99 Grand Prix GTP questions

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99 Grand Prix GTP questions

Postby Ozzwoman9 » Mon May 04, 2015 3:18 pm

As some know, my stepson gets his driving permit next month, so I bought him a 99 Grand Prix. Overall it's in decent shape, runs great. Body has some clear coat fading and hail damage (but being that it's black it's not that noticeable). Only problems are slight noise in the belt tensioner and the rear caliper is shot. Can't complain for picking it up for $600! So, I'm not all that familiar with the 3880 SC motors. Any bugs I need to know about? I know after he earns his part money and I get the brakes fixed that I'm going to be doing some overall maintenance to it. I plan on changing the SC oil. I understand I can take my mity vac and suck the oil out and replace that way. What kind of oil should I use and how much?

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Re: 99 Grand Prix GTP questions

Postby 1988GTU » Mon May 04, 2015 6:48 pm

that sc snout is a common wear item. The lower intake elbow and gaskets fail as much if not more often than the 3x00 60*v6's. Valve covers tend to leak oil, more so the rear vc. Dogbone mount bushing fatigue at a higher rate from isolating that boat anchor in place. Bigger Aux trans cooler is a must, especially being a first time kid driver with a supercharged pontiac gp.
EGR is a carbon caking culprit.
Wheel bearings all around and rear braking system is a high attention area.

Im most likely missing some stuff. I'm sure others will catch it.


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Re: 99 Grand Prix GTP questions

Postby ronaconda » Tue May 05, 2015 3:00 pm

For sure changed the valve cover gaskets if they are leaking. The leaking gaskets are the #1 cause of engine fires on these engines.

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Re: 99 Grand Prix GTP questions

Postby SuperLbody » Tue May 05, 2015 8:21 pm

Definitely check the supercharger to see if the oil has been changed and change it if not. Other than that, basic fluid checks/changes and such, you'll have a great car to have for awhile.

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Re: 99 Grand Prix GTP questions

Postby RobertISaar » Wed May 06, 2015 12:17 pm

depending on your location, you may want to take a good look in the strut towers, usually only the rear, to make sure there isn't any hidden rust going on. it isn't nearly as bad with a 2nd gen w-body, but it still happens.

rocker panels also like to crumble apart in those same locations.

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Re: 99 Grand Prix GTP questions

Postby Slinky » Fri May 08, 2015 9:18 am

yes as everyone said check the normal stuff and also pull the belt loose and check if there's any play in the end of the supercharger snout bearing, other than that in my opinion 3800 engines are pretty bulletproof

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Re: 99 Grand Prix GTP questions

Postby heavywoody » Fri May 08, 2015 9:48 am

Injector o-rings should be replaced to prevent engine fires (IMHO). And, depending on how good your husband is with a pick, the o-rings inside the quick connect setup where the lines connect to the fuel rails on top of the supercharger.

If you are going to change the SC oil, replace it with the GM stuff (available at dealer). I would also replace the SC coupler inside the snout while changing the oil ($30 part).

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