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I'm lookt AT a DOHC GTP....

SnakeEyeSS

By SnakeEyeSS
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SnakeEyeSS Senior Enthusiast

SnakeEyeSS

Posted
Posted

the car is:

1995 Pointiac Grand Prix GTP

aero package

the GTP wheels

dark forest green metallic

PERFECT flawless beige leather interior

sunroof

127 thousand miles

 

has the 3.4L DOHC engine with 210HP and 215tq

 

only problems is the rear spoiler and front bumper need to be repaint(could probably get it done for 400)

 

Price: 5,300!!!!

I could sell the truck and have insurance and mod money

 

Jon, is there a decent aftermarket following for the older DOCH GTP's?

CMNTMXR81 Senior Enthusiast

CMNTMXR81

Posted
Posted

STAY AWAY...STAY VERY FAR AWAY FROM THIS MOTOR!

 

I've owned two of them and currently still have one.  We had one in our 1995 Lumina (which I traded in on the truck) and my Mother's 1996 Monte Carlo Z34 has it.

 

There were a few changes between 95 and 96 in order to become OBDII compliant, but to some it up, THESE ENGINES ARE VERY TEMPERMENTAL AND VERY HIGH COST TO MAINTAIN!

 

They make GREAT power, but that great power comes at a cost.  It is nearly impossible to work coupled with the fact that they constantly HAVE to be worked on compounds the fact.

 

Simply replacing the plugs requires the intake plenum to be removed in order to get to 2,4, & 6.  This is a little harder on the 95's as the 95's intake plenum and throttle body with internal coolant passage are all one piece.  96's are seperate so it comes off easier.  You probably thinking...So what!  One of the constant problems with this engine is faulty plug wires.  The plug wire on this engine is a regular plug wire that fits into a plastic sleeve which giudes it down the hole in the heads (between the cams) and snaps onto the plugs.  One of the earlier faulty designs (which would be on a 95) is that this sleeve is a two piece design.  the two pieces are way at the bottom inside the head when fully installed.  This point where the two pieces come together has been known to short out there causing the electricty to ground out to the head before going through the plug therefore resulting in a misfire.  I had to replace two sets of these wires until GM came out with a one piece revision.

 

I recently had to replace B1S1 O2 sensor on the Monte.  The rocket scientists at GM put in a place where you can't get a wrench on it from underneath.  Your only alternative once again is to remove that intake plenum, get a come along out, crank the engine forward, and then you're barely able to get it out (providing you have the right tools like a specific O2 sensor socket.

 

If the A/C, alternator, or A.I.R. injection pump goes out on 95's, it requires the entire engine cradle being dropped to get to them.  The alternator for instance is inside this cradle in the passenger portion of the firewall.  Even replacing the serpentine is a bitch and a half on this engine as there is simply no room (unless you have small hands and arms which I don't) to work in.  Thankfully for 96, the put the A.I.R. pump under the PCM in the passenger fender as it's now an electric solenoid instead of a belt driven pump.

 

And fair warning...the cam drive belts are notorious for breaking especially if it is a higher mileage engine.  When this belt goes, kiss the engine goodbye.  This 3.4 doesn't have the safegaurd inplace that closes the valves like the Northstar/Aurora V8's nor the ZR1's LT5 V8.  So if any of those valves are hung open when that belt breaks, expect it to go through a piston and these engines are $5k to replace.

 

This is why GM discontinued them in 1997...to much cost for warranty repairs.

 

I've got 110,000 on the Monte and I've got all fingers and toes crossed that it'll make it to 200,000.  I truly hope the cam drive belt doesn't snap on me before then, otherwise the car will be worth nothing.

