1989 C4 Functional Restoration

[SirReal63]

The door cards needed a lot of attention, thankfully it was over 90 degrees so the epoxy set quickly, instead of the overnight issue I had with the console pieces.

The passenger side was actually ok, some cracks and a little missing plastic but mostly intact.
Drivers side, broken, missing plastic, missing the metal brace, drywall screws holding it sort of together, etc. I think I can make this work again without drywall screws



Let's see if I can make a mess of the drivers door, I don't think I can make it worse.

Epoxy, wood, clamps, tape, Baggies, etc.






After round one cured,








After touching up and round two





Lots of sanding, shaping, drilling and a little paint. I did find the metal brace in the bottom of the door but no missing plastic.

 

[SirReal63]

Since I have the doors apart it was time for some maintenance and changes. I cleaned the dust and dirt off of them, only the driver side had a water barrier on it, the bottom of the doors were thick with dirt and misc. debris that I was able to loosen with a brush and vacuum out. The weep holes on these doors are huge and would be nearly impossible to clog up, good on GM for that. I cleaned and lubricated the window tracks and rods. The electric lock actuators work just fine but both doors had the rods removed, more things to ponder on this cars past.

I decided to make the speaker pods function with 6.5" speakers as I like the idea of using them and the way the old Boston Acoustics speakers were mounted was atrocious. Step one remove them, it was actually easy once the seal was broken, they just peeled right out of there.



Their design worked well for the small Bose speakers but the angle of the baffle meant putting a 6.5" in there would require some re-design and the port tube would no longer function, which is fine since the enclosure would not be tuned to take advantage of that port with a different speaker but it would add some rigidity to the area.



I cut down some ABS sheet to make a new baffle that would accommodate the 6.5 and figured out where it needed to be placed to add strength and heated up top and bent it to make the bend at the top. I used ABS cleaner and glue to bond the new baffle.This gave me a nicely sealed enclosure to mount the driver to.



The mounting hole had been cut and enough of the guts of the enclosure removed to fit the basket and magnet. I did further trimming after this pic was taken to ensure the driver sat perfectly on the baffle.



Driver mounted to baffle and enclosure with added Polyfill



Enclosure mounted and a little deadening added. I played around with the mounting position to get the driver as evenly centered in the door opening as I could which meant painstakingly measuring the existing holes and making new ones. In the end I will probably go back to the original holes, they were actually close and I wasted time fixing an issue that wasn't an issue. lol



Everything buttoned up, for the moment.



The sound improvement was dramatic, the mid bass tightened up and there is now actually bass below 50hz which it did not have prior as it was basically playing in free air because of the shape of the enclosure and the driver not being able to seal against it. I have ordered some Ensolite door barriers to replace the missing passenger and original poly one on the drivers side.

I put the brakes on this part of the project because I won a bid on a pair of Infinity Kappa 62iX which are discontinued and the new replacement from Infinity is a cheaper version of this driver that doesn't play as low, Harmon is making their Kappa line look better but built cheaper. When they arrive I am going to see if the will fit in the enclosure. I have used these speakers on a few projects, they are one of the best mid-fi car audio 6.5's you can get. On my Yukon Denali I ripped out the Bose LUX system and replaced the door drivers with these and a couple Kenwood KAC-M3004 bridged amps and the difference in SQ was incredible. I have doubts they will fit in the C4 enclosure but I will find out, I also have doubts the SQ will be noticeable, the Denali is whisper quiet inside so it is apparent while the convertible is anything but quiet inside. While I have no problem running the antique Boston drivers in this car, if I can make an improvement I will.

Once I have the enclosures finalized with the drivers I get to work on how to integrate that into the door cards and fit a round item into a square hole and make it look decent. The stock covers will not work with a 2-way design.

