TD aux. coolant pump

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jolotter
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TD aux. coolant pump

Post by jolotter »

So while looking for good deals on unobtainable cooling hoses for a WBX to TD conversion, I came across this page:
Image

No. 33 in that pic, the auxiliary cooling pump seems to be standard on European TDs. Presumably it's thermostatically controlled and circulates coolant from the cold side of the rad, through the stock (to us) oil cooler and back to the rad. This seems like a really efficient method of cooling the oil.

Maybe I could even reuse my wbx fuel pump to move the coolant through the circuit?
(He quickly ducks to avoid rotten tomatos.)

But seriously, how do electric water and fuel pumps differ, apart from the orifice size? Delivery volume? Internal lubrication?

Johann
83.5 Westy 1.6 TD
93 1.9TD engine in the shed
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Post by libbybapa »

_________________
Last edited by libbybapa on Wed Aug 17, 2011 11:38 pm, edited 1 time in total.
jolotter
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Post by jolotter »

Since I have no experience with this system I can't disagree with you but I have been studying it over the past few days printing out numerous copies and going over them with my daughter's coloured markers.
This is what I have come up with:
Image

This flow path would be with the engine cold and the thermostat closed.
It seems that both the supply and the return for the oil cooler and it's aux coolant pump are on a totally separate circuit from the engine - cabin heater - expansion tank - water pump circuit as shown below, in yellow.
The two circuits do not cross.
Image

As well as being redundant since the engine and therefore the oil are not up to temperature, and the engine and cooling paths do not cross which would aid in heating the oil, and the flow to the rad and through the expansion tank is backwards ... I will assume that the aux. pump is thermostatically controlled and would simply not be running until the thermostat opened.

A quick sidenote: The coolant goes in the end of the pump and out the side. Right?

OK. So now the thermostat opens. It looks now like the stock na cooling system where the engine heats the coolant, which heats the oil which heats the lower temp coolant coming from the rad, and round again. Not very smart. This has been covered in Michael's tirade on the vanagon diesel cooling system. I see why Shawn Wright's pump did him no good.

But what if we plumb the aux coolant pump backwards and run it only when the engine is warm? For simplicity, I'll draw it as though I've simply reversed the polarity of the aux coolant pump, effectively running it backwards.
Image

Now the coolant is pulled out of the return line from the rad, through the pump, the oil cooler and joins the hot water going back out to the rad.

That was a load to get off my brain. I hope it's understandable.

Johann
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Post by libbybapa »

Well, you've got it all pretty much backwards. :D In fact, you can see on the hoses to and from the radiator, there are little arrows on the ETKA diagram that show the flow reversed from your arrows. All three of the hose connections draw coolant into the pump. The top big part of the pump is the only high pressure side and is bolted directly to the block.

Here's a diagram I did a while ago:
Image

I'm sure the flow is path is correct. Not sure why I used Red for cold coolant and blue for hot, but I'm sure the green arrows are correct. Bear in mind that the water pump is the driving force and all coolant will flow the easiest route to it.

Here is the ETKA diagram redrawn with the corrected flow paths when cold:

Image

Again, the only flow FROM the pump is shown by the green arrow at the bottom of the picture with the (slightly readable) text "into block". All hoses connections at the pump are flow INTO the pump (all roads lead to Rome?). The coolant on the "oil cooler/aux pump" circuit flows from the head flange near hose clamp 32 to 29, through cooler and aux pump to cold hose from radiator and is blocked by the thermostat when the thermostat is closed. When the thermostat opens it also blocks the bypass hose shown with orange arrow. Heater circuit always flows unless both heater valves are closed.

I would reiterate that the only individual I know who has both used the aux pump in the stock config and taken oil temp readings was showing oil temps (IIRC) of 270°F+ on extended grades which is a whole lot higher than I would want to see. The oil temps also took an incredibly long time to stabilize after the grade. If you want to read the first-hand account, you can do a search in the diesel-vanagon yahoo groups archives with the author of Shawn Wright and come up with the info fairly easily. I personally would not waste the time or money installing the stock pump (or any other rigged setup) when alternatives that actually control the oil temp are more easily and less expensively implemented.