 

I know this engine pretty well.  :uhoh:

east350 New Member

east350

Posted
Posted
Don't the newer one's (late 1990s?) have a 3.8L V6 with a little bit more hp and torque?  If so, when did they change them over?  From what I've gathered the 3.8L is a fairly reliable though somewhat outdated powerplant but, with any engine, try to make sure it wasn't driven to death by a previous owner with a lead foot.  Also, I think that the Bonneville's also had a supercharged version which might be worth checking out as well.  Good luck, these really are sharp looking cars.
SnakeEyeSS Senior Enthusiast

SnakeEyeSS

Posted
  • Author
Posted

thanks for the info. the engine was strong, but on the highway the brake shimmied terribly, is was almost unreal. it was a quart low on oil(although clean), and the A/C was stuck on, not something I want to mess with when winter is around the corner. but the interior was perfect.

I'm no longer interested though.

 

Well, I figured since they shared some engine design with the bulletproof 3.1(we had one that nothing every went wrong on for the 80,000 miles we had it, between 140,000 and 220,000), it must have been reliable, but thanks for the info!

chevy4x4trucks Senior Enthusiast

chevy4x4trucks

Posted
Posted
Jon, is there a decent aftermarket following for the older DOCH GTP's?

Not as much as the 97-up Grand Prix's.

 

You may want to poke around clubgp.com in there forum for the 88-96's and post this question.  You'd be able to get a bunch more info.

 

But, if you want a fast car, for a decent price, that you can mod easily look at a 97 or 98, the prices are very reasonable.

chevy4x4trucks Senior Enthusiast

chevy4x4trucks

Posted
Posted
Don't the newer one's (late 1990s?) have a 3.8L V6 with a little bit more hp and torque?  If so, when did they change them over?  From what I've gathered the 3.8L is a fairly reliable though somewhat outdated powerplant but, with any engine, try to make sure it wasn't driven to death by a previous owner with a lead foot.  Also, I think that the Bonneville's also had a supercharged version which might be worth checking out as well.  Good luck, these really are sharp looking cars.

In 1997 they put the 3.1 (I believe) in the SE's and the 3.8 in the GT, and the 3.8 Series II supercharged in the GTP's.  Definetly worth checking out.  Trust me, if you think the powertrain is outdated come for a ride with me in my GTP.  

 

Actually, they are using the 3.8 in bonnevilles, Monte Carlo's, Impala's.  And in the coming years chevy will hopefully be slapping the eaton supercharger on them like pontiac.

 

Definetly a strong engine choice and w/ some fairly easy mods and good driving skills you can be pulling 13's w/ a GTP.  Some guys are pulling 14's with them bone stock, which is actually fairly common.  I've yet to race mine at the strip, and probably never will, but it's good to know that I've got a car that can haul @ss when I need it to.

CMNTMXR81 Senior Enthusiast

CMNTMXR81

Posted
Posted
Don't the newer one's (late 1990s?) have a 3.8L V6 with a little bit more hp and torque?  If so, when did they change them over?  From what I've gathered the 3.8L is a fairly reliable though somewhat outdated powerplant but, with any engine, try to make sure it wasn't driven to death by a previous owner with a lead foot.  Also, I think that the Bonneville's also had a supercharged version which might be worth checking out as well.  Good luck, these really are sharp looking cars.

East, 1996 was the last year for the 3.4L DOHC V6 due to high warranty costs which I detailed above.  Other complaints I commonly heard about them (as I was the one who they gave all of them too as I worked on them so often), was that they were noisy.  Something I never understood.  I thought they sounded pretty cool and they sounded downright like a mechanical symphony at WOT bumping up against the rev limiter.  If you could find one of these in a Lumina Z34 with the 5 speed manual, that was the shiznit.  Otherwise they are all laden with the 4T60E (Tranverse version of the 4L60E) auto.

 

1997 was when they went to the more reliable 200hp 3.8L V6 as the upgrade engine.

 

90, it doesn't surprise me that it pulled strong up top, that's where all it's power is made.  :uhoh:  OUt on the highway was when our Lumina was insane.  Just bury the pedal into the carpet and let it sing it's mechanical symphony I mentioned above.

 

They are based off of the 3.1L V6.  They are both 60 degree engines.  It was bored out to 3.4L and had a set of DOHC heads fitted as well as a cam drive on the block.  This was also GM's first own IN HOUSE attempt at aluminum casting, which was another problem they had to conquer before the LS1 came out.

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