1998 XJ8 VdP.....you sneaky bee. After a LONG search for an intermittent issue and spending hours reading on here, I followed all the advice and spent four hours with a mirror, a clean cloth and inspected every square inch of pipe and area where coolant flows. After having a mechanic cross the dreaded coolant hoses at one shop after doing a non-coolant related repair, after having one place find a 'broken clamp', after finding stray duct tape on a pipe, after dealing with the paranoia of a water pump with a plastic impeller, after worrying about head gaskets and testing for exhaust gasses in the coolant, after worrying about secondary tensioners, and after the Jaguar dealer doing a thorough search (at great expense!) with pressure test and insisting there is no leak....I finally found it after hard driving, making sure the fan was on, and letting the car run on full heat in the driveway. A few drops of green coolant coming from underneath the driver's side, running out right where the lower recovery tank is.

A few questions (thanks for your patience!).
1. Can this expansion tank overflow if the car is bled incorrectly when re-filling the coolant (dumping syndrome, secondary to trapped air etc.)?
2. Is this symptom more likely from a small crack in the recovery tank?
3. How do I best get to the expansion tank - above or below, and will I need any special tools? I can see only where the overflow, bleed hose goes in from above, and I can readily pull it out.
4. The top coolant tank cap feels a bit odd. I am open to this being a bad O ring or something and I have ordered a new one. For the sake of $20, I thought what the heck.

-- Lastly, what else could it be based on what I described? Keep in mind I only see the coolant coming right out from where the lower recovery tank is. The car has never overheated. I am desperate.

I love my Jaguar. I want this fixed. I am very disappointed in my Jaguar dealer who is apparently 4th in the nation for diagnosing problems on the first visit. I am ready to fly solo. Any advice would be most appreciated, and I will pay the favor forward. Please explain it to me like I am a two-year-old, preferably with diagrams.

 

is the coolant leaking from the hole in the overflow tank that lets it dump onto the ground or out of the bottom from a crack or something? Also good call on the new
cap...

 

Thanks! I cannot tell, as I need to be able to see the tank and how to best get to it - part of why I posted, and I'm still hoping for additional input to those questions from many of the wiser enthusiasts than I.

 

Hi, to replace the overflow tank, it's an on your back job.
Car on stands.
Remove the undertray or complete front bumper first.
(The bumper removal is for when the undertray fasteners are rusted up solid).
From memory it's held to the chassis with 3 10mm bolts, a good thing may be spray the threads top side before attempting to budge them. A 3/8th drive socket with 12" extension gets to the bolts.
Has the car been overfilled with coolant, how much water have you ever seen come from the overflow tank?
Have you looked at the schematic for the coolant circuit and how to fill/bleed the system?

 

ok so I just went out and looked under mine. you will have to loosen or remove the lower splash shield <the big black plastic cover attached to the bottom of the front bumper> . A phillips should do it. if they're plastic clips take a small flathead and pop em out from the head and the rest of the clip will follow. go under the car and look staright up at the bottom of the tank. You should see two or three 8mm bolts. Remove them and the tank should follow. Now i didnt pop the hood because my wife has the key and isnt home today so i dont remember if it had a sensor attached or not. If there is a sensor remove it by unhooking the cable attached to it. look for either a pair of"latches" to pry open or a spot to press down firmly on <im going from memory here ill pop the hood when the wifes home and check for sure and let you know on the sensor> . Probably best to pull out the hose and unhook sensor if applicable before doing the rest. Good Luck

 

The caps do fail -- but I'm not seeing how that would cause a leak. They are often hard to remove -- at least my three x300's have been.

It is my understanding that the overflow is just that -- just for expansion. I think you should look at it and make sure it is not filled with coolant.

I have never had to look at mine -- but normally they are only partially filled so that the coolant can expand and then be drawn back in. You should never have a situation where the tank would fill all the way up and then overflow.

Does the coolant drop in the upper tank? The one with the cap.