 

[SirReal63]

Early in my management career my mentor told me to never change anything until you know why it was being done the way it was. This advice mostly served me well for decades, but sometimes we get off on a tangent that was flawed from the beginning and didn't realize the flaw until we step back and look on things as a whole. I knew I changed the position of the center of the driver, which should have changed it's relationship to the door card. It did but not by as much as I thought it did, it changed it by 3/8 to 1/2 an inch, not the inch my brain extrapolated.

I just set the door card on the door and noticed two things, I can drop the enclosure down a half an inch and it will be fine. I can also use the original speaker covers, by mounting the driver to the face of the enclosure it is now far enough inward that minimal trimming on the cover will be needed to make it fit back like it is supposed to be.

This may not be the same with the Kappa drivers, time will tell.

 

[SirReal63]

It is now officially too dang hot to be in the shop for more than a few hours each day. I had originally planned on A/C in the shop but the cheap Janus doors and the hideous expense to replace them with insulated 10' doors made that a very long term goal. I could go out there in the evening but typically the evenings are our time together, dinner, movie, etc. I have been going out in the morning before the day heats up the shop too much. Those dang doors are a cold plate in the Winter and a hot plate in the Summer. lol

The Kappa's came in and they did fit the enclosure, not much modification was needed to get them in. I finished cutting out the port tube, leaving about 1/8-1/4" ridge to match the original for strength purposes.





Installed in the door, with some cheap butyl 50 mil sound deadening added in key places. The interior of the doors give a nice thud now instead of a ring, I will take that as a win for sound deadening. I was wrong, the difference in SQ was more than noticeable, it was stark, at least sitting still with the engine off but they do play lower and overall clarity was a great improvement as well as actual mid-bass.











With that part of the door refresh done, I also replaced the door lock actuator rod bushings and lubed everything up again. Everything works as expected now.

 

[SirReal63]

I had some time to kill while waiting on parts so I tackled a little issue, the black insert on the drivers door card only had 2 points of attachment at the top instead of all 3. I decided to try and correct that.

A piece of 1/8" ABS plastic, cut oversize, would fill in the missing piece of plastic the speed nut attached to. I sanded the area with coarse grit paper, used the correct ABS cleaner and glue and glued the replacement oversized piece in place. I replaced the speed nut and popped a new screw into it, it held perfectly. I did the passenger side as well as it was missing the same speed nut and screw.













I had ordered a pair of Ensolite door vapor barriers a couple weeks ago and the Post Office finally decided to deliver them. They are only 1/8" but will work nicely to seal the moisture out of the interior. I wanted to use butyl rope to seal them to the door but being foam I did not want them to rip if I ever take them off. I anticipate I will will have to get back in this door some day and do not like the idea of having to replace these again. I needed a way to seal these to the door and have them be removable. I decided on some clear Scotch Heavy Duty packing tape, the thick and sticky stuff. I applied it to the perimeter of the foam where the butyl rope will be. It works as intended, the butyl sticks to the tape but will release with a little pressure while keeping the butyl affixed to the door. The tape stuck very well to the Ensolite and I can remove the vapor barrier without damage.

These vapor barriers are supposed to be an exact fit but in reality they are not and I had to do some trimming and modifying. I ran out of the tape and have ordered some more, when it comes in I will go back over these and fix the areas that are not sealed to the inside, at least where I can.





My last problem to address is the round speaker with a square cover. The Boston speakers worked with the stock square speaker covers but the Kappa's do not, the tweeter sticks out too far. I had some old 6x9 speaker grills left over and played around with them, they will work until I think of a better solution or replace the door carpet. With the doors closed you do not see the corners and with the door open you have to really look to see they do not cover completely. I am waiting on some black nuts and bolts to secure them with as I don't like the speed nuts here. When those come in I think I can finally put the door cards back on the car and move onto something else.





I charged the A/C after finding the leak was the Schrader valve not being tight. I tightened it up and charged the system and used my little R134 sniffer and can find no other leaks, it blows nice and cold. My idle is still all over the place and A/C still coming out all of the vents at once. I probably won't worry about the vent issue now, though I do have the parts to fix it, most of my Summer driving will be with the top down so I can live with it. Getting under the dash is a job I am not looking forward to, my back is still a little twingy and I don't have to have A/C so it can wait a little while. The idle is something that cannot wait so I may be taking the whole intake off and looking for something obvious. It isn't a vacuum leak from the A/C or cruise control as I have those lines plugged. It is always something.

