water pump R&R

[92EcoDiesel Jetta]

I have a new water pump without housing. I currently have the power steering pump, alternator,  A/C compressor, upper and lower timing belt cover removed.
.
Should I

1. Remove the intermediate shaft timing belt idler, then remove the 9 water pump bolts while leaving the water pump housing on the block? or

2. Remove the 4 bolts that secures the water pump housing to the block, then remove the 9 water pump to hosuing bolts? This way I don't have to remove the timing belt idler.

Which is less risky, less chance of things to go wrong.

[theman53]

I have always done 1...but I suggest #2 as if when 5 of the 9 bolts break off then you can put the housing into a vice to heat and vice grip them out. I have done it on the car and I know for a fact it would be lots easier to do it not on the car.

[lovinthedeez]

if you don't pull the whole thing out, and switch the pump afterwards, you're setting yourself up for a great big headache if one of the 9 bolts break.

[92EcoDiesel Jetta]

If you know FOR CERTAIN that whoever installed the 9 pump bolts used copious anti-seize on them, then go for the nine.  If not, then I would most definitely pull the housing with the pump.  I would then most definitely  heat the bolts HOT with a propane or mapp gas torch and copious amounts of penetrating oil prior to attempting to remove them.  I have been so unlucky as to snap ALL NINE before.     I would also make sure that the new pump has a cast iron impeller.  The stamped steel ones move noticeably less water.  Your temp gauge will run noticeably hotter.  The plastic impeller ones are known for spinning on the shaft when they get some age.

How was it determined that the stamped ones move less water? Too bad I didn't know this before I ordered mine (from Germanautoparts.com) and it's a stamped one. Is it possible to tell what's in the old pump without taking it apart? Can the impeller be seen from the T-stat opening? The bearing feels fine on the old pump and it is not leaking. If it has a cast impeller, I'd just leave the old pump alone. Who sells a cast impeller pump?

[92EcoDiesel Jetta]

Thanks for the warning about the Autohaus impeller. Speaking of plastic. Where can I get an aluminum hose flange for the water pump? 

[92EcoDiesel Jetta]

I looked and the water pump in the car and it has a plastic impeller (not spinning on its shaft). I think I'm just going to leave it in there for now and not mess with it until it fails.

Did OEM water pumps have the cast iron impeller?

[vixentd]

installed a new water pump cast iron, on a new AAZ motor.  Motor ran about 10 degrees warme. Tried everything to determine why, from new temp sensor, new voltage stablizer in cluster, etc.  5 years later it started to see and installed a stamped steel one, as that was what was available.  10 degrees cooler.  Big difference. One of other fellow also swapped to a stamped impeller and noticed the same.

The stamped ones actually cool better.

[arb]

2. Remove the 4 bolts that secures the water pump housing to the block, then remove the 9 water pump to hosuing bolts? This way I don't have to remove the timing belt idler.

I would do this one because it gives you a change to inspect the o-ring at the block. They usually last forever, but I've had some get old and cracked. Plus, like everyone said, if you snap a bolt....

Why were you going to replace the pump if it had not failed yet? Did you notice any weeping of the shaft seal? If so, failure is a heart beat away.

[92EcoDiesel Jetta]

I was going to replace the WP because it was recommended that it should be replaced when I do the timing belt.  I ended up leaving the old WP in because I did not have a new housing.

I guess the only way to know which WP (cast iron or stamped sheet metal impeller) is to do a bench flow rate test. Anybody have both who wants to run a test?

[arb]

I was going to replace the WP because it was recommended that it should be replaced when I do the timing belt.  I ended up leaving the old WP in because I did not have a new housing.

I had a new pump on hand, but thought I'd run my unknown life pump until it failed... good thing a bolt snapped when I was putting the pump back on (had to remove it because I R&R the thermostat and one of those bolts snapped.) because the shaft seal was starting to leak.

[92EcoDiesel Jetta]

I was going to replace the WP because it was recommended that it should be replaced when I do the timing belt.  I ended up leaving the old WP in because I did not have a new housing.

I had a new pump on hand, but thought I'd run my unknown life pump until it failed... good thing a bolt snapped when I was putting the pump back on (had to remove it because I R&R the thermostat and one of those bolts snapped.) because the shaft seal was starting to leak.

Is your flange for the thermostat aluminum? If so do you have another one or know who does?

[arb]

I was going to replace the WP because it was recommended that it should be replaced when I do the timing belt.  I ended up leaving the old WP in because I did not have a new housing.

I had a new pump on hand, but thought I'd run my unknown life pump until it failed... good thing a bolt snapped when I was putting the pump back on (had to remove it because I R&R the thermostat and one of those bolts snapped.) because the shaft seal was starting to leak.

Is your flange for the thermostat aluminum? If so do you have another one or know who does?

Yes, its aluminum. I also have a new o-ring that I was going to return... Send me a PM.

[GEE-BEE]

I purchased my engine and spare parts from Qualitygermanautoparts.com

He imports engines from europe along with partsfor the AAZ's

1.9 AAZ

I INSTALLED A NEW TIMING BELT AND WATERPUMP BEFORE THE SWAP !

Gee-Bee

[92EcoDiesel Jetta]

The stamped ones actually cool better.

That's very interesting and contrary to every other report I've heard.  Looking at the actual fit of the blades to housing I can't see how the stamped one could flow better but I'd definitely be interested in seeing a flow test.  I have a used cast impeller pump I'd donate, but no stamped version here. 
[/quote]

I can do the flow test if you send it to me. I have a stamped impeller but have to get a housing to do the test.  May take a few weeks to setup. I can also take videos of the test.

[rabbitman]

I have been so unlucky as to snap ALL NINE before.    

LOL, I had to laugh at that....one of those days