Prado 120 Diesel Engine Rebuild? Please give lots of advice





Results 1 to 19 of 19
  1. #1
    Join Date
    Apr 2009
    Location
    Randburg
    Age
    52
    Posts
    26
    Thanked: 0

    Question Prado 120 Diesel Engine Rebuild? Please give lots of advice

    So, my beloved 2004 Prado 120 Diesel (KZ-TE) GX has finally decided she needs some serious attention, after 194 000 kms.

    Leaving Villiers yesterday, she overheated. I let her cool down a bit, added some water, checked the oil, and all seemed to be fine. I took it easy on the way home, and got some heavy rain from De Hoek all the way to Randburg. She never gave any indication of having a problem. Temperature steady on the normal mark, as she always did. No loss of power, even with the off-road trailer hitched to the back.

    This morning, I wanted to start her to see if I could notice any abnormal smoking or anything, and... nothing. The engine is rock solid. The starter kicks in, but the engine is not turning even a little bit. Check the water level - absolutely empty. I knew I should have fitted that EGT sensor.

    So, I guess that's that. Bearings ceased solid. Engine rebuild coming my way. Unless I am wrong?

    Now here are the big questions:

    1. Rebuild, or second hand engine? Can you still get second hand KZ-TE's? What would the costs be?

    2. Who to trust with this job? SAC? or does someone know of a good place in Randburg? Or do I tackle it myself? That is a big motor to pull in my garage...

    3. The only thing that I would change on my Prado, if I could, would be the fuel consumption, so what are the chances of replacing the motor with a D4D? I know that the D4D was used in some of the last 120's sold in the Middle East, but never locally.
    Last edited by Rudolfs; 2014/12/01 at 07:02 PM.

  2. #2
    Join Date
    Oct 2010
    Location
    Windhoek
    Age
    60
    Posts
    1,743
    Thanked: 110

    Default

    Give that engine a break. I think it is nowhere as serious as you want it to be. Most probably a hydraulic lock - the coolant water is trapped on top of the piston. Unscrew the injectors or glow plugs and turn the engine by hand to allow the water to blow out.

    Triton DC, Jimny and K1200GT scooter.

  3. #3
    Join Date
    Apr 2009
    Location
    Randburg
    Age
    52
    Posts
    26
    Thanked: 0

    Default

    Hi Kobus,

    Thanks for this bit of optimism. I will try that first. How would the water have gotten in there? Blown top Gasket? Would this then also be the reason for the overheating in the first place?

  4. #4
    Join Date
    Oct 2010
    Location
    Windhoek
    Age
    60
    Posts
    1,743
    Thanked: 110

    Default

    With overheating, the top gasket usually goes. As long as the engine is running, the compression keeps the water out of the combustion chamber. This is where you see bubbling in the radiator when you open it. As soon as you stop the engine, the water makes it's way into the cylinder and over a period of time it will by-pass the piston rings to the sump.

    If you want to re-start the engine, two things can happen. Firstly, you have enough water on top of the piston to prevent the engine from turning - lucky you. Secondly, you have a little bit of water on the cylinder and the starter starts swinging the engine and then abruptly stops when the water blocks it - bad news since it can bend connecting rods.

    The cause of overheating can be due to numerous reasons. I am no Toyota expert but recall something about KZ cylinder heads cracking. Could be due to a crack or any other reason which caused a loss of cooling water with the resultant overheating. The bad news is that once you have lost your cooling water, the temp probe will not register a temp rise since the probe is not covered by water anymore. That is why so many people do not realise that the engine is overheating before it is too late.

    Let an expert strip the cylinder head off, test the head for cracks and warping. They will then inspect the cylinder bores also for wear and other damage. Engines can take a lot of abuse before a bottom end overhaul is needed. I doubt if your engine will need an overhaul with 190k km. Way too soon for those diesels.

    Triton DC, Jimny and K1200GT scooter.

  5. #5
    Join Date
    Mar 2008
    Location
    De Wildt
    Age
    57
    Posts
    35,144
    Thanked: 10243

    Default

    Hydraulic lock is also my guess.