 

[SirReal63]

I am still chasing a high idle issue, after my check of the IAC and minimum air position, checking the TPS voltage and making sure everything is still plugged in correctly. I used my little injector pulser and all 8 injectors are pulsing, correctly it appears, so I bought a little clamp meter to see if something was shorting out but it checked out fine. The clamp has a DVM built in so for grins I decided to check the TPS with it, I am glad I did as my 10 year old Klein DVM gives a very wrong reading on the appropriate DCV scale. I set it with the new DVM and realized just how far off it was. This did not cure the high idle but for a while it would start at 1100 and after closed loop it went as high as 1800 rpm's. Now it is back to starting up at 700-800 rpm's and climbing to 1000-1100 rpms.

I have never checked base timing on this engine, or any engine in decades, so I bought a cheap inductive timing light and set about that task. It wasn't as easy as reading the timing, the indicator tab and balancer were both rusty messes, really rusty and impossible to read/see. I got the balancer cleaned up with some 400 grit sand paper and a piece of long and flat wood, gently polishing it with the engine running. (I will not recommend that method as it has hazards associated with it, but it worked perfectly, for me.) Getting the tab cleaned up was another matter, I soaked it in rust remover and that kind of cleaned it up, but not enough to read the timing marks. I went after it with sandpaper, emery boards and brake clean. The indentations are very faint/non-existent. I painted it white and used the emery board again to hopefully remove enough paint to expose the indentations but that also did not work. I went searching around on the internet to find another example the same as mine, with the deep cut at 0 deg. I finally found one on a YouTube video that was the same and could see the first peak from the zero valley was 4 deg. and the next peak was 8 deg, meaning the valleys fell in between. Perfect, so now I know where 6 and 8 degrees are, time to mark them in black, unplug the EST and hook up the light.





I found the base timing set at approx. zero deg. so I went looking for my distributor wrench, didn't find it which wasn't a surprise as I haven't see it in a long time. I ordered one from Amazon and it arrived and was put to use. It did loosen up the bolt for the dist. but was not really very easy to maneuver. I reached in the toolbox and pulled out a 9/16 ratcheting wrench with an adjustable head and used it for the bolt, worked perfectly, tossed the distributor wrench in the box, it will probably never be used again. I set the timing between 6 and 8 degrees, it bounces a little, tightened the bolt back down and checked it again, it didn't move.

Yay me, I wasted a couple of weeks with an inaccurate DVM, delivery lead times. At least all of these tasks will be easier next time with no waiting, so I call it a win.

I had decided months ago that I wanted to be able to data log what was happening with the engine, but that required more collecting parts, the bane of my existence lately. There are numerous choices from commercial made mechanic specialty tools like the Snap On MT2500, the OTC 4000 series, etc. but not really any new pieces of equipment. I considered ALDL Droid as I have numerous Android devices but file transfer between formats is a pain. I decided on a laptop but I wasn't going to spend the money for a new one when the only thing it would do is data log from the C4. It took me a week of shopping to find just the right tool, a ThinkPad T490 from 2019 that was in pristine condition. It was only slightly more expensive than others on Ebay and Marketplace and it had all the specs I wanted, 500g NVME drive and 16 gigs of Ram. The local Marketplace options were downright silly for what you are getting, I quickly passed them by and I won't buy a Dell, HP or other brand. I scored with this laptop, the battery has 90% health and the device itself has zero wear. It looks like it came out of the box brand new and functions perfectly. Typically the cases are scratched and the touchpads worn, this one has none of that, it looks like it was never used and came with a brand new Lenova charger. A nice score for $200 and I also got a pristine UltraDock for it for another $25. I will take it.







