AndyBees
Top Post Dawg
- Joined
- May 27, 2003
- Location
- Southeast Kentucky
- TDI
- Silver 2003 Jetta TDI, Silver 2000 Jetta TDI (sold), '84 Vanagon with '02 ALH engine
As many of you know, I did an ALH TDI install in an 84 Vanagon (http://forums.tdiclub.com/showthread.php?t=276798) which was finished and put on the road in August, 2012 (about 84k miles on it now).
So, I've noticed the engine temperature runs a bit on the high side during cold days. Observation is via Scan Gauge as well as two on-dash temp gauges. One gauge is an aircraft grade and the other is a McNally EGT/Coolant temp combo. This temp increase is nothing new but with cooler weather upon us, I've been reminded.
Anyway, this is my theory on why the engine temp may be increasing during cold weather. But, first, in case you are not familiar or have not given it any thought, circulation of the coolant in VW engines is somewhat complicated. Coolant leaves the engine at the end of head next to bell housing thru the coolant flange and one small metal pipe down below the coolant flange.
From the coolant flange, one hose goes to the EGR/Heater circuit, one hose goes to the Oil Cooler and the big hose goes over to the top of the Radiator. From the one small pipe, coolant flows to the top of the expansion tank .......... for the moment forget about the coolant flow to the Radiator (big hose). So, coolant from all those circuits flows back to the Water Pump housing via a single black metal pipe. That coolant, when hot enough, is what activates the T-stat which is mounted in the side of the WP housing (which is where the return coolant from the Radiator enters). If that coolant stays below the opening temp of the T-stat, it doesn't open.
So, back to my Theory on why the engine tends to run on the hot side in winter. With my set-up the coolant that circulates to the front of the Van where the heater is located is through at least a 32 foot long loop. Thus, by the time it goes to the front, thru the heater and returns to the Water Pump housing it is, in effect, only lukewarm. This coolant, even when mixed with the hot coolant returning from the Oil Cooler and Expansion Tank, is too cool to open the T-stat, but hot enough to increase engine block and head temp. The McNally temp sensor is on the coolant flange and the aircraft temp gauge sensor is on the return hose from the Oil Cooler......... and, they both show the temp increases. And, the OE coolant temp sensor is on or at the coolant flange and it shows the temp increase via the Scan Gauge......
Oh, and I eliminated the EGR Cooler circuit when I did the engine conversion.... not sure if this has anything to do with the heat differences.
So, what's your thoughts on this?
With your conversion project, have you noticed or had a coolant temp issue?
So, I've noticed the engine temperature runs a bit on the high side during cold days. Observation is via Scan Gauge as well as two on-dash temp gauges. One gauge is an aircraft grade and the other is a McNally EGT/Coolant temp combo. This temp increase is nothing new but with cooler weather upon us, I've been reminded.
Anyway, this is my theory on why the engine temp may be increasing during cold weather. But, first, in case you are not familiar or have not given it any thought, circulation of the coolant in VW engines is somewhat complicated. Coolant leaves the engine at the end of head next to bell housing thru the coolant flange and one small metal pipe down below the coolant flange.
From the coolant flange, one hose goes to the EGR/Heater circuit, one hose goes to the Oil Cooler and the big hose goes over to the top of the Radiator. From the one small pipe, coolant flows to the top of the expansion tank .......... for the moment forget about the coolant flow to the Radiator (big hose). So, coolant from all those circuits flows back to the Water Pump housing via a single black metal pipe. That coolant, when hot enough, is what activates the T-stat which is mounted in the side of the WP housing (which is where the return coolant from the Radiator enters). If that coolant stays below the opening temp of the T-stat, it doesn't open.
So, back to my Theory on why the engine tends to run on the hot side in winter. With my set-up the coolant that circulates to the front of the Van where the heater is located is through at least a 32 foot long loop. Thus, by the time it goes to the front, thru the heater and returns to the Water Pump housing it is, in effect, only lukewarm. This coolant, even when mixed with the hot coolant returning from the Oil Cooler and Expansion Tank, is too cool to open the T-stat, but hot enough to increase engine block and head temp. The McNally temp sensor is on the coolant flange and the aircraft temp gauge sensor is on the return hose from the Oil Cooler......... and, they both show the temp increases. And, the OE coolant temp sensor is on or at the coolant flange and it shows the temp increase via the Scan Gauge......
Oh, and I eliminated the EGR Cooler circuit when I did the engine conversion.... not sure if this has anything to do with the heat differences.
So, what's your thoughts on this?
With your conversion project, have you noticed or had a coolant temp issue?
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