I found my coolant leak!? What is it?

I believe I found my coolant leak finally! Now how do I fix it? and what part is this? Attach is a picture of me laying on my back looking up on the right* edit* hand side/ passenger side. I top off coolant every 50 miles or so. Thanks!

here is another picture to help identify what I’m talking about. The green fluid you see is downhill from the pipe I highlighted. On the same line pipe

I am just hazarding a guess here but I think you are pointing to the exhaust gas recirculating pipes, never had them on my car so as I say just guessing. If so then they are just the transport medium for the leak which is coming from higher up on the engine.

What year is your Jag ?

The only thing that I can think of on that side of the engine is the upper radiator hose. It’s the other side that has all the coolant plumbing. I think Robin is right that the leak is not from the pipe but just running down it.

Sadly there is one other thing it could be. A head gasket failure on the right side of the engine allowing coolant to leak out of a water gallery. This one’s kind of sneaky because it won’t show up on a compression check. Hopefully it’s not that.

Thanks for the replies! Yes it does look like the leak is further up and that pipe is transporting it. I hope it isn’t a head gasket. Draining the coolant there wasn’t any sludge but there was some black sand like substance that seemed magnetic! I have tried doing a combustion gas test on the coolant and the results were good, and the car runs really good minus having to top off coolant. No signs of coolant on the oil dip stick

Car is a 1991, 40k miles.

What Year and Model car? Is the motor a V8? You may or may not have found your coolant leak.


As per the previous post its a ‘91 and would be the AJ6 engine, xj40 only came out with the i6 or the v12 (very late model)

Here are some more picture, any obvious signs of head gasket failure to you guys?? I just want to be certain before I start dissembling the head. I have done a block combustion test and results were good. I will try a compression test again later tonight and figure out how to do a leak down test as well.

Stran …

If your coolant leak is caused by a failed head gasket it’s very possible that it won’t affect your cylinder compression or introduce any combustable gases in the coolant.

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If you look at where my head gasket failed a few years back (black arrow) you can see where the coolant was being sucked into the cylinder from the water gallery and actually steam cleaned the piston. It’s possible that your head gasket may have failed to the outside of a water gallery (white arrow) somewhere along the right side of the engine. This would not affect the oil or cylinders.

This kind of failure is much rarer that mine because of the difference in pressures involved. The piston is producing 160-170psi against the head gasket whereas the water pressure is usually below the rating on your header tank cap usually 13-15psi. Any increased pressure pushes the coolant into the recovery bottle.

So do a super examination of the right side of your engine and eliminate all other possibilities before you pull off the head.

Here’s a good picture of the possible type of head gasket failures …

Thanks for the information Grooveman and everyone else! I did a compression test and got 149 on all cylinders. I did find some obvious green dye on my rear cover. What are your guys thoughts on these pictures? It does look like my water pump and “bastard hose” is leaking very little as I see white dried up small deposits in that area. I will most likely take off the intake manifold too replace all the coolant/heater hoses and water rail gaskets. Just still deciding what to do about the head gasket, I already purchased the cam timing alignment tool.

Stran …

Wow, looking at you upside down photos gave me vertigo and I fell off my chair :grinning:

I would suggest that you give the right side of the engine a really good high pressure cleaning and then
check for that coolant leak with an inspection mirror or a borescope camera (they can get into all those tight places).

As far as leaks on the left side of the engine there are coolant hoses running all over the place. Pulling the intake manifold is very straight forward and not terribly difficult. The only problem I ran into were the fuel injector connectors that had become very brittle and some broke apart. I replaced them all with new style “push to release” connectors with pigtails, so a bit of soldering was required.

With the intake manifold removed any coolant leak should be fairly obvious. Of course you don’t want to remove and reinstall your intake manifold before you determine if the head has to come off then you’d have to remove the intake manifold all over again.

Number 3 spark plug is the only one that looks a little suspect with the side electrode not being that tan color like the others.


Here are some pictures of the progress I have made. Anything concerning you guys see? Some of my coolant passages are clogged solid! I have a lot of things disconnected, so if anyone wants any pictures please let me know

Your PO was some piece of work all right!

That is one cruddy engine interior.:face_vomiting:

looks like the previous owner forgot to add 50% water to his coolant, saw a head like that about 2 years ago same storey.

I think we might be in some competition for worst head damage.

I’ve ultimately decided to source another engine because both my head and block would require extensive repairs to be able to overcome the corrosion damage.

I feel for you, I’m right with you.

After cleaning it up a bit, I don’t think mine looks tooooo bad but I am definitely worried about using JB weld to fill in the corrosion spots and it leaking still after I put it back together

Stran0020 …

Can’t see from your pictures what kind of corrosion damage there is to the block.

As @Grooveman indicates, it’s hard to see the condition of your block. That was ultimately why I’ve gone with replacement engine strategy. If your block isn’t in need of repair, you have more options for sure.

Here is the pictures of my engine block, I haven’t had a chance to clean it off but the pitting is similar to the cylinder heads, will be applying JB weld on the engine block as well, unless that is not recommended?

I would be very doubtful that jb weld would seal for long on those cylinders.