I ordered two different ALDL cables, the Red Devil River one that took a week to get and the BoostedNW one that is supposed to be the replacement for the Moates ALDU1 but there is no telling when I will get that, the company is horrible with communication.

I downloaded WinALDL and after configuring the ports got a successful data log but it was a pain to read and reminds me of 1995. I also downloaded TunerPro RT v5 and have been trying to take on the steep learning curve. Today I did manage to get a couple successful connects and logs and I imported them into Log Analyzer v32-18, such a better log viewer. The good/bad news is I cannot find anything obviously wrong. I haven't driven it and logged yet as it is raining and muddy here and will be for another week, my logs have been idling in the shop so things may change when I drive it or learn more about what the correct parameters are.

Nothing beats new toys and the chance to learn something new, well, old and outdated. The good news is I can also get a deeper scan into our OBD2 vehicles with the same software and laptop.

 

[SirReal63]

Overall update from the work I have done since October to August.

I took the car out on one of our very bumpy back roads and I have no rattles of any kind, top up or down. No dash rattles, no door window rattles, no rattles of any kind. I can say without a doubt to take the time to repair any broken plastic in the dash, lube and go over the door window and lock components to correct any broken clips or missing plastic and check function. It is amazing the difference in how a car feels when it isn't rattling, it went from feeling like a tired old 80's car to a much newer and higher quality car.

The sound deadening and insulation made an incredible difference in how quiet the car is with the top up. I was surprised, though I have done this treatment to several of my cars in the past, it made the biggest difference on this car. I am not ready to take it on a long trip yet but I do know it won't be a tiring drive. With the windows up or down the stereo now sounds decent, I want more lower bass but that is only going to happen with the addition of a sub which is a low priority right now, it is passable as it is.

I have spent the past few weeks trying to learn OBD diagnostics to figure out why my idle is so crazy. I have a pile of logs both driving and idling. With the help from some good people on a EFI forum and looking over my log files there does not appear to be anything wrong mechanically but there is a high probability that there is something wrong in the ECM as the Desired Idle is set at 1050 and the car does what it is supposed to to keep that idle speed and it does. I do run lean more than rich and the ECM adds or removes fuel as it is supposed to. I am not far from adding in another system to control the engine, whether that is Holley, FiTech, EBL or ??? I am leaning towards the FiTech Ultimate TPI as it appears to be the most user friendly and plug and play system and has the added benefit of being the cheapest with the least amount of work to install and tune. I will leave it as it is for now, I hate for things to not work correctly but it also isn't the most important thing to worry about right now, it is just annoying.

I am not sure where I am going next with this car, paint and body work is probably going to be next but I really want to wait for cooler weather before taking that task on.

 

[SirReal63]

Time for a short update, (short on work and long on words)...not a lot has happened with the car, too dang hot, but I have done a few things.

I replaced the sun visors, this has been on my list since day one, but hasn't been a priority. I had considered rebuilding them but with plastic insides instead of the hardboard the originals had. I could replace the fabric/foam easily enough but the hardboard structure has disintegrated. I also considered just replacing but most places wanted $200+ for new ones, which I find silly as there is no value in that. Another member here found a set on Amazon that were half the price and looked just as good. I had these in a shopping list on Amazon and saw the price had dropped to $65 for the pair and I pulled the trigger. I did not expect them to be a quality piece, but that didn't really matter as these are more of a wear item with the amount of sun exposure they get. I was surprised, the quality appears to be every bit as good as the stock ones are, even the weight is about the same. At $65 bucks if they last a year they are still a bargain but I suspect they will last many years.
https://www.amazon.com/dp/B0BMLFDPWP




I had recharged my A/C but it only lasted a little while, which did not surprise me one bit. I decided to learn a little about what my Dad did not want to teach me and bought a cheap set of gauges and a cheap vacuum pump, I have two other better quality vacuum pumps but they are for our food freeze dryer and I wasn't sure about cross contamination and the $108 kit came with a pump, so I could leave my expensive pumps out of the equation. I already had a refrigerant "sniffer" and found no leaks other than the low side port so while the system was uncharged I replaced all of the o-rings with the correct R134 compatible ones, the only exception was the manifold to compressor ones as my kit did not include the correct ones. I did manage to find what appears to be the correct ones but it would be weeks before they arrived and the original ones were in great condition so I put them back in. I relaced the orifice tube with an ACDelco 15-50122 .0165 tube and noted the old one was in perfect condition, no dirt, no black debris no clogged screen but also no markings to tell me what it was so the new one went in.

