I see the general area with dampness where I have a minor coolant leak. I want to perform a pressure test at 20+ psi to observe exactly where the leak is coming from, and I want to do this with the engine off so I can get my hands in there and feel around.

My pressure test kit has 10 cap adapters for the coolant reservoir but none of them fit. Under normal circumstances this would surprise me, but since it's a Land Rover I calmly shrugged it off.

Has anyone found a cap adapter that fits the coolant reservoir?

 

You could probably buy a cheap cap on amazon, or a used one, drill a hole and install a schrader valve.

Or depending on where the leak is, you might be able to run the engine just long enough to get the coolant up to normal temp (and pressure) without heating up the block much.

 

After some online sleuthing, I found four options for getting a cooling system pressure test performed on the LR2:

1) Modify a spare coolant reservoir cap. See Merlin's suggestion above. It's a feasibe solution, but I confess that I'm not ambitious enough to tackle this DIY project.

2) Buy an off-the-shelf adapter cap that fits the LR2 coolant reservoir. I found an online reference that indicates the threads for the cap are 48mm x 2.5. There is an adapter that claims to work on the LR2, it's the CTA Tools 7118 Tank Adapter. The Amazon reviews are mixed. And the size for this cap is shown as 49mm x 25, slightly larger than the reference size of 48mm. So I'm not confident about this item, but listing it here for completeness.

3) Instead of connecting the pressure pump to the cap of the coolant reservoir, the OTC 6977 Cooling Pressure Test Kit provides a T-adapter that goes onto the coolant hose connected to the reservoir. To create pressure, you pump into the hose instead of the tank itself. This solution has the added value of testing the coolant reservoir cap for leaks along with the rest of the cooling system. The setup for this test is convenient when the hose connects to the side of the reservoir for easy on/off. However, the LR2's hose connection is at the bottom of the reservoir. I would have to remove the tank to get access to the underside, and then put it back in place along with the other connectors for the overflow tube and fill sensor. I have already replaced this tank once and know how to do this, but it's a hassle I want to avoid if there's an easier alternative.

4) What I settled on is a universal set of adapters that work with most vehicles, so I can use it for other cars in addition to the LR2. This style of adapter does not connect to the reservoir cap threads, but is inserted into the interior hole within the cap receiver. A connector is then fastened to the top of the adapter which when turned causes the surface bladder of the adapter to expand, creating a tight seal with the reservoir opening. This is clever and simple. It connects to standard connectors and hand pumps that come with common pressure test kits like I already have. The only downside is that the inserted adapter must be very dry so it doesn't slip loose when under pressure and launch into the air! The test pressure for the LR2 is 20 psi, which is higher than what I'm used to with other vehicles. (I think I will wrap a few windings of fishing line around it to prevent it from going airborne if it happens to comes loose). This adapter kit is sold under multiple brands, including OEMTools 27068, RedLine 95-0750, Matco SMART750, and Harbor Freight's Maddox 56204. There are several videos on Youtube demonstrating how it works. I bought the kit today at HF for less than $50 with a coupon.

https://www.harborfreight.com/univer...set-56204.html

The weather here was too stormy today to work on the car, so I will post back after I try it.

 

I found it much easier to buy a small bottle of UV additive and a UV light source.

 

That's Plan B if I get nowhere with the pressure test.

 

Update: The pressure test worked as described (see photos). The middle size adapter in the universal Maddox set is the one that fits the LR2.

Before the test, I saw moisture near the top of the radiator and I suspected the leak was coming from around there. I was wrong, it's underneath where I can't see from the top. So this week I need to jack up the front of the car, remove the underbody cover, and pressurize again while looking under the car to find the source.

Interestingly, the leak is a stream when pressurized at 20psi. It's just a dribble otherwise, so the typical pressure is well below 20psi while driving.

 

While driving the coolant circulation prevents the coolant around the sleeves from getting hot enough to boil. The system pressure while the engine is running is due to thermal expansion of the coolant.

Immediately after the engine is shut down, you probably get localized boiling or bubbles around the sleeves, which raises system pressure. Peak pressure occurs shortly after shutdown. The bubbles don't hurt anything since it's only residual heat, and there's not additional heat being introduced.

 

The coolant reservoir cap appears to be sealed. It doesn't have an integrated pressure relief valve like the traditional radiator caps. How is the pressure released when it exceeds the max?

 

The forward end of the reservoir has two lines, one of them to the radiator and one of them to the engine block. Apparently that keeps things balanced and under control. Or so we hope.

 

Update: I just got back to this diagnosis project. My vehicle has been sitting disabled for the past month with a serious coolant leak that prevents me from even idling the engine.

I removed some trim panels from under the front bumper so I could get a better look at the area where the coolant is coming from. It starts leaking with as little as 5 psi of pressure that I apply in the coolant bottle using a pressure tester.

I have a borescope attached via USB to an Android tablet. Going in from the top-front of the engine, I inspected the hoses in that area. I can't see anything with my own eyes as these hoses are buried too deep, so I'm just fishing around with the borescope.

As shown in the first photo, bottom-left, I saw what looked like a couple of damage areas on one of the hoses near a puddle of coolant. But I'm not sure at this point since it could be crud on the hose.

So then I pumped in a few psi of pressure and looked again. As you can see in the second photo, coolant is spraying out of the hose at that spot. Bingo!

Based on the position of this hose, my best guess is that it's the oil cooler hose (LR005563) where the top piece bends to the left. And it looks like it might be in contact with the engine block, which could explain the damage to the hose.

The good news is that it's just a hose. The bad news is the intake manifold needs to be removed to get access to this hose. I will have to get my vehicle towed to a shop, and will probably have all the hoses replaced.

The coolant pressure tester and borescope tools came in handy for this diagnosis. I still can't fix the problem myself, but feel satisfied to be more informed when I go to the shop and discuss this problem along with the photos in hand.


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