There are several threads about deleting the ACSD off the pump and running a simple bypass hose. A 1/2 banana job and worth its weight in gold. The thing is there a little more discovery buried in 1HZ/HDT engines that warrants a deeper dive.
A little history
In 2006 I transplanted a JDM 1HDT sourced engine in a BJ74 and drove it for 65,000 miles with a few issues along the way. No severe breakdowns until 2010 and then 2015 when I broke a ring. The transplant in 2006 included new radiator with and regular green coolant. In 2010, I was taking kids out of town for 2 week trip and 100 miles out of town I went from nothing to overheating in seconds. Gauge pegged from operating temp. After cooling for 30 minutes I made it 10 miles and I had a mechanic do an emergency fluid exchange, then drove to another open lot and did a second. Limping back to Tucson, I ran with full heater on (100 degree daytime temps) and stopped 4 x getting back to cool truck off. After vacation I did an oxalic acid/baking powder wash and replaced the radiator. All seemed well until I swapped frames on truck and cracked the ring. In tear down I found that the oil cooler was clogged with rusty paste and had thrown rust clots again into the radiator, heater cores, and hoses but had not yet obstructed the flow. The head also was cracked. I have taken down five 1HDT’s and one 13BT and found identical issues with the coolers being clogged in all but one of the HDT’s (the only photo series I still have).
It is at this point I will STRONGLY SUGGEST that the oil coolers be opened, inspected and cleaned if needed ideally before any transplant. Not an easy job, but you can do it at home. The best benefit for HDT owners is a complete delete of the ACSD system. The new oil cooler cover, 15721-17012 eliminates the ACSD cooler spud and also includes provision for the oil filter drip cup. I will provide part numbers for conversion but just general details on the steps that should be followed in FSM.
1 each unless noted
15721-17012 late model 1HZ oil cooler cover
15725-17010 cooler cover gasket
15785-66010 gaskets cooler to cover need two (2)
91551-60820 short 6mm bolts for cover need two (2)
15674-17010 100 series oil filter cup (optional)
96411-42500 head freeze plug
90301-49003 injection pump O ring.
The kicker is the Injection pump must come off. Follow service manual and Ideally a smaller puller to pop the pump out of the timing cover. You will also need a plunge dial indicator (VW etc) to reset pump timing 1.35-1.40 without ACSD.
1) With the pump off there is easy access to the spud in head for water cooler for acsd. I use a fat round pry bar to get the water spud out and replace with plug 96411-42500 with Permatex Form-A-Gasket No. 1 Sealant or other freeze plug goo.
2) The original oil cooler cover comes off HDT’s with a majority of short bolts and four longer bolts. The new cover only takes two long bolts hence the need for two extra shorties. The cooler itself bolts in the cover with four 12mm nuts and the two 15785-66010. Just reverse of breakdown to reinstall. You will need to swap over the oil filter threaded bung, and two pressure mounts from old cover, and the temp sensor.
3) Reinstall and time the pump.
I have taken the coolers down to get hot tanked at machine shops but you can spend time manually cleaning them. The rust can be tenacious so take your time. The check valve and temp sensor easily swap over to new cover. The 10mm Allen head plugs do not need to be removed from the old cover and just can go to the recycler.
Again, I strongly suggest the oxalic acid wash following details online. Oxalic acid (AKA wood bleach in paint section ACE hardware) is mixed with hot water and introduced into empty cooling system. After 15 minutes at idle, rinse with distilled water and introduce baking powder mixed in distilled water to neutralize any remaining oxalic acid. Rinse once more with distilled water. Add new coolant and go.
#99-06-02-012D - Rust in Cooling System, Heater Inoperative, Blows Cold Air, Engine Overheats (Flush Cooling System) - (Apr 9, 2002)
A little history
In 2006 I transplanted a JDM 1HDT sourced engine in a BJ74 and drove it for 65,000 miles with a few issues along the way. No severe breakdowns until 2010 and then 2015 when I broke a ring. The transplant in 2006 included new radiator with and regular green coolant. In 2010, I was taking kids out of town for 2 week trip and 100 miles out of town I went from nothing to overheating in seconds. Gauge pegged from operating temp. After cooling for 30 minutes I made it 10 miles and I had a mechanic do an emergency fluid exchange, then drove to another open lot and did a second. Limping back to Tucson, I ran with full heater on (100 degree daytime temps) and stopped 4 x getting back to cool truck off. After vacation I did an oxalic acid/baking powder wash and replaced the radiator. All seemed well until I swapped frames on truck and cracked the ring. In tear down I found that the oil cooler was clogged with rusty paste and had thrown rust clots again into the radiator, heater cores, and hoses but had not yet obstructed the flow. The head also was cracked. I have taken down five 1HDT’s and one 13BT and found identical issues with the coolers being clogged in all but one of the HDT’s (the only photo series I still have).
It is at this point I will STRONGLY SUGGEST that the oil coolers be opened, inspected and cleaned if needed ideally before any transplant. Not an easy job, but you can do it at home. The best benefit for HDT owners is a complete delete of the ACSD system. The new oil cooler cover, 15721-17012 eliminates the ACSD cooler spud and also includes provision for the oil filter drip cup. I will provide part numbers for conversion but just general details on the steps that should be followed in FSM.
1 each unless noted
15721-17012 late model 1HZ oil cooler cover
15725-17010 cooler cover gasket
15785-66010 gaskets cooler to cover need two (2)
91551-60820 short 6mm bolts for cover need two (2)
15674-17010 100 series oil filter cup (optional)
96411-42500 head freeze plug
90301-49003 injection pump O ring.
The kicker is the Injection pump must come off. Follow service manual and Ideally a smaller puller to pop the pump out of the timing cover. You will also need a plunge dial indicator (VW etc) to reset pump timing 1.35-1.40 without ACSD.
1) With the pump off there is easy access to the spud in head for water cooler for acsd. I use a fat round pry bar to get the water spud out and replace with plug 96411-42500 with Permatex Form-A-Gasket No. 1 Sealant or other freeze plug goo.
2) The original oil cooler cover comes off HDT’s with a majority of short bolts and four longer bolts. The new cover only takes two long bolts hence the need for two extra shorties. The cooler itself bolts in the cover with four 12mm nuts and the two 15785-66010. Just reverse of breakdown to reinstall. You will need to swap over the oil filter threaded bung, and two pressure mounts from old cover, and the temp sensor.
3) Reinstall and time the pump.
I have taken the coolers down to get hot tanked at machine shops but you can spend time manually cleaning them. The rust can be tenacious so take your time. The check valve and temp sensor easily swap over to new cover. The 10mm Allen head plugs do not need to be removed from the old cover and just can go to the recycler.
Again, I strongly suggest the oxalic acid wash following details online. Oxalic acid (AKA wood bleach in paint section ACE hardware) is mixed with hot water and introduced into empty cooling system. After 15 minutes at idle, rinse with distilled water and introduce baking powder mixed in distilled water to neutralize any remaining oxalic acid. Rinse once more with distilled water. Add new coolant and go.
#99-06-02-012D - Rust in Cooling System, Heater Inoperative, Blows Cold Air, Engine Overheats (Flush Cooling System) - (Apr 9, 2002)
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