I am chasing a coolant leak and have leak detector in the coolant and have a small spot directly below the front edge of the oil pan right by the boss where the oil filter screws on, but I can't see a leak source from below or above.

I've pulled the engine cover, the radiator top cowl and the air box top and SC intake tract and still can't see where it is coming from. Is it possible to run the engine with the MAF off? I'd like to check it with a black light while it is running, but that airbox/intake tract covers everything up.

BTW, the AC Delco leak detector is great. 1 Oz and in black light the coolant looks like glowing milk in the reservoir tank and on the plastic sheet I have under the car where it dripped just a small spot. I can see it on the front lip of the oil pan too, but just a thin line.

 

yes it will run . but will throw a code and be in restricted performance. so be sure to have a code reader ready to clear it . my bet is water pump as thats were mine leaked when it failed. it could also be the thermostat manifold o-rings also but most likely the water pump , the check holes in the pump are well hidden behind the pulleys .

 

Thanks, I changed the thermostat and used a new O ring, so I think it is OK. The water pump is in a likely location for where it dripped. the leak is not very fast - it takes about 100 miles to lose enough coolant to cause an overheat (done that twice now).

I've also had the fans come on at startup a time or two and had codes U2199 and B2139 set in the instrument pack module indicating that the temp data is invalid and/or there is a data mismatch, so I could have a temp sensor problem too.

I am considering trying some aluminum powder leak stop for the short term (it has worked in the minivan's V6 when on a trip away from home) but I hesitate to try it in the Jaguar;s complex cooling system. Years ago jaguar used to recommend a certain brand of stop leak in the series III XK engines as a matter of routine maintenance, but stopped recommending it after many had sludge build up in the radiators.

What's the consensus on stop leak? Try stop leak once or bite the bullet and change the water pump? The car has 133K miles on it and I don't know if the water pump has ever been changed, but it cools normally as loing as it has enough coolant in the system.

 

Stop leak would in my opinion be very risky if you are using Jaguar recommended 5 year coolant.

I am doing work on a boat engine and adding an FWC system. In the instructions it warns about using 5 year coolant if the engine has used ordinary coolant. It states that any corrosion build up will cause 5 year coolant to develop sludge/ gel.

My take on this is that the 5 year coolant is very likely to gel if there are "contaminants" in the system.

 

Thanks for the advice,

It had orange coolant in it and I've topped it up with Prestone Extended Life that says GM Dex-Cool approved and 5 year 150,000 mile and is also orange.

Guess I'll be changing the water pump then and checking out the auxiliary pump at the same time. I tried using a mirror to check behind the WP pulley, but not much joy. Does the pulley come off just by removing the bolts? And do you use an open end wrench (spanner) on the flats at the top of the belt tension arm to move it to remove the belt? I might try taking the pulley off first, but I'd bet it is the pump leaking now that it was mentioned as the most likely place.

 

I used a long torque wrench with a 1/2" adapter to fit in the 1/2" slot on the tensioner pulley arm to release the SC belt and same technique on the auxiliary belt.

If there was a slight leak from the water pump behind the pulley could you not feel for it with a paper towel and then use the black lite?

When I changed the water pump the pulley was easy to take off.

I use the 5 year Dexcool as well.

 

I know its tempting to use stop-leak products, but dont. I have used them also in older steel blocks, but won't in a alum system. We have enough issues with heater cores plugging up without the help of stop-leak. I have never heard of a manufacture paying anyone to replace their heater core, even when they say there safe for them.
Plus, if it is the weep hole dripping in the water pump, the bearings are about to go and the stop-leak won't fix the bearing or the leak. The weep hole is there to let you know it's on the way out. I have even heard of fools plugging the weep hole to stop a leak. It will give you a false sense of security, until the bearing/seal goes to hell, and can come apart. If you haven't seen what a radiator looks like after a spinning pulley/fan blade goes thew it, it's not a pretty sight. Oh, now you'll be replacing a pump, and a radiator.
Good decision to change the pump!

 

I couldn't get anything behind the pulley to check for coolant so I decided to take the pulley off.

Thanks for the long torque wrench suggestion; my tension arm has a 3/8 square in it that I had not noticed before and a 1/2"torque wrench with a 1/2" to 3/8" square adapter worked like a charm. I had loosened the three WP pulley bolts before slipping off the belt (I was surprised that the bolts have 5/16 hex heads) and I got the bolts off, but haven't been able to slip the pulley out.

In the process of pushing hoses and pulley around I found drops of coolant on my hand and on the belt (blacklight confirmed as coolant) and thought great! That confirms the water pump as the leak, but then I saw that the coolant was actually coming from the plastic hose connector just above the water pump that connects to a long hose that I had been pushing around.

