Thread: Knock Knock?

If you're taking it to a mechanic, the last thing he'll want to hear is internet theories of what it might be.


Give him some free time with the car & let him diagnose it.








It might well be in the handbrake...

he's had value from your recommendations on this forum before so thought I'd ask. generally I just write them down on a bit of paper, take it in and say right, this is what I've noticed with the car, bit of paper shows a few clues that might mean something to you, ring me when you know something lol.
Actually input from the forum saved me getting fuel pump unnecessarily replaced too (fuel pump first diagnosis, I posted the result here and was strongly urged to ask mechanic to do a specific couple of tests and though I felt uncomfortable insisting he do so, he did the tests and found fuel pump fine, and narrowed it down to MAF sensor ). So, I'd rather he roll his eyes when I hand over little paper of cheats, than miss a little pearl of wisdom that only someone who's been working on landies for years, might know.
but thank you, I do understand your point

If you're going to go to the length of top hat liners then may as well go 4.6 at the same time, and send the ECU off to Mark Adams for a reprogram while off the rd. You won't know it when it's back.

I have a two builders here that I trust, one I'd have do liner work and rover V8 build for longevity work. But my rate is $200/hr. Hence he does major machining and advisory on my maths and plans and I assemble (oft under his supervision for more ambitious stuff).

Other option is see what TR Spares in Adelaide have.

As for the noise, does it change with RPM? What sort of note is it, lower (knocking) or higher (tapping, like lifter). Deep knocking could be bad (bearing). Handbrake is usually an issue on TD5's.

It would probably help if you start the car cold, open the bonnet and listen closely to see if you can get an idea of the general location of the noise. You could be so lucky to just have loose or cracked exhaust manifolds, an easy fix. You could have a cracked drive plate to the automatic transmission, this does often get quieter with revs. Any problems with main engine bearings would also lead to low oil pressure and probably a flickering oil light at hot idle. Bearings also tend to make more noise at higher revs.

Couldn't tell you the tone without a comparison (only other I've heard was a recurring tappet problem with my 72 and 74 crowns.. this sounds deeper than that sound). Problem is not the handbrake just I can feel the vibration that accompanies the noise (was just an observation). Disappears with higher RPM (eg as soon as start to drive the sound goes, only hear it coasting at low speeds). The knock itself, when audible.. might be roughly 216 per min (though would vary with revs)

Originally Posted by bee utey

It would probably help if you start the car cold, open the bonnet and listen closely to see if you can get an idea of the general location of the noise. You could be so lucky to just have loose or cracked exhaust manifolds, an easy fix. You could have a cracked drive plate to the automatic transmission, this does often get quieter with revs. Any problems with main engine bearings would also lead to low oil pressure and probably a flickering oil light at hot idle. Bearings also tend to make more noise at higher revs.

Will start car cold and get my head under the bonnet tomorrow. No oil light issues (though haven't tested oil pressure.... guessing Mechanic will)
Thankyou

From the symptoms you describe, my money is on piston slap. Noise only there on light idle, no oil light so pressure good(!) noise disappears when revved or under load.

Originally Posted by RickRover

From the symptoms you describe, my money is on piston slap. Noise only there on light idle, no oil light so pressure good(!) noise disappears when revved or under load.

... ugh.. wonderful...