I'm finishing up a project of replacing parts, some that have been on the car for over 18 years and 178k miles, and one of those replacements is going from a WP with a plastic impeller to one with a metal one. The new WP didn't come with a gasket, so while looking for one, I noticed that there are two thicknesses available; a .4mm and a 1.5mm. My current gasket is a 1.5, so I ordered a .4mm. I also noticed that the flange on both of the WPs is a bit shorter than the recess in the hole that it goes into. I did some measurements with my trusty Husky calipers and the flange is 9.66mm with the recess at 12.24mm. That leaves a gap in the hole of 4.08mm with the 1.5 gasket and 2.98 with the .4mm. And, I don't know if these WPs are OEM or aftermarket and the original is somewhere in a box somewhere in a storage room, so I can't measure the flange depth on that one. The one I'm replacing is from Eurotoys but I don't remember where I got the WP with the metal impeller.

So here's the question for the fluid dynamics experts (I know you're out there as I've seen your posts in other threads): Can those gaps between the WP flange and the end of the recess cause any swirling or cavitation that can affect the coolant flow?

I'm asking as I had four overheat events during the summer where the ECT got up to 236F while climbing the grades from where I live up to Lake Tahoe. I know these SC engines run hot, and worse at high altitudes; I'm just looking for any remedies to not have to turn around and go back down the hill to cool the ECT back down to normal.

 

113C when being loaded really hard on a hot day isn’t anything too crazy. hot is good up to a certain point. the acdelco metal impeller pumps are known for being slightly undersized and causing the the car to run a little hot but idk if welsh sells the same one

what’s your normal cruising temp, should be 90-100

 

I've been running it at 85C/185F. It stays there or just above most of the time on hot days and driving around town or cruising on the highway at 70-75. The elevation here is 4750; going up to the lake is a 3,000 foot climb on a fun winding road. The ECT starts going up slowly as the grade isn't too steep at the lower part of the road, but gets steeper above the 6,000 foot mark, and the ECT goes up quicker to the summit. I also have the Jag Wranglers Real Gauge temp mod installed and the overheat warning buzzer goes off at 113C/236F. That's when I let off the pedal, but the temp is still going up. The new pump flange is 60mm and wobbles in the recess a little; guessing about 1/2mm.

 

The gap between the bottom of the recess and the pump flange will practically have no effect on the coolant flow. Well, perhaps some 0.0000001%. The flange of the pump has to be shorter and a bit smaller than the recess in order for the gasket to sit well. You should look elsewhere for what might be causing the overheating:

Thermostat - recommended to be replaced every 2 years. This is a very short period but it seems that there were issues with thermostats as Jaguar issued a couple of TSB-s (303-25 & 303-54) on thermostat malfunctions.

Otherwise, it could be partially clogged radiator (assuming that the cooling fans are operating correctly) and, if you have to top-up the coolant from time to time but have no leaks, possibly small head gasket leaks which can be checked with a combustion gas leak tester.

 

Just stumbled over this thread, was interested when I see Fluid Dynamics ;-)

Please note there has never been a metal impeller version for the Jaguar engines, only for the Lincoln version a metal impeller version was used. The latter has also a different coolant with more silica in it to protect the metal impeller from cavitation, hence my advise would be to stick with the Jaguar plastic versions, especially as there have been enough issues reported with metal impeller versions (leaking and so on). Its your choice if you go for the metal impeller version and with the Jaguar coolant though am not sure when you would need to check your impellers, i.e. 30Kmiles or 50 for damage? Of course f you drive much less, you may not get to that stage even.

 

orange dexcool can protect that metal impeller just like the millions of GMs that used one...the original yellow coolant in the 97-99 308 had like 10x the amount of silicates than the ford coolant. all asian manufacturers banned silicates 30 years ago because of water pump wear when not changed on time

 

There where other additives like nitrate that (not Present in OATs) that are helping against cavitation, anyway these additives where not needed for protecting the plastic impellers. I am not following it anymore closely and maybe there are new OAT formulas work just a well to protect against cavitation, so as long as you have a coolant that does that you're good.

