High Tack does also come in liquid, and is appropriate for some applications, (low heat and petroleum based fluids) but I am speaking to the aerosol for this application. (high heat and antifreeze) Fitting dry or without elastomers can allow seepage or leakage. Some gaskets are pre-treated and some are not. The one shipped with my Airtex pump was not. The reason the OE gasket doesn't call for sealant in the service manual is because it is a rubberized (elastomer) metal gasket.

 

I take it none of this applies to the metal gasket?

 

Not to the factory OE gasket and pump, however, the Airtex pump's cast body is not machined and is a different style than the original, which requires a paper gasket to take up the variations in the casting.

 

Well 2000 miles later and the Airtex pump is leaking between the sandwich halves as well. So word of advice, do not buy any pump based on the two piece assembly. They all leak. Buy the single piece body design pumps.

 

That's a bummer, V12StealthHunter,

Out of curiosity, did you use the Workshop Manual torque spec, some other spec, or the feel method?

Cheers,

Don

 

The pump is not leaking at the engine/pump gasket, its leaking at the gasket that makes up the two halves of the pump body itself. I believe the AC Delco 252-800 is a single piece body pump that eliminates this sandwich gasket. I have one on order. Will report back when I get it.


I've never ever used a torque spec for a compressible gasket like paper, cork or rubber.

 

I believe you'll find the AC-Delco pump to be a metal impeller. OAT is not recommended with it.

 

I remember now that the two halves are held together by screws that are separate from the mounting screws. I recently replaced the original pump on an S-Type R and it was a two-part pump - I know this because I inadvertently removed the screws that hold the halves together. I wonder if the screws on your pump were not torqued properly at the factory?

Just for the benefit of others who may refer to this thread in the future, the Workshop Manual torque spec table states that on the 3.5L / 4.2L engines the water pump retaining bolts should be torqued to 12 Nm / 9 ft. lbs. However, abonano recently pointed out to me that in the actual water pump replacement section, the manual gives the torque procedure as 8 Nm+90 degrees. Not something easy to guess by feel.

The spec for the water pump pulley screws is 10 Nm + 45 degrees.

Cheers,

Don

 

Yes this is very much a possibility. The paper gasket is also a weak point. Its like they used recycled toilet paper or something. It completely disintegrated in just 2000 miles.

The ACDelco 252-800 I just switched to has a better design in my opinion. Its single piece. And the main inlet/outlet hole seals against the engine with a large O-ring as opposed to a paper gasket like the Airtex pump. The smaller two holes on either side are sealed with an aluminium gasket with preformed rubber sealing surface.

But proof is in the miles. So lets see how long this one lasts this time.

 

V12StealthHunter Any update on how the ACDelco unit is performing? I’m about to be on my 3rd water pump in 2 years and I’m considering switching from the Airtex unit, which has failed twice now in a similar fashion to yours.

 

They are on both of mine, so far just fine

 

10k miles later and still good.

If you have time on your hands, I highly recommend ordering a set of new bolts for the job. The last time I did the job the allen heads were almost destroyed from corrosion.

 

Thanks Wingrider and V12StealthHunter - that’s great news. Looks like I’ll be going with the ACDelco unit and I’ll grab some replacement bolts for the job as well.

 

Thought I'd add my experience: Airtex failed on me after 14 months. The impeller completely fell apart.

It happened at the worse time and I was very annoyed. I decided to fork the extra money for an OEM water pump (which had a white impeller, unlike the Airtex) and never look back. It still operates fine after 5 years and 40k miles. I should probably replace it soon, but the point is that the OEM pump is a solid unit. It's worth the extra money, don't waste your time on a $35 Airtex like I did. Not worth the risk

My car is a 1998 XJ8 fyi

 

As I said before. Jaguar OEM. Penny wise dollar foolish with those cheap $35 units...

 

The interesting thing is that our members have proven that the water pump Jaguar currently supplies as a replacement is the Airtex, and the same Airtex pump is available from Rock Auto for around $35.00. Somewhere here in the forums we have pictures of the two pumps side by side. Airtex is a long-time OEM to Ford, Chrysler, GM and others.

Over the past few years, I have installed well over a dozen of these Airtex pumps with the supplied paper gaskets (treated with Permatex Spray-A-Gasket) and have had no problems with any of them. Theoretically I like the OE style metal gasket with rubber edges, but I've tried that type gasket with an Airtex pump and it won't work.

I suspect that one potential cause of problems is that the two screws that secure the two halves of the pump may not always be properly torqued. Also, I suspect the screws securing the pump to the engine are often not properly torqued. Many DIY owners do not own a torque wrench that is accurate in this low torque range (torque wrenches are considered unreliable in the lower 20% of their range). Also, I've adopted the practice of cleaning the threaded holes in the engine with a tap before installing a new water pump, and that seems to prevent a false torque reading due to resistance from corrosion and helps ensure the proper torque is achieved.

If I'm not mistaken, the ACDelco pump has a metal impeller, which will probably be fine for years, but the reason Jaguar and many other manufacturers switched to plastic impellers is that OAT coolants do not protect metal impellers from electrolysis and cavitation erosion.

Cheers,

Don

 

Appreciate your input Don! I found the thread you described that compares Airtex vs Jaguar pumps (https://www.jaguarforums.com/forum/s...5/#post1764127). And I believe that was the thread I read when researching my water pump the first time around. It's why I went with the $35 Airtex from RockAuto. So now I'm faced with a dilemma - obviously, I'd like to use the Airtex (OEM) pump, but they've failed me twice now...

Do I hand feed the installation instructions to the mechanic to ensure they install it properly, but risking they don't and having the pump fail... again. Or do I go with the ACDelco pump, which seems to a more foolproof install...? With the Airtex, seems like proper torque (according to this image you had previously shared) and treating the paper gasket with Permatex Spray-A-Gasket are the most essential steps to a proper install.

 

I wish I could make the decision for you but I have no idea how methodical or conscientious the mechanics at your shop are, and whether they have the type of high-quality inch-pound range torque wrench required to properly torque the water pump screws, or whether they will be willing to carefully follow the Workshop Manual instructions and the TSB that comes with the revised Airtex pump. I can only report my own excellent results with the Airtex pumps.

Plenty of our members have had good results with the ACDelco pump, and I certainly like the OE gasket and O-ring design. However, remember that "paper" gaskets have been successfully used since the turn of the last century (they were actually made of asbestos), and modern versions are made of fibrous materials like matted graphite, so they are impervious to water when properly torqued.

Cheers,

Don

 

I think the problem with the airtex pump is that the halves are coming from the factory not torqued together properly. I don't think anyone thinks to retorque the bolts on a new pump but I think this is an important step if you're installing an airtex pump.
Having said that I think the ACDelco design is superior and I would only ever recommend that one.

 

I have been watching this thread and reviewing many past threads on the water pump (and cooling system) while I prepare to chase down a very slow loss of coolant and service my 2004 with 94,994 miles on her. I have no problem with the Airtex pump's gasket however I do like the 1 piece design of the ACDelco. I guess my only concern is the continued use of OAT coolant with the metal impeller. One post I have read seemed to indicate the impeller wore out after about 10,000 miles. Is there any additive that can be used to slow the corrosion of the metal and aid with preventing cavitation?

I have read of a OAT coolant for use in diesel engines that is supposed to be superior to a standard, regular duty, automotive grade OAT coolant like DexCool. I really do not want to change from the OAT.