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I thought I'd share a resto-mod thread of my '86 Buick Grand National with the vintage car freaks here. First, the back-story; I'm 46 now, but 2 or 3 years before the Turbo Buicks hit the scene, I was reading about the pre-intercooled GNs in Popular Hot Rodding. I must've been 16-ish. I liked the mean look, but was blown away by the articles on the '86 GN when it was made...to very little fan-fare. In '86, hardly anybody knew about the GN. Only a little over 5500 were made, but the infamous spanking the GN put on GM's flagship performance car Corvette (and pretty much every other mass-produced car in '86, for that matter) was legendary. My dad was considering buying a "toy" car at that time, maybe a Camaro or even a Corvette, but those were so impractical to the "family man" with a family & 4 kids...hardly a back-seat, barely a trunk. I encouraged him to check out this Buick car at a local dealership. He had no idea what the GN was all about, I take full credit for bringing it to his attention. If I hadn't convinced him to check out the GN that fateful day, I know I wouldn't presently own this car. I feel blessed to have been a part of the car's history and extremely fortunate to own one in this good condition.

Needless to say, after my dad's test-drive with a burgundy Regal Turbo T (the salesman couldn't find the keys for the GN on the lot for some reason), he was signing the pink slips on the GN! That was my first experience of buying a new car at a dealership, too...I was all of 17 or 18, I was in disbelief that me dragging my dad to this car lot on the other side of town resulted in him buying the car on the spot!

The GN has a lot of history...I got to drive it to my grad, a number of weddings, my younger brother drove it for his grad...when the parents were out of town, we'd sneak out and drive it and make mischief, and blow the doors off of Corvettes, embarrassed well-to-do preppies (this was the late 80's, haha!) in their shiny red Camaros, wasted tons of 5.0L Mustangs, had a number of Porsche drivers puss out at stoplights...and eventually my dad caught me after recording the mileage.

Fast-forward to today. About 7 years ago, I bought it from my dad with I believe about 74K kilometers on the odometer. He took extremely good care of the car, never winter-drove it, frequent maintenance & engine shampoos...I knew what I was getting for the family-friendly price of $10,000 CDN. The main problem is, in the last several years before I bought it, my father had driven it like an old man, and the GN certainly wasn't meant to putter around...so by now, although it still runs great, it's rather sluggish right off the line compared to how I remembered it. It still has stupid mid-range power though.

My dad originally purchased the car with Centerline clone wheels (another suggestion of mine; 15 x 7" with stock P215-65-15 tires)...the original GN wheels hardly saw the road other than the drive from the freight truck to the dealership. (I still have the OEM wheels & center-caps, they're in near-mint condition.) My dad also had a wing installed on the day he bought it; one of the salespeople recommended it, I believe it's a Fiero wing. It actually fits and looks great, and certainly sets the car apart from all the other GN's (not that there's many around these days).

Since I bought the car, I bought new, genuine Centerline Auto Drag wheels, 15 x 7" in the front, and 15 x 8.5" on the rear with wider P235-60-15 tires to properly fill out the wheel-wells. I always thought the 15 x 7"/215's in the rear were sucked in too far and didn't look aggressive enough. I also added variable-rate springs in the back to stiffen up the rear suspension.

Pictures of how it looks these days...

Bad ass car Marc! I enjoyed the story as well, it's nice that it stayed in the family! What did your dad pay for that off the dealer floor?

I wasn't able to drive the car much the last couple summers because it had some issues with the brakes & coolant leaking. The brakes were spongy and the brake warning light would come on every time I pressed the pedal, so I couldn't drive it until that was resolved, and I didn't have the funds. My buddy came over to help me bleed the brakes, I topped up the master cylinder, and...same thing. Spongy brakes, brake warning light every time the pedal was touched. The problem was ignorance. The GNs had a different brake system than the Hydroboost system that's like every other vacuum-operated brake system you see on GM cars. The Powermaster system only appeared for a few years on the GNs/Turbo T's and operates differently. It's fickle but once you know how it's supposed to work, it's actually quite easy to troubleshoot. The problem was we were overfilling the cylinder reservoirs. The fender-side one should be about 75% full when cold, and the engine-side is only about 25% full. When you turn the car on, the reservoirs should normally fill up to the correct levels. So once I turkey-basted out the extra fluid and drove around a while, everything sorted itself out.

However, even after only a 5-minute drive, after I stopped & turned off the car, it would puke coolant everywhere under the rad. I started off by replacing the "simple things", buying a new 16-lb. rad cap & 160° t-stat. Replacing a t-stat on a Turbo 3.8L is anything but simple, mind you...you have to do a lot of work just to get at it; it doesn't use a gasket like every other car, it has an O-ring; and even more annoying, the "correct" t-stat won't fit directly in the hole; I had to cut it down to reduce the diameter by about 1/2" with tin snips and a file. But even after this, it still puked coolant after a short drive. The rad looked pretty bad on the inside, and hadn't ever been replaced, so now was the time. Unfortunately, a drop-in direct-fit rad for these cars have built-in tranny & engine oil coolers and cost over $500 plus shipping! I read about many people doing an F-body ('82 - '92 Camaro) radiator swap, those can be had for under $150 but require an external oil cooler to be installed, and a fair bit of modding to re-route & connect the tranny cooler lines. Since that would save me about $300 after all was said & done, that's what I decided to do.

Pic with old rad removed: B & M oil cooler mounted: New oil cooler lines reconnected: Fan & new rad installed:

slotcarrod wrote:Bad ass car Marc! I enjoyed the story as well, it's nice that it stayed in the family! What did your dad pay for that off the dealer floor?

Thank you Rod! It was somewhere around 24K...for some reason, I have the number $23,740 or $24,370 or something in my memory. A steal compared to the price of a Camaro or Corvette at the time!