    Import low kilo KZ-TE engines are available. Quickest and cheapest option, but the heads are the weak point.

    If your head is cracked, (common issue), fit an AMC head. About R12k.
    2012 Jeep Sahara Unlimited 3.6 V6
    Percivamus

  6. #6
    Join Date
    Feb 2013
    Location
    Doornlaagte, Rustenburg
    Age
    53
    Posts
    136
    Thanked: 0

    Default

    I had the same issue, started her up yesterday. Head was cracked properly!!!

    I did a swap with a new complete head with gaskets and new top bolts for under R11 000, just remove and replace, easy.

    Took some time after hours and a bit of "bloed en vloek", but everything 100%!!
    * '03 Prado 120 3.0 diesel
    Iron Man suspension
    Snorkel, DIY fitted
    LED light bar
    ARB bumper (almost black...)
    Custom 63mm exhaust
    Charging thing for...
    * '11 Oryx campervaantjie
    C-Tec DC-DC charger

  7. #7
    Join Date
    Feb 2013
    Location
    Doornlaagte, Rustenburg
    Age
    53
    Posts
    136
    Thanked: 0

    Default

    O ja, a D4D transplant will set you back 75 000, quotes from all over, tried everywhere, even private "boffins".
    * '03 Prado 120 3.0 diesel
    Iron Man suspension
    Snorkel, DIY fitted
    LED light bar
    ARB bumper (almost black...)
    Custom 63mm exhaust
    Charging thing for...
    * '11 Oryx campervaantjie
    C-Tec DC-DC charger

  8. #8
    Join Date
    Apr 2009
    Location
    Randburg
    Age
    52
    Posts
    26
    Thanked: 0

    Default

    Eina, That's heavy for a D4D. And then you have the potential for expensive injector issues at some point.

    In the process of pulling the top. Let's find out...

  9. #9
    Join Date
    Mar 2008
    Location
    De Wildt
    Age
    57
    Posts
    35,144
    Thanked: 10243

    Default

    Quote Originally Posted by Beestekruger View Post
    O ja, a D4D transplant will set you back 75 000, quotes from all over, tried everywhere, even private "boffins".
    Too much work yes. Electronics are just the start. Fuel lines and pumps would be next.

    Rather get a proper intercooler (thread is here http://www.4x4community.co.za/forum/...0&goto=newpost )

    Then get a VNT turbo, an EGT gauge and tweak the pump until you're happy.

    If the head is replaced with AMC, the engine will handle the power.
    2012 Jeep Sahara Unlimited 3.6 V6
    Percivamus

  10. #10
    Join Date
    Apr 2007
    Location
    Nigel
    Age
    58
    Posts
    15,812
    Thanked: 2078

    Default

    I would also guess an hydraulic lock.

    My suggestions.
    Replace
    Head
    Injector tips
    Radiator
    Waterpump
    Thermostat (Fit the 76degC unit)

    If you can, do as suggested. Fit a Variable vane turbo. Also at least a 76mm exhaust pipe.

    Also fit a EGT gauge. ASAP.
    That block is a brilliant block. It will give you plenty more miles.
    LC 78 Troopie 1HD-FTE
    Uniglide
    +27 zero eight 2 four 95 9252

  11. #11
    Join Date
    Apr 2009
    Location
    Randburg
    Age
    52
    Posts
    26
    Thanked: 0

    Default

    Hi Henris & Jelo

    I understand the egt sensor and larger intercooler, but what would the larger exhaust's function be? Better outflow from the turbo? Less backpressure?
    And the v v turbo. Does it reduce turbo lag? This is quite a big problem on the standard turbo. Pretty much dead at less than 2000 rpm. Would it also give higher input pressures?
    Lastly, can a larger ic be fitted in the horisontal position of the Prado's ic? Or would it need to be vertical at the front with the other radiators?
    Rudolf
    "..and I,
    I took the one less traveled by.." (Robert Frost)

    Prado 120 3.0 Diesel GX 2004 (My Baby)
    NL Dual Battery
    EFS Suspension (50mm Lift)
    Rear Airbags
    Stofpad Bash Plate
    African Outback Roofrack
    (EGT monitor coming soon!)

