A few thoughts on a 1KZTE engine rebuild using a Toyota genuine short block. All relate to a 1994 KZJ78W Prado.
I started this saga as a consequence of the dreaded cracked head syndrome. On removing the engine I discovered that not only was the head very obviously cracked on three cylinders but that I had come very close to total engine melt down. All of the bores were scored and the big ends had all been “wiped” but hadn’t picked up. A new head and bottom end rebuild was clearly on the cards but just to tick a box I asked our local Toyota dealer what a short block would cost. They came back with a really good price and so I decided on that thinking it would be quicker...
There have been a few issues:
All part numbers are Toyota OE ones.
I took the head off in the car. With the benefit of hindsight I think that taking the whole engine out is probably easier unless you have tentacles. Take lots of pictures before you dissemble, vacuum hoses can be a swine to figure out. Be careful to separate the torque converter from the flex plate before the engine comes out very far. If you don’t there will be oil all over the floor and you risk damaging the transmission oil seal.
There is a water feed union in the head that goes to the throttle body. It is a press fit and cannot be re-used. For the new head you will need to buy a screw in one: (part # 9040452004).
There are two types of head, one has longer valves than the other. From researching forums like this one it appears that as a complete assembly they are interchangeable but don't try to fit long valves into a short valve one. New short valve head is part # 1110169128. As far as I know they can't be distinguished externally but you can tell when they are off. The short valve has the valves sitting in small pockets in the head but in the long valve version they are flush.
The diesel return union rail on the injectors can easily be damaged unless you take the inlet manifold off first and then stop the injectors from turning with a spanner before undoing the lock nuts on the injectors. I found this out the hard way.
There is a tiny packet in the box with the new block containing a small brass plug with a hole in it and a small core plug. What's that for? The brass plug is the restrictor for the oil supply to the head and goes into the oil feed gallery at the back of the block. Leave it out and you'll have low oil pressure. It is a rattling good fit so if you turn the engine over without the head on watch that it doesn’t fall on the floor. The small core plug is to block whichever dip stick hole you don’t use, there's one on both sides.
The short block is obviously designed to be generic. The turbo water feed pipe is a press fit and cannot be removed, you will need to buy a new one (part # 9040510044).
The new short block block (part # 1140067041) has larger reinforcing webs at the rear of the sump and a different bolt arrangement for the two bracing members that fit between the transmission and block. Toyota wasn’t able to say what was supposed to done about this so I ended up cutting mine to fit. This means that there is now only one bolt fixing per side instead of two. I reckon this will be OK because a) the block is a lot stronger now in this area and b) because I don’t intend to ramp over any sand dunes.
The short block is very short – pistons, rods, crank and block only so if going this route the rest of your engine needs to be in good shape. Buy lots of parts cleaner because you are going to need it!
The idler gear which sits between the crank and the injector pump drive gears sits on a pedestal that in my engine was secured by two 8mm bolts. Apparently in early 1995 this was re-engineered because of some failures so it doesn’t fit the new block. You will need a new pedestal (part# 1358167041), thrust washer (part # 1357267041) and bolts (part # 9010510398) as the new ones are 10mm and the pedestal and thrust washer are changed accordingly. Don’t be tempted to make a plan because if the thing fails it makes a huge mess. There is a dimple on the new thrust washer which faces out and goes below the top bolt. Don’t know why that’s important but that’s what the manual says. Before you remove the idler gear remember to lock it up with a 6mm bolt if you aren't planning on inspecting its internals and even more importantly remember to remove it before you try to fit the front casing.
As an observation that’s maybe obvious but still needs to be made if you are disorganised like me try to order everything at once because there can be significant delays. For example Mr Toyota only had the pedestal and one of the bolts in stock here in NZ despite there being approximately 1 billion 1KZ's here. The other stuff had to come from Japan which took weeks so I got it from Aus.
Yes the crank pulley is torqued up to that ridiculous number. Most of us don’t have a torque wrench that size or a torque multiplier so I did mine up to the maximum my torque wrench offers (210Nm) then got out my 3/4 drive power bar, put a piece of pipe on the end and pulled as hard as I could. Hope it works......
