2003 Random Coolant Leaks from both ends?

[SeanPwnery]

Today - coincidentally I made the final payment on my 2003 bird - by and large it's been a great driver. When I purchased it, the odometer read 42k which is why the dealership I picked the car up from was willing to finance. Fast forward 4 years and I'm right at 70k. About two years ago the thermostat housing decided that the cast plug on the drivers side didn't want to be there any more. This was during the bomb cyclone freeze over Houston, and I was driving 15 miles away just to get gas for my generator. I was on the interstate, accelerated a bit briskly because I was tired of looking for gas and finally finding an open station when suddenly the back of my car looked like a mosquito fogger - when it was sub 20 degrees outside. Not even a quarter-mile later the temp gauge was pegged out and I was pulled over. Long story short, I ended up replacing the thermostat housing (the entire assembly), all the hoses up front, new clamps, and new water pump. I even did a video over on Youtube to share the experience with people in case anyone needed it for reference material.

Anyway - a couple weeks ago I began to notice a coolant smell after keying off in the middle of a hot Houston summer. This smell was only occasionally - say once every 3-4 days and usually there was nothing dripping under the car. Then it began to drip near the harmonic balancer and oil cooler up at the front of the engine (instant thought was the T-stat housing failed because it was one of the plastic-fantastics on Amazon). I pulled the T-stat housing bit, and noticed the O-ring was a little janky so I ended up replacing the O-ring and giving the whole area it sits in a squirt of RTV as a precaution. Again, the coolant leak seemed schizophrenic - it was completely inconsistent. Sometimes I'd hear a groaning sound near the passenger side cylinder head when it would leak that almost sounded like some kind of electric solenoid, but could never actually spot it.

Yesterday as I drove to work, I forgot to check the coolant level (which I've been having to top off now every 4-5 days). About a mile from work the dash beeped away, the needle stopped just short of the red mark, and the engine bogged down something horrible. Turns out the ECU has a limp mode, pulled all the timing out, fuel pressure I assume and refused to let me run more than about 1200 rpm. I made it to work (still never reached the red mark on the gauge - just short of it), keyed off and allowed it to cool down naturally the entire day. The car took 2 gallons of water and my co-worker began noticing water dripped from the front *and* the back near the bellhousing. I too noticed the drips at the back several days prior as well and decided to keep an eye on it. Here's where things get strange - I drove the 14 miles home without the A/C on, the windows down (it was kinda nice outside so it was tolerable) and not only did the car remain perfectly fine on the gauge, but when I arrived home, not a single drop under the car. This morning I checked the coolant level and it's right where I left it before heading home yesterday from work. I've tried looking for "engine cooling diagrams" for the *rear* of the engine in case there are hose assemblies I simply don't see, and can't seem to find anything concrete.

So, question - what gives? I don't really know where to begin looking at this point. There's not much visually to see at the back of the engine once the cover is off, and I can't seem to see where the bleeder hose goes to from the other end (not the end near the bottle). The water pump I replaced did have the metal gasket, and the only hoses I can see that I didn't replace are the heater valve hoses that run down the passenger "framerail" area but the leaks aren't anywhere near those. I'm a bit at my wits end with this one. Also, I checked the oil before setting off, no water in the oil or vice-versa - I believe the HG's are ok.

Edit : I'm beginning to think maybe it's part number 11 (since it appears to run from the front to the rear of the engine) - but I'm not 100% sure where that is. Is this running under the intake towards the rear to the bleeder?

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[SeanPwnery]

Ok, it's not part 11 - I managed to find that one and traced it from the T-stat housing to the bottle. She's old, but she holds. I also managed to finally trace the bleeder line as well, it looks like two lines from the bottle meet two aluminum hard lines bolted to the firewall, both looked clean and dry (Respectively - a little dusty from time). Topped off the coolant and just took the car on a short trip, a/c on, bit of idling, maybe 7 mile circle to get up to operating temp. The CEL is still on from the overheat event yesterday but otherwise ran fine. Not a drip anywhere. The mystery continues.

