Related Test Articles

What if you tested the engine compression on your 3.8L Chevy or Pontiac, or Buick, or Oldsmobile and the compression test indicates the engine is healthy? Well, the following articles will help you to track down the misfire condition on the other systems or components that can cause misfires:

  1. GM 3.8L Fuel Injector Noid Light Test.
  2. How To Test The Fuel Injectors (GM 3.8L).
  3. How To Diagnose Misfire Codes P0300-P0306 (GM 3.8L).
  4. GM 3.8L Ignition System Tests (this info is found at easyauto- diagnostics.com).

Reader's Real Life Case Studies And Solutions

In this section is input and feedback from all of the folks who have had a similar issue with their vehicle and found a solution. If you're one of them, I want to thank you for sharing your experience with all of us!

If you want to share your repair and/or diagnostic experience, you can use the contact form below.

Real Life Case Study 1

Vehicle: 2000 Buick Park Ave. (Base) 3.8L V-6, 172,000 miles

Trouble Codes: P0303 and P0304

Complaint: LOW COMPRESSION ON #3 AND #4 “I lost a water pump going up a 6% grade incline at high speed and wasn't watching the temp. gauge. I used some Duraseal to overcome some coolant leak problems, but still had a 70 lb. compression reading on #3 and #4 and was throwing P0303 and P0304 codes. Even after I solved the coolant leaks, which I don't know if those were from the head gasket or the intake manifold, I was still getting those codes. Another compression test gave the same results, and when we added a spoonful of oil (for a wet compression test) it only came up ten pounds, to about 80 psi. At that point, I figure that it may be a valve problem, a burnt seat or a bent valve, etc.”

Test Notes: The DuraSeal headgasket treatment I used (without any sodium silicate in it's formula) did seal the head gasket problem, but made no difference on the compression values, obviously). I wanted to believe that I could solve the problem without tearing into the heads, but the reality is that even if the intake manifold gasket were bad, or if the plastic intake manifold were warped (as the local Buick Dealer Tech suggested), that would not change the compression problem. The initial compression test indicated a problem and I wanted to believe a head gasket problem was the source of that loss of compression. But even after doing the chemical fix –which worked –I still had loss of compression. With the wet test showing little improvement, the inescapable conclusion was that the valves were compromised. I didn't do the leak down test to confirm if it was the intake valves or the exhaust valves. All I knew is that the valves were bad. ”

“At that point I looked at the cost of paying someone to tear it all down, then magnaflux the heads and fix the bad valves and put it all back together: not a small amount. The problem is that even once you do that, if you do that, you then have a strong upper engine working on a 170,000 lower engine. The prospect is that then – as many times it has been seen – that later the lower end is blown out and you have to start all over again to do a ring job. Tilt!”

Repair: REPLACED ENGINE “I called the S** V***** area salvage yards to find a low mileage used engine in the L*** area. The salvage yard gave me a price of $1,500 to buy the engine AND install it. He used my existing plastic intake manifold, not the metal one on the 'new' engine, and got it to work.”

Advice: “That is the key thing I learned. IF YOU ARE LOSING COOLANT OVER TIME, CHECK THE WEEP HOLE ON YOUR WATER PUMP FIRST. That is the first place to look. If I had done that and replaced the water pump when it was telling me it was about to go, I would have avoided all the time and cost of the repairs I incurred. But now I am even better off, in a way, with a low mileage engine to go with my already rebuilt tranny. ”

Courtesy of: Dave Cramer

Notes: You can read Dave's entire post here: Dave's Post.

Thank You For Your Donation

If this info saved the day, buy me a beer!

If This Info Saved the Day, Buy Me a Beer!


Buick Vehicles:

  • Century 3.8L
    • 1993
  • LeSabre 3.8L
    • 1993, 1994, 1995, 1996, 1997, 1998, 1999, 2000, 2001, 2002, 2003, 2004, 2005
  • Park Avenue (& Ultra) 3.8L
    • 1993, 1994, 1995, 1996, 1997, 1998, 1999, 2000, 2001, 2002, 2003, 2004, 2005

Buick Vehicles:

  • Regal 3.8L
    • 1993, 1994, 1995, 1996, 1997, 1998, 1999, 2000, 2001, 2002, 2003, 2004
  • Riviera 3.8L
    • 1993, 1994, 1995, 1996, 1997, 1998, 1999
  • Skylark 3.8L
    • 1993

Chevrolet Vehicles:

  • Camaro 3.8L
    • 1995, 1996, 1997, 1998, 1999, 2000, 2001, 2002
  • Impala 3.8L
    • 2000, 2001, 2002, 2003, 2004, 2005
  • Lumina (& MPV)
    • 1993, 1994, 1995, 1998, 1999
  • Monte Carlo 3.8L
    • 1998, 1999, 2000, 2001, 2002, 2003, 2004, 2005

Oldsmobile Vehicles:

  • 88 (& 88 Royale) 3.8L
    • 1993, 1994, 1995, 1996, 1997, 1998
  • 98 Regency 3.8L
    • 1993, 1994, 1995, 1996
  • Achieva 3.8L
    • 1993

Oldsmobile Vehicles:

  • Cutlass Ciera (& Cruiser) 3.8L
    • 1993
  • Intrigue 3.8L
    • 1998, 1999
  • LSS 3.8L
    • 1996, 1997, 1998, 1999
  • Regency 3.8L
    • 1997, 1998
  • Silhouette 3.8L
    • 1993, 1994, 1995

Pontiac Vehicles:

  • Bonneville 3.8L
    • 1993, 1994, 1995, 1996, 1997, 1998, 1999, 2000, 2001, 2002, 2003, 2004, 2005
  • Firebird 3.8L
    • 1995, 1996, 1997, 1998, 1999, 2000, 2001, 2002
  • Grand Am 3.8L
    • 1993

Pontiac Vehicles:

  • Grand Prix 3.8L
    • 1997, 1998, 1999, 2000, 2001, 2002, 2003, 2004, 2005, 2006, 2007, 2008
  • Trans Sport 3.8L
    • 1993, 1994, 1995