Well I just got done letting it idle for 5-10 mins... using the infrared heat gun I seem to be getting readings all over the place. One section of the water rail will be 70c and another 90c. Thermostat housings showing like 80c. The aav was 80c on one section then blasted up to like 120 in another. So I don't know how much the infrared gun is to be trusted....but all seemed fine untill coolant started leaking out of the top fill cap. Now I had to bleed it a bit yesterday and might've switched the caps around(the 16lb cap on top 20lb on side) but still don't think that should be happening. 😕

 

I would not run that engine any more until the cooling is sorted.

The laser dot and the sensor beam only align at one point. If you can determine this distance you can be more accurate in where you are taking readings from.

Regardless, a reading of 120C anywhere is too high to risk. The exhaust manifold would be far higher, but no portion of the engine should reach 120C.

 

none of the rail or hoses are getting to boiling it seems... I'm wondering if the cap has a bad seal. I don't understand why the aav on the backside would read 120 and an inch over read 80...

 

I can't explain the 120º at the AAV

Been awhile but I recall my water rails reading aproximately the same along their length aft of the thermostat...certainly not a 20º difference....although the RH side was a bit higher overall.

I'm wondering if your rails are clear?

Also, the front of the rails gets a bit more flow than the rear...thus the "Lutz" modification.



It shouldn't. At minimum the caps should not be leaking. Not properly seated? Worn out seals? Sealing surface not smooth?

Even if the caps leak the coolant shouldn't become that hot (and thus pressurized) after 10 minutes of idling. or....maybe it was burping, which brings us to......

"...bleed it a bit..." has me wondering.

The systems must be fully bled, no exceptions. Sometimes it takes a couple tries. Air pockets can give all sorts of weird symptoms and can hurt the engine. What procedure are you using? We have some write-ups of a good bleeding procedure.

I can't remember what if any work you've already done to the cooling system but it has to be 100% up-to-snuff, no weak links, no short cuts. There's no two ways about it. Professionally cleaned radiator, correct thermostats, clean/flushed system, good fan clutch, all those small diameter pipes and hoses cleaned out, good caps, good bleeding

Cheers
DD

 

Like I said, thermostats done, new coolant sensor and switch. maybe my bleeding isn't proper. I'm almost wondering now if it isn't. I'll check the forums

 

That's a start!

If there's doubt about other parts of the system then there's no doubt that it needs to be addressed.



Here's my method. Others use variations of the same theme

https://www.jaguarforums.com/forum/x...method-157448/

Cheers
DD

 

The IR heat guns can be very inaccurate on shiny metals. They work best on dull surfaces. So that may explain why you are getting different readings so close to each other.

 

haha ahhh another dumbarse mistake from myself. This is nowhere near what I've done(in fact I didn't really bleed it at all). I need to start clearing my head better before working on this car. Thank you once again, I will be properly bleeding the system tomorrow.

 

What the heck I go to bleed the system and the thread is not found. 😬

 

if your coolant is low the fan does not switch on as soon as if you have it topped up.


and this works for me on the cross-over filler cap.

 

Elevate the front of the car about 8" and then elevate the left front another 2-3" beyond that. Set the climate control for max heat so the heater valve opens.

Remove the bleeder plug from the left radiator tank. You'll see an access hole in the radiator upper mounting panel. The plug is some arcane size but you'll find something in your toolbox that fits.

Remove the caps from the expansion/header tank and from the filler pipe at the front of the engine....up there by the A/C compressor.

Add coolant/water to via the filler pipe until it reaches the bottom of the pipe. Start engine, set heater control to max heat. Let it run at idle until it warms up. Peek inside the filler pipe every minute or so and top up as needed.

When the engine gets warm increase the idle to about 1000-1200 rpm (a helper is helpful here...or just wedge a little something in the throttle linkage to hold it slightly open for a high idle.

Let 'er run and run. Give the upper radiator hoses a few squeezes now and again. Keep checking your coolant level in the filler pipe and top off as needed. Eventually you'll see some coolant coming out of the bleeder. That's good. Wait a while longer and (hopefully) you'll see coolant *really* pouring out of the bleeder. (How much? It's one of those "you'll know it when you see it" things..very messy)

When it's *really* pouring out of the bleeder hole, put the plug back in. Wear some gloves so you don't get scalded. If you can't get the plug back in thru all the gushing, shut off the engine and do it....but I like to leave the engine running if I can. Not worth getting burned, though.

