Cameronjames

Trying to diag what could be causing my car to cough up a barely visible amount of grey smoke at the top of 4th. I’ve seen it once in third but usually it’s when I’m wide open at the top of 4th. With the smoke comes a nasty smell so I’m thinking it’s the Cat or fuel system. Fuel filter needs to be replaced as well as strainer. Any help would be greatly appreciated 👍

walfreyydo

Or it could be headgasket (burning coolant), rings (burning oil)

Compression test will reveal some evidence (but Ive seen a bad headgasket come out with perfectly fine compression numbers before)

Usually unburnt fuel is black, coolant white, oil blueish all with distinct smells as well

A bad cat usually has a rotten egg/sulfur type smell but does not typically produce any smoke

Petza914

If it was coolant the level would eventually go down and most likely yiud also have a startup cloud that smells sweet as the pressurized cooling system after driving forces some into the cylinders that burns on restart.

I'd say it's probably just blowby since it it only happens at high rpm when maximum fuel, air, and combustion pressure are in the cylinders. A compression test is a good place to start though.

Cameronjames

[QUOTE=Petza914;19394592]If it was coolant the level would eventually go down and most likely yiud also have a startup cloud that smells sweet as the pressurized cooling system after driving forces some into the cylinders that burns on restart.

I'd say it's probably just blowby since it it only happens at high rpm when maximum fuel, air, and combustion pressure are in the cylinders. A compression test is a good place to start though.[/QUOTE
Now that you mention it my coolant level has been going down slowly. I always thought that was just from overfill and when I run it wide open for extended periods. Injectors need a good cleaning so I put some Lucas fuel treatment in about a week ago and I was thinking maybe that was why the smoke

Petza914

Get a cooling system pressure tester. Pressurize it to 16 psi and leave it for 30-60 minutes. If the pressure drops and you don't see an external leak it's likely the head gasket. Pull the plugs, put a boroscope into each hole and see if there is any coolant in the cylinders.