 

[Bobwheeler]

Have a coolant pressure test done or do it yourself. The procedure is in the book further down from the picture you sent. I got the same advice and had it done and sure enough, the tstat housing leaks. It was new 3 years ago and two years prior to that. It's a chronic problem. I have heard that Jag makes aluminum housings. Maybe someone has a line on that. Also, the nipple on the degas/exp. tank that hose 11 connects to fractured and was leaking to begin with. Replace the bottle if you haven't. Get the bottle with the lower hose already on. Makes install easier. If you clamp off hose 11 prior to removing the lower hose from the metal pipe ( you have to cut it) you will lose very little coolant as the top is not vented. I just had the test done 2 days ago so studying my options. The car is drivable as the leak is very small.

 

[Bobwheeler]

OK. Checked my records on the tstat housing replacement as memory is lousy. Was changed out in 2015 and 2018 and is leaking again.

 

[SeanPwnery]

OK. Checked my records on the tstat housing replacement as memory is lousy. Was changed out in 2015 and 2018 and is leaking again.

Yikes ... I guess I'll snatch up another one just in case.

 

[tbird.blue]

Yikes ... I guess I'll snatch up another one just in case.

Hello, I would check part #23 also. I had that part fail on my 05 after about 70k miles. Coolant would flow from both front of engine and the back of engine. It is hard to remove as the inlet manifold covers it. You can either remove inlet manifold and get good access to the pipe (which almost crumbled in my hands when removed!) or you can grind some of the inlet off above the two rear bolts to get room to remove them. I went the inlet removal direction as there is also a shortish rubber coolant hose under the manifold that should be replaced as a matter of caution. This plastic coolant pipe setup on the 02-05 Tbird is probably the biggest weakspot and cause of headaches on the car overall, in my opinion lol
Ian

 

[SeanPwnery]

Hello, I would check part #23 also. I had that part fail on my 05 after about 70k miles. Coolant would flow from both front of engine and the back of engine. It is hard to remove as the inlet manifold covers it. You can either remove inlet manifold and get good access to the pipe (which almost crumbled in my hands when removed!) or you can grind some of the inlet off above the two rear bolts to get room to remove them. I went the inlet removal direction as there is also a shortish rubber coolant hose under the manifold that should be replaced as a matter of caution. This plastic coolant pipe setup on the 02-05 Tbird is probably the biggest weakspot and cause of headaches on the car overall, in my opinion lol
Ian

When I replaced the Thermostat housing, I chipped the upper lip of that piece, it just comes up as "pipe assembly" which is inexpensive, but it looks like the intake has to come off to get to the back two bolts. Since I was afforded two days downtime, I built that flange back up via Acraglass and filed it back to the original profile, though I wouldn't doubt for a second another section of it may have crumbled. I can't believe a pipe that large in diameter flows coolant, but it clearly must. Sure would be nice to find someone with an Aluminum 3d Printer.

 

[Merk]

You know I did the thermostat housing, water pump hoses quite a job only to find a small leak very frustrating what I ended up doing is some stop leak this is done at the factory from what I read it took care of my leaks

 

[SeanPwnery]

You know I did the thermostat housing, water pump hoses quite a job only to find a small leak very frustrating what I ended up doing is some stop leak this is done at the factory from what I read it took care of my leaks

I just did that very thing on Sunday - so far not a drop - crossing fingers

 

[SeanPwnery]

I'm revisiting this thread because it's now October ... and ... I have a new coolant leak - right in the same spot as before.

I replaced the Thermostat housing and the "Tube Assembly" that it pushes in to with Dorman units back in March ... I have a leak - it hisses like no tomorrow in that same area.
Ran out of daylight tonight as I write this, but I managed to get the hoses, T-stat housing, and the throttle body off before I couldn't see what I was working on. Next will be the front third of the intake manifold itself like I did before to get a better look at the "tube" that 45's down into the front of the engine's intake valley.

This is the 4th time I've fought a cooling issue - and ... well, I have oil milkshake too. I originally found it in the bottle on the firewall, but it was a small skim layer. When I took the thermostat housing off tonight, it had a thin coating too... not good. The oil pan has zero coolant in it, I checked it daily. I began to think when I replaced the "tube assembly" that some oil might have dribbled in from the exposed intake that had a little oil in it from years of PCV fumes pooling. Now I'm not so sure. Overheating was never an issue when I noticed the skim layer so I'm crossing my fingers.

