Just getting to check this ... BOY u102768, where did you get that color pdf of the V8 engine "X150 XK?"???? It has what looks like the hose I now suspect it the culprit and seems to be the same one chased and fixed in the post by funkymonkeybooze kindly supplied by meirion1. It seems to be the only one that could leak into the "V" and find its way back. It is the yellow reflex curved one in the pdf top pix and the (same) red hose not numbered, but just below the left fork of the call-out circled #2 and just above the circled #12 in the bottom pic. It appears to come from the bottom of the throttle body and snakes back around into (? who knows ?). I suppose I won't really know the reason for the reflex route till I expose it and see if it is leaking. It does appear, from the pics at least, to be unnecessarily tortured though. I will investigate further when the weather permits.

Both of these posts are perfect. Thanks for your perseverance and for sharing as this is exactly the sort of picture I was looking for, but did not find in the X350 literature.
Best regards, Brian

 

Thanks Merion for this pdf. I didn't find anything like it in about a week of searching everywhere and everything. Here's where I am. I followed the JTIS and removed the intake manifold after much doing and took off the infamous hose that was the most suspicious of the causes, BUT found nothing amiss - no cuts, holes, etc. I ordered a new hose, new intake manifold gaskets and new O-rings for the various connections I removed. Nothing obviously amiss. I explored the hoses back at the firewall, now somewhat available for inspection, but all is dry with no traces of having been wet. Upon looking at the O-ring that seals the thermostat tower to the block, the ring loos somewhat tired and suspect, but will have to wait till the new one arrives to confirm. In any case. I will re-assamble the whole mess with all new parts and hope that does the trick. Otherwise, it remains a mystery. This, so far, has been a real journey into darkness for me as this is more complicated than it need to be. The most glaring engineering hiccup or flaw, IMHO, I found was the fact that the center of the intake manifold is made of plastic and could easily have been made to disassemble from the two aluminum banks which hold the injectors from the top, but is, instead screwed in from the bottom making that impossible. Had that been engineered to be removed from the top, this whole job would have been cut in half. JEEEEeeeezzzzzzzze!!

 

Leak fixed?

 

Well, I found the leak and the job is finished and buttoned up, BUT it was a devilish journey. I will try to write my notes as if we were all rank novices to this. I apologize if it is too primer-ish.

I replaced the reflex-curved hose with new and dried and cleaned up the area as well as I could. As mentioned, the "old" hose I found was in great shape, but I decided not to risk it as this is so stupid an arrangement and abominable to get at. Rube Goldberg would have been proud and I feel this is some kind of insidious homage to his memory.

While putting the intake manifold back on, it's very important to insure all the rear electrical connections are remade AND the brake booster vacuum line is reconnected. As an aside, I first thought the horizontal top plastic closing panel just under the windshield could come off affording me better access to the rear engine area, but after fiddling with it for a while and studying the way it was connected I gave up. So, as I said VERY IMPORTANT to remake all the rearmost connections.That closing panel may, indeed, come off, but seemed to be more difficult to put back on as to not be worth what looked to be considerable effort. Additionally, there is some other vertical "shielding" to be removed for full access, so - not worth it (and not mentioned as necessary in the JTIS).

As to the brake booster vacuum line ... the most successful way I found to connect it was the way it had to be disconnected. That is, have one half connected to the intake manifold beforehand and the heat sleeve drawn up and scrunched around the top, booster hose half. After installing the rearmost gang connector and the other connector/s on the passenger (right) side, and having the intake manifold settled onto the head, snap the booster vacuum lines together and work the heat sleeve down around the entire length of the hose.

Install the intake manifold bolts and torque them down. Then it's onto connect the throttle body 8mm bolts to the intake manifold. The lower ones are pretty hard to reach being located under the thermostat tower branches and other obstructions (more on that in a moment). Be very careful that you do NOT drop any of the bolts ( or anything else) in the process as they will fall into the valley and you might not be able to retrieve it with a strong, long magnet pick-up. The thermostat tower is a bit like the one on the X308 being slightly under the intake manifold face, but I replaced the hex-head bolts with slightly shorter Allen-head SS bolts and they worked fine with a wobble Allen Key.

After installing the throttle body, I hooked up the water hoses and performed another pressure test on the system. Much to my chagrin, the thing leaked!!! Knowing that the reflex-curved hose was new, that only left to thermostat tower to be the culprit. I took off the throttle body again and connected the water hoses enough to perform another pressure check and VOILA, telltale Orange liquid! I did an internet search and, found and ordered the whole tower complex with thermostat, temp sender and all seals/rings for $60 shipped - all OE. After a couple of days it came, I installed it and the odyssey was almost over. Another pressure test with no leaks and it was time to install the throttle body again. This is a tedious task, as I mentioned, - having to be very careful - made more tedious by having to reconnect to EGR valve which only moves very slightly to the left - tantalizingly with just enough room to insert the lozenge-shaped metal gasket between it and the throttle body. Drop it at you own time-wasting peri ..., er don't drop it.

I think the best way (of the several I tried) to connect the EGR valve to the throttle body is to, while the throttle body is positioned, but not bolted in any way, to oh so carefully insert the EGR gasket and insert, by a couple of threads, the valve's long bolts. That way the gasket is secure enough to not loose it into the abyss, but the whole shebang (technical term) is loose enough to insert the throttle body bolts but a few turns, line everything up, make sure everything is there, then proceed to tighten everything by degrees till torqued and done.

Now connect the myriad of electrical connections and fill the coolant system, bleeding it via the method in the JTIS. Start the car and check how or IF it runs. Mine started, but since I had neglected to attach the throttle position sensor plug, it ran crappy till I found that and connected it. At first a myriad of warning and caution lights were on, but early on the went away. Now the car runs almost as before this Odyssey, except for the fact that the idle takes a while to settle decreasing with increasing temperature and normalizes when temp is reached. I don't know, but I assume that will normalize with driving.

If any of you can suggest something I can do to hurry that along, I'd be very interested.

In summation because the removal of the intake manifold is such a PITA and complicated procedure, I would recommend, if after you have performed an initial pressure check of the coolant system and re-confirmed it was leaking (necessary tools available on loan from parts places) but still could not determine where it was coming from, you seriously consider removing the throttle body FIRST. Then bridge and seal off any hoses to make a completely tight system and retest as it will now be possible to actually see if any part of the thermostat tower and/or branches have "given up the Ghost". If they are fine and the thing is still leaking and showing up primarily below the transmission or rear of the engine, the only thing left is to assume the "U" shaped reflex hose has a leak and be prepared to become more intimate than you really care to get with the satanic engineering of the top half of your engine. Patience, rigid attention to detail and a methodical approach to slaying the beast is your only recourse. Anything less will result in the same kind of joy Mudville experienced after Casey's struck out.

Best regards, Brian

 

Well done Brian.

 

I had the same problem then i was sitting waiting for someone to come out and blew a line. Under the intake manifold is the throttle body return line. That is probably where your leak is coming from. It burns off before you can spot where the leak is coming from and they are prone to blow out due to no real air flow and the heat make them dry out alot faster