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Thread: Sudden power loss- any ideas?

  1. #1
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    Sudden power loss- any ideas?

    I've had a series of disasters with my 1993 Vogue SE fitted with a 4.6 cross-bolted top-hatted engine - running dual fuel.

    First the bad joint between the oil cooler spigot and the internal tube failed (crap manufacturing) and dumped engine oil into the radiator. I replaced that radiator with a Chinese aluminium unit that lasted all of 20 km before that failed too - this time dumping transmission oil (not engine oil) into the coolant. Can I have damaged the transmission contributing to the problem outlined below?

    After a very thorough clean-out of the cooling system (but bypassing the new radiator to avoid contaminating it) with Liquid Intelligence cleaner, a very expensive re-manufactured copper/brass OEM unit has been installed. At first drive with the new radiator, the engine was trembling, lacked power and engine oil was leaking from the distributor seal so that has been replaced and I was assured the ignition timing is correct.

    Another test drive started well with plenty of power and acceleration, but when it got onto the expressway at higher speed, it started blowing blue smoke and power dropped right off. The mechanic decided to have the car towed rather than risk driving it. I'm told the engine starts but sounds as though it is missing on one or more cylinders.

    Obviously, the next job is to compression-test all cylinders and try to work out whether the rings and/or bearings have to be changed OR if it is just a head gasket that has failed. My dilemma is whether to spend another heap on rings, bearings, head gaskets etc without really knowing what is actually needed. If the heads have to come off anyway, it would probably be best to do the lot.

    Any suggestions are most welcome

  2. #2
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    Sell it

  3. #3
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    Quote Originally Posted by Mercguy View Post
    Sell it


    RANGE ROVER VOGUE 1993 SE – bargain at $7500

  4. #4
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    If a compression test reveals 1 or 2 adjacent cylinders are down then if removing that head reveals the cause being a blown head gasket or something wrong with the head then why go any further?
    MY12 RRV 4.4 TDV8 AB, +LLAMS, +e-diff, +ACC stop/go. Produce LLAMS for LR/RR, Jeep GC/Dodge Ram
    VK2HFG and APRS W1 digi

  5. #5
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    wouldn't a simple leak down test give you the answers you are after .... If it's just head gaskets .... Its not really a big issue.
    Proper cars--
    '92 Range Rover 3.8V8 ... 5spd manual
    '85 Series II CX2500 GTi Turbo I :burnrubber:
    '63 ID19 x 2 :wheelchair:
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    Modern Junk:
    '07 Poogoe 407 HDi 6spd manual :zzz:
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  6. #6
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    Sarcasm aside, pretty much everyone familiar with the buick/rover v8 is aware of the issues.

    What we know:

    you run dual fuel. *(this is a key contributor due to combustion temp differences and lubricative properties of the fuels.)

    You have had 2 radiators "fail" due to poor manufacturing. First time, the oil cooler capillary tube, and the second time, the transmission.

    You stated that you have cleaned out the engine cooling system with a proprietary cleaning product. *(note this may have been effective enough to highlight a deeper issue of corrosion)

    radiator #3 installed and engine "trembled". It also leaked oil at the distributor o-ring

    noting that the distributor oring had failed (no big deal, but makes a mess) distributor removed, oring was replaced distributor reinstalled and timing was checked.

    The vehicle was driven on a road, the engine continued to misbehave and power delivery was "down".

    Whether the power delivery was erratic or lacking entirely is not stated, but it was noted there was "blue" smoke.

    It is not stated whether the vehicle was running on LPG or Petrol or both for the tests or during this process. (makes a difference, twice as many things to look at)


    So, the blue smoke thing, that's an obvious incomplete combustion of oil-related issue - however, was that tailpipe emission checked and verified to actually be blue, or, instead, could it have been a bluish white, or a dark bluish grey - ???
    I mean, we're not told if this was a massive blue cloud or if it is just wisps of blue on full throttle... which could just as easily be unburnt fuel or fuel and oil.....

    So before racing off and ripping heads and all the other stuff, if the vehicle was running on petrol, check the purge valve isn't stuck open, and check all the vacuum hoses are properly connected and not leaking, cracked, broken or disconnected.

    Following on from that, yes, a compression test is an indication of individual cylinder pressures, and can guide you towards an obvious issue if there is a significant disparity between one or more cylinders from the rest. The key here is that if everything is within about 15% of each other, it's unlikely to be something 'damaged' - but if the pressures are below what is considered to be adequate, then you would have a couple of culprits to investigate....

