Thread: 300 tdi blow by... theories

Its common for 200's and 300's to have a little blow by.
Dont know why, but a LR mechaninc told me so,....

ummm, what ive found, when the sep belts age, they glaze up a bit, as soon as it rains and water everywhere, or creek crossings its starts a squeeling. can prolong a change by using drylube, oil blah blah blah but whack on a new belt and all sweet (new belt with the rough back side)

This of course is if the squeel is NOT idler bearings, tensioner bearings, water pump, thermo fan bearing, alternator bearing????? a few weeks back i had noticed a light squeel as well as a bearing rumble, i changed out the two idler bearings and tensioner bearing, new air compressor belt from the spares kit and the serp belt on was glazed so i threw on my spare which was less glazed (being sunday nothing open).... was okay for a week or two but this recent rain started that one squeeling so went and bought a new one....

steve

sclarke yeah there is always some blow by in the 300tdi, excess gasses int he rocker cover are scavenged through the PCV valve, oil returned to sump and blow-by sent to intake manifold pre-turbo ... but this was excessive. I guess I could have waited for things to be more severe but wanted to get on top of the problem before more damage occured.
s

UPDATE...

didnt do a leak down test, probably shoulda but couldnt find anyone to do it?
anyway pulled the head off, took head and gasket to mech this am. In his experience when 300tdi get the amount of blowby we had it is usually a breakdown in the gasket between cylinder and crankcase, he had some gaskets in the shop where the gasses were tracking through the middle of the gasket!

Anyway, the fender head "looks" okay, gasket "looks" okay. The bores dont look too flash, very very smooth and shiny... small lip which i am still yet to clean up and measure.

The local machine shop cant test between combustion and crank-case, mechanic thinks it will be rings as called by people above but could still be a leak inside the head???

So, pistons out, new rings, light skim of the head to clean it up, bolt it back together and see what we have.

I guess the truck was bought with 170k on it, service history for first 80 then nothing so I was expecting this sort of thing... maybe it had the same oil in it for 80,000km!!!
Should be a bit of fun. Will let you know once I have the pistons out.

Steve

UPDATE UPDATE

Just getting into the block now:

Lip on number 1 cylinder 0.1mm as best i can measure with a set of feeler gauges and a straight edge...
Lip on number 2 is 0.1mm
Lip on number 3 is 0.25mm
Lip on number 4 is 0.08mm

So me guessing num 3 was letting gasses into the crankcase.
off to see what we can do about it!

Also noticed about same wear on the slip big ends as has been posted on AULRO before, top slips were down to copper colour, bottom slips no copper colour. hone marks still present on crank journals and conrods.

cylinder bores appear very slick.

S

Curious as to how much the "cap bouncing away when loosely in place" was. Did the cap escape the hole?
I've noticed on mine that it bounces a little (when loose) at idle but once you rev it a little is seems to suck down somewhat. I take it this is normal....??