TheSamba.com :: View topic - Diesel engine coolant diagram with arrows showing flow

Mon Dec 01, 2025 2:16 pm

I have scoured the stupidnet looking for an diagram of a diesel vanagon engine bay hose flow showing which way the pump pushes the water through the spaghetti of hoses in the engine bay. To my luck the internet has assured me the coolant flows from the back of the van to the radiator and then back. WOW so if any of you all out their have a diagram with flow arrows I would appreciate a response. Im in the process of moving and cannot get to my Bentley

Cheers
Gregg.

Mon Dec 01, 2025 3:45 pm

the early green service manual has the diagram as I recall

Mon Dec 01, 2025 5:27 pm

It should be fairly self explanatory if you have all thee pieces. Usually the hoses have a memory.

What pieces do you not have?
.

Roland

Mon Dec 01, 2025 5:46 pm

If you have a specific question about a diesel hose, ask away.

The water pump attaches low to the engine block.
It sucks coolant in and pushes it through the block and up into the head.
All of that all warmed coolant then comes out of the engine at the cylinder head.
Where it goes from there can vary depending on how warm the engine has gotten and whether the heater valve is turned on or off.

Mark

gchristensen wrote: I have scoured the stupidnet looking for an diagram of a diesel vanagon engine bay hose flow showing which way the pump pushes the water through the spaghetti of hoses in the engine bay. To my luck the internet has assured me the coolant flows from the back of the van to the radiator and then back. WOW so if any of you all out their have a diagram with flow arrows I would appreciate a response. Im in the process of moving and cannot get to my Bentley

Cheers
Gregg.

Mon Dec 01, 2025 6:18 pm

Here is an 82 as a start

now another one

Mon Dec 01, 2025 6:33 pm

Mon Dec 01, 2025 10:02 pm

Thanks waldo you were the only one that read the post.

Tue Dec 02, 2025 5:12 am

I believe the heater flow from the head to the core is missing. That would be the coolant flange at the back of the cylinder head. Opposite end of the timing belt.

Also missing is the radiator end. I have to check the manual every time, but unlike its brother in the sedans, coolant flow goes into the bottom of the radiator and out the top back to the engine. This is more obvious on the 82 diesel radiator, but later VW incorporated the radiator return into the r/s radiator tank so both fittings are at the bottom.

I mention this because it’s possible to mix this up.

Tue Dec 02, 2025 5:37 pm

I apologize for not precisely answering your flow direction question, but when you have all of the correct pieces in place, does it matter?

That said, I do not have the tee shown between the alternator and the pressure tank. It would help to get a look at the water pump outlets, and what attaches there.

Roland

Wed Dec 03, 2025 6:52 am

RolandD wrote: That said, I do not have the tee shown between the alternator and the pressure tank. It would help to get a look at the water pump outlets, and what attaches there.

All of the stock diesel hose sets have that tee although stock it is a single molded hose.

The water pump has 3 hose connections:
Top is the bypass connection which allows flow until the smaller disc of the thermostat blocks it as the thermostat opens.
Middle is the heater return (hose to the pressure tank) and it is always free flowing at the water pump.
Bottom is the radiator return and it is closed until the thermostat starts to open.