    If the compression is markedly down Because you run dual fuel, you will more than likely have a more pronounced possibility of having multiple issues.

    1. valve guide wear
    2. valve seat wear
    3. piston ring wear
    4. possible burnt valves.

    Now, this is not the fault of LPG alone. But these are issues that come up in just about every engine fitted with LPG that was not initially designed or has been rebuilt with this specific fuel in mind.

    If the engine has hardened valve seats (stellite) and valves of an appropriate material (stellite tipped stainless or sodium filled exhaust valves at minimum) then the likelihood of there being a top-end issue is markedly reduced, as these materials are designed to work with a hot dry fuel like LPG.

    Valve guides - again, if the guides haven't been replaced, then there is possible potential for these to be excessively worn, due to the fuel combination useage.
    Valve guide stem seals - if the engine has been rebuilt within the last 20K, then these should have been replaced and the guides reamed/replaced along with valves as appropriate - especially if "lpg" was mentioned.

    The abovementioned are areas which can allow excessive oil to pass into the combustion chamber on the intake stroke, or onto the back of the exhaust valve, in the case of excessively worn exhaust valve guides and stem seals.

    This can contibute to the erratic running, and the "blue" smoke emission. However it is not the only contributor.

    Back to the compression:
    Obviously a poor cylinder seal will create compression issues / disparity.

    Contributors - worn rings / broken rings / piston ring land damage, stuck oil control rings or sealing ring, pinched etc.

    These are going to be more apparent in a compression test result. However, without a borescope, you're not going to be able to make a more educated guess, without taking the heads off.

    Okay, so that's a really generalized guide to the ovbious.

    Now some less obvious:

    Engine vacuum: You can very easily be pulling in oil vapour from PCV, if certain "things" aren't checked. This can cause misfires and blue smoke.... So check the PCV one-way valves, hoses and flame trap, check the plenum for any excessive oil and the idle air control solenoid for correct operation.

    A quick way to test leaks is on a running engine with a can of carby clean / maf sensor cleaner or brake cleaner, or in a workshop X55 / B1 and a pressure spray bottle.
    Run the vehicle on petrol when performing the test.

    Any leak will be noticed by an obvious rpm increase without interference to the throttle linkage.

    Check the LPG delivery for any leaks at the mixer and manifold. soapy water test....
    Check the LPG solenoid is not sticky or malfunctioning.

    Lastly, like all Rover v8's, You have been informed that the timing is correct. But, for the sake of the exercise, verify through one full combustion rotation (2 crank rotations) that the cam timing and distributor timing is OK.

    The reason I say this, is because by the time you get to this point in diagnosis, you're more than likely to have identified some cylinder pressure issues and be heading towards pulling heads.... So naturally, the radiator and water pump are 'automatically excluded' from further investigation, because the belief is that it is something more major.

    But here's the thing.

    If perchance you do have a head gasket issue - it is very easily checked. Rover v8's are known for the "steam cleaning" effect, where the cylinder liners allow water to pass into the combustion chamber when a head gasket fails.

    two obvious clues are most likely apparent when this happens....

    1. the piston crown / valves / spark plug look ABSOLUTELY cleaner than the rest of the cylinders (unless they all went out together)
    2. there will be dissolved combustion gasses present in the cooling system.

    There is a cheap, quick easy test to confirm that combustion gases are present in the cooling system - aka "Tee-Kay head check" which is a coolant sampling test kit. similar to a pool chlorine / pH test kit, uses a colour change to indicate combustion gases in coolant.

    If you have them, then obviously it is a confirmed issue - pull the heads, do the gaskets, look for any other problems, fix as necessary...


    But, being a 4.6, There are matters which complicate, and they are not always paletable.

    1. Liners. If youve had the steam clean of death, or about to do heads, then unless funds do not extend far, budget for block out and machining for stepped liners, if they haven't been done.

    2. LPG - if you're running LPG, why not consider ditching the petrol completely, and rebuild for straight LPG use (a cam, head components, HPC coated piston crown / skirt / underside), which will net you power gains and some fuel efficiency gains.

    Consider that if you're going to the trouble of overhauling a 4.6, that you increase the displacement, and change the cam to a profile that suits your application better - I.e. if you're towing, you would prefer a profile that delivers more torque down low, than a top-end screamer.

    Needless to say, all of these possibilities exist if you feel comitted to pulling down the engine. But the suggestion is to first just confirm everything - because an overhaul isn't just about the block and head gaskets.... You also have all the ancillary stuff to recondition too - and replacing stuff like temp senders and thermostats, water pumps, injector overhaul/clean/replace..... so costs absolutely DO escalate when you do a proper full recondition.

