Oh, no, I'm sick about this. I posted a thread about someone changing my t stats, now I took the car out, and, it's running hot. It never ran between the N and top of the gauge before. I read Doug's bleeding technique, I'll do that, but I am afraid the t stats were installed wrong. I read they have to be installed with the jiggle pins at 12 o'clock? What is the probability a mechanic did THAT? Do you guys think it is the wrong installation of the stats, or no bleeding, or both. The bleed bolt looks like it hasn't been touched. The stats were purchased from a reputable Jaguar supplier that I always deal with.

 

Firstly CALM DOWN, panic and/or anger never fixed a car yet.

Bleed it first. That is the MOST probable reason for the temp issues.

After that, let us know, then a quiet systematic diagnosis will be done and the beast will be sorted.

 

The stats are relatively easy to get at. Its a simple job to change them. If you are having doubts about your mechanic, you have the wrong mechanic. These cars are good an honest but have a lot of quirks and familiarity is key. Doug and Grant on here are both guru's - as he has said above it probably just needs proper burping.


There are quite a few stats about without jiggle pins to compound matters. As a rule put in what came out. While your at it, fiddle a relay to overrun the fan on shutdown - its after you turn it off you really want to worry about temps!

 

Thanks Grant and Tyran. Yes, Grant, I tend to panic... I will be all over this tomorrow after work. I'll use Doug's bleeding process, and, let you know what happens. Thanks for your time.

 

Results. I see Doug just reposted the procedure I just attempted. Grant, I used Doug's burping method. There was so much coolant under the main cap that I had to leave that one on, loosely. Coolant was gushing out. I took the expansion tank cap off, and, the bleeder screw. After it warmed up, and, I had it idling about 1200 RPM's, I squeezed the top hoses some, and, finally coolant started coming out of the bleeder. It seems that it will gush out if I rev it up, or, squeeze the upper hose. I put the caps and bleeder screw back on. The gauge was on N the whole time. The upper radiator hoses got hot, I guess the stats are working. Done??? I guess I have to test drive it. Is the air bubble out??? Seemed too easy.

 

Sounds like you nailed it. If there is air in the system a dead give away is a "gurgle" from the heater matrix when you have the hot air on. But if you followed DD to the letter you should be A-OK!

 

Nope, still running hot. I took it on a test drive today. After about 2 miles the needle hit N, then kept going to between N and H. I stopped on a steep hill forward and backward to try and dislodge a bubble. Shut it down. Upper radiator hoses were hot! Huh? It seems like T stats are opening. Why is it running hot? It never went above N before. Maybe I need to let more gush out of the bleeder valve, I did screw it in shortly after I got coolant pouring out?????

 

Just checked the coolant level, it could use some in the aux tank and the radiator. You can see coolant in there, just low, I can't imagine it needs more than a quart. It is still warm, half an hour after shut down.

 

Don't be shy with that coolant. It needs to bubble out for a bit, its surprising how an air bubble just pops out just when you think "surely that's got to be enough?"

 

I put 15 ounces in, I guess I'll go through the burping procedure again tomorrow. I think I learned why you rev it up while doing this, it then ingests more coolant. I mean what else can I do.

 

Use the thermostats with the bleed holes and jiggle pins (installed at the top).
Your cooling system won't bleed otherwise...

 

Roger, I bought the Jaguar thermostats from Terry's, I looked at the pics on Terry's site, yes, they have jiggle pins as they should. The mechanic who installed them has been in business for 40? years, they say "TOP" on the 12 o'clock position. The upper radiator hoses get hot. I'm thinking the t stats are working.

 

Adding what may already be happening.

I remove the small vac hose from the heater tap, which puts the tap in default ON mode, so coolant flow and AIR goes via the heater core and to the radiator LH tank, and up and out the bleed hole.

When you run that engine and coolant exits that hole, you MUST top up via the filler spout to maintain a full level in that system, or the level will drop, and be replaced with air and the cycle goes on FOREVER.

In all the V12's I have owned and worked on, I have never had issues with bleeding that system, but as said it is messy, and can be time consuming, and above all, frustrating.

Many associated items must "line up" as they say, to get that air out, and shortcut filling will have that engine running hot forever.

 

Grant and Tyran, thanks for sticking with me, I'll get after the car today,Grant, thanks for the tips. Will report back.

 

OK, spent 25 minutes burping Jaguar, that seems to be more work, went according to Doug's instructions, pulled the vacuum hose off the heater thing as per Grant. Both caps off, it kept overflowing from the main cap, OK, sloppy, you are right. The gauge went half way, the stats seemed to open because the upper hoses were hot, then finally coolant started coming out the weep hole. Revved up, my wife was in the car, she said only one movement on the gauge, it started to go quickly above the N, but, reversed immediately, and, settled on the N, where it remained. I left it weep a few minutes, topping up, then put everything together with both tanks topped up. Well, sloppy, longer, no overheating as it sat for about 25 minutes, running. I'll take it for a test drive later. I saw no dramatic burping bubbles, or steam, or anything to indicate progress. Keeping my fingers crossed.

 

Sounds promising. If you have heat concerns it really is worth wiring the rad fan to overrun on shut down, as heat is just about the only thing that will kill a V12. (When I say kill, I mean damage beyond economic repair). Mine is a garaged weekend beast so I have got in the habit of after a run, popping the bonnet to help cool off. Also check you don't have a nasty yellow plastic fan, if you do replace it while your doing the timer relay as they have a nasty habit of disintegrating and punching your rad full of holes.

 

Yes, I almost immediately bypassed the thermo switch by wring the two thermo switch wires together. My electric fan comes on with the ignition, and, stays on. I was paranoid that the fan wouldn't come on when needed as the engine heated up. One minor problem. When I turn the ignition off, the fan still runs. I either pull the fan relay, then push it right back in, or, I have a quick disconnect on the battery, I disconnect it. I may have solved a problem here. The quick disconnect was added to stop a mysterious drain on the battery. I suspect it was this relay drawing power without the fan going on. Anyway, I think the power drain is gone. ??????

 

I think I got it!!!!!!! Just took it for a run in the neighborhood, about 2.5 miles not over 30mph. Never went above N!!!!!!!!!!!!!! Hot, muggy day. Do I call it a success?????? I will, but I need to drive it more. I try and drive it every day, I'm addicted to the XJS. Looking good. Thanks Doug, Tyran, and, Grant!!!