FWIW, I enjoy the conversations regarding the coolant flow paths so feel free to keep the comments coming. Hope that helps.

Andrew
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Post by libbybapa »

I would add that if the flow were altered from what I have shown by reversing the flow through the aux pump, you would be effectively pushing against the flow of the waterpump and reduce the flow of coolant through every other circuit by creating high and low pressure areas that fought the waterpump on both sides of the "oil cooler" circuit. That would not be a good thing.

Andrew
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Post by jolotter »

This is hard for my brain, not to mention my graphical editing skills, so I'll tackle this one issue at a time.

Michael, in your diagram you mark the aux pump coolant flow as going into the large radiator hose and then into the waterpump and through the block. That orifice is blocked by the thermostat at low temperature. I propose that the flow is like this:

Image

At the point marked A, in red, the flow cannot enter the waterpump due to the closed thermostat (like you stated, Michael,) so I propose it must travel to the rad, in the opposite to normal direction. When it comes from the rad back to the 4-way hose it is drawn into the oil cooler by the auxiliary pump, completing the circuit. Thus, until the thermostat opens, there is no mixing of the auxiliary coolant flow through the oil cooler and the regular flow through the engine.

I've found a simpler diagram in the Euro Bentley:
Image

Here's a clean version for anyone's rebuttal.
Image



Johann
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93 1.9TD engine in the shed
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Post by jolotter »

Edit: Remove duplicate post
Last edited by jolotter on Wed Feb 13, 2008 1:37 am, edited 1 time in total.
83.5 Westy 1.6 TD
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Post by libbybapa »

I'm pretty sure that the stock aux pump setup has a temperature sensor control so that it does not run until the engine gets in the high end of normal operating temperatures. Additionally, you would not want it to. If it did run, it would significantly extend normal warm-up times, causing considerable additional engine wear and a significant drop in fuel economy. The stock diesel vanagon without the aux pump also has no flow through the "oil cooler" another significant blunder in the system design.

Yes, the Euro Bentley digram corresponds exactly to the two that I posted.

Your goal should be fast warm-ups to normal operating temperature and then consistent oil and coolant temps under all conditions. To that goal, the system I would recommend would be as follows. I would allow coolant flow through the stock heat exchanger until the engine warms up, making sure that the coolant used would be on the engine side of the thermostat. Coolant heats faster than oil initially, so that would significantly assist the oil coming up to temp. When the thermostat is full open I would cease any flow through the stock "oil cooler" (notice I always put it in quotes...). I would add a sandwich plate adapter with thermostatic control in order to run the oil, when hot, to an auxiliary oil to air cooler. That setup would relieve the heat soak in the stock setup that is caused by running the super-heated coolant (coolant from hot head getting a little hotter going through the stock cooler) right back into the engine without running it to the radiator. Understanding that flow and remedying it goes a very long way to establishing effective temperature control. The combination outlined above would most effectively meet the design goal.

Andrew

P.S. My name is Andrew. Not sure who Michael is.
jolotter
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Post by jolotter »

Sorry Andrew. I don't know why I called you Michael, (a couple of times.) Michael is my 10 year old son's friend that I've been arranging car pooling with...

OK. I'm concentrating now.

Here's my proposed reverse-flow-pump with the coolant hot and the thermostat open.

Image

The coolant would be drawn out of the cool return flow from the radiator, sent through the circuit and enter the hot stream going to the rad. I don't see any issues of "pushing against the flow of the waterpump" since the amount of coolant being pushed into the stream at the 4-way hose is equal to the amount being pulled out by the aux pump before the main stream heads back to the the waterpump. The only disadvantage I see is that the "oil cooler" or heat exchanger would not be useful for warming up the oil from a cold start.