    And that leaves me to the last overlooked issue. The electrics. Now, I know it hasn't been mentioned, but always check the distributor module, the coil, and the hall sensor for operation. Check the wiring to the coil and the airflow meter and make sure that is it clean and serviceable. If the wiring insulation is hard, or cracking, replace it.

    The key is simply to check everything thoroughly before jumping in at the deep end and pulling the engine out. Because you absolutely do not want to discover that your rebuild was unnecessary and the cause of the issue was something unrelated.

    It happens.

    I'm sure there will be someone who will provide a detail I have overlooked, but understand the general principle is to check first, before comitting to the full monty.

  7. #7
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    Thank you for your very detailed response and NO I am not going to sell this vehicle unless the repair costs look like something very major indeed - like a cracked block but that's looking increasingly unlikely. Please see my comments inserted below:

    Quote Originally Posted by Mercguy View Post
    Sarcasm aside, pretty much everyone familiar with the buick/rover v8 is aware of the issues.

    You stated that you have cleaned out the engine cooling system with a proprietary cleaning product. *(note this may have been effective enough to highlight a deeper issue of corrosion)

    Agree

    Whether the power delivery was erratic or lacking entirely is not stated, but it was noted there was "blue" smoke. It is not stated whether the vehicle was running on LPG or Petrol or both for the tests or during this process. (makes a difference, twice as many things to look at)

    It was not me driving so can't be sure of the answers but I'm told it was run on both LPG and petrol and initially it seems the have plenty of power, then lost power fairly quickly. I do not know how much smoke was being emitted but I'll ask

    So, the blue smoke thing, that's an obvious incomplete combustion of oil-related issue - however, was that tailpipe emission checked and verified to actually be blue, or, instead, could it have been a bluish white, or a dark bluish grey - ???
    I mean, we're not told if this was a massive blue cloud or if it is just wisps of blue on full throttle... which could just as easily be unburnt fuel or fuel and oil.....

    Ditto

    So before racing off and ripping heads and all the other stuff, if the vehicle was running on petrol, check the purge valve isn't stuck open, and check all the vacuum hoses are properly connected and not leaking, cracked, broken or disconnected.

    Good advice - I'll be sure to ask the mechanic to do this

    Following on from that, yes, a compression test is an indication of individual cylinder pressures, and can guide you towards an obvious issue if there is a significant disparity between one or more cylinders from the rest. The key here is that if everything is within about 15% of each other, it's unlikely to be something 'damaged' - but if the pressures are below what is considered to be adequate, then you would have a couple of culprits to investigate.... If the compression is markedly down Because you run dual fuel, you will more than likely have a more pronounced possibility of having multiple issues.

    1. valve guide wear
    2. valve seat wear
    3. piston ring wear
    4. possible burnt valves.

    Agree - the last two seem more likely - especially an oil ring damaged by the radiator event

    Now, this is not the fault of LPG alone. But these are issues that come up in just about every engine fitted with LPG that was not initially designed or has been rebuilt with this specific fuel in mind.

    If the engine has hardened valve seats (stellite) and valves of an appropriate material (stellite tipped stainless or sodium filled exhaust valves at minimum) then the likelihood of there being a top-end issue is markedly reduced, as these materials are designed to work with a hot dry fuel like LPG. Valve guides - again, if the guides haven't been replaced, then there is possible potential for these to be excessively worn, due to the fuel combination useage. Valve guide stem seals - if the engine has been rebuilt within the last 20K, then these should have been replaced and the guides reamed/replaced along with valves as appropriate - especially if "lpg" was mentioned.

    Probably not relevant because the 4.6 conversion was done 8 years ago and has worked impeccably until this recent event. Also, looking at the expense log, it seems the LPG work had already been done before that
    The above mentioned are areas which can allow excessive oil to pass into the combustion chamber on the intake stroke, or onto the back of the exhaust valve, in the case of excessively worn exhaust valve guides and stem seals.
    This can contribute to the erratic running, and the "blue" smoke emission.

    Will have a better idea once the compression test has been done, but unless the problem turns out to be something very obvious, the heads will have to come off at a minimum

    Back to the compression:
    Obviously a poor cylinder seal will create compression issues / disparity.

    Contributors - worn rings / broken rings / piston ring land damage, stuck oil control rings or sealing ring, pinched etc.

    These are going to be more apparent in a compression test result. However, without a borescope, you're not going to be able to make a more educated guess, without taking the heads off.

    Okay, so that's a really generalized guide to the obvious.