I read that there are hoses that run down the valley behind that tube assembly - and I'm dreading finding that's where my leak is coming from. The hoses are 20 years old, so I'm anticipating their necessary replacement. What I want to know is - can I gain access to those hoses by removing the upper half of the intake only? I avoided this operation before thinking I had to mess with the fuel rails, but it appears I can dodge that bullet by taking the top half of the intake off only.

Any of you guys done this? I've already ordered the FelPro 96923 set just in case.

 

[SeanPwnery]

Small update : I spent the better part of yesterday during the eclipse removing the front intake elbow (the aluminum bit that the EGR bolts to) and all of the intake bolts out only to discover that while it does appear that the upper plenum and runners are separate pieces, the sleeves that guide the bolts down the runners work like a press fit to hold them all together... so that was a no go. All of the connectors as you would all imagine are crunchy and brittle, but I managed to unplug the fuel rail temp sensor, all 4 injectors, and the harness master connector on the passenger side as well as pull up the brace that holds the top cover plastic. The driver's side is a lot tighter, and after a while, I realized I needed the spring clip tool for the fuel feed line which I do not have. Additionally the 2 bolts and nuts that hold the wiring harness along the back of the intake were all removed, but I couldn't get the bundle to budge up and out of the way - so... I'm stuck there too.

At this point that annoying hose barb that faces rearward down the intake valley is laughing at me and the bulk hose I wanted to push over it wont "start" as I have very little leverage to "pull" the hose over the barb. For now, I've conceded defeat but last night I managed to find the part number for the actual form-fit hose - which by most counts is pretty scarce and out of stock (there are a few floating around as near as I can tell - will call a few places tomorrow to confirm). In the mean time, I decided I'll try to acquire a set of "hose grip pliers" and try again with those since they have a way to "grab around" the hose while I try to pull it over the barb... all through a gap less than 1 inch wide between the back 2-thirds of the intake and the "tube assembly" port. Licking wounds and having really sore legs and lower back this morning >_<

 

[SeanPwnery]

Hose grip pliers did the trick - though I went the bulk-hose route. The part number for that annoying hose is 3W4Z-9F814-AA however I ordered it from 3 places that claimed to have it in stock, only to have the orders cancelled shortly afterwards. I bought 3 feet of bulk hose and went to work - it seems to fit the bill for now, but I only have 45 minutes a day to try to get the engine back together before I run out of daylight. By tonight, I managed to get the intake torqued back down, the intake elbow back in (got delayed having to chase the threads for the EGR provision), the "tube assembly" that 45's down the valley, and the thermostat housing (which the darn O-ring fought me for a good 20 minutes constantly trying to squirt out of the opposing side I'd push from!) Also... it should be noted - a little vaseline goes a long way. I rubbed a Q-tip in some, then swabbed the inside of the hose to help move things along the barb, and again on the T-stat housing O-ring. If all goes well, tomorrow I just have to bolt the throttle body back on, plug in a few connectors, run the other end of my bulk hose after I trim it down a bit to the underside, and start bleeding. The car was down 10 days because of my 9-to-5 and little access to daylight, waiting on tools, etc.

This is a good little engine, but in all honesty if anything catastrophic ever happens to it, I'm not going to miss it as I start looking for a Coyote 5-liter and 6-speed manual to replace it some day. Whoever designed the AJ series engine clearly didn't keep the technician in mind and should be tortured, slowly, and painfully for all of eternity for the placement of some of its auxiliary line placements, and veritable plethora of endless form-fit coolant hoses.

One other side-note - I've been running Xerex G40 coolant since about March of this year - the pink stuff. It is originally billed for use in Porsche, Mercedes and a few other makes as they are mostly aluminum block/head engines. I went ahead and verified with Valvoline (who make this stuff) that it indeed has beneficial antioxidation qualities for our AJ engines and they indeed recommend it for use in later model Jaguar V8's. It IS a little pricey, but only half as much as Evanscool - which in all honesty for anyone who keeps their bird as a collector vehicle with little use and low miles, would probably be the best way to go.