XJ40 ( XJ81 ) 1986 - 1994

Leaky ol' tub

 
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Old 04-06-2019, 08:34 PM
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Default Leaky ol' tub

Afraid the old pride and joy has developed a small case of incontinence and at the moment marks its territory at every parking spot.

Have looked/felt without success to spot the source of the leak from above and most frustratingly, can see the coolant drip while peering down beside the oil/trans dipsticks - it looks like it's dripping from the horizontal trans? metal dipstick tube directly below the dipsticks, but obviously coming from somewhere else and ending up there....

Any ideas where it could be coming from? It looks like it's a lower down leak and until I can find a place to get her lifted can't see any place it could be coming from ...

Larry
 
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Old 04-06-2019, 11:11 PM
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Hi Larry,

My first suspects would be the water rail hose, part 3, or one or both of the water rail gaskets, part 17. These parts are on the left side of the engine and are very common leak points. Unfortunately they are virtually impossible to access without disconnecting the intake manifold and pulling it away from the head:



Hope it's something simpler, like a heater hose.

Cheers,

Don
 
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Old 04-07-2019, 09:55 AM
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HeyLarry,Ijust did one on Cin's car,andit had me fooled forquite some time.

Check the heater hose that comes from the firewall and makes a sharp bend to the back of the engine.It connects to a spigot on the head,just under the intake manifold.

Coolant will pool by the dipstick,on the engine block,down low be the oil pan.Most will just evaporate,and your coolant will just disappear!

You will need a mechanic's mirror,7MM 1\4 drive socket to undo the clamp,and pull the hose.Lordco matched me one up, with the right bend and diameter,just trim to length.

Boiling water,and stuff a socket in the end to expand the hose slightly,and stuff it on the cyl. head end,I had to kneel on the top of the engine with blankets,and plywood just to get the tip of one finger to touch the clamp!

Not easy,but do-able.

Or pull the whole intake off,and do everything!........NOT!

I have all the gaskets here,in case of emergency.

Cheers,Jim an Cin.
 
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Old 04-07-2019, 10:01 AM
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Thanks Don, I hope it's the heater hose too, but even if it is (#5), it too seems well buried and out-of-sight.

Do you just remove the intake plumbing TB bellows etc to get at it or does it have to be changed from under the car?

Larry
 
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Old 04-07-2019, 10:52 AM
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Originally Posted by Lawrence View Post
Thanks Don, I hope it's the heater hose too, but even if it is (#5), it too seems well buried and out-of-sight.

Do you just remove the intake plumbing TB bellows etc to get at it or does it have to be changed from under the car?
You can't really get at it from under the car, so the most expedient route is to remove the air intake plumbing and TB, remove the intake manifold nuts and bolts, pull the manifold away from the head and tie it back with rope or bungee cords. You then have good access to the entire left side of the engine. That makes it a great time to replace that large water rail hose, the gaskets on the water rail, the oil seals on the oil filter housing, the O-rings on the cooler lines or cooler bypass U, the dipstick tube seal, etc. I think your car has the oil fill in the cam cover so you don't have an oil fill tube seal on top of the crankcase. The spigot Jim mentions is probably the heater water control valve, which threads into the cylinder head at the rear end, just under the intake manifold. Also much easier to get to with the intake pulled away.
 

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Old 04-07-2019, 02:58 PM
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Originally Posted by manwich66 View Post
HeyLarry,Ijust did one on Cin's car,andit had me fooled forquite some time.

Check the heater hose that comes from the firewall and makes a sharp bend to the back of the engine.It connects to a spigot on the head,just under the intake manifold.

Coolant will pool by the dipstick,on the engine block,down low be the oil pan.Most will just evaporate,and your coolant will just disappear!

You will need a mechanic's mirror,7MM 1\4 drive socket to undo the clamp,and pull the hose.Lordco matched me one up, with the right bend and diameter,just trim to length.

Boiling water,and stuff a socket in the end to expand the hose slightly,and stuff it on the cyl. head end,I had to kneel on the top of the engine with blankets,and plywood just to get the tip of one finger to touch the clamp!

Not easy,but do-able.

Or pull the whole intake off,and do everything!........NOT!

I have all the gaskets here,in case of emergency.

Cheers,Jim an Cin.
Good to hear from you Jim, that bit about sitting on the engine sounds like fun (NOT!) ...getting a bit long in the tooth for that stuff!

BTW how's the black monster in the backyard? Progress?

Larry
 

Last edited by Lawrence; 04-08-2019 at 10:50 AM.
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Old 04-08-2019, 08:11 PM
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Hey Larry, I changed those heater hoses on the Moneyfunnel last spring. As I recall it was a matter of doing one and then the other. I could reach the top one with the bottom one out of the way. Vision was absent and all done by feel, but there was no sitting on the motor.... that I remember anyway.... Good luck!
 
