Date:         Sun, 1 Jul 2012 11:26:04 -0700
Reply-To:     Poppie Jagersand <poppie.jagersand@YAHOO.CA>
Sender:       Vanagon Mailing List <vanagon@gerry.vanagon.com>
From:         Poppie Jagersand <poppie.jagersand@YAHOO.CA>
Subject:      Questions: 1.9l Turbo Diesel Westy running hot. Weak cooling?
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In the previous post I described how we had to interrupt our BC vacation and turn back on the first day because the 1.9l Turbo Diesel was running hot.

Before the trip I had prepared the cooling system by a flush with Prestone super cleaner, which is based on sodium citrate, and fill with the modern pink coolant (Havoline 5year 100,000 miles Dexcool compatible -- I've been using this before).

I also tightened the water pump belt with 1 shim as it was slipping on start up. The belt ended up a bit tighter than I prefer, but there's really no option less than one shim with this tighten system. Belt is a newer Contitech that seems stiffer and more slippery than typical belts.

The water pump is VW Brazil made with cast iron impeller. Have used this one before with good results. I found it much better than the after market pumps with flimsy stamped steel impellers.

I'm not so surprised if the belt tightening caused the bearing and seal on the water pump to fail.

What I wonder is if and why cooling efficiency depends on the system being pressurized? Since I had no air inside I was puzzled about the temp increase and wondering if something else may also be amiss. I also saw no signs of boiling over (which I thought would have made the coolant overflow from the reservoir and splatter in the back of the engine compartment). So if coolant was properly circulating I was thinking it would cool even if under atmospheric pressure instead of the usual 15psi over pressure kept by the pressure cap.

I'll also change the thermostat for good measure.

My past experience with thermostats is that they usually fail by warping so they don't close tightly, and the engine takes longer to warm up, or runs too cold in the winter.

Have anyone had a thermostats fail to open properly, and cause hot running? Thermostat not open fully would prevent full coolant circulation to the radiator, and perhaps worse, may not fully close the coolant bypass loop, so coolant just recirculates in the engine instead of going through the radiator. Anyone experienced this?

The thermostat does appear to open at about the right temp. When starting cold and driving temp rises quickly to temp gauge middle, then much more more slowly.
On idle tests rad remains cool until temp gauge reaches middle, then heats up when temp gauge needle passes middle LED.

I'm not sure how to test a radiator. Running the engine at 1500rpm high idle fan stage 1 comes on at about 90C temp and stays on low. Using an IR thermometer to measure the temp of the coolant I get:
Coolant to radiator: 90-92C
Coolant from radiator: 75-80C
Outside temp 20-25C
So radiator reduced coolant temp with 10-15C
Normal?

Any other thoughts on what might have gone wrong?
And what else should I test?

We're about to leave for a 3-4000km trip in rural BC so I don;t want more surprises further down the road...

Thanks,
Martin (and Diesel Westy 1.9l TD "Poppie")