2005 Mazda 3 Engine noise and smell

SMACKD1

MEMBER
2005 MAZDA 3
4 CYL
2WD
AUTOMATIC
73,000 MILES

I was driving back from a town in germany on the autobahn going about 90-100 mph, had the cruise on at some points which isn't probably the smartest thing to do so I stopped it, especially after the hills hit it pretty hard. Anyways I pulled up to the AF base gate and noticed a smell that smelled like burnt oil. It was coming from my car, then came a clicking noise. The noise stopped after a bit and I started it it 3 days later and no smell but haven't driven it yet but still a small clicking noise. I just changed the oil about 2 weeks ago, checked the level again and it is fine along with trans fluid. The clicking noise is there when the car is stationary as well so I don't think it is a lug from the wheels or the brakes. Any thoughts

2 Replies

CARADIODOC

MECHANIC
33,752 POSTS

HI smackd1. Welcome to the forum. If the noise goes away after a few miles of normal driving, I suspect air was whipped into the oil from the rotating crankshaft. Many engines use a "windage tray" under the crank to reduce that effect.

Air bubbles in the oil allow the oil to compress. This results in a reduced ability to isolate moving parts, (crankshaft from bearings, pistons from cylinder walls), and hydraulic lash adjusters or lifters won't pump up properly resulting in clattering. That noise will go away once the air bubbles are expelled.

As for the smell, extended high speed driving can cause excessive oil to build up on top of the cylinder head when it can't run back down fast enough. That's a temporary problem but it can lead to oil being pushed out of the fill cap or vapors being pushed out that condense on top of the engine and look like a leak. That oil will burn off eventually if there are no other problems.

Caradiodoc