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Old 04-08-2019, 09:54 PM
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but there was no sitting on the motor
good to know

Weirdest thing tho Jerry, pi$$ing out on Saturday, topped it off, seems to have stopped leaking?? HUH?

Larry
 
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Old 04-09-2019, 06:03 AM
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Coolant gremlins. They'll be back
 
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Old 04-09-2019, 09:12 AM
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Hey Larry,like I said,a real fooler,until the hose pimple goes POP!

Around here,shop in the back is built,complete with shed attached for the XJS to get work done.This springs's project is a driveway in the front to park said Jag's on.

Not much time or space to work on cars yet i'm afraid.

Kneeling on a 2x2 bit of plywood,placed on the fender/cam cover,with some blankets to protect,was the only way I could get a finger on the clamp to secure it tight.

Keep an eye on things,and keep us posted,gotta go to work now...

Cheers,Jim and Cin
 
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Old 04-09-2019, 09:50 AM
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Coolant gremlins. They'll be back
I have no doubt about that!

Around here,shop in the back is built,complete with shed attached for the XJS to get work done.This springs's project is a driveway in the front to park said Jag's on.
Sounds great guys, new driveways are great until wifey decides no more parking Jags 'cos the old car might drip oil on that beautiful new expensive concrete .. (Not you tho Cin! )

Larry
 
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Old 04-12-2019, 12:13 AM
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Ok lads, further developments ..after it quit leaking (totally stopped) I had no idea where to look for the leak. Thought that was weird, header tank still ok level after a week of driving ....but ...It got a bit chilly this afternoon so I cranked up the heat ...BUT no heat!

a/c working, blowers working, just no warming trend ..

So no hot water getting to the heater then? Engine temp normal, btw.

Bit lost on what/where/how here lads..any ideas?

Larry
 
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Old 04-12-2019, 08:55 AM
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The heater control valve on your '94 threads into the cylinder head below the cylinder 6 or 5 intake manifold runner. You can start at the heater hoses at the firewall and feel your way back along the one that leads to the valve. The other heater hose, I think, goes under the intake manifold and connects to the back of the water pump housing. With the engine at operating temp and the heat turned on, the hose from the control valve to the firewall should be hot and the return hose to the water pump should be warm. If not, the valve may have failed. Maybe it leaked and then failed?
 
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Old 04-12-2019, 10:20 AM
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Ahhh now were getting somewhere. The valve is suspect. Can giving it a few taps open it? I remember someone removing theirs, and soaking it in wd40 and then a good oke rinse.
 
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Old 04-12-2019, 11:10 AM
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Thanks - now I have something to go on! Leaking failing valve makes sense, plus the location of the valve seems about right for the dripping spot ..will go see if I have a spare valve in stock.

This 'no heat' scenario has been happening a few times before (for short periods), noticeable when changing from cold temp (a/c) back to heat and car still blowing cold. Seemed to resolve itself on next morning cold start, but often adjusting while driving produced no change. Always thought it was a blend flap issue ...

Of course it could be both a failing valve AND a blend flap issue, this is the 25 year old XJ40 climate control we're talking about here!!

Larry
 
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Old 04-12-2019, 11:45 AM
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These valves are unobtainum apparently, so lets hope I have one in the spares pile!

Part # MMB6711AA

 
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Old 04-23-2019, 01:38 PM
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Well I checked the parts bin and yes I do have a spare valve and all associated hoses, in fact and entire spare cooling system including a rad.

So, prepared to dive in and fix it, (whatever it was) when suddenly the car stopped losing coolant and even though I've been taking it up steep hills/long drives, spent time in stop and go traffic, parked up with a hot engine and waited, checked below car on cold start ..every possible scenario for the last 2 weeks, no more signs of leaking ..so a bit frustrated at this point ...I guess I'll have to wait till it leaks again?

Plus heater does work, hoses are hot etc ...occasional A/C stuck on is probably just blend door flaps sticking.

grrr

Larry
 
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Old 04-23-2019, 03:30 PM
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When your valve sticks, it leaks. Thats whats happening.
 
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Old 04-23-2019, 03:38 PM
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Ok I hope so! Will keep an eye on it!

thanks

Larry
 
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Old 04-23-2019, 03:39 PM
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No heat in winter, no A/c in summer, its just the jag reverting to form If the heater valve is scrap and the one you have is also NFG then there are generic ones that will fit. I have one on my ‘66 ‘S’ that I fitted 20+ years ago.
 

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