Engine Knocking 2001 Disco II

[nolift911]

So I have a 01 Disco II with 175k miles on it - have replaced the MAF, the wires, the plugs, the heads and still get a slight knock on accleration with 93 octane.


Any ideas? What are the odds the knock sensors are bad? (never heard of anyone mentioning them before.

Thanks -

 

[joey]

With 175k miles it could be anything from a valve to cam chain.... to a U-joint... hard to say.

 

[nolift911]

Just had the heads and the front cover off - cam and chain looked good, valves looked good, front driveshaft is about a month old.

This is engine pinging on acceleration...

 

[joey]

Plugs and wires? What type and how old.

 

[nolift911]

Plugs are OEM Champion and Magnecores - both about 500 miles

 

[joey]

Can you hear the ping in park if you rev the engine? i.e. under the hood... I would try to find it via a mechanic stethoscope... could be a cracked manifold or something internal.

 

[nolift911]

This is a detonation ping - only on acceleration or load on the engine - otherwise no noise.

Can be heard accelerating from a stop up thru 30-40 mph. Sound like popcorn popping, it is def detonation and not mechanical.

My wrench would have found anything internally that was wrong when he had the engine apart - I told him to check for everything.

It does go awayif I add octane boost. I get 93 around here on a regular basis. If I add octane boost it is minimized substantially or goes away all together.

 

[Disco Mike]

Just had the heads and the front cover off - cam and chain looked good, valves looked good, front driveshaft is about a month old.

This is engine pinging on acceleration...

At your mileage, nothing looks good, chain has to have some slop in it the valve guides have to be showing some serious wear. I don't think you have been looking carefully enough.
What about oil pressure, check it, cold at idle and at 2000 RPM's and warm at idle and at 2000 RPM's and get back to us.

 

[nolift911]

Oil pressure was done before the teear down and looked great. I asked them to replace the valve guides and the timing chain - they told me it was a waste of money and time - and said it all looked great. I said whatever needs to be replace please do.

Only internal issue was the oil pump ring gear (which is fairly common) was cracked in 3 places - which they caught before it imploded, so new pump, cover, gear etc.

Other than that everything looked good.

Do the knock sensors never go bad?

 

[joey]

With the info provided and you said the mechanic said it looked good I ruled out common issues for what you are saying.. i.e. Timing gears and the cam... both of which will cause your issue.

Knock sensors will go bad and you will get a code for them when they do.