 

I did follow the instructions for filling coolant.....run at around 2000 rpm, a/c on, then heat to full. When cool top off upper expansion tank, then repeat when cool.

Is it possible to overfill the upper coolant bottle? I have been filling that pretty much right up.

Yes, the level in the upper coolant bottle has dropped down (enough that the red low coolant warning light came on for a split second when I was on a hill). This is what I have been using to assess coolant drop. Now that some posters have kindly given instructions as to how I can get to the lower, overfill recovery tank, I will assess it's fullness and integrity.

If I rev the engine hard, I hear sort of bubbling/air in the left side of the engine as though coolant is being sucked into the lower, overfill recovery tank. What does this mean? Am I over-filling?

My understanding if one has a poor seal on the upper, coolant tank, loss of pressure in the system leads to warm coolant being 'pushed' out into the thick plastic hose that goes to the lower, expansion overfill tank near the driver side front wheel. Can anyone please verify that? I hope it's that - seems like an easy fix to this horrible, horrible, intermittent issue I am having.

 

I filled up to the brim of the upper, coolant tank - in hindsight, this is above the level of the plastic hose that leads to the lower, right expansion overfill tank.

If it helps, I recently had the wiper motor replaced at a shop and they need to take the upper coolant bottle off to do that....red, low coolant light cam on as I drove home....I inspected the two plastic hoses and, indeed, they had reversed them (so they no longer crossed), and I assume that the car dumped the coolant into, and out of the lower, expansion tank near the front driver side wheel. Of course I noticed this right away and then switched them back. If this is the case, then indeed that lower tank will be full, and if I overfill, it will go to the lower tank and end up as drops on the road which I saw (and dripping off the left bumper/shield below the lower expansion tank). That makes sense.

However, the level before I topped it off last week (in the upper, coolant bottle) was unacceptably low. I see no leaks in any hoses, clamps, from the upper coolant bottle, from the water pump, and there are no exhaust fumes in the coolant.

Arrgh...I am plagued. What is causing this? As simple as a coolant bottle cap with a poor seal? That seems like too easy a fix for such a complicated car..... Any advice, comments, or insight are much appreciated.

 

The upper tank is not fill all the way up --- I think you fill it to the bottom of a plastic marker inside the tank. I have only added coolant a few times in all these years

 

Update on mystery coolant loss - Jaguar XJ8, VdP (1998).

Okay, so here we go. Hopefully this will help some other folks with a similar problem.

Two changes this week:
1) I replaced the expansion (upper) coolant tank cap this week. I had read that if pressure is lost from a faulty cap, coolant will constantly be ejected into the overflow recovery tank (lower tank, adjacent to right front wheel arch). I measured the coolant level in the upper expansion tank before and two days after changing the cap. The level actually rose by over two inches after changing the cap! It never did this before - it only ever fell. Presumably, this means it is now pulling coolant back out of the lower, recovery tank as it should until the expansion tank is suitably full.

2) I got the car up on ramps today to inspect underneath, and there was a fine, green coolant trail coming out from where the lower recovery tank is adjacent to the front wheel arch. I tried unsuccessfully to get the black splash guard off (looks like it is attached by stupid plastic pins and I have no clue how to get those off without damaging the guard - no bolts or screws) - taking the front bumper off seemed the only way and that's extreme. Anyway, I got under car and could inspect the recovery tank carefully. The integrity is excellent (and keep in mind that Jaugar did a pressure test and found no leaks). There are no cracks, and the coolant trail localized clearly to the overflow outlet hole around 3/4 of the way up on the tank. Clearly, coolant was overflowing, and ending up on the ground.

It's unclear (to me) how the physics of this system works, but it seem that there must be a vacuum from the recovery tank toward the expansion tank, and a cold system in the recovery tank which once collected warm, expanded coolant when under pressure from a warm engine now can deliver it back to the upper expansion tank, and this is why the level there rose. When the dealer switched the configuration of the two hoses on from of the upper expansion tank, I'll bet the rapid coolant loss was a dump into the lower, recovery (overflow) tank as the vacuum effect was reversed, then spilling excess out onto the street, and I kept (insanely) filling up the expansion tank with coolant wondering where on earth it is going.

