2000 Chevrolet Blazer Zr2 Cold start knocking from engine


Asked by Jan 27, 2015 at 10:59 AM about the 2000 Chevrolet Blazer LS 2-Door 4WD

Question type: Maintenance & Repair

I have 2000 Chevrolet Blazer Zr2, it has about 148,000 miles. When i start MY truck up in the morning the engine knocks, not severly or violently but there is definetly some light knocking. The knocking will increase in tempo when I increase the throttle as well. When the truck warms up after 2-3 mins the knocking stops and it sounds fine. Also, at cold starts I noticed that the oil pressure gauge is reading really high but then once the truck warms up it goes back to normal. I have noticed no power changes from the  engine just a cold start knocking. Also Oil levels are full. What could this be and how do I fix it?

2 Answers


Your oil viscosity might be affected by the cold weather, if you're living in the north, otherwise use oil for high-mileage engines. Higher oil pressure at startup could be due to the oil being thicker at lower temperatures. Make sure you haven't overfilled the oil. Try changing the oil to a recommended viscosity for your climate/mileage and see how it affect the noise. - One other consideration too, is an exhaust leak, it goes away once the vehicle has warmed up. You'll have to put your ear to the engine (mech's stethoscope or long screwdriver) might help just where the noise is coming from.

1 of 1 people found this helpful.

Vortec piston slap. Most of them do it. Has something to do with the material the piston is made from expanding at a different rate when it warms up. I had a full size that made that noise until it warmed up for years. Never used a drop of oil. Still running at near 250K.

Your Answer

Chevrolet Blazer Experts

  • #1
    Andrew Olsen
  • #2
  • #3
View All

Related Models For Sale

Used Chevrolet Tahoe
646 Great Deals out of 38,083 listings starting at $995
Used Chevrolet S-10
11 Great Deals out of 1,058 listings starting at $950
Used Chevrolet Silverado 1500
2,287 Great Deals out of 152,362 listings starting at $1,499
Used GMC Jimmy
147 listings
Used Ford Explorer
896 Great Deals out of 64,566 listings starting at $1,995
Used Ford F-150
2,603 Great Deals out of 222,393 listings starting at $1,222
Used Chevrolet C/K 1500
736 listings starting at $2,995
Used Chevrolet Camaro
267 Great Deals out of 30,512 listings starting at $4,200
Used Chevrolet Suburban
427 Great Deals out of 22,518 listings starting at $2,495
Used Jeep Grand Cherokee
800 Great Deals out of 73,393 listings starting at $950
Used Jeep Cherokee
290 Great Deals out of 63,306 listings starting at $9,480

Content submitted by Users is not endorsed by CarGurus, does not express the opinions of CarGurus, and should not be considered reviewed, screened, or approved by CarGurus. Please refer to CarGurus Terms of Use.