water pump interchangeabilty?

[92EcoDiesel Jetta]

My 1.6 Caddy water pump has a 40 mm hub with a 40 mm hole pulley. Will the water pump/ pulley from a 92 Jetta 1.6 (with a 30 mm hub/pulley) fit in the Caddy?
Will the pulley fit diameter wise and will the belt grooves line up? I don't have all the parts here so can't check.

[thegimpster]

yes it will fit. you may have to shim the water pump pully some, but you may not. i've had em both ways. but the waterpump will wok in the caddy housing.

[libbydiesel]

A pulley from a 40mm hub water pump will not fit onto a 30mm hub water pump.

[R.O.R-2.0]

92 Jetta has 30mm pump..

like libby mentioned, you need the right pulley for the pump...

if you on ly have access to a 40mm pulley, then use a 40mm pump..

if you can get the proper diesel specific 30mm pump pulley, then upgrade to the 30mm pump..

mk3 2.0L pumps have tougher bearings in them, and last longer..

[92EcoDiesel Jetta]

92 Jetta has 30mm pump..

like libby mentioned, you need the right pulley for the pump...

if you on ly have access to a 40mm pulley, then use a 40mm pump..

if you can get the proper diesel specific 30mm pump pulley, then upgrade to the 30mm pump..

mk3 2.0L pumps have tougher bearings in them, and last longer..

Aren't mk3 diesels all 1.9L?  mk4's are 2.0 and its water pump won't fit mk2 or mk3?

Anyway I bought this (30  mm hub) pump/housing http://www.germanautoparts.com/productdisplay/1824 for the Caddy that (with 40 mm hub) that suffered one snapped thermostat housing bolt when I went to drain the coolant while replacing a leaky radiator (doesn't that sound familiar on our VW's, fixing one thing leads to breaking something else?).

The new 30 mm pump not only requires a new pulley, but also a new pump to pipe hose (different size barbs on pump). The spare 30 mm pulley on my spare 92 Eco engine is smaller diameter and also takes a wider belt (13 mm) vs 10 mm belt on the 40 mm pulley from the Caddy.

Not having all the parts needed (pulley, belt, hose)  I decided to drill out and re-tap the broken bolt in the Caddy pump. I am glad that went well. Taking the water pump off the Caddy was a pleasure compared to the 92 Eco Jetta with power steering and AC. It took only half an hour since I did not have to remove the injection pump like on the Eco, which took much much longer.

I still have to mount the re-tapped pump and finish the new radiator install.

[92EcoDiesel Jetta]

The water pump  bolt that did not snap was all rusty and I was able get it out going back and forth tightening/ loosening with lot's of penetrating oil. Maybe whoever did the water pump last did not use anti-seize? Would anti seize would have helped? Does anti seize loose effectiveness with age?

I am thinking instead on anti seize, I'll use RTV instead. The idea is is keep water out, no water = no rust. What do you think?

[vanbcguy]

I'd use anti-seize personally. It won't go anywhere.  It is designed specifically for coating threads and preventing bolts from seizing in place, while providing a bit of thread locking at the same time.  I've used it on injectors that I haven't touched for 3+ years, it is noticeably still in place upon removal.  I'm one of those "anti-seize on anything that gets sticky" guys.

In contrast RTV silicon is designed for sealing flat surfaces against each other, or for filling up your oil passages with RTV strings when applied excessively...   I tried to use some to seal a leaky fuel bowl bolt on a Holley carb once, result was tiny bits of RTV all through the metering block.  Yay.  RTV should only ever be used as a very thin skim coat where absolutely required.

[TylerDurden]

Anti-seize prevents galvanic reaction between the alloy and the steel, and lasts for years.

RTV on threads may be wiped by the threads and you could still get the galvanic corrosion.

[theman53]

I use stainless bolts and anti seeze as the galvanic reaction between the stainless and aluminum I think is worse than aluminum to steel.

[92EcoDiesel Jetta]

I have read that stainless should not be used on aluminum even if anti seize is used. How true is that? Anyone with long term experience doing so?

[92EcoDiesel Jetta]

yes it will fit. you may have to shim the water pump pully some, but you may not. i've had em both ways. but the waterpump will wok in the caddy housing.

Thanks. I will rig it up out and see if the pulleys line up even though I am putting the 40 mm pump back on.

[theman53]

It isn't true. I have customers that OEM stuff and use it all the time. Stainless is stronger than Aluminum and they don't want it to rust, that is why they are using the 2 non rusting things to start with. Also if you think about it the MLS head gasket is yep stainless and your head is aluminum. IIRC even in the fiber gaskets the compression rings are stainless. I think you have heard incorrectly.

[92EcoDiesel Jetta]

According to this  document http://www.fastenal.com/content/feds/pdf/Article%20-%20Corrosion.pdf stainless fasteners in aluminum is not a good idea. But according to this post http://www.practicalmachinist.com/vb/general-archive/will-s-s-bolts-work-aluminum-88508/ , field expereince shows that it is fine. I am tending to believe the latter and will try for myself. I am putting in stainless bolts/ washers with anti seize in the thermostat housing.

[R.O.R-2.0]

I have read that stainless should not be used on aluminum even if anti seize is used. How true is that? Anyone with long term experience doing so?

My dad uses STAINLESS hardware on all their aluminum boats, specifically because it doesnt have the galvanic reaction that steel/ally has...

long term experience, sure... longer term than i have been alive..

[theman53]

Fastenal is a somewhat competitor to my business so I have not much good to say about them. If I have time I think there is a chart of how fast certain alloys will have a galvanizing reaction to each other and I will try to find it. Bottom line is if you are putting in a T stat that is probably again stainless, it will probably need replaced before the stainless bolts will freeze up in the aluminum housing.