Thread: Why are Stage 1 Isuzu's so noisy ??

I remember my '85 120" to be considerably more noisy than my '88 110.

The '88 doesn't seem more noisy than my 300tdi, maybe that's wishful thinking.

I guess I could dig out the sound meter thingy and compare.


Nah.

Simon

I am pretty sure all of the stage 1 Isuzu motors were not fitted with the valve rocker cover "hush kits" The black external tin cover on top of the motor. Makes a heap of difference to the level of valve noise that can be heard.

It's got something to do with the head/cam set up I'm sure of it. I rebuilt one a few years back out of a stage 1 and used all new/reconditioned parts except for the short block,head,and cam and it was noticably knockier than my engine that had the exact same parts sourced, except for the previously listed items.
I even tried my rocker cover and tappet assembly on his to see if we could track down the noise. We never did quiet figure out why exactly, we could only put it down to the head/cam as they were different no's.

Hope this helps

interesting. I had a drive of YT110's 86? and it was considerably as in a very big way quieter and much smother though the rev range than my 85. So much so that when I got home I checked my engine mounts. I have even gone as far as pricing replacements thinking mine may have hardened over the last 24 years.

In fact YT110 was no more noisy than my TDI300 disco and a lot nicer to drive.

What are the different cam part numbers, are there different followers and push rods, rocker arms etc.

The difference is that great that I would consider changing cams for that reason alone. depending on price

Was there a different power rating with the different cams ?

Very interesting. My motor is out of an 85 county and is very loud and harsh.

IRC:
Stage 1s are rated at 85Bhp - same as mil spec engines.

Countys are rated at 99 Bhp.

So there must be some differences.

I have been told by someone who should know, that if you retard the timing slightly they will quieten down.

This was mentioned to me years ago by Fred Smith, and he told me the Stage 1 had slightly higher compression.

John

Yes I'm wondering if it's more injector/combustion noise too.
Some engines of any family are noisier than others, I've had this mentioned to me before about 300Tdi's too, and I think it usually comes down to the state of the injectors/pump and timing.