I took an I.V. line and syringe and placed it into the lower, recovery tank, and pulled back around 500mL overflow coolant from the recovery tank, leaving maybe 100mL still in there.

I am hoping this fixes my mystery coolant loss over the last several months. Hopefully this helps others, and I appreciate additional thoughts as much as I have appreciated the advice of those patient Jaguar enthusiasts that took the time to post and help me. I will let you know if it still is unresolved.

 

Thanks , hopefully it will work for you

 

Update:-

There still appears to be some coolant over-flowing from the recovery tank behind front right wheel.

As a recap:
- Pressure tested cold and no leaks.
- No leaks seen in any hose, the expansion tank, or the recovery tank.
- Exhaust fumes not detected in coolant.
- No appearance of oil in coolant.
- Thermostat + housing was reaplced six months ago.
- Replaced expansion tank cap one week ago.
- Coolant level in expansion tank does down by about 1-2cm each week (120 miles), and the level in the recovery tank increases.

Curiously, the week after I replaced the expansion tank cap, I noted that the coolant in the expansion tank had risen for the first time (presumably pulling back from recovery tank). Now, it slowly goes down, and then overflows. Possible that the threads on the expansion tank itself are bad?

I drained the recovery tank two weeks ago so I could keep an eye on where coolant is going, and I now see it filling - am fairly certain that it is all going there, and then overflowing out of the nozzle on the side which is open to the air.

When I accelerate and when I stop, I usually do hear a whooshing sound from the front left of the car--assuming this is coolant moving back and forth between expansion and reovery tank. Do you guys hear this?


Any ideas on what could be causing all the coolant to go into the recovery tank, and overflowing?

 

The physics of the coolant system are pretty simple; when above the designed pressure level of the coolant reservoir the reservoir cap will pass coolant to the recovery tank. When the engine cools, there is a vacuum created by the cooling coolant in the engine/radiator and the reservoir cap allows the vacuum to 'recover' coolant from the recovery tank.

A failing reservoir cap will suck the radiator hoses flat.

Reservoir cap keeps coming up. If you have replaced the tank/cap check the 'O' ring on the cap. This is not rocket surgery.

No whooshing where I live.

 

Are you sure the norma (quick connect) hoses on the expansion tank are correct now ? If they were incorrect it would cause the overflow tank to fill and overflow. If they are correct and you've lowered the level in the overflow tank and the system has been pressure tested by the dealer then that only leaves the cap - or the threads holding the cap on. If pressure leaks past the cap it (and coolant) will flow into the overflow tank. When everything cools down and there is sufficient vacuum space in the expansion tank, coolant will flow back into the expansion tank from the overflow tank. Of course if you have a "real" leak somewhere all this is completely useless info. The level in my expansion tank is about where the seam is (I think), about 1 1/2 inches below full to the brim. There needs to be some space for expansion.

 

Yeah, they cross - I forgot to mention that, sorry. I have experienced them uncrossed (when a mechanic replaced the wiper motor and needed to take the expansion tank off....uncrossing the hoses when they put it back on, and it dumped all the coolant quickly).

Curiously, your level of 1 1/2 inches below full to the brim seems loe to me - lower than where mine is now. I don't *think* I am overfilling it - the level is a good 2-3cm below the openings of the hoses on the expansion tank. I can understand if it was over-filled - it would dump into the recovery tank and onto the road until you stopped overfilling it. It is hard for me to tell where the max fill line is.

I will tell you that every time I take the (new) cap off the expansion tank, I hear it dump a bunch of coolant into the recovery tank behind the front wheel. Have you noticed this? To my simple mind there must be a vacuum in there keeping coolant (to a certain degree) out of the recovery tank.