I pulled a vacuum and found no leaks, it held a steady -30 inHg for a few hours, all should be good. I replaced the accumulator/drier and added about 2 oz. of Esther oil to the drier as well as a smattering of dye. The system called for 2.25 pounds (or 36 oz) of R12 so I added 80% of that ( approx. 28.8 oz) of R134. With the system all buttoned up I was only getting about 60 degrees out of the center vent, with an ambient temp of 105, which is a 45 degree delta, not bad but also not great. I had wanted to change the condenser as I am certain it is the original one designed for R12. I had been shopping for a Spectra Premium 7-4020 parallel flow unit but they were out of stock everywhere except Canada and the price was ridiculous so I passed. I noticed this morning the Spectra unit is back in stock in a few places so I ordered one for $90 bucks dlvd. which is way better than the $210 Napa version that could be special ordered. (This is why I almost never buy anything from Napa) The new condenser will be here later this week, so I have it and the manifold gaskets on hand if I want to try and get better cooling.

I have been making preparations to paint my doors, which is going to be a fun learning experiment. Step one is getting the excess junk out of the shop that was never intended to store it. I was going to build a 12x24 pole barn structure out by the well but started looking at other options. It would cost me about $2,000 to build my shed and most of that was in steel. We have challenges with building on this property, we have anywhere from 6" to 16" of topsoil and below that is solid limestone in most places, kind of tough to sink poles into solid limestone. I had hired a guy with the proper equipment to do our fence posts but he got out of that business and my antique auger will not do it. I started looking at portable garages and decided on the 12x20 Harbor Freight one. It is not a durable structure but it can be made into one once the tarp material disintegrates. That is the short term and long term plan, use it as is until the tarp material goes away then cover the structure in steel roofing.

I needed a somewhat solid structure to put this on. Our property is not level, it has a slight slope from North to Southwest and when it rains hard the watershed can be substantial. I decided on 4x4 treated posts that had been leveled on each side, 3.5" on the North and 5" on the Southwest side. This gave me a mostly level surface to put the frame on. To keep water from flowing under the 4x4's I added 2x4's dug down about 3" all around the perimeter. I was initially going to pour a concrete base to hold the frame but the cost was too high and my old body could not stand the digging in 105 degree weather. It would also have been mostly permanent and the treated lumber was about a quarter of the price, could be removed and moved easily and my old body could do it. I got lucky, after the 4x4 base had been built, my wife's workers came in and dug the perimeter for the 2x4's so I ended up digging almost zero of this brutally hard clay soil. I did not want to store anything directly on the ground so I built a 2x4 treated subframe and glued and screwed 3/4" plywood to it for a floor that won't get water on it if hard rains manage to flow under the base. I painted the floor white and will go over that with some Varathane for added durability.

All that will remain is some shelving and to fill it up.







I have more bracing to add, and I did drive 36" rebar at an angle through the 4x4's into the limestone with a sledge and the screw anchors as far down as I could get them into the soil. Ratchet straps hold the entire structure to the ground, it will take a serious wind storm to uproot this.

Now I can begin collecting more painting supplies and go through the shop junk and move what I want to keep and toss the rest.

I have been putting some miles on the car, it is currently filthy which is a good feeling, getting miles on it, cranking the tunes and happy that there are currently no rattles.

