HZ 100 Series Engine Rattle

Hi nuboy

I had a high metallic rattle at about the same revs and it was traced to the large muffler. May not be your cause but worth a check.

Do search as there was a recent discussion about a ticking type noise at certain revs which is apparently crankshaft flex.

Hi Nuboy

I have a 2002 1hz 100 series with a ticking noise that is audible at about 1900 evs through to 2300 revs. Mine actually does it from 1000 through to 1400 as well so your lucky if it is the same problem as you have done 247k's I have only done 90k's. Toyota call it crankshaft flex and arent fixing the problem as they have had no engine failure resulting from this noise it seems to be the block where the crank sits in that is out of wack causing the crank to flex resulting in this noise. An easy way to diagnose this prob is stick you head in under the car whilst reving the throtte with youre hand and you will hear this noise quite easely coming from the sump. Remember Handbrake!!!

Try different grades of oil through you oil changes...

I initially tried some heavier oils but lately I am thinking of trying a thinner oil to see if the noise can be heard louder or quieter... I am only trying this as my engine always seemed a little noiser towards the end of the oil life and nice and quiet once the oil was changed.. however lately it seems to be that the motor is noisy until it has done at least 10k's of driving so I am assuming that the oil has had a chance to thin down with the heat.

Could have something to do with the oil pump or galleries not letting the heavy oil through or something.

Also it may be worth having a look at the actuator arms on the fuel pump... there is a small arm that is pulled in by a vaccuum from the Air Con.. the arm that then pushes the throttle link has a nylon bush that wears out and gives sideways movement.... when your motor gets to a particular rev it rattles! I had this problem and was thinking it was something serious until I found this out and took it off... that problem was then fixed!

I do have the crankshaft flex (detonation) noise though... very different type of noise and once you have heard it you know it.. a sound all of its own. as described as a little man with a hammer tapping away.. I describe it as a tin with a couple of marbles in it being rattled.

Hope that helps you out.

by the way.. I have found that different fuel mixtures etc does affect the amount of noise that is put out so it may be worth your time to have that checked out!

Some years ago mine had a rattle [noise] Found it was the alternater mount lose .Who knows..Murranji

Try posting on www.lcool.org .There is a forum here dedicated to 100 series LC's and a lot of good advice is posted

It could be rattly springs or dampers in the springs of the clutch plate if you've got a turbo diesel. Casper

For those that have been following this thread I have had a Diesel Mechanic check out the engine rattle and he is 98.9% convinced its only a loose tappet,
therory being the rattle when you listen to it, is double the pulse speed of the engine pulse speed or RPM. I will pull the rocker cover off on the weekend and check out his theory ?