Buying a GN - What to watch out for

[robk46]

I'm looking at buying an '86 GN w/70k miles on it. It's been sitting for 8 years due to the brakes failing and the owner not knowing how to fix them or having the money. I'm very familiar with "A" bodies, and the "G" body looks like a smaller version, so I think I'm O.K on general mechanicals. I'd like to know what the weak parts are on these cars, and any specific areas I should spend extra time looking at. Rust areas, weak mechanical areas, etc.. I think these cars had an early verion of ABS, right? How hard is it to fix? Am I better off converting it to non-ABS from a Gran Prix or Monte? This car is complete with no mods. He only wants 1k for it, so buying it is a no brainer.

[Keller]

Sounds like a steal.

These cars do not have ABS. But the 86/87 cars do have an electro-hydraulic brake system known as a "Powermaster". It can be a bear to work with. But when its working well, it is great. The failure is likely the accumulator. See the diagnostics on this website. All you likely have to do is replace that with a new unit from www.kirbanperformance.com and it will work fine. A friend picked up a GN for $4K years ago under similar circumstances.

See the Buyers Guide elsewhere on this site. Details for people in your situation are all over www.gnttype.org.

[87geeinn]

The stock MAF sensors usually peter out and it's a safe bet that the one on the car in question is probably shot too. Vacuum leaks, even small ones, cause a lots of problems but aren't a problem once you get familiar with the car and get good at troubleshooting. Header cracks, especially on the driver's side manifold between cylinders 3 and 5 are a common problem but usually aren't a problem unless the car was dogged. The entire fuel system (especially pump) should be updated. The stock pump is notoriously weak mostly due to poor wiring and the sock/strainer on the pump is probably collapsed by now.

There are probably some other issues that haven't come to mind at the moment, but there are solutions to all of the aforementioned problems. For 1k though, you better snap that one up quick no matter what condition it's in! The powermaster system could be an easy fix as Keller mentioned earlier, but in the worse case scenario, you could go to good ol' vacuum brakes if need be.

[Keller]

Read everything in http://www.gnttype.org/forums/forumdisplay.php?f=42, plus all the info at www.gnttype.org, partictularly in the tech area.

I disagree about MAFs. Mine has been fine for probably a decade or more. Regardless, the "Translator" products are excellent replacement paths. That need not be your first concern.

[JHensberry]

Common rust areas, prob for any car in the weather for 20+ years if not covered/garage kept, would be the pillars around the windshield. Water can come in and then collect along the drain grommets on the back floorboard. There is a brief write up on rust in the tech articles/body.

Get a service/chassis manual from helm.com. Will make life so much easier since you have a good mech. background to do things yourself.

Get some goals and get a plan. These cars can eat up a check book in a hurry if you just throw parts at it and not see the whole picture as far as knowing exactly what you want out of the car. Also, try to make a well informed list of what is wrong/needed with the car in order of importance and work it from there.

[robk46]

Thanks for the advice. I bought the car yesterday, but can't pick it up until the end of the month. This will be a project for my teenage son and I. I think we're going to be fighting for the keys though, since I've wanted on of these since high school. Lucky for him (and me) My high school car was/is a '71 Lemans convertible, which I have restored myself. The only thing I didn't do with my own two hands was the machine work on the engine, and the paint. these "G" bodies look like 7/8 size "A" bodies, so working on the basics should not be a problem. Here's a breakdown of the car:

1986 Buick Gand National
72k miles
Original owner
No missing parts
Sunroof
Driven up to 2 years ago - driven and parked where it sits today
trunk FULL of NOS parts

Paint oxidation everywhere
small rust bubbles on drivers side of sunroof
superficial rust at base of windshield
rust area where an emblem used to be on the drivers side of the trunk
bad PowerMaster system

[Keller]

http://www.gnttype.org/techarea/brakes/brakespage.html

Start reading...

[robk46]

Here is a pic. I will get some better ones next week.

[Keller]

Insurance for a teenage son might be a problem. Teaching him restraint might be problems, too.

At least he won't be driving a Honda. Make sure he understands that neon and 5" exhaust tips do not make a car go faster.