillac-how-to-faq/

Cadillac History & Specifications Year by Year  http://www.motorera.com/cadillac/index.htm

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Lowering the cradle is a great idea. If you do that and remove the coil packs, it should become an easy job.

I once took mine to a mechanic instead of changing mine myself because I couldn't get the boot off number 1 without pulling the coil packs and realized that the trade between my time and money was tipped to get a professional. They used a young guy with small hands and an enthusiastic attitude, working under the supervision an ASE-certified mechanic.

Since it's so much trouble, I changed the wires at the same time.

Be sure and get them to put back all the wire looms and such when they put the wires in. Lots of mechanics will simply throw them away and that makes cross-firing more likely. This sometime happens with a plug change even when the wires aren't changed.

CTS-V_LateralGs_6-2018_tiny.jpg
-- Click Here for CaddyInfo page on "How To" Read Your OBD Codes
-- Click Here for my personal page to download my OBD code list as an Excel file, plus other Cadillac data
-- See my CaddyInfo car blogs: 2011 CTS-V, 1997 ETC
Yes, I was Jims_97_ETC before I changed cars.

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Thanks again for more info. I thought about the eng. tilt as a way. My 4.9 doesn't have coil packs....just one coil under the rotor cap. But still....there is no room between the eng. and firewall to get at these plugs.

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There are NO coil packs on a 4.9 as mentioned above by Jim, nor is it necessary to lower the engine.

Its a tight fit, the plugs are ringed by heat shields, use a proper extension length wear gloves. Use 1/2 inch drive tools and a good spark plug socket. I have done this job, it's tight but it can be done.

It is always necessary to get 2 hands on a ratchet it you ask me. One pulling or pushing and the other grasping the pivot point where the extension connects to the ratchet pushing or pulling in the opposite direction to create stability. Lay a tarp or cushion over the engine and get up there.

Pre-1995 - DTC codes OBD1  >>

1996 and newer - DTC codes OBD2 >> https://www.obd-codes.com/trouble_codes/gm/obd_codes.htm

How to check for codes Caddyinfo How To Technical Archive >> http://www.caddyinfo.com/wordpress/cadillac-how-to-faq/

Cadillac History & Specifications Year by Year  http://www.motorera.com/cadillac/index.htm

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Lowering the cradle is a great idea. If you do that and remove the coil packs, it should become an easy job.

I once took mine to a mechanic instead of changing mine myself because I couldn't get the boot off number 1 without pulling the coil packs and realized that the trade between my time and money was tipped to get a professional. They used a young guy with small hands and an enthusiastic attitude, working under the supervision an ASE-certified mechanic.

No coil packs on a 4.9 engine - it has a single coil and distributor.

Kevin
'93 Fleetwood Brougham
'05 Deville
'04 Deville
2013 Silverado Z71

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Yeah, I didn't realize that it was a 4.9, of which I know little, unfortunately. The 4.9 is a great engine.

CTS-V_LateralGs_6-2018_tiny.jpg
-- Click Here for CaddyInfo page on "How To" Read Your OBD Codes
-- Click Here for my personal page to download my OBD code list as an Excel file, plus other Cadillac data
-- See my CaddyInfo car blogs: 2011 CTS-V, 1997 ETC
Yes, I was Jims_97_ETC before I changed cars.

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Why anyone would put a 4.9 in a Fiero is beyond me....I think something like a Quad 4 would be a more realiistic mod....anyway...nice, clean, rear bank 4.9L spark plug pictures on this link.

http://www.fiero.nl/cgi-bin/fiero/showThread.cgi?forum=2&thread=129733&style=printable

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The hot setup is a Northstar in a Fiero!

I'll agree that a Quad 4 HO with a 5-speed would be a great setup for a Fiero.

CTS-V_LateralGs_6-2018_tiny.jpg
-- Click Here for CaddyInfo page on "How To" Read Your OBD Codes
-- Click Here for my personal page to download my OBD code list as an Excel file, plus other Cadillac data
-- See my CaddyInfo car blogs: 2011 CTS-V, 1997 ETC
Yes, I was Jims_97_ETC before I changed cars.

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