 

Intall an AC Delco out of the box and forget about it. But do the TST every few years.

 

Well, there's some more information to think about. I guess I should add more to the equation by admitting that I'm a hot-rodder, so I have some after market goodies on the car that can affect the overheating issue. I've had the Eurotoys big intercooler radiator, oversized lower SC pulley, and 185 degree TST on the car for the last 12 years. Never had any problems with those mods until I moved to this high altitude area, though. I was living in Sacramento, CA when I put that stuff on, it's hot and dry in the summer and I drove 22 miles each way to work. Then I spent five years in DC where it's hot and humid during the summer and sometimes sat in traffic on my way to the golf courses; didn't drive to work too much there, but no problems. Only here, and when climbing steep grades, is when I get the overheating. The Real Gauge direct read ECT is probably keeping me from getting to the magic number to blow a head gasket; isn't that at 118C/245F?

 

I have read somewhere that going above 240F should be avoided and that going past 260F, the head gasket failure is almost inevitable.

 

If you have a 98 or 99 i’d be more worried about blowing the head gasket than with a 00-03. you don’t really need a real gauge, as soon as it moves off the middle just turn the car off. if you’re really in the red for a while i guess you’ll have to pray it doesn’t drop a valve seat.

 

So, 240F is the yellow line and 260F is the red line; good to know and happy that I'm shutting down at 236F. The real gauge mod that I have is made by JagWrangler. He's a forum member in the XK section(s) and occasionally visits us here. The mod plugs in to the instrument panel and turns the existing ECT gauge into a direct read gauge. It's a really well engineered product and the instructions on where to put the temp stickers are spot on. 185F is the middle mark on the gauge and it matches number to number with my live data readings. It also matches at 236F ... LOL. Interesting that you mentioned a dropped valve seat. xalty. I've had a rattle, kind of a tinkle sound, for a while now that is only heard during acceleration before the engine is close to normal operating temp. The engine runs as advertised, even with the rattle going on, and after the rattle stops. I've had suggestions that it was the SC, but I know what that rattle sounds like, not it. I thought that it might be a dropped valve, so pulled the cam covers and checked each valve while rotating the engine, all good. Then one day, while coming down the hill from the lake, the ECT cooled below 185 and I heard the rattle again. I figured that it was a bad catalytic converter making that sound, so one of the things I did during the current project was replace both downpipes with the Nameless downpipes with 200-cell cats. Another hot-rod mod ... I'm almost done getting the engine back together; just have to put on the TB and hook up the wiring harnesses and intercooler plumbing. I'm hoping that the rattle is gone, cause if it's not, a dropped valve seat is about the only thing left that could make that noise. And, please don't say 'wrist pin'.

 

One possible cause of the "tinkle/rattle" sound on acceleration is detonation (pinging) in the cylinders caused by too high compression, carbon build-up, too advanced ignition timing or bad or lower octane fuel. The engine is more prone to detonation when the mixture is richer which is the case when your engine temp goes down. The knock sensors should prevent the detonation but maybe they are unable to do it in more extreme detonation conditions. As you have increased the SC boost, it could be due to increased compression. Have you, perhaps, also advanced the ignition timing in some way? In the case of engine detonation, the first thing to try is higher octane fuel.

Rattles from the conrod bearings are mostly heard on the transition from acceleration to deceleration so I don't think you have an issue there.

 

Your 02 should have been delivered with the final pump and Ford spec coolant (red/orange) .... the earlier cars were delivered with different fluid. My 95 X300 was blue ... then Jaguar used a blue/ green. My 98 had yellow and it was changed twice under service actions as well as the pump ...

I don't think the pump was ever plastic ..... the vanes did change color more than once. All the changes did create massive confusion later on when servicing.

