Hi,

a month ago, when heating season just started, I noticed my Pathy does not blow hot air. Checked coolant and it was low in radiator and in expansion tank. Ok, I added some 3/4 quart/liter, but was wandering, where did it go...

Now I discovered some LEAKS and it seems to be coming right at the gasket between engine block and engine head. As of now it's dripping, maybe a dozen drops per day, but I've started worrying...

If this is GASKET only, then it's very uncommon to leak at the OUTER side and not inside. More often gasket gets blown between combustin chamber and cooling channels inside engine block.
But this one...leaking to outer walls...is this a sign of engine block cracking?

Here some pics:


Here, 2.5 dCi engine 174 HP....let's zoom closer


Here, right below the gasket. And the strange triangle grey ear, that's the EDGE OF THE GASKET. Weird, should not be visible as such, I think...


Here we can see drips of coolant/antifreeze all around the edge.

did you ever find out what the issue was ?

Hi,

yes, just yesterday...I hope so

I disassembled some piping in engine bay to get down to thermostat housing:
- air intake pipe with MAF sensor
- oil recirculation hose (from air intake pipe)
- some vacuum hoses
- air hose from turbo outlet, going to air intercooler
- turbo air inlet aluminium 90 degree pipe adapter (2 screws) from turbo housing



I also drained radiator and pressure tank, removed TOP hose from heater lines for cabin heaters and relief gasket on return pipe (both located on engine bay firewall, side by side, both pipes facing UP.
Then I used WATER vacuum cleaner to soak out as much coolant as possible from all over the disassembled system. It's better to vacuum out than blow it with pressurized air, because you can do no harm with vacuum.

Then I went down into removing thermostat (3 screws). This assembly does not require any special gasket, except for the gasket, which attaches to thermostat itself on its very edge.
This is the part, which actually holds thermostat and if I was only to change thermostat, it's as far as you need to go.

But I went one step deeper and removed thermostat housing underneath (5 screws), which has metal gasket and where my leak was. To remove this metal gasket (which usually stays on engine side), I followed the outer edge of gasket with tiny flathead screwdriver, just to get to the point to be able to pry it off the gasket surface. Then metal gasket just stipped off easily.

Cleaning surfaces:
All disassembled parts I resurfaced on 120 grit sandpaper, which I put on flat table, until clean gasket surface shined out. Say, some 15 minutes of sanding for all parts.
The remaining gasketing surface on engine block I sanded with some smaller pieces of sanding paper, guiding with a mirror on extension hand so I could see what I was doing. I put some CLEAN paper towels inside engine block openings, so grinded material did not enter engine water cooling openings.

Before final assembly I cleaned all possible piping with degreaser (yes, TURBO pipes are clogged with oily residue) and all aluminium parts with kitchen alu cleaning detergent, so it was all shiny new.




Now, time to put everything together.
As I did not have torque tool, I just tug all screws as much as SMALLEST rachet allowed me. I could do some 1/4 of turn with bigger rachet, but I did not go with such force, because I did not want to overtight screws.
Double- checked all vacuum hoses, all fine...

...now prepared some 50/50 BLUE coolant (GREEN is also ok for this car) and poured some 10 quarts in engine, radiator and expansion tank.

Heated up engine, went for a test drive and impressive results:
- no leaks anymore!
- engine running smoothly (...or it was just my perception)
- and surprisingly, no smoking when giving it full gas!

excellent job labsy, glad it wasnt too expensive a repair