    Jeep GC 2.7 Laredo 2003 (Junior's troublesome toy)
    Stock

  12. #12
    Join Date
    Apr 2009
    Location
    Randburg
    Age
    52
    Posts
    26
    Thanked: 0

    Default

    And then, what would the overall aim of these mods be? More power, hence better fuel economy, or to have the engine run cooler, last longer?
    Rudolf
    "..and I,
    I took the one less traveled by.." (Robert Frost)

    Prado 120 3.0 Diesel GX 2004 (My Baby)
    NL Dual Battery
    EFS Suspension (50mm Lift)
    Rear Airbags
    Stofpad Bash Plate
    African Outback Roofrack
    (EGT monitor coming soon!)

    Jeep GC 2.7 Laredo 2003 (Junior's troublesome toy)
    Stock

  13. #13
    Join Date
    Apr 2007
    Location
    Nigel
    Age
    58
    Posts
    15,812
    Thanked: 2078

    Default

    The VV turbo just gives better power spread.

    Bigger bore xhaust gives faster turbo response and gets rid of the back pressure. Thus reducing the heat.
    LC 78 Troopie 1HD-FTE
    Uniglide
    +27 zero eight 2 four 95 9252

  14. #14
    Join Date
    Mar 2008
    Location
    De Wildt
    Age
    57
    Posts
    35,144
    Thanked: 10243

    Default

    "I understand the egt sensor and larger intercooler, but what would the larger exhaust's function be? Better outflow from the turbo? Less backpressure?
    And the v v turbo. Does it reduce turbo lag? This is quite a big problem on the standard turbo. Pretty much dead at less than 2000 rpm. Would it also give higher input pressures?
    Lastly, can a larger ic be fitted in the horisontal position of the Prado's ic? Or would it need to be vertical at the front with the other radiators?

    And then, what would the overall aim of these mods be? More power, hence better fuel economy, or to have the engine run cooler, last longer? "

    Larger exhaust: faster gas speed out of the exhaust due to less back-pressure. You don't need back pressure on a TD.

    VVT/VNT: broader spread of power due to variable vanes/nozzles. Less turbo lag, longer power delivery. Traditionally turbos that spool up fast, hit full boost sooner and then cavitate and are restricted from overspooling by the waste-gate. Turbos that spool up slower have huge lag. A variable delivery turbo is the way to reduce both issues. You get power across the rev range, and by matching the impeller to the compressor side you also get better power.

    Can't say about the IC, I don't know the LC layout.

    Input = output, so by running a TD lean or close to perfect air/fuel mix at all revs, you reduce EGTs.
    By reducing the compressed air temps, you reduce EGTs.
    By getting the exhaust gasses out faster, you reduce residual temps on the turbo housing hence less EGTs.
    2012 Jeep Sahara Unlimited 3.6 V6
    Percivamus

  15. #15
    Join Date
    Apr 2008
    Location
    Irene, Pretoria
    Age
    58
    Posts
    324
    Thanked: 49

    Default

    Question on this topic: I have had an EGT fitted soon after I bought the Prado and it definitely gives some peace of mind. It's alarm is set at 700 degC & has (luckily) never breached this temp.
    Will it peep as soon as there is a loss of water?
    I recently bought a caravan and will be towing to KNP in the next 2 weeks. Just want to make sure I do not overheat the engine.
    '15 Prado 4.0 VX
    '18 Echo Chobe

  16. #16
    Join Date
    Apr 2009
    Location
    Randburg
    Age
    52
    Posts
    26
    Thanked: 0

    Default

    The Prado is running again!

    You were all correct in diagnosing hydraulic lock. Turned out top gasket had blown, and top cracked in a few places.

    So:

    Replaced the complete head with the AMC one, with gaskets etc.
    Replaced the innards of the turbo.
    Replaced glo plugs.
    Replaced injector nozzles.
    Replaced thermostat and coolant.
    Also did the cambelt and idler pullies while it was all open.
    Also did normal service with fuel, oil and air filter, and engine oil change.

    Now the Prado runs beautifully. Fuel consumption is a LOT less than before. Avg 13.5 as opposed to 15.7 before.

