Hello all,

I am currently installing an lpg kit. Therefore, I need hot coolant for the lpg vaporizer. This has to be taken of the hoses going to the interior heating. Now, on the AJ6 engine, the hot water from the engine comes out roughly under the inlet port closest to the steering wheel. The hot water, however, has to go through a valve first. (vacuum operated) Can be seen on picture below.


When does this valve let hot water through, and when doesn't it? For the lpg kit, coolant should circulate all the time. Therefore, is it better to take of this valve?

Does anybody run an aj6 on lpg here, who can tell me how the coolant hoses are connected

 

Hi Wilfred,

That valve is controlled by the Climate Control ECU and opens via vacuum to allow hot water to pass through the heater core in the Climate Control Unit in the center of the dash. You don't mention the model year of your XJ40 but I assume it is prior to '93 since the valve is in the hose and not mounted on the cylinder head.

I would think you could put a T-fitting in that heater feed hose (Part 2 in the diagram below) and get a constant supply of heated water there:





You could put another T-fitting in the heater return hose (the hose marked "REFER TO ENGINE SECTION" in the diagram) for the return from your LPG equipment.

The two nipples shown in the upper right hand corner of the diagram are the ends of the heater core pipes that extend through the firewall.

There are probably some LPG experts on this forum, but the one I am familiar with is active on the Jag-Lovers X300 forum under the user name "Jags on gas," and if you post your question there there's a good chance he will respond. If you're not a member of Jag-Lovers, send me a private message and I'll put you in touch with him.

Cheers,

Don

 

Hey, thanks for your reply Don. It's sorted already, but just wanted to clear things up. first, it's a 94 4.0 engine, so the valve was attached to the cilinder head. Otherwise, I could take of the coolant BEFORE the valve.

Second, the engine resides in my series 1, which means that the heater controls are not all in place.

I took of the inlet manifold, to install lpg injectors, which gave space to check the valve. It turs out to be open in rest position, and closes when vacuum is applied. So I just disconnected the vacuum hose, so it's now open at all times.

 

Hah! I should have looked a little more closely at your photo! :-) I'm going blind with age!

Cheers,

Don