Tribute knocking


#1

i have a 2005 mazda tribute v6. it has been knocking for about a year slowly geting worse. no check engine lite on, so i think it may be the egr valve. just wonder how to check it and if anyone had any input on this
thanks dave


#2

You need to clarify this a bit better. Knocking or rattling in the mechanic world is construed differently.

Rattle/knock at idle too or only when warmed up and under a load? (passing, going uphill, etc)

If it’s the latter then it’s quite possible you’re hearing a pre-ignition rattle and in most cases this is caused by an EGR fault but it may not necessarily be the EGR itself. Clogged passages, EGR control solenoid, electrical fault, etc. are possibilities.)


#3

If you have a steady, rhythmic knock at idle that increases with engine speed, it’s much more likely you have an internal engine problem. If this is the case, has the oil been changed regularly? Has the engine ever been run low on oil or overheated?

If the knock appears or worsens when the engine warms up, it doesn’t bode well for your bearings. If it only knocks when cold, then smooths out when warm, you may have “piston slap” (google it for info) If the knock is more of a ‘click’ and occurs at approximately 1 per every 2 revolutions of the engine, it may be the valve train.

If it is sporadic, only occurring under load, and more of a rattling sound, it could be the EGR, or you may be using lower octane fuel than the engine calls for.


#4

the engine knock iswhen going up hills when accelerating does not matter what temp it is. it thought it might might be the knock sensor but someone told me to check the egr first cause the check engine lite is not on.


#5

the car only has 46,000 mile on it. gas mileage has gone done, oil change every 3000. always service when needed, does not get driven much. tryed differnt grade of gas and even octaine booster has not helped. never had any major prblems like overheating, not changeing oil, does not use oil or leak oil so it has never been low on oil. hope this helps and you can help me. i would like to know how to test the egr and its components.


#6

Under load (when going up hills when accelerating) sounds like big end bearings. Could be somethign else, but you’d need to get a mechanic to diagnose it up close and personal like.


#7

no its not bearings. its a knock cause by a bad egr or knock sensor


#8

Sounds like an ignition rattle being described to me. You can scan the car to see if there are any EGR codes present.

It’s also possible to have an EGR problem such as clogged ports without any codes at all being set. Considering the vehicle is 6 years old and has apparently seen light use due to the low mileage, this can exacerbate things like clogged ports.

If this is the case one generally has to dig in by removing the EGR and start scraping the soot out.
One could try feeding a can of SeaFoam through an intake manifold vacuum port. There is at least a chance the SF can work it’s way back through the EGR ports and clear some of it up; assuming it’s not plugged up solid.
(If you go the SF route be advised that the engine will smoke quite a bit after use. This is normal and will clear up pretty quickly.)