Here's a solution for that:
Image

There are two stacked oil-coolant heat exchangers on the stock flange with the oil filter. The first is connected to the hose between the flange/cylinder head (3) and the coolant pump (4). It is teed in and out on that hose with a suitable restrictor to guarantee sufficient flow through the heat exchanger. This will help to warm the oil quickly on startup.
When the engine warms and the thermostat opens, the first heat exchanger will stop receiving coolant flow and the thermostatically controlled, running-in-reverse auxiliary coolant pump will start, feeding the second heat exchanger coolant directly from the rad, as described in the above picture.

The potential problem I see is that the coolant returning from the rad may be too cool, resulting in over-cooling of the oil. If the aux pump was switched by an oil temp sender on the return trip from the heat exchanger rather than the coolant temp sender that controls the glow plugs, (stock setup,) this could overcome that problem.

Is this easier than the system you propose, with the remote oil cooler, Andrew? Maybe. It involves an electric motor which could fail, but eliminates longish runs oil lines and istallation of the oil-air exchanger. Hmmm.


Johann

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Post by libbybapa »

Ok, sorry if I state the obvious, but that's just an attempt at good communication. The flow throughout the system is based on fluid moving from a higher pressure zone to a lower pressure zone. In the system the waterpumps produce the higher pressure zones. If you have two higher pressure zones converging at a tee (the situation you would have with the reversed flow) that convergence will reduce the effectiveness of both pumps. The situation is the same on the side where both pumps would be drawing from the same tee. The point is, that prior to reversing the flow of the aux pump, at the top tee was a lower pressure point than the main waterpump side. That reduced pressure is what causes the coolant to flow through the tee. If the aux pump is adding it's flow to that point as well, then the tee area's pressure will not be as low and affect the flow of the main pump's side of the circuit. The same is true on the low pressure side of the pump. Both pumps drawing from the same point will reduce the effectiveness of both of them.

With regard to the oil-to-air cooler and long runs. I would add the aux cooler to the passenger side of the engine compartment, taking advantage of the air flow through the stock air scoop. I would also use a thermostatically controlled fan. The run of hoses would be less than 4'.

If you are convinced you want to stay away from the oil-to-air cooler, then consider this untested modification that I proposed a couple of years ago.

http://www.vwdiesel.net/phpBB/viewtopic.php?t=2412

Andrew
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Post by jolotter »

After reading some, (much,) of the information referenced above, and thinking it over for a bit, I've decided to delete my previous post which was made with in haste. :oops: When I get my van up and running as a diesel with an aux coolant pump, I will make some experiments and post the results.

Johann
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93 1.9TD engine in the shed
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Post by jolotter »

Does the heater core provide heat to the cabin before the thermostat open?

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Post by libbybapa »

Yes, it does. The heater return hose is always open at the waterpump. There is a heater valve above the spare tire that will shut off the flow along with one on the rear heater itself. If both are closed, then the flow will stop on the circuit, but that is entirely independent of the thermostat.

Andrew
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Post by caveman »

I'm pretty sure all those pumps were used for an after run i.e. they would turn on after the vehicle was turned off in order to circulate coolant in the system so not to create any hot spots etc. they were installed in any vehicle where high load / high performance / hot under hood temps were involved. i would try to find a euro spec wiring diagram to see if it's not switched on that way
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Post by stopping »

Hello Vanahead folks (Hey Andrew can we have another video sometime?)

I recently had to make a coolant manifold for the head,ex tank,oil cooler,rad supply. I noticed something and I am not sure it has been mentioned.

The tee off the main rad supply to the expansion tank has a plug in there that limits the flow. The hold through the plug is just over 1/4" maybe it's 5/16" (7-8mm). This would have the effect of heating the oil until the rad/ thermo starts flowing. About 90% of the water would flow through the oil cooler/heater if the heater core(s) in the van were shut.

Perhaps it would be useful to restrict the flow to the expansion tank further?
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