Had one hell of a heat wave in the northeast this weekend. Around 100F and muggy. I took the jag out a few times, and sitting in traffic, I saw coolant temps go up to 216F. Maybe I'm just paranoid, but even in those extreme conditions, that seems way too high. On the highway, it cooled back down to the low 190s. I'm used to seeing it sit around 185, though.

Am I being paranoid? I have yet to do the water pump and thermostat replacement, but I'm now thinking this might be the impetus to just go ahead and do it. Oddly, the hoses seem to be in very good condition--almost to the point where I wonder if my uncle had them done during his ownership (I'll have to check the records), but would seem odd to do those and not also the pump and thermostat.

In any case, it might not be worth waiting until it becomes and actual problem. Aluminum thermostat housing is easy enough to find. No debate there. But the water pump--I'm seeing conflicting opinions on here on the metal vs. plastic oem impeller. Has anyone had bad experiences with the metal impeller? If oem has lasted this long, would be tempted to just use it again. It's not a terrible job to replace one. But if I can add reliability, I will.

 

The normal temperature range, i.e. when the gauge doesn't move from its centre position is 181°F - 230°F = 83°C to 110°C

Max on the factory gauge is 260°F = 127°C

When it's hot here (30°C +) I get over 100°C showing on my autool at peak (long uphill on a motorway at 130kph) which is around the same as you are getting.

As it is within the normal range for the factory gauge, I'm not concerned.

 

you are ok!! Our temps here in the Charleston SC area typically hit 100+ several times during the summer (have already had at least 10 days above100 so far this summer). I usually see temps reach 216-218 after about 20 minutes of driving in stop/go traffic but they drop back down once I start moving again.

 

Thanks, both! I guess I'll stop worrying about that (will always continue to monitor, though). Maybe I just have an addiction to buying parts and messing with my car.

Maybe it's finally time to do all the cosmetic stuff. Swirl marks upon swirl marks...

 

This is why Jaguar fitted an idiot gauge for the temperature - so we wouldn't have to worry about the engine temp until it goes bang.

 

Your car coolant system is fine, but you’ll need to R&R coolant on a 2 year interval ... just to be sure.

Your addiction is commendable esp. if we are to keep the X100 on the road. I seem to remember a Forum member hoarding spare parts, akin to a “time capsule” , just in case. Wish I had the budget for spares for
1. Chain tensioner spares
2. Coil harness
3. Valley hoses
4. Upper strut mounts
5. Convertible hydraulic rams
6. Front lower fog lights
7. ABS module
8. Centre dash vent
..... and all plastic trim pieces. But guess that’s why they invented 3D printing.

Chill buddy! If anyone has access to a cryogenic deep freeze please let us know as I’ll know where to store X100 spare parts for the good of mankind.... LOL

 

I've definitely thought about this, but haven't gone too far. At work right now, but off the top of my head I have an odd collection of spare things laying around the garage:

1. 2 coils
2. 1 spark plug
3. 3 refurbished injectors
4. 4 unrefurbished but completely functional injectors
5. A complete set of vents for the interior
6. 2 new valve cover gaskets
7. Maybe 30 titanium bolts for the BBS wheels
8. The window switch you sent me
9. 1 Oil drain plug and 2 washers
10. 1 air intake hose
11. 1 coil cover

Oh, and a set of Revolver wheels (+tires). But I don't really count those since those are for colder weather.

I often browse for parts I *might* eventually need, just because it's so annoying to have to wait for a part when you finally need to replace something.

 

When you start buying parts for the aluminum tower be sure and get the crossover pipe and gaskets (2). Bit of a pain on a couple of the bolts but lots of write ups on how to get around that.
That water pump will be setting right there in plain site, while you are in there sort of thing.
What you are dealing with on the high temperature during a hot day is pretty normal.

 

Ok, today was definitely abnormal behavior. Was sitting around 217-221 on the highway without traffic and it's 67F outside. Blasted the heat to see if it would help. Good news: heat works great. But temp only dropped 5F. Wondering if the impeller on the water pump has finally broken. I went through the car's records over the weekend and didn't see anything about the water pump ever being replaced.

 

Having grown up in Arizona dealing with a hot climate you learn how to survive. Before going after the water pump I would first check all of the hoses and make sure none of them have gone soft. A soft hose will restrict the water flow. If you have the original radiator perhaps the system needs a good flush and fresh coolant. Next I think would be the thermostat and if its still hot then the water pump and possibly the radiator itself. BTW in boiling Florida weather my 2000 XK8 runs around 200 - 205 F.

 

A 1997 X100 with the original water pump ? It's not worth worrying over in my opinion. I would replace it. There are numerous posts about these water pumps failing. I think the consensus is that the
metal impellors aren't the way to go due to cavitation. But it's really not a bad job, and the water pumps are not expensive. The aluminum thermo housing is also a good idea, although it is a little tough to get to a bolt - posts on that using a crow's foot wrench, or just breaking the old one into pieces. On my old XJ8 with a 4.0, I just did the valley hoses and the thermo housing and crossover at the same time since I had to remove the intake anyway. But you might want to wait for cooler weather for that. ;^)

 

You mentioned you often run as low as 185 F. If you're measuring that through the OBD it's way too low and 220 is too high. I would change both the water pump and thermostat. Of course, the tower and outlet pipe should be done at the same time, and thehoses checked.

 

Interesting development, folks. Currently replacing water pump, thermostat and its housing, hoses. Those last two thermostat bolts are a pain. I had two plugs in the way, and it took me two days to figure out I could move them out of the way. D'oh.

Just got the water pump off, and was surprised to see a metal impeller. Paper gasket, too, with some RTV slathered on. I'm replacing it anyway, and I'm using a metal gasket.

I could see some crust around the thermostat cap and upper/lower radiator hoses. When cold, upper hose was collapsed. It's possible that this had to do with a malfunctioning thermostat (I did get some really jumpy readings). It's also possible that coolant had leaked out through aforementioned points, and when the car was cold, a vacuum would form due to low coolant. I did notice before I drained that it was below the filler neck.

Maybe some combination of all that. All I know is that I'm replacing it all.

Side note--got a socket stuck on the tensioner pulley bolt. That'll be real fun to get off.

 

Finally all done. Checked for leaks. Saw a pretty sizeable leak come out of the thermostat tower cap. Turns out the thing needs the cone-shaped gasket from the original cap (or I guess you could install the old cap).

Went for a few drives. All is well. My knees hurt a lot, and there's coolant residue all over the garage from draining originally. I'll deal with it tomorrow.

Boy, does it feel good to be back on the road again.

 

As a footnote: I overtightened the metal cap and chewed up the o-ring, leading to a very small leak. Decided to remedy with a careful but liberal smattering of black gasket maker under the bottom of the cap. Leak is gone now.