I just looked at your radiator mod. I think I would have kept it stock/oem. That car is going to gain in value over the years, and the more original, the higher the value! IMO!

I worked in a high performance shop for a few years, I'm still into hp but not in the business anymore....anyway...
We always had a lot of trouble with even reputable t-stat companies when they didn't have a weep hole. Some do, some don't. After drilling a 1/8" hole in the ones that don't, it allows just a bit of coolant to pass and helps burp the system. It also helps to keep the system from shocking the t-stat open and closed. We worked on quite a few built V6 turbo Buick fitted cars, from T-types to a shoebox nova. Very fun powerplants

The F-body rad swap requires modding of the tranny cooler lines to make them connect to the new rad, because the original GN rad had both fittings located fairly close together, between the filler hole and lower rad hose, whereas the F-body rad has the upper fitting a bit higher and lower fitting is below the lower rad hose. I'm no expert with a pipe bender/cutter/flaring tool, but I have the kit and put it to good use when I installed an external tranny cooler on my Charger, so I figured I could do some creative re-bending of the tranny lines...but they still would be several inches too short to reach the new rad's fittings.

The original rad had these weird 5/16" steel line extensions that had couplers on the ends, and wrapped around near the top of the rad, to connect to weird 90-degree fittings for the built-in oil cooler. After looking at it, I thought I might be able to disconnect those 5/16" extension lines and re-bend & cut them, add a pair of new pipe fittings, and use the existing couplers to mate up to the tranny cooler lines, so with some careful measuring and bending, that's what I ended up doing. (I figured it would be more work to fabricate all-new tranny cooler lines.) One advantage of this mod over stock is this reduces the number of connections & potential leak points from 8 to 6. After I got everything reconnected, it looked pretty good.

Tranny cooler lines/lower rad hose reconnected: I also noticed something odd when I was reinstalling a few things under the car that needed to be removed to access the electric fan bolts...this plastic piece (no idea what it's correct name is, it's a fairing of some sort) looked like it was overlapping & obstructing airflow to the turbo/up-pipe intake, so I'll mark it, remove it and cut away about an inch from either side, so it's more flush with the intake rectangle. That should reduce airflow turbulence coming through the intake.

gomachv wrote:I worked in a high performance shop for a few years, I'm still into hp but not in the business anymore....anyway...
We always had a lot of trouble with even reputable t-stat companies when they didn't have a weep hole. Some do, some don't. After drilling a 1/8" hole in the ones that don't, it allows just a bit of coolant to pass and helps burp the system. It also helps to keep the system from shocking the t-stat open and closed. We worked on quite a few built V6 turbo Buick fitted cars, from T-types to a shoebox nova. Very fun powerplants

You're bang-on about that, that's what I did too, after reading through stuff on http://www.turbobuick.com & http://www.gnttype.org. Helps release steam and burp air out of the cooling system.

slotcarrod wrote:I just looked at your radiator mod. I think I would have kept it stock/oem. That car is going to gain in value over the years, and the more original, the higher the value! IMO!

Rod, you're also right...but resale value is only a concern if you're ever planning to sell. I'm not, and I have plans to do some mild performance mods with the engine. I'll keep the original messed-up rad and weird 90-degree fittings, and the only thing I actually destroyed were the 5/16" steel line extensions. Buy two new tranny cooler lines and it'd be right back to stock.

Sweet story Marc. Still my all time favorite car. I wanted one so bad as a teenager that I actually talked a few car salesman into a test drive.
Very easy to get these into 10 second quarter miles without getting into the short block.

Sweet ride. The fastest quarter mile production car for 1986............

that duct is just for the intercooler, it's not a super efficient setup anyway, so you probably won't get much seat of the pants in making any modifications to those ducts.

jwscab wrote:that duct is just for the intercooler, it's not a super efficient setup anyway, so you probably won't get much seat of the pants in making any modifications to those ducts.

I know, but why have it creating turbulence when it can be easily rectified? While I'm under the car anyway and it's only 4 bolts holding it on, might as well do it. As with my RC builds, I'm never one to just leave well enough alone. I'm also thinking of replacing that floppy plastic protective mesh with something less restrictive.

I like turbo Buicks but I prefer the F-body with one. I would love to have a GN don't get me wrong but after driving the TTA it would be my first choice. It is cool to see someone else working on one.

Last night, I got back under the car, reached into the intake duct behind the obstructing fairing and marked off where to cut it so it'll be flush with tire marking chalk. I then pulled out the flexible plastic grille and look what I found:

View from under car View from above Removed Nice... 28 years' accumulated ancient insect bodies and greasy, dusty crud. You couldn't even see through the thing. Kind of ironic to be worrying about airflow through the restrictive plastic intake grille when the cooler itself is probably hardly letting any air through.

I started out trying to brush out the crud from the front of the cooler while it was still installed in the car, but figured that would just push the crud deeper into the fins and not really clean it...so out it came. It was actually quite a pain to clean because it's kind of a sandwich of 2 air radiators, and spraying water or compressed air from one side just blew the crud into the fins on the other side. I used Super Clean, windshield washer fluid with bug remover additive, garden hose sprayer and compressed air and got it 95% clean. You can actually see through it again!

I fabricated a significantly less restrictive intake grille to replace the quite restrictive plastic grille, which looked like it might only allow 50% airflow. The steel mesh I used looks more like 75%. I also widened that bottom plastic fairing to remove the obstruction shown in previous pics, and reinstalled everything the last few days. That, plus cleaning out 28 years' worth of bugsh!t clogging the intercooler rad should help wake her up!
Comparison of the 2 grilles at relatively the same angle as intake air would go:
With widened fairing reinstalled; I'm liking how this looks much better than the way it was originally: