CaveVan Forum
VW T4 "Eurovans" => VR6 Engine tech => Topic started by: Itsamoto on August 18, 2015, 03:28:43 pm
-
Wanted to post this information for any who need it. This is from the Bentley manual and applies to both 12v and 24v engines.
FLOW DIAGRAM
(https://farm6.staticflickr.com/5761/20500073829_9b5a3865c0_o.jpg)
LEGEND:
1 - Expansion Tank
2 - Flow Control Valve (optional)
3 - ATF Cooler
4 - Vacuum Valve
5 - Radiator: a=bottom, b=top
6 - After-run Coolant Pump (V51)
7 - Coolant Pipe (aka crack pipe)
8 - Engine Block
9 - Oil Cooler
10- Coolant Pipe Drain Screw
11- Coolant Pump
12- Cylinder Head
13- Thermostat Housing
14- Throttle Body
15- Heater Core (Cabin)
16- Solenoid Valve (optional)
17- Aux Heater Core (Rear)
-
Here's one observation on this diagram -- is that it shows general flows, but the flow of coolant is dependent on the thermostats position (open vs closed).
For example, with the ATF cooler/heater (#3 on diagram) -- when the thermostat is closed, this actually acts to heat up the transmission fluid. When the thermostat is closed, the flow of coolant through the radiator is stopped, which then diverts coolant off the radiator return line and through the ATF cooler back to the recirculation (bypass line). When the thermostat is open, coolant flow through the radiator is restored and I would theorize that flow through the ATF cooler then either reverses, or if the pressure is equal on both the recirculation line and return line -- that flow stagnates altogether.
-
Good stuff!
I've often considered trying to simplify the hoses under the hood.
When I install transmission coolers for example. I don't insert a barbed fitting to patch the two hoses together but rather just route one hose to the others old fitting. Thus eliminating 2 connections and one complete hose!
-
Thanks Cole.
One other thing for simplification that I was looking at the other day -- was to run the front and rear heat exchangers in series, rather than in parallel. This would allow the removal of some T-junctions and the flow control valve. I figure the front heater core performance won't be affected, and the rear core already seems like the weaker of the two - so it would clean up things quite a bit. One hose from the back of the cylinder head to the front heater core, then the return line goes straight down to the hard lines for the rear heater and then back to the recirculation inlet on the thermostat housing.
Another thing I looked at -- but its more for those who don't drive in freezing temperatures, is that the throttle body coolant line (which heats the throttle body to prevent freezing up) can be removed. This would eliminate and clean up the coolant lines as well - eliminating another couple of T junctions. The return line from the throttle body is pretty ugly -- just a long 3ft hose that drapes over the engine. One other option here to clean this up (rather than to delete) -- is to route the return line (off the TB) back into the front heater cores' return line. Not as clean, but certainly more elegant and retains function.
-
I had that tee blow out three times then I replaced it with a brass barbed tee. If the secondary air pump fails the strip fuse (s1 near battery) is shared with the after run cooling pump and the pressue builds after the van is shut down.
-
I don't suppose anyone makes a silicone engine hose kit for these, do they?
-
Need advice on a front heater core issue: shop says there is no flow through it. No front heat. Just replaced thermostat. They took off return line at core and replaced with clear hose, said flow was a dribble. They don’t think it is blocked, not sure why. They also flushed coolant system. Not sure what lower valve with vacuum line does, but vacuum is good, causing valve to move from off position (plunge downward). When I pull off hose, plunger goes up. What else may affect flow to heater core?
Anyway, mechanic wants to replace water pump, another grand. I don’t want him throwing parts at this without clear idea. Van does not over heat, temp stays at 190. Water pump is only 4 years old, replaced when chains were done at 175k.
Matt
2002 weekender 211k
Durham, N.H.
Sent from my iPhone using Tapatalk
-
Thanks Cole.
One other thing for simplification that I was looking at the other day -- was to run the front and rear heat exchangers in series, rather than in parallel. This would allow the removal of some T-junctions and the flow control valve. I figure the front heater core performance won't be affected, and the rear core already seems like the weaker of the two - so it would clean up things quite a bit. One hose from the back of the cylinder head to the front heater core, then the return line goes straight down to the hard lines for the rear heater and then back to the recirculation inlet on the thermostat housing.
Another thing I looked at -- but its more for those who don't drive in freezing temperatures, is that the throttle body coolant line (which heats the throttle body to prevent freezing up) can be removed. This would eliminate and clean up the coolant lines as well - eliminating another couple of T junctions. The return line from the throttle body is pretty ugly -- just a long 3ft hose that drapes over the engine. One other option here to clean this up (rather than to delete) -- is to route the return line (off the TB) back into the front heater cores' return line. Not as clean, but certainly more elegant and retains function.
Itsamoto - love that idea, and just wanted to follow up on this to see if you have tried this setup. I might give it a shot here soon, as I am about to replace the upper coolant pipes and crossover/crack pipe.