140k Service

[CrazyHorst]

This is a brief summary of the 140,000 mile service I just did to my 2000 GTP.

Original intent...

- change supercharger oil (never previously done)
- change plugs and wires (had low rpm/high load "misfire condition", original parts)
- change A/C compressor (charge leaking down over 3-4 months' time thru shaft seal)
- change tstat and CTS (SES code, unsure which one was causing the issue)
- change upper and lower rad hoses (maintenance item)
- change post-cat O2 sensor (SES code)
- change front brake rotors and pads, power-flush all 4 corners

The project expanded due to findings later to include

- flow straightener (found damaged)
- air filter (found chewed by a mouse!)
- A/C condensor (lower corners folded over and looked suspect)
- A/C accumulator, suction and discharge hoses, orifice tube, new PAG oil (recommendation of A/C tech)
- main and S/C accessory drive multigroove belts (cracking)

First a little background on the car, my brother owned this car since purchased new from the dealer as a 2000 model GTP. It lost the 4T65 around 85k and the fuel pump around 120k. Not sure what other service or problems it had but not being DIY he wanted something newer with less probability of expensive repair work...so we worked out a deal.

One thing you'll note from looking over the photos is the cage is rusty underneath...spent most of its life in west Michigan which is prone to a lake-effect snow every time a system goes thru...so it has seen its share of salt spray durability.

Here are a couple of pictures of the project. All parts purchased were Rockauto - AC Delco with the exception of the supercharger oil which was purchased from the dealer.

I started looking over the thermostat housing planning ahead and had these funny winged seeds inside the engine, strange, but continued on..



Inside the airbox and below the PCM there were two heaping handfuls of the durn things...apparently a mouse had started stashing them inside there while the car sat outside for about a month in October! The mouse had also chewed the air filter (presumably looking for more storage space ). Luckily I had only driven about 2000 miles since then.



When removing the intake ductwork boot I found the flow straightener (honeycomb) had been damaged...perhaps the source of my low-rpm misfire (???). I am guessing this happened at the time when the Trans was replaced.



Next, changing the spark plug wires I found this...also possibly related to the low-rpm misfire condition. I cleaned these with a wire brush and gooped a lot of dielectric grease on both boots. Carefully followed the GM routing and transferred all the split black conduits and aluminum heatshields over.



The A/C condensor had many many folded fins on the lower portion...I changed this as to improve cooling performance but also to eliminate any chance of having a weak spot and having to do the job again twice.

[CrazyHorst]

Couple more related photos...

I removed the front fascias (there are two parts) as I wasn't sure what I really needed. I could have done the project without it...but I think it ended up being easier, especially with the lower/horizontal part removed.



The new flow straightener...coax the "snap ring" out of the groove with 2 pocket screwdrivers...work gently as the new part is fragile. I used a 2x2 block of wood to help seat it in the counterbore...I was worried I'd damage it with my fingers. This worked well, and the snap-ring needs a little coaxing to get back into the groove...it is not nearly as tough as a traditional spring-steel snap-ring used as a bearing retainer or other. Either the flow straightener or cleaning the coil pack posts cured the low rpm misfire completely (approx 45 mph, 4th gear locked with 2 bars of boost going uphill)



If you change the A/C compressor, removing the coil pack bracket helps greatly. There are 3x 15mm nuts on the pulley end of the compressor and 2x 15mm bolts on the back end of the compressor. I also had the advantage of the AC condensor and the radiator out of the way...but definitely not necessary. I assembled the suction and discharge hoses to the compressor to avoid any contamination before I installed this assembly into the car.



The radiator can only be removed or installed like this...the reason is the radiator "pilot" which seats in the sheetmetal support must "hook" under the connections to the AC condensor which is directly above this. The trans cooler lines I found easy to use a pocket screwdriver and very carefully pry out the spring-wire clips. Advance Auto sold me the "proper tool" which wouldn't even fit over the lines...I returned this. The spring wire clips are easily reinstalled into the connector bodies later. The lower fascia must be off to access the lower line unless you have a 3 foot long neck or the dexterity of a cirque de soleil performer

[CrazyHorst]

I own and use the Motive Products 1-man brake bleeder...best one I've yetused...bought this from Summit Racing.



I had to order a new 3-prong adapter for the GTP...the older pickup trucks use the big "bathtub" brake fluid reservoir which uses a different adapter.



Last...as a final insult, I broke my dipstick handle...in two places. One up under the "cover" and the other right thru the o-ring gland. Being in somewhat of a hurry but not wanting to drop the parts down the stick and into the oil pan, I elected to use some globs of RTV sealant...this worked very well until I can get another part. The looped handle is the "corporate" handle which is pinned to different sticks for different carlines and many many many were broken at the assembly plants. The newer handle is tougher...




This is how I "roll" the engine forward to work on the rear cylinder bank or the O2 sensor..with a ratchet-strap. With the radiator in the car, be careful not to damage the fan motor's heatshield with the exhaust manifold. Note the wiring harness doesn't have to be like that...just happened to be that way by circumstance.



Quick note regarding the A/C system...my A/C tech recommended that I buy 8oz of the GM PAG oil (from the dealer) and put 6oz in the crankcase of the V5 compressor (thru a bolt on the OD of the case), 1oz in the accumulator and 1oz on the condensor. He asked that I rotate the compressor by hand a few times after the oil was in there. The A/C system evac'd properly and showed no leaks and was working well when I tested it over the weekend...had some 65F days in Atlanta area on a road trip.

On the brakes, I have no pictures but I bought a green synthetic "brake lube" product by Permatex. This went on the guide "ears" on each pad, and the piston and the "backer" part of the caliper casting (basically where the caliper contacts the pads). It is safe for the rubber piston with the caveat that it is not to get on the friction surfaces. I break in the pads by "driving like a grandma" with long gradual stops for the first tank of gas and then build up to my normal harder braking level.

[CrazyHorst]

A "Stage 2" project is planned for the near future.

- head gaskets
- lower intake gaskets
- supercharger gasket
- coolant elbow
- heater hoses & tensioner bracket connectors
- accessory drive idlers (bearings sounding iffy)
- crank position sensor
- anything else that comes up between now and then......

[tblake]

Very nice job!

You should be all set.

If I remember right I snapped my dipstick handle in half in the same place you did when I changed my front 3 plugs. Same deal. I got a replacement from the dealer.

[CrazyHorst]

FWIW....used the AC Delco 41-101 spark plugs on this job.

My mileage (here indicated by the DIC and not yet from actual gas-pump and mile data) went from best of 25.2 up to a brief 25.9 on a 250 mile trip that I do regularly and drive about the same speed (target 75-77mph).