 

Detonation is one thing that I have not considered as a cause of the rattle with the controls (knock sensors) on the engine that are supposed to not let that happen, but will now. You did get me thinking, and this rattle has only showed up after I moved to this high altitude, just like the overheat issue. Add in that they only sell 91 octane fuel around here and it definitely becomes a possibility, although the rattle is somewhat different than the detonation pinging that I've heard in other cars. And adding a can of octane boost is a lot easier than checking for a dropped valve seat. No, I haven't done anything to the heads, yet, or the ECU. I would like to get the heads done and might do that when I get to 200k miles; the ECU seems to handle the mods that I have done, and the car runs really well, so I haven't seen a need to mess with it. I sent the injectors out for cleaning and flow testing during this project (they tested good and now the connectors are green instead of crud-buildup-black), so maybe that will help, too.

Back to the water pump; good info on that above. I'll make a decision today on which one to use, but I won't know if the issue is resolved until summer comes around. Hopefully I'll have the car out of the garage this weekend; I only get two to three hours a day to work on it with all the other things going on this time of year, and having to heat up the garage to at least 50F (it's 30F out there at 6am ... LOL) before doing anything.

Happy Holidays !!!

 

Happy Holidays! Great info in this thread. At high altitude, I would expect the engine to run warmer. Especially a boosted engine. I would make sure there isn't any road debris in front of the radiator.

 

The sound of detonation can vary quite a bit from engine to engine. It can be like frying/sizzling, like ringing, can also sound very metallic. Have a go with some good octane booster.

 

Just to add to this great discussion, the early water pumps with plastic impellers made of Nylon 66 did suffer high failure rates, but the improved plastic impellers seem to hold up very well. The reason Jaguar and many other manufacturers switched to plastic impellers is that OAT coolant (Ford Orange/GM DexCool) does not protect metal impellers from electrolysis and cavitation erosion. This information comes from the early documentation on OAT coolants. To this day, if you buy a water pump from Jaguar (or Ford, or Land Rover), it will have a plastic impeller.

The great news is that the pump your local dealership will sell you in a Jaguar box is the Airtex AW4124, which Rock Auto carries for $35.79 plus tax and shipping. Airtex is a Ford OEM. The same pump fits N/A and S/C 4.0L & 4.2L X100s, X150s, X200s, X250s, X308s, X350s, X358s, some Land Rovers and Range Rovers, and the Ford Thunderbird and Lincoln LS.

The Airtex pump comes with a TSB explaining that the pump design has been revised and uses a graphite "paper" gasket instead of the original steel/rubber gasket. I have installed many of these with no problems. Just follow the torque specifications for the screws carefully and also check that the two screws that hold the halves of the pump case together are torqued. I usually spray both sides of the gasket with a light coat of Permatex High Tack Spray-a-Gasket, but it's not strictly necessary.

P.S. Mahle still offers the original style metal/rubber gasket, but I've tried it and it will not work with the Airtex pump. But I've had no problems with leaks with the graphite gasket.

Cheers,

Don

 

I read through the thread this morning and it really has been a great discussion. A big Tank You to everyone! After the read through, I decided to order the Airtex water pump. I really wasn't too impressed with the metal impeller pump and the only discussion that I had seen before was that the plastic impeller could slip on the shaft where the metal one won't. So, the added info from above makes me want to just throw it in the garbage. I'll keep the WP with the plastic impeller; it will be interesting to see the differences with the Airtex pump. It's supposed to be here Tuesday.

Forgot to mention the coolant that I've been using, which is the OEM Jag (orange) diluted with distilled water. I've been refreshing it every five years and even have a brand new 5-liter jug waiting to be poured in. I probably paid about $40 for the Jaguar labelled jug, but I can use that to store the two-year-old coolant that was drained for this project, and use that if I get any "burps" after the initial fill.

Happy New Year !!!

 

Don B - got the pump today and the instruction sheet is the one that was printed when the toner was running low. Of course, the one instruction that isn't readable is the one with the torque values. Do you recall what those are?

Thanks,