 

[SirReal63]

Time for an update though I have done very little to the car in the past month. I have been collecting parts, paint supplies mostly and I managed to get a parallel flow A/C condenser, well, actually 2 as the first was somehow run over in transit. UPS is really good at delivering labels. no matter what happens to the package they are shipping. This was hanging halfway out of the box with a tire tread over it. Fortunately Amazon promptly replaced it. I was in a panic, the Spectra 7-4020 units seem to always be in short supply and I was concerned a replacement might not be available for a while. The replacement came in and was in pristine condition. The original was pretty mangled and banana shaped. It is not installed yet but I at least have the right one for when the time comes.







Time to address the mis-matched paint. If you remember, the car had been repainted prior to my ownership, poorly painted and they did not paint the doors, for some unknown reason. I had concerns about getting a decent enough match because I had no idea who painted the car and if they got a good enough match to the original Brilliant Red Metallic 68/WA9239. I took the front license plate cover off as we are required to run a front plate here in Texas. I used it to compare the color on the rest of the car. It too had been repainted and there are several different shades in the repaint. Great, it is going to be fun making this look halfway decent. The goal is not a perfect paint job, the goal is a close enough match to the existing paint. I would love to strip the whole car down and paint it all at once but that isn't going to happen, at least not at this time. I am ready for criticism, laughter, jokes and for someone to poke me in the eye for doing this.

I ordered 5 cans from PaintScratch.com and a can of primer. I won't need the primer for the doors but I may for other areas and it is always good to have primer on hand. Five cans is probably way more paint than I need but I figured I would need to do some testing to see if I could make it match close enough. Spraying metallic is a gamble, and I knew this going in, it is a mistake to spray heavy coats as the metallic particles can rise in the carrier before it dries and the color of the base will effect the end result. I decided to do what was probably done when the repaint was done, sand the original enough to get some "tooth" and paint. Looking at the areas where it is chipping, like around the antennae, it looks like that is exactly what was done. If I have any hopes of this matching close enough then I need to follow the same procedure, no matter how much I do not want to.

I had planned on using a 2K clear coat but decided to not as I understand it can be difficult to work with and the guy at PaintScratch suggested a 1K product. I think he may be right, the clear that is on the car probably isn't a high quality clear, it has failed in a few places and will be easier to remove if I need to. As far as I know this could be a Maaco paint job as it wasn't done very well. I ordered some Eagle Abrasives Super Assilex paper in a variety of grits from 600 and up. I decided against the Mirka product based on the recommendation of a few videos I watched on this process. I got a 3M 6211 mask, tack cloths, a variety of blocks, 3M taped plastic drop cloth, a comfort grip to hold the cans and give my arthritic fingers a break, paint-prep wax and grease remover and SprayWay cleaner. I have enough to stuff to do the first test.

The problem before any repair attempt is made, just de-waxed and clayed...












A little masking...




A little paint...





It is clear that I need to do a little more sanding in a few places and move up in grit as the 600 grit scratches are visible under light, thought they are not visible with the naked eye. Next is a little Upol Clear and a prayer it is a close enough match.

 

[SirReal63]

I experimented with some U-pol 1k clear last night, it was a disaster. It was around 72-75 degrees in the shop and the stuff just would not lay out correctly. I had a lot of dusting and uneven spray from drying way too fast. The only way to get a decent coat was to be about 3" from the surface and at that distance it tiger striped excessively, as expected. It was warmer when I sprayed the base so I suspect some of the issue is the nozzle on the clear, it is way too wide of a pattern. It took one 12 oz can to do the door and the battery cover, 75% of that was on the top half of the door. I ordered some SprayMax 2k gloss that will be in this weekend, I will give that a try.

The only part that came out good was the rear view mirror, the rest is not good at all. I don't mind orange peel, it will get wet sanded when I wet sand the rest of the car. In a couple days I will sand this clear mostly off and get ready for the 2K. I still need to mask off, sand and paint the passenger door so I have plenty of work to do before the 2K clear gets here.

The most flattering shots I could take. The bottom of the door looks like sand was blown all over it because of the dusting.