When you come to putting the thing back in the car take some time to get the engine to hang squarely. Mr Toyota's handy head hooks didn’t do that for me and caused no end of grief because there isn’t much wiggle room. Make sure that you remember to attach the earth lead on the back of the block before you get the engine all the way in. You'll regret it if you don’t! Many of the tranny to engine fixing bolts are best tightened (or loosened) by using some long half inch extensions joined together and a universal joint so that the ratchet is near the back of the gearbox. Take the transmission dip stick off or it gets in the way. There is a joint towards the bottom and a bracket onto the transmission. If you don't it gets in the way big time and bends. I put a scissors jack between the transmission oil pan and the anti roll bar that was very helpful in adjusting the angle of dangle for refitting and supporting the tranny whilst the engine was out. Make sure that the torque converter is pushed all the way in before you put the engine in as otherwise it can hang up and cause problems. Also get at least one bolt in on the flex plate before the engine is fully home so that you can rotate the torque converter relative to the flex plate with a stubby screwdriver. There is no way to turn it when the engine is fully home so if the bolt holes don’t line up at that point you'll not be a happy bunny.
There are a number of O rings around the timing gear train, front cover etc that will need to be replaced. Get a good manual and check where they are because they ain't easy to get at afterwards and have a talent for falling off when you try to install the covers over them.
The engine overhaul set (part # 0411167023) doesn’t include O rings for the vacuum pump, power steering pump and turbo to exhaust manifold gasket. You'll need to buy these separately. Apparently Mr Toyota can rebuild an engine without taking these things off.
I had lower than normal oil pressure for some time before this rebuild and consequently had replaced the pressure relief valve spring, big end bearings and thermostat hoping for a cure. I now suspect the idler gear mentioned above. The original thrust washer was quite worn and the gear had clearly been running at a slight angle. I suspect that it was just enough to bleed 4 or 5 psi of oil pressure off.
There is lots and lots of stuff about the overheating head cracking ways of this engine on this and other forums so I won't waste space pulling that one to bits. However what makes the most sense to me is the discussion around the siting of the thermostat. My personal “fix” has been to fit the 71 degree thermostat (part # 9091603121), refill the fan viscous coupling and to fit a EGT gauge. Here's hoping.....
I started this saga as a consequence of the dreaded cracked head syndrome. On removing the engine I discovered that not only was the head very obviously cracked on three cylinders but that I had come very close to total engine melt down. All of the bores were scored and the big ends had all been “wiped” but hadn’t picked up. A new head and bottom end rebuild was clearly on the cards but just to tick a box I asked our local Toyota dealer what a short block would cost. They came back with a really good price and so I decided on that thinking it would be quicker...
There have been a few issues:
All part numbers are Toyota OE ones.
I took the head off in the car. With the benefit of hindsight I think that taking the whole engine out is probably easier unless you have tentacles. Take lots of pictures before you dissemble, vacuum hoses can be a swine to figure out. Be careful to separate the torque converter from the flex plate before the engine comes out very far. If you don’t there will be oil all over the floor and you risk damaging the transmission oil seal.
There is a water feed union in the head that goes to the throttle body. It is a press fit and cannot be re-used. For the new head you will need to buy a screw in one: (part # 9040452004).
There are two types of head, one has longer valves than the other. From researching forums like this one it appears that as a complete assembly they are interchangeable but don't try to fit long valves into a short valve one. New short valve head is part # 1110169128. As far as I know they can't be distinguished externally but you can tell when they are off. The short valve has the valves sitting in small pockets in the head but in the long valve version they are flush.
The diesel return union rail on the injectors can easily be damaged unless you take the inlet manifold off first and then stop the injectors from turning with a spanner before undoing the lock nuts on the injectors. I found this out the hard way.
There is a tiny packet in the box with the new block containing a small brass plug with a hole in it and a small core plug. What's that for? The brass plug is the restrictor for the oil supply to the head and goes into the oil feed gallery at the back of the block. Leave it out and you'll have low oil pressure. It is a rattling good fit so if you turn the engine over without the head on watch that it doesn’t fall on the floor. The small core plug is to block whichever dip stick hole you don’t use, there's one on both sides.
The short block is obviously designed to be generic. The turbo water feed pipe is a press fit and cannot be removed, you will need to buy a new one (part # 9040510044).