Top off the coolant in the filler pipe...I go right to the top but some fill just to the bottom of the neck... add a quart or so to the expansion tank if you suspect it might be low, button everything up, and yer off to the races. If you've overfilled the excess will be pushed into the atmospheric tank mounted inside the fenderwell. If you've *really* overfilled the excess will exit the atmospheric tank and end up on the ground.

Lower the car and clean the driveway :-)

 

Elevated it and cracked open the bleeder... topped off the fluid and started it. Instantly the coolant started gushing out of the bleed hole. Didn't even wait a second. Shut it off and started over. Same thing! So I screwed in the bleed screw and let it run. Engine felt pretty hot and the temp gauge was near the H. I had zero heat coming out of the vents. So... is the heater core shot, flaps not working or is it the banjo bolt I've heard about? Obviously I'm not opening up the banjo bolt now after getting up to temp. Ugh

 

i was looking at those... using the infrared heat gun right under the cap I was only hitting 70c.

 

This is my experience too. If you pull this bleed screw out and run the motor for a
couple minutes then you better have a couple extra gallons of coolant handy.

the pump is driving water into that top rad port at quite a pace and opening a hole to that does exactly what you'd expect.

I crack the bleed screw. Just like brakes. It bubbles ( good! Air escaping ) and squirts but it won't gush. You can do it by hand if the coolant is cool or get a snug-fitting socket
on a long extension. If your socket isn't snug, just put some tape inside to outside and press the bolt in.

What youre trying to accomplish is to push all the air bubbles trapped anywhere inside the system to come past one of the open vents and escape the fluid.

I have had good results by following the normal procedure, but very slowly filling the system trying to allow it to push air out as it fills, until coolant rises to the top of the crossover fill pipe
Crank the engine
Continue feeding it coolant until the expansion tank overflows
Cap the overflow
Open bleed screw completely, but the screw it back in just a bit to hold it in place.
watch for bubbles, maybe pull it completely out a few times. For science. once you stop seeing bubbles in the fill pipe and the bleed screw then I close them both and have a drink.

The system is designed to bleed itself right into the expansion tank. What you do not want is an air pocket in the head. That can cause a localized hot spots that, themselves, cause expense and cursing.

 

is dougs writeup more for if the system has been fully drained and that's why it went geyser on me? I'm almost more concerned with the heater not working...

 

Was the engine already fully warmed up or were you starting from cold?

Did you remove the filler cap first?

It might be that you removed the bleeder plug on a cooling system that was already under pressure.... thus the geyser.

Or maybe you didn't have any air pockets to bleed out

Or....hate to say this and I don't really consider it likely.....you have a leaky head gasket and compression is being pumped into the cooling system



Cheers
DD

 

I use the same procedure if fully drained or only partially drained but always start the process with a cold engine


Could be a control problem where the heater valve isn't opening.

Could be an air lock in the heater core or a clogged heater core...both fairly common.

Remove the vacuum hose from the heater valve. This will open the valve...assuming the valve isn't broken or physically stuck. Warm up the engine. Any change? Feel the heater hoses in the engine bay. Is one hot and the other cold?

Cheers
DD

 

It was a fully cold engine when I started. I'm not sure if I undid the bleed screw or cap first. I got a new cap and after many minutes of running there was no leaking from the cap. I'm just sitting around waiting for the thing to blast off Ha. I really don't think its overheating for some reason. The ir gun never got above 90 anywhere I pointed it. Seemed like the highest point was found right around the temp sender( not sure how affected that is from header heat?). I don't think I have a gasket leak as there's not smoke from the exhaust and the coolant seems to stay put. I need an actual thermometer reading! I've read the advance can make it overheat or the retarding can. I'd like to drive it and see if it cools with air but I'm paranoid with that gauge staring me in the face.

 

Well I went and tested the Jaguar coolant sensor and it's reading that it's not overheating the gauge is showing that it's overheating but the car itself actually isn't.

 

Well I finally got to take it out for a longer spin today and of course stopped and took a few pics. Got back to the house and noticed the aux fan had finally kicked on and ran for maybe 30 seconds after shutoff. I read the ohms across the coolant sensor and seems it must be overheating. I got 165ohms. Which registers over 100c probably boiling? No steam or leaking from the radiator cap. I've heard the advance can cause an overheat? I'm going to clean the radiators when I get the chance but I'm wondering if my centrifugal advance is the issue. I know I had to oil that sucker and it moved but never really wanted to snap back.