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2001 Land Rover Discovery Cooling System - Photo 62166281

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  • The cooling system really deserves an article all it’s own. It’s the reason this head gasket blew in the first place. The stock thermostat should definitely be replaced with the cooler-opening Motorad 180-degree version. It only keeps the engine cooler by a few degrees, but this engine needs that few degrees to not trip dash lights. Also, no Dexcool! Dexcool, along with air bubbles or other coolants mixed in, can break down aluminum. Get rid of it. A later photo illustrates the dissolved block water jacket ports. Flush the engine well, and replace coolant with standard green ethylene glycol antifreeze (50 percent), plus a new lower temp (180 degree) thermostat, a new radiator, and new water pump. This is all very important stuff.
The cooling system really deserves an article all it’s own. It’s the reason this head gasket blew in the first place. The stock thermostat should definitely be replaced with the cooler-opening Motorad 180-degree version. It only keeps the engine cooler by a few degrees, but this engine needs that few degrees to not trip dash lights. Also, no Dexcool! Dexcool, along with air bubbles or other coolants mixed in, can break down aluminum. Get rid of it. A later photo illustrates the dissolved block water jacket ports. Flush the engine well, and replace coolant with standard green ethylene glycol antifreeze (50 percent), plus a new lower temp (180 degree) thermostat, a new radiator, and new water pump. This is all very important stuff.
Here she is on day one of purchase. The $500 buy in was due to the initial diagnosis of a blown head gasket. This was based on the bone-dry cooling system, lack of compression while cranking (on the driver’s side), and apparent seepage from the driver’s side head gasket area. Also, it’s a given that the Discovery II head gaskets fail every 90,000 miles or so. Its time was up. Here she is on day one of purchase. The $500 buy in was due to the initial diagnosis of a blown head gasket. This was based on the bone-dry cooling system, lack of compression while cranking (on the driver’s side), and apparent seepage from the driver’s side head gasket area. Also, it’s a given that the Discovery II head gaskets fail every 90,000 miles or so. Its time was up. In addition to a head stud kit ARP supplied manifold and header bolts, a thread chaser kit, and some of its ARP Ultra-Torque Fastener Assembly Lubricant. British Parts of Utah supplied a complete head gasket set, which included rocker cover gaskets, head gaskets, exhaust manifold gaskets, valley pan gasket, and fuel injector O-rings. We also ordered an intake manifold gasket, throttle body heater plate gasket, coolant input and output O-rings, a throttle body to intake plenum gasket, and valve seals. British Parts of Utah also supplied a set of Magnecore 8mm silicone spark-plug wires and a set of standard coil packs. The wires offer good heat resistance, which this engine requires, and helps minimize misfires. In addition to a head stud kit ARP supplied manifold and header bolts, a thread chaser kit, and some of its ARP Ultra-Torque Fastener Assembly Lubricant. British Parts of Utah supplied a complete head gasket set, which included rocker cover gaskets, head gaskets, exhaust manifold gaskets, valley pan gasket, and fuel injector O-rings. We also ordered an intake manifold gasket, throttle body heater plate gasket, coolant input and output O-rings, a throttle body to intake plenum gasket, and valve seals. We removed the hood for better access to the engine area. We also clearly marked and labeled all parts upon removal to make reassembly easier. The cobwebs were clear evidence the Disco had been sitting around for a while.
All coolant lines had become as brittle as eggshells. Be prepared for this, or just replace them all with 5/16-inch ID fuel line. That’s what we did, including coolant reservoir to and from throttle body heater, and coolant reservoir to radiator hoses. This is a shot of the throttle body heater lines that we replaced with fuel hose. Take the opportunity to clean the parts that need to be cleaned, especially a dirty throttle body and all sensors (crankshaft position, throttle position, coolant temperature). The cooling system really deserves an article all it’s own. It’s the reason this head gasket blew in the first place. The stock thermostat should definitely be replaced with the cooler-opening Motorad 180-degree version. It only keeps the engine cooler by a few degrees, but this engine needs that few degrees to not trip dash lights. Also, no Dexcool! Dexcool, along with air bubbles or other coolants mixed in, can break down aluminum. Get rid of it. A later photo illustrates the dissolved block water jacket ports. Flush the engine well, and replace coolant with standard green ethylene glycol antifreeze (50 percent), plus a new lower temp (180 degree) thermostat, a new radiator, and new water pump. This is all very important stuff. Here is some evidence of corrosion within the cooling system. CLR helped. We soaked the inlet/outlet pipes in CLR and got in there with a brush to clean it out. If the pipes are this bad, imagine the tiny water jacket crevices. Radiator removal was tough. The best bet is to remove the grille then remove the scrivets (plastic screw rivets) holding the side deflectors in place. Then you can stick a screwdriver through and undo the radiator support bracket. The coolant outlet pipe was very hard to remove. First we removed the bolt from the flange and sprayed it with penetrant, letting it sit for a while. Then pulled and struggled and twisted weated and cracked our knuckles until it eventually came out. Be prepared to replace the O-ring on the coolant outlet pipe. It is not included in the head gasket kit. The coil packs and plug wires were removed. This is relatively simple once the intake plenum and the hood have been removed. Tip: It can be done without removing the plenum, but you need small hands, patience, and a bent screwdriver to get around corners and pull wires.
The intake plenum, intake manifold, rocker covers, coil packs, and wires were all removed. Note the buildup of grease on the valley pan gasket, which indicates high (above the heads) leaks, such as the intake manifold gasket (which is the valley pan gasket) or the intake plenum gasket. Possibly, leaks in the inlet or outlet pipes, too. The valley pan gasket was removed along with the rocker assembly bolts, which were marked before removal. We found it was best to loosen the outside bolts first and then the inside bolts, in steps, to avoid warping or binding (i.e. 1-4-2-3). The driver’s side head was removed. This was the side lacking compression, so we expected to find problems here.
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