300tdi oil leaks vs water crossings

[brendanmac]

Over the last few months I've attended to various oil leaks on my 300tdi Defender.
These include engine sump, rocker cover gasket, p gasket, pcv, breather hose next to the pcv, rear pinion seal, transfer case extended sump.

There is still an engine oil leak rather low down on passenger side of engine towards firewall but I don't know where it is coming from. Any suggestions as to the source?

The transfer case is still leaking from somewhere above the sump. A small droplet has accumulated about 5mm above the sump gasket on the forward passenger side. It has a slight tail indicating it is originating from higher up but I can't see from where. I know it's not the sump gasket because there is no evidence of oil being blown upwards. Again, any suggestions as to the source?

I think the swivel hubs may also be leaking although not too badly.

I've got a trip coming up which will involve water crossings so I am wondering whether these leaks are show stoppers if not fixed beforehand?

If not show stoppers, what are the most likely and worst case scenarios for each leak if not fixed prior to water crossings, or not fixed for a few weeks after water crossings, and what is the highest priority to get fixed either prior or after water crossings?

[mrb505]

Worst case scenario, the oil slick your leaving behind in the creek

[brendanmac]

So no chance of hydrolock?

Or water being sucked in because of sudden change of temp?

[AK83]

....

Or water being sucked in because of sudden change of temp?

Into the engine(if it's a motor oil leak) .. very unlikely.
The oil system in the engine is under pressure .. I think it's supposed to be a minimum of 9psi before the light comes on(can't recall exactly).
A tdi in good nik would ideally run at a min 20+ psi. Mine idles with about mid 20 when really hot, higher 20s when at normal operating temp.

So even with the rapid cooling of a creek crossing, the oil is still under pressure(oil pump remember!).

You're probably thinking of diffs (don't use oil pump).
They get hot to a point, into the drink and then cool .. losing the pressure they had when hot. Sudden pressure drop can equate to slight vacuum effect sucking water into axle.

Oil leak on passenger side near firewall .. maybe the cyclone hose to the air inlet?
If that had a split facing downwards near the back there .. could look like an engine oil leak.
Another prime suspect could be oil drain pipe/junctions .. one on the turbo one on the block.

[brendanmac]

thanks AK83,

A very clear explanation. I will check the the cyclone air inlet.

If the water is deep enough, is it possible water could be sucked into the TC through a leaking seal?

[AK83]

I'm pretty sure that hose that wraps behind the engine and into the main inlet hose is the cyclone outlet.
That is, the smoke/vapour that is sent back into the engine intake.


....

If the water is deep enough, is it possible water could be sucked into the TC through a leaking seal?

Hopefully someone with more experience and knowledge will chime in and explain .. I reckon it'd have to be a severe leak too .. but I really dunno.

Hottest I've measured my transfer case body has been low 80 degrees, after a long run on the highway in about 35+ ambient.
Not sure how hot the transfer case gets normally, or in extreme instances, but I'd assume not too hot when pottering about on some track prior to a creek crossing.
I did measure the transfer and auto in my D1 only one time in slow track going .. the auto trans temp globe popped up as a warning, so got under to make sure everything was OK.
Trans in the 80's and TC in the high 60's that time. Turned out the trans temp switch was playing up(replaced and never come again).

So with that, unless you're really working the vehicle hard up some serious steep stuff in low range and struggling with the track .. I doubt the TC case will get hot enough to cause a temp difference pressure drop when traversing water deep enough.
But like I said, not enough experience with my D1 yet, and even tho I had a RRC with an Lt77 and Lt230 back in the day .. never had issues with it, nor its original LT95.
That LT95 was a middle eastern oil well in terms of out output too!

[86mud]

Also check the rocker cover gasket. they can leak at the back and run down the block