Then I noticed that there is coolant along the back edge of what appears to be another aluminum piece about 1/2" thick behind the water pump and bolted to the block with a second gasket behind it. I was hoping to get the pulley off to confirm a leak from the water pump, but now I don't know. Looks like I'd have to drain the radiator and disconnect the plastic hose connector to get the pulley off and then still may not know which was leaking. Although the drip spot below is a little further back than the hose connection, that lower radiator cowl may be directing the leak back.

So...I have to decide if I order the pump and change it anyhow, or drain the radiator and get the pulley off before ordering the pump. And then what about that other aluminum piece and gasket behind the pump? The EPC shows only the water pump itself. BTW, from the looks of the pulley bolts the pulley has been off before so the pump is probably not be the original one.

I'm also considering putting pressure on the system again to see if the hose connection is leaking. I assume there is an O ring involved in that plastic connector? Things sure are tight in there with all those hoses.

 

There is an O-ring behind the water pump, the new one will come with it. Motorcraft pump fit nicely.


The pulley might have thrown coolant around a bit. Our leaking water pump was dripping from the same location on the bottom corner of the block.

 

Behind the pump is an "oversize" metal combination gasket. It extends beyond the pump connection to the block.

I am not sure what long hose above the pump you are referring to Phil?

The only hoses I see are the ones going in and out of the thermostat housing and the large diameter short hose going into the engine block.

All the plastic connectors I have with metal securing clips have a rubber "O" ring inside. I mentioned before that the one going into the bottom of the reservoir is a terrible design and will leak if it is under any stress.

 

The hose I mentioned comes off the bottom of the thermostat housing and runs diagonally behind the radiator to the auxiliary pump. This may not be an original hose; many of the hoses look like they have been cobbled together from hose bends with straight pipes running between them and this one has a larger hose that was split and wrapped around it and is wire tied to the back side of the fan housing.

Not sure why I was so hesitant to drain the radiator except fear of old plastic parts coming apart and replacements not being available, but the radiator drain opened OK and it is draining now. I'll just have to wire tie the under cowl back again when I put it back on, but I have the Jag in the garage so I can work on the auxiliary pump even if it storms all day tomorrow.

 

Ok that does not look like an original hose to me Phil. That hose looks very suspect in several places to me.


Mine has the Jaguar pressure clip type clamp where the hose attaches to the T housing.

 

The EPC doesn't show that connector either, but then the thermostat housing it shows for a supercharged V8 doesn't quite look like mine either. It does show the two bend radiator hose with the pipe between so I guess that is original. I can't quite imagine a shade tree mechanic adding that type of connector rather than just a hose and hose clamp, though. It seems an odd choice if it was not OEM.

 

Your thermostat housing does look different as compared to mine. The aluminum outlet to the long hose looks longer on your unit than mine.

Maybe a difference between 2005 and 2006 model years. Mine is a late 2004 build.

 

Yeah, it looks different than the EPC drawings too. I took the reservoir off this morning and released that plastic connector from the thermostat housing and it looks pretty groady inside. I'll clean it up and see if there is an O ring to replace. It may be the leak I was chasing.

I got the WP pulley off and didn't see any evidence of a leak on the bottom of the pump or on the inside of the pulley, and the pump feels smooth turning it by hand and I can feel no play in the shaft, but as long as I am this far into it I might as well change the pump just for insurance. Ordered one from O'Reillys for $45 plus tax that will be here Tuesday.

I got the auxiliary pump out and checked it for continuity. On the continuity setting my meter didn't beep, and on the ohms setting it read 4 to 8 Meg ohms - apparently that is too much for it to see continuity. Guess I'll take the pump motor apart and see if a brush change might be possible. It looks like the original Bosch pump.

 

You probably have noticed but just in case note the slots in pic #4 at 10 o'clock and 4 o'clock in the outer rim of the female plastic connector.

Very important for lining up the male and female connectors.

I missed these the first time!

My water pump seemed to be just fine at 103,000 but since I was in there I replaced it. The original had a plastic impeller and the new one metal.

Did you detect voltage at the auxiliary pump connector lead ?

 

Haven't checked the connector yet for voltage, but fuse 8 in the rear power distribution box had battery voltage with ignition and climate control on before. I'll be checking the connector after lunch. (and looking for the wire keeper from the reservoir connector that flipped off and hid somewhere).

 

Same happened to me with the wire clip. I did not find it until weeks later!

There is a pre engaged position for the clip which helps a lot in re connection of the hose. I think you are showing the clip in that position in pic #4.

However I had ordered new hoses so was able to use clips from old hoses that I was replacing.

I could not find the wire clip on-line anywhere.

 

I was not meaning the thermostat o-ring , I said the thermostat manifold o-rings as in two of them were it connects to the block with four torx bolts ,wilst you have the coolant out you may want to do those o-rings as well , common leak area, it does look like you found the culprate , it is differant to mine as well , my water pump failed at 150000km so my guess is yours is on borrowed time .

 

+1 on those "O" rings. When my new O rings were delivered I was surprised to see that they were like a thick rubber band i.e a flat cross section and not round. They scrunch up and produce a better seal with this design maybe?