1. This site uses cookies. By continuing to use this site, you are agreeing to our use of cookies. Learn More.

broken valve?

Discussion in 'T3 & T4 Tech Help Clinic' started by Wolf River, Dec 22, 2016.

  1. Wolf River

    Wolf River Member

    Messages:
    95
    Location:
    Gold coast
    Mechanic mate fixed the Syncro. He said he replaced the lifters and told me "everything was seized up".
    Drove it home from Sunshine Coast to Goldy and it ran nice whole way.

    Problem is my son must have toasted the sender unit when he cooked the beast because it was pretty Psycho during drive home... o_O
    At first the low fluid light kept flashing despite plenty of water.
    I stopped at a servo, bled system and topped up the inch or so. It stayed off for about 30 seconds of driving then started its urgent flashing again. :confused:
    Stopped to check but fluid bottle was still full so kept driving.
    Then the temp stayed so low it was off the dial for the first 1/2 hour of driving. I thought, OK, the temp guage is f-ed so kept driving to next servo (near Mt Tibro).
    Allowed vehicle to cool after bleeding again, checked fluid... fine, so off we go again. :)
    Within a couple of Ks it started flashing again. Still no reaction from temp needle.
    Then at about Caboolture the needle suddenly came alive in a big way! It shot all the way to the highest point! EEK! :eek:
    I stopped, checked fluid and felt bottle with hand. It was fine so I kept going thinking the guage must just be expressing its newly diagnosed ADHD.
    The thing couldn't decide if it was hot or cold for the next 1/2 hour... shooting off the range, then dropping back halfway before shooting up again.:confused:

    By the time I was going over the Gateway Bridge it decided it wasn't getting the attention it was seeking so began to behave :rolleyes:
    The low-level light stopped flashing and the needle dropped to where it always used to sit before my son cooked it. :D
    From the bridge to home it went mental three times more briefly (flashing light, erratic temp) but I ignored it and it went back to normal again after a few seconds each time.

    When I got home I told my mate about it's naughty behaviour and he reckoned my fan must be screwy. He told me to replace the thermostat ASAP as he drilled holes in it, and said to get some SealUp right away.
    I put said SealUp in it and drove it around for an hour or so. Told him I will drain it tomorrow and refill with coolant but he told me to leave it in despite instructions on bottle saying it will react with the coolant if not flushed after use. o_O

    Next step: get new thermostat and sender unit from JustKampers, and do an oil and filter change.
    My question to anyone willing to answer... Is the temp sensor the same unit as the level sensor? Both are behaving very badly.
     
    Luckyphil likes this.
  2. Grantus

    Grantus Well-Known Member

    Messages:
    18,838
    Location:
    Southern ACT
    It's a simple temp sensor failure, giving erratic signals to the ECU, is my guess. :rolleyes:

    Working properly, the flashing light has some clever electrickery - it flashes if the bus has lost some coolant, with a signal from the sensor from the top of the pressure bottle, but it ALSO flashes if the coolant / engine temp is way too high, (even with no coolant loss) with a signal from the temp sensor.

    So a faulty temp sensor sending wrong signals to the ECU and temp needle, will cause your symptoms.

    Hope I've explained it well enough to help with your diagnosis..........o_O
     
  3. syncro

    syncro Well-Known Member

    Messages:
    10,368
    Location:
    Southern Highlands
    I would guess that the gauge is faulty if the light is flashing and the needle points low.
     
  4. Luckyphil

    Luckyphil Well-Known Member

    Messages:
    7,076
    Location