    Now some less obvious:

    Engine vacuum: You can very easily be pulling in oil vapour from PCV, if certain "things" aren't checked. This can cause misfires and blue smoke.... So check the PCV one-way valves, hoses and flame trap, check the plenum for any excessive oil and the idle air control solenoid for correct operation.

    A quick way to test leaks is on a running engine with a can of carby clean / maf sensor cleaner or brake cleaner, or in a workshop X55 / B1 and a pressure spray bottle.
    Run the vehicle on petrol when performing the test.

    Any leak will be noticed by an obvious rpm increase without interference to the throttle linkage.

    Check the LPG delivery for any leaks at the mixer and manifold. soapy water test....
    Check the LPG solenoid is not sticky or malfunctioning.

    Lastly, like all Rover v8's, You have been informed that the timing is correct. But, for the sake of the exercise, verify through one full combustion rotation (2 crank rotations) that the cam timing and distributor timing is OK.

    The reason I say this, is because by the time you get to this point in diagnosis, you're more than likely to have identified some cylinder pressure issues and be heading towards pulling heads.... So naturally, the radiator and water pump are 'automatically excluded' from further investigation, because the belief is that it is something more major.

    But here's the thing.

    If perchance you do have a head gasket issue - it is very easily checked. Rover v8's are known for the "steam cleaning" effect, where the cylinder liners allow water to pass into the combustion chamber when a head gasket fails.

    two obvious clues are most likely apparent when this happens....

    1. the piston crown / valves / spark plug look ABSOLUTELY cleaner than the rest of the cylinders (unless they all went out together)
    2. there will be dissolved combustion gasses present in the cooling system.

    There is a cheap, quick easy test to confirm that combustion gases are present in the cooling system - aka "Tee-Kay head check" which is a coolant sampling test kit. similar to a pool chlorine / pH test kit, uses a colour change to indicate combustion gases in coolant.

    This HAS been done within the last few days and there was NO evidence of any problem

    If you have them, then obviously it is a confirmed issue - pull the heads, do the gaskets, look for any other problems, fix as necessary...




    1. Liners. If youve had the steam clean of death, or about to do heads, then unless funds do not extend far, budget for block out and machining for stepped liners, if they haven't been done.

    2. LPG - if you're running LPG, why not consider ditching the petrol completely, and rebuild for straight LPG use (a cam, head components, HPC coated piston crown / skirt / underside), which will net you power gains and some fuel efficiency gains.

    Consider that if you're going to the trouble of overhauling a 4.6, that you increase the displacement, and change the cam to a profile that suits your application better - I.e. if you're towing, you would prefer a profile that delivers more torque down low, than a top-end screamer.

    Needless to say, all of these possibilities exist if you feel comitted to pulling down the engine. But the suggestion is to first just confirm everything - because an overhaul isn't just about the block and head gaskets.... You also have all the ancillary stuff to recondition too - and replacing stuff like temp senders and thermostats, water pumps, injector overhaul/clean/replace..... so costs absolutely DO escalate when you do a proper full recondition.

    And that leaves me to the last overlooked issue. The electrics. Now, I know it hasn't been mentioned, but always check the distributor module, the coil, and the hall sensor for operation. Check the wiring to the coil and the airflow meter and make sure that is it clean and serviceable. If the wiring insulation is hard, or cracking, replace it.

    The key is simply to check everything thoroughly before jumping in at the deep end and pulling the engine out. Because you absolutely do not want to discover that your rebuild was unnecessary and the cause of the issue was something unrelated.

    It happens.

    I'm sure there will be someone who will provide a detail I have overlooked, but understand the general principle is to check first, before comitting to the full monty.

  8. #8
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    Progress

    The compression test eliminated any need to change the head gasket or the rings - all pressures were well within a few pounds of each other - an average of 120. The cooling passages have been flushed again and the mechanic claims the engine is now running smoothly but that is only under idling conditions and there is as yet no guarantee it will be reliable at speed on the road. He has been "playing" with this vehicle on and off for a couple of weeks now. I would have done most of the things myself but it is over 75 Km away and he keeps locking the bloody thing up so I can't get to it easily.

    MercGuy's comments are absolutely accurate and a soon as I can get the car back to my place in the bush, I'll be doing several things the mechanic has not done, despite me insisting he do them. These include:

    • Cleaning out the crankcase breather and flame traps
    • Checking all vacuum hoses and wiring
    • Checking the mechanical advance on the distributor
    • Replacing the thermostat
    • Adding a chemical enhancer to the oil to clean the oil control rings and valves



    We shall see!

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