Hi,
I’m looking for ideas before is start the pain of taking things apart.

Symptom: small puddle of coolant dripping for bump on the front of the sump that occurs sometime after the engine is turned off. No detectable leak with the engine idling long enough for the thermostat to open (temp gauge registers).

Background: I did a service last year where I replaced the water pump and the major hoses under the supercharger. I did that because I was getting a leak near the front of the engine and I assumed it must be one of the things I replaced. I can’t promise the my current leak is the same as what I saw then, but I’m starting to wonder if I totally missed the real leak. I’ve looked from under the car and can’t find something obvious besides wetness on the sump that originates from the intake side of the engine.

So, please help me thing of a way to avoid taking everything apart which has a high risk of being inconclusive.

Thanks,
Daniel

 

Pressure test the system. Find leak and repair?
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there are two coolant flow circuits on the driver side engine bay. One is for the engine cooling and the other is for the supercharger circuit, the supercharger air intercooler is integrated to the intake manifold. You can remove the supercharger air inlet to the intake manifold and check for any residual coolant or feel around the underside of the supercharger area.

 

Thanks guys for the replies. What baffles me is there is no observable leak when running and up to temperature (system is under pressure). So, all I can think is that pressure must go up during shutdown somewhere in the system. Can anyone think of how that would happen and where in the circuit it would be?

I’m thinking that somehow pressure could build somewhere after the thermostat closes. That sounds really strange….

Daniel

 

Most water pump assemblies have a weep hole on the bottom as the shaft goes fwd to the pully

When the system is pressurized if you have a bad bearing seal , coolant will pass through the bearing and out the hole , you may have not gotten the temp high enough to boil since the AJ16 is hard to bring up that high

The seal and bearing can be replaced by yourself keeping the original pump

On the intake side of the block under the intake manifold there is a metal coolant pipe / rail with seal up against the block , best from underneath

Genuine Water Rail-3.2/4.0 Litre (less 6.0 Litre) For Jaguar Xj 1995 - 1997 (from 720125 To 812255) (x300) Classic | Jaguar Land Rover Classic Parts

The pic is misleading as a EGR valve line coming from the aft is looking at you

Coolant Leak; Water rail to engine - Jaguar Forums - Jaguar Enthusiasts Forum

 

Thanks again for the feedback. I think the leak is gone, but I’m not left with high confidence that I actually fixed something. I noticed that the long hose that goes in front of the engine to the intercooler had managed to start wearing on the supercharger pulley. It hadn’t broken through, but was too close for comfort. So, I cut out a small length of the hose and spliced the two pieces back together. After putting it back together and running it, the end at the intercooler was leaking so I tightened it. Since then I haven’t seen any leaks, but I don’t think it was leaking at the intercooler before. Either I’m wrong or the mystery will have to wait for some symptoms to return.

Daniel

 

Hello, May I suggest pressure testing the system when cold!! Hoses and fittings loosen when cold, When and where will be found then. Stant sells great pressure testing tools.

Thank you.
Larry Louton