    Unfortunately I was pressed for time, and could not source the variable vain turbo or the egt sensor. I will keep that as options for the future.

    I do have a few niggles, though.

    1. It seems to have less power than before. Have to gear down sooner on a serious uphill, battles a bit more in thick sand, and needs an even longer stretch to overtake than before.
    2. It is puffing quite a bit of black smoke when the engine is working hard. It never used to smoke before. I was always impressed with how clean the KZ-TE diesel runs.

    Any ideas? Does it just need a good tuning?

    3. Which EGT sensor and where to source it?
    Rudolf
    "..and I,
    I took the one less traveled by.." (Robert Frost)

    Prado 120 3.0 Diesel GX 2004 (My Baby)
    NL Dual Battery
    EFS Suspension (50mm Lift)
    Rear Airbags
    Stofpad Bash Plate
    African Outback Roofrack
    (EGT monitor coming soon!)

    Jeep GC 2.7 Laredo 2003 (Junior's troublesome toy)
    Stock

  17. #17
    Join Date
    Aug 2010
    Location
    Durban
    Age
    46
    Posts
    75
    Thanked: 1

    Default

    Quote Originally Posted by Henris View Post
    The VV turbo just gives better power spread.

    Bigger bore xhaust gives faster turbo response and gets rid of the back pressure. Thus reducing the heat.
    I guess one could use the D4D vnt turbo....?

  18. #18
    Join Date
    Aug 2010
    Location
    Pretoria
    Age
    56
    Posts
    429
    Thanked: 47

    Default

    Couple of thoughts

    Did you have the diesel pump calibrated with the new nozzles??. It's usually a good idea, and could contribute to your power issue.

    Also check all your hoses and couplings to and from the turbo and the inter cooler are a. Secure, and b. Not collapsing under load, and choking the airflow.

    Secondly I would fit a full madman system to the car, same as the (shhh landrover guys) fit. Speak to Brian Cotton at madman it gives a lot more peace of mind than just an EGT gauge.

    Finally the bigger exhaust makes a difference however even if you just remove the huge drum silencer and fit a freeflow straight through in its place you will achieve a lot

    For the future, when I had mine I investigated the replacement with the D4D. It is a fairly straightforward bolt in. But you have to get the ECU and the matched keys for the ecu as well. The quote I got for a second hand motor with low mileage was R31k from g/tree.

    The D4d was used overseas just not in rsa, until later.

  19. #19
    Join Date
    Jan 2009
    Location
    Germiston
    Age
    38
    Posts
    3,787
    Thanked: 93

    Default

    Question regarding head gasket, on my isuzu i have noticed less power than an unopened one, although it has quite a bit of power its lacking. Now i have wondered and asked many guys, head gasket that was used was a victor reinz, very good and not having any hassles, but seems the non oem ones are a standard size(thick) to cater for pretty much any piston protrusion. Where as measuring and getting correct notch head gasket for your motor from toyota or whoever. i suspect my CR is lower and not getting the bang unopened ones gets. Im soon going to open mine, measure and replace with correct spec head gasket, then i will know. Pretty sure if i do a compression test i will see lower figures on mine.

    Any thoughts?

    Cheers
    Last edited by sweeper; 2015/01/01 at 11:00 AM.
    __________________
    '01 Isuzu Frontier LX 4x4 Diesel8) - For the brown Stuff
    '14 Renault Sandero 900cc Dynamique, small with a big heart

Similar Threads

  1. Replies: 5
    Last Post: 2016/09/26, 08:40 PM
  2. Advantage of a Diesel vehicle?
    By Krimpie in forum Mitsubishi
    Replies: 54
    Last Post: 2014/12/26, 12:05 PM
  3. New Generation 2012 spec Discovery 4
    By Koos Best in forum Land Rover
    Replies: 6
    Last Post: 2012/08/23, 10:46 PM
  4. NEw Isuzu beats new Yota offroad.
    By Bryan Webber in forum Isuzu
    Replies: 29
    Last Post: 2006/12/20, 09:31 PM

Tags for this Thread

Bookmarks

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •