Blown Header Tank

[ghost123uk]

On mine the coolant pipe that comes from the rear of the left hand head tapers down to a thin section that goes to a "T" piece on the metal pipe that runs around the engine bay got blocked in just the same way as the one in that picture (which is not my pic, it is from someone else on here, from years ago). The lack of flow around the left hand head caused the coolant in there to boil, the cap obviously could not keep up and it "blew" a hose. At the time I thought the blown hose was just caused by a weakness, but a day or so later the left hand rear piston partially seized. I did not immediately understand why this had happened. It resulted in me having to source another motor. I tested it and found the new motor was suffering from a lack of coolant flow around that left hand head, it was then I discovered the blockage, (just the same as shown in that pic). So, I suppose my blockage was not in the actual bleed ring, but certainly part of the same "circuit",

[itchyfeet]

My understanding is the main flow to cool the head is not via the bleed ring as can be seen on the coolant diagram

[ghost123uk]

Where does the coolant exit on the left hand head? (I find the direction arrows on that part of the diagram confusing )

My blockage was in the pipe, lowest left in the pic, marked "to upper bleeder ring".

[NicBeeee]

Where does the coolant exit on the left hand head? (I find the direction arrows on that part of the diagram confusing )

My blockage was in the pipe, lowest left in the pic, marked "to upper bleeder ring".

By following that drawing I would say the water in the left hand jacket circulates back to the pump through the metal by pass tube, continues to circulate through the left hand and the right hand and back to the pump via the distribution unit until the thermostat opens. Then a mixture of warm engine water and cooled water via the rad circulates back to the pump through the metal bypass pump. From the pump through both water jackets with an even temp. If the top bleed ring is blocked then maybe your left hand jacket never filled up so over heated.

[ghost123uk]

Ah, that seems to make sense, and -->

If the top bleed ring is blocked then maybe your left hand jacket never filled up so over heated.

That would make sense too

I should have realised by looking at the engine bay that my blocked "upper bleeder ring" pipe was too thin to be the main return from the head

[itchyfeet]

If the top bleed ring is blocked then maybe your left hand jacket never filled up so over heated.

Yes main flow it out through thermostat housing and back via metal pipe.
You may get an air pocket in there but I doubt it would last long, my guess is bleed ring blockage does not cause failure it's something else.

[itchyfeet]

I spent some time looking at the flow diagrams recently for early and late, iteresting that an early system flows in and out the same side of the water jacket and head where the late flows in and out opposite sides.

Also I came to the conclusion that the coolant flow direction in the bypass hose over the gearbox (purple on diagram above) has to reverse flow when the thermostat opens in the late cooling system, if not it wouod not flow via radiator

Early diagram

[Smosh]

I'm commenting because I need to find this thread whilst working on the van today. I need to combine early and late system?!

[Smosh]

I'm a bit stumped by this coolant distributor, not convinced they sent it with the engine. Anyone got a pic?

[multisi]

Look in your Haynes manual page 3.5 there is a diagram. Numbers 16 early, 17 late for that distribution. I may have a late one and some other bits.