Do the pressure test with Advance Auto kit and fix all the leaks. If the tank was not replaced 5 years ago when your brother did the rest, then not a bad idea to do that now. Stay with the green coolant, generic is fine. After the leaks are fixed do the inline mod.

 

Thanks, how much pressure do you give the system? Any other considerations in doing this?

 

Go ahead and pump it up as high as it will go, they system should easily hold 20 psi overnight if it is in good condition. If there are leaks you will probably hear them if they are large and external. Look for drips.

 

Thanks man, I'll see if I can get the tester out here. There's just an O'Reilly and Autozone that I know of, unless you meant that Advance Auto will send the tester to you.

I'll replace the expansion tank too I guess - do you suggest sticking with the genuine LR part or is it OK to use the replacement Atlantic British has? Or some other Uro, Britpart, etc. Is there something you do when you're installing the bottle to bypass the TB heater plate? I wouldn't mind leaving out that rigid pipe that goes from the bottle to the TB heater plater that got messed up when I replaced the TB heater plate recently.

 

I personally do not have any data that there is significant quality difference between ebay tanks and oem, although I know others on here do. I believe it is more important for it to be new/not aged/deteriorate than a certain brand. I split an end tank on the radiator on by off road truck two years ago sitting in traffic in cool weather on one of my trucks - never got hot. That's when I started running the caps one turn loose which eliminates pressure related quality concerns.

As far as the throttle plate bypass, get some 5/16 automatic transmission hose at Oreilly and run from the intake manifold fitting to the bottle, throw the hard line away. Make sure it is ATF hose and not fuel hose, the fuel hose is not rated for the temperature.

 

Are you saying you want to bypass the TBH entirely? If so, you can simply use a short bolt of an appropriate diameter to plug the short hose below the coolant reservoir where the line from the TBH connects and use a small hose clamp to keep the bolt in place.

Next, disconnect the other hose that runs from the intake to the other port of the TBH and plug that hose the same way.

No more leaking TBH. Ever.

The two lines running to and from the TBH serve no purpose other than heating the TBH, so it's okay to block both lines.

 

Somehow on my expansion tank, with the new genuine cap I got last year at the recommendation of an old British cat at a local LR/Jag independent shop who said he didn’t want to look into any of the issues any further, a 360-degree turn still leaves the cap on very tight, although just a 180 feels very loose. I’m really not sure what to do - I feel like my situation isn’t normal. The seal of the cap with its o ring to the expansion tank is weird. I think I need to get a new tank like you recommended and try it then.

I think I’m too afraid of having the throttle body frozen open to try bypassing it, though. I might live in California, but it’s different where I am. I’m up a bit higher and it’s regularly foggy and cold with a good amount of wintry days that I’m worried could possibly freeze the throttle body while I’m driving down from this altitude for 20 minutes without giving much gas at all. I probably need to replace that hard line from the tank to the heater plate though since the heater plate end got chewed as I had to pry it off when I replaced the heater plate. Looks like the genuine line is about $50 and the Uro is about $20 - not sure which you’d go with. I probably don’t have the genuine one in there now.

Hopefully that plate doesn’t leak for a while - I did my best to seal it up with gasket tacking, but I think it’s just got issues no matter what. I’ll keep the bypass in mind though in case I need to run it like that in some kind of emergency.

I’m waiting for the pressure tester to be available and I’ll try everything out. I think it can really put a lot of pressure on the system though - I’m worried I’ll cause problems if I put too much pressure in it. Maybe I should limit it? I’m wondering how much pressure the system usually has when it’s running. Hoping this over pressure issue isn’t anything major. Thanks again

 

Factory cap vents at 140KPA (marked on the cap) which is 20.3 psi

 

If you are actually in SOCAL there is very close to no chance of your throttle plate freezing up if you bypass the TB heater. Maybe a consideration if you live in the arctic but still there are very few reports of that actually happening.

 

I run mine tight and have not tried the cap loose yet. If I have any leak anywhere it will drip out of the overflow tube. I put the cup seen in the picture so I can see if anything is leaking. Without it most will evaporate on the frame or wires below and you cannot tell unless you see it happening or notice the level drop. Looks kind of hillbilly but works. This has helped identify two leaks. One was a small hairline crack in the tank itself which I replaced. This was difficult to find because the crack itself did not leak coolant. The other was the small tube that returns to the radiator had the clamp loosen. In both case the fixes stopped the overflow drip completely. Your tank looks old, I would start there with a new tank/cap.