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I have a leak in the recovery bottle, which is the tank in the lower fender, ahead of the left front wheel. Here is a picture. What is that little port for? I don’t think it should be leaking, should it? Is it some kind of breather? Help me figure out if it’s supposed to leak/weep, and then we’ll figure out how to fix it. What you’re looking at is the bottle mounted in the fender, with the left front wheel and fender liner removed. The leaking port that you see is quite low on the bottle. There’s a zoomed in picture and a zoomed out picture. Thank you!
Last edited by aquifer; Dec 29, 2018 at 02:28 PM.
Reason: Add picture
Not sure if its a port or not, I suppose it is but the first question I would ask is are you loosing coolant, i.e. having to frequently top up the header tank?
Yes I’ve been losing coolant very slowly for 2-3 years. I top up the coolant maybe every 1500-2000 miles, so it doesn’t leak much. In fact, until today, I could not figure out where the coolant was going. I never saw any drips, until just recently when I saw a tiny drop hanging from the tray to the left of the radiator. I started digging, and found this. I had always believed it was a questionable head gasket, but it never got worse.
Of how much coolant that you have to refill you're talking about? Will the expansion tank be almost emptied after 1500/2000 mls with the low coolant light going on?
The reason why I'm asking is that the level in the expansion tank stabilises usually a few mm up to 1 cm below the filler neck.
..and each excess amount will overflow to the atmospheric bottle/recovery tank. Meaning if your coolant level stabilises somewhere below the filler neck there's no need to top it up till 100% full.
I have tried letting it stabilize, but eventually the low coolant light will come on. I typically add about a pint every 1500 miles or so. It’s been that way for 2-3 years. It’s never been excessive, but something I regularly monitor. Seems to be a little worse after spirited driving but that’s probably my imagination.
Did you ever replaced the expansion tank cap? As it doublefunctions as a valve which allows excess coolant to overflow to the recovery tank at pressure ratios above 1 bar there might be something wrong with it due to age. The cap usually also allows the coolant to be returned into the expansion tank when the car is cooling down.
Yes I have tried replacing the cap but it didn’t make any difference. I’ve sometimes thought I should do a compression test to see if I have a failing head gasket. Just haven’t done it yet, I guess. I can’t help thinking that if the head gasket was failing, it would have gone out long before now. The coolant issue has been there since I bought the car, but it’s never gotten worse, and there’s no residue in the tail pipes, which would indicate I’m burning water. It’s been a long running mystery, but I figured I’d either figure out where the coolant was going, or the head gasket would blow.
The hole in that "port" should not go through to the inside of the tank. It is not clear why the "nose" extension is there - perhaps for a level sensor that was never implemented (and it would not really make sense to have a sensor there) or to act as a socket for a self tapping screw to attach something (short screw which would not penetrate the tank wall) on some cars other than XJ8.
I would plug the hole, ideally by tapping a thread in it and installing a short stainless steel bolt with some teflon tape or hard setting sealant on it. With a hole-through there, the recovery tank cannot hold much of the overflowed coolant as the hole is quite low down. If the hole is plugged, there will be no issue with breathing of the tank as it is not pressure tight. It will breathe around the (loose) entry hole of the pipe going into it and, if for any reason the tank is overfilled, the coolant will go out through the same point.
Yes. The overflow tank in the left front fender had a hole in it, about halfway up. The hole looks like it was designed to be there, but should have had a cap or plug of some kind. Mine did not. When the overflow tank got to that level, a little bit trickled out the hole. I never saw a single drop of antifreeze under the car until one day I saw a drop hanging from the front splash panel as I was changing oil. A search led me to the hole. There was a white trail of dried antifreeze down the side of the overflow tank, coming from the hole. My theory was that it leaked so little, and so infrequently, that it dried up before I parked in the garage. I plugged the hole and it’s been fine since. As I recall, I used some epoxy and a piece of plastic to cover the hole.
The atmospheric catchment tank is SUPPOSED to have the hole in that spot. The tank does not hold much coolant, just enough to draw back into the reservoir when the system cools. The overflow tube is routed to the bottom of the catchment tank and connects to the reservoir. The cap allows coolant to the tank if the expansion is great enough and then draws it back upon cooling.
If the coolant overflows the catchment tank, then you have an overheating engine, cooling system too full, a faulty reservoir cap or coolant air bleed lines incorrectly routed!!
Same as motorcarman. The expansion tank boss on my car is clear to the inside. And there is no evidence of a coolant dribble.
Originally Posted by motorcarman
The atmospheric catchment tank is SUPPOSED to have the hole in that spot. The tank does not hold much coolant, just enough to draw back into the reservoir when the system cools. The overflow tube is routed to the bottom of the catchment tank and connects to the reservoir. The cap allows coolant to the tank if the expansion is great enough and then draws it back upon cooling.
If the coolant overflows the catchment tank, then you have an overheating engine, cooling system too full, a faulty reservoir cap or coolant air bleed lines incorrectly routed!!
Make sure that the two plastic hoses are connected to the right outlets on the fluid reservoir. The top most port is where the overflow hose should be connected.
Do what Dave said: it is likely you have your hoses wrongly aligned. Happens all the time. Do a search: lots of threads, lots of pictures. The hoses must cross over .. .
I first noticed the common mistake when these cars were introduced. I was working a little later than usual and the shop foreman had left for the day.
A customer showed up late afternoon to get his car. He came back a little after 5PM with a COOLANT LEAK!!!!!!!!!!!
The shop foreman had done some work on the cooling system and topped it up.
The service writer came over to me and asked if I would look at the customer car for the leak.
The coolant was 'dumping' out of the atmospheric catchment tank. I was going to pressure test the system but I saw that the air bleed and overflow lines were 'mixed-up'.
I swapped the lines and filled the system.
Next day to foreman was told what happened. He thanked me for getting it done quick.
Can't blame him really because the cars were quite new and we were still learning about all the differences!!!
Recovery bottle / header tank