This is more of a chronic loss of coolant - maybe 50mL every 200 miles or so. It is depressing. Any other ideas? I appreciate all the advice I can get.

 

1998 XJ8 VdP

Not to sound like a broken record, friends, but this gremlin is back again.

After replacing the expansion tank cap< I drove around 800 miles without the requirement of coolant top off. Now, I'm back to having to topping up coolant (around 200-300cc) every 120 miles or so and I see an intermittent, green coolant pool under the front left wheel and I am 99% confident it's from continued overflow into the recovery tank. I can see the trail coming from there and I have measured the coolant in the recovery tank and it perpetually rises until overflow-- exiting the open hole on the side of the recovery tank (i.e. coolant is not being drawn back into the expansion tank when the car is switched off).

I promise I 'burped' it appropriately after each refill.

As a recap:
- Pressure tested cold and no leaks.
- No leaks seen in any hose, the expansion tank, or the recovery tank.
- Exhaust fumes not detected in coolant.
- No appearance of oil in coolant.
- Thermostat + housing was 'allegedly' replaced by last owner.
- Replaced expansion tank cap.
- Hoses on the front of expansion tank criss-cross as they should.
- Unsure if the water pump is the original but I can't see any leaks from there....it all seems to be recovery tank overflow.

The week after I replaced the expansion tank cap, I noted that the coolant in the expansion tank had risen for the first time by around one inch (presumably pulling back from recovery tank). I assumed my issue was a bad cap or o-ring, but it has not fixed the problem. Now, coolant slowly goes down, and then overflows from the recovery tank near the wheel.

I am at my wits end. Where do I go from here?

- Is is possible that the expansion tank cap I bought online is faulty (it was not Jaguar brand).
- Is there an issue somewhere else that may prevent recovery tank coolant from being drawn back into the expansion tank, or causing expansion tank coolant to be constantly pushed out into the recovery tank with each drive or both (a thermostat issue, for example?). I appreciate this outflow and inflow is a balance in a normal functioning system, but it's clearly not balanced in mine....coolant exits and does not appear to come back into the expansion tank or radiator.

There is an intermittent issue with the heater starting to blow warn air, and then hot air every 10 minutes or so---this resets when the fan is switched off then on again. I did consider that there may be a leak in the hater core, but it does get really hot, there is no smell of coolant in the car, no coolant fog on the windshield, and the carpet is not wet.....all the coolant seems to do a one-way trip to the recovery tank without returning as it should.

I don't want to just throw parts at this thing. There a few people that posted identical symptoms online here but without any follow up. I have read EVERY post relating to this issue...many times. This may be a question for the veterans. Thanks in advance.

 

If the coolant expansion tank,not the overflow in the fender, is overfilled it will puke more coolant into the overflow. I think its very plausible that the non-pressurized tank in the fender is also full. I would say pull the tube off the expansion tank and blow some air into the hose to force the reservoir to push out any excess. This would let you do it without taking loose the fender liner. I caution you though that the plastic tubes on the coolant expansion tank LOVE to crack after they have just a little age on them.

In short, make sure the fender tank has a good coolant level. Are you ever seeing the low engine coolant message? Once its normal, see how long it takes to start puking fluid again. When I read your first post, I was thinking from the symptoms "radiator cap!" I think you may have fixed it when you replaced that. Keep us posted!

 

I thought about this (don't perpetually fill it, so as to overfill)......I wait for the low coolant light, and it ALWAYS comes on. It's clearly leaving the expansion tank on a one way trip to the recovery tank.

I THOUGHT I had it with the new radiator cap, but it's started up again.

Any additional insights?

 

Hey there buddy, sorry to hear about your continuing issues......have you thought about a pm to Brutal or one of the other Tech legends here asking for advice?
Its gotta be worth a punt?

Good luck

 

Cheers, Jim.

I've had very limited success with this method, but am trying anything at this point. I was hoping to post in the open forum so that all the other people out there with the same issue who are too shy to post would also benefit. We'll see what happens..

SC