The new short block block (part # 1140067041) has larger reinforcing webs at the rear of the sump and a different bolt arrangement for the two bracing members that fit between the transmission and block. Toyota wasn’t able to say what was supposed to done about this so I ended up cutting mine to fit. This means that there is now only one bolt fixing per side instead of two. I reckon this will be OK because a) the block is a lot stronger now in this area and b) because I don’t intend to ramp over any sand dunes.
The short block is very short – pistons, rods, crank and block only so if going this route the rest of your engine needs to be in good shape. Buy lots of parts cleaner because you are going to need it!
The idler gear which sits between the crank and the injector pump drive gears sits on a pedestal that in my engine was secured by two 8mm bolts. Apparently in early 1995 this was re-engineered because of some failures so it doesn’t fit the new block. You will need a new pedestal (part# 1358167041), thrust washer (part # 1357267041) and bolts (part # 9010510398) as the new ones are 10mm and the pedestal and thrust washer are changed accordingly. Don’t be tempted to make a plan because if the thing fails it makes a huge mess. There is a dimple on the new thrust washer which faces out and goes below the top bolt. Don’t know why that’s important but that’s what the manual says. Before you remove the idler gear remember to lock it up with a 6mm bolt if you aren't planning on inspecting its internals and even more importantly remember to remove it before you try to fit the front casing.
As an observation that’s maybe obvious but still needs to be made if you are disorganised like me try to order everything at once because there can be significant delays. For example Mr Toyota only had the pedestal and one of the bolts in stock here in NZ despite there being approximately 1 billion 1KZ's here. The other stuff had to come from Japan which took weeks so I got it from Aus.
Yes the crank pulley is torqued up to that ridiculous number. Most of us don’t have a torque wrench that size or a torque multiplier so I did mine up to the maximum my torque wrench offers (210Nm) then got out my 3/4 drive power bar, put a piece of pipe on the end and pulled as hard as I could. Hope it works......
When you come to putting the thing back in the car take some time to get the engine to hang squarely. Mr Toyota's handy head hooks didn’t do that for me and caused no end of grief because there isn’t much wiggle room. Make sure that you remember to attach the earth lead on the back of the block before you get the engine all the way in. You'll regret it if you don’t! Many of the tranny to engine fixing bolts are best tightened (or loosened) by using some long half inch extensions joined together and a universal joint so that the ratchet is near the back of the gearbox. Take the transmission dip stick off or it gets in the way. There is a joint towards the bottom and a bracket onto the transmission. If you don't it gets in the way big time and bends. I put a scissors jack between the transmission oil pan and the anti roll bar that was very helpful in adjusting the angle of dangle for refitting and supporting the tranny whilst the engine was out. Make sure that the torque converter is pushed all the way in before you put the engine in as otherwise it can hang up and cause problems. Also get at least one bolt in on the flex plate before the engine is fully home so that you can rotate the torque converter relative to the flex plate with a stubby screwdriver. There is no way to turn it when the engine is fully home so if the bolt holes don’t line up at that point you'll not be a happy bunny.
There are a number of O rings around the timing gear train, front cover etc that will need to be replaced. Get a good manual and check where they are because they ain't easy to get at afterwards and have a talent for falling off when you try to install the covers over them.
The engine overhaul set (part # 0411167023) doesn’t include O rings for the vacuum pump, power steering pump and turbo to exhaust manifold gasket. You'll need to buy these separately. Apparently Mr Toyota can rebuild an engine without taking these things off.
I had lower than normal oil pressure for some time before this rebuild and consequently had replaced the pressure relief valve spring, big end bearings and thermostat hoping for a cure. I now suspect the idler gear mentioned above. The original thrust washer was quite worn and the gear had clearly been running at a slight angle. I suspect that it was just enough to bleed 4 or 5 psi of oil pressure off.
There is lots and lots of stuff about the overheating head cracking ways of this engine on this and other forums so I won't waste space pulling that one to bits. However what makes the most sense to me is the discussion around the siting of the thermostat. My personal “fix” has been to fit the 71 degree thermostat (part # 9091603121), refill the fan viscous coupling and to fit a EGT gauge. Here's hoping.....
