Thread: Defender 300TDI Water to Air Intercooler

Members,
I was inspired recently to change my Intercooler to a Water-To-Air type. It seemed like a fairly simple, straightforward, task. What could possibly go wrong, right?
Well, now that I’ve done it, and I’m pretty impressed with the results, I thought I should ask you guys what landmines I might have created for myself.

The Intercooler came from ‘Frozen Boost’, in the US. It’s an ‘offset’ Input/Output type, that was shorter with a larger cooler area, than the ‘Barrel’ type available in Aust (and a lot cheaper). It fit neatly alongside the engine, with the Inlet at the same level as the Turbo Discharge and the Outlet at the same level as the Manifold Intake.
Frozen Boost also provided a small 5”x 9” oil/water cooler that would almost fit in the intercooler space beside the radiator.
A small bilge pump, that accepted ½” hoses, circulated the coolant. A crude speed control was put on the pump.

After a bit of trial-and-error (that involved turbo hoses splitting or popping off under full load) the arrangement was simplified down to one elbow out of the turbo and one 180degree bend out of the intercooler. I also discovered the limits of Jubilee Clamps and replaced everything with Bolt-Type hose clamps.

This simple arrangement gave good performance, until I hit the first hill. Under moderate load, the cooling water temp reached more than 80degC (after cooling) and the small radiator wasn’t big enough to cool it down before the next hill.
I added a small reservoir (about 1litre) into the cooling circuit. This evened out the temperature spikes and performed good enough to keep for a few weeks. It was obvious though that the small radiator wasn’t coping. It was a pity, ‘cos with a bit of effort it did fit nicely in beside the engine radiator.

Plan ‘B’ was to add another cooler in the water circuit, but where and how to mount it was becoming a problem. The added complexity to the plumbing made me re-think it and go straight to plan ‘C’ – use the old air intercooler as a radiator.

This worked brilliantly. The old intercooler fits nicely into the space beside the engine radiator. It already has the cowling in place to allow the engine fan to pull air through it. The plumbing could be kept short & simple.

The water temp now sits around 40-50degC under normal loads. It reaches 55-60degC when fully loaded for several minutes, and then recovers back below 50degC in a reasonable time. The temperature was measured after the radiator had cooled it. There didn’t seem much point measuring before the radiator, other than curiosity.

Performance wise, it’s like a different engine. There’s almost no Turbo-Lag. Noticeably more grunt at lower speeds. Marginally more grunt at higher speeds, 100-110kph. It doesn’t bleed speed at every small hill.
I’ve had Exhaust Gas Temp & Boost Pressure gauges in the dashboard for a coupla years now. Based on nothing more than my experience years ago with high performance V16 marine Cruise Diesels, I’ve limited myself to around 700degC as full load when climbing highway hills. This usually means backing off from 100kph, down to below 80kph, in the case of the hills surrounding my village, with no power left to go any harder anyway. Now I find that I’m not losing as much speed (maybe 10kph, or so) and there feels like there’s still more available, if I wanted to push it.
The performance is so good, that I’m considering backing off some of the fuel pump tweeks I’ve made over the years.

Now, the odd things.
I can hear a funny noise that I thought was an exhaust leak (it sounded like a holey muffler). I eventually twigged that it was from the air inlet, below the driver’s window. It was back-pressure noise when decelerating – changing gears or cruising downhill. I’m not real sure if this noise was to be expected, or if I’ve upset the turbo during the trial-and-error phase when I had hose clamps failing under load. Any thoughts?

The engine now has more of a rattle about it – if that’s possible.
To put that in perspective - About six weeks before this mod, I changed the head gasket after a blow out at the back of No.4 cylinder. The engine has done over 320k. The head and everything else appeared to be in good order. After the gasket change, and adjusting the tappets, the engine was as smooth and quiet as I had ever heard it. Then, a couple of weeks later, I drowned it in the creek.
The How-What-Why’s are irrelevant and too embarrassing to repeat, but on the creek bank I had to pull injectors and blow water out of the engine, then spend the rest of the weekend changing oils and fluids. That was about two months ago and I’m still finding places that I never knew existed, that need water drained out of them.
I’m not sure if I’m imagining new noises in the engine, or if the creek experience has damaged something, or if the intercooler mod has changed something. I’d appreciate any thoughts anyone has this.

Cheers.

Tank,
I'm onto it.
I'll try to get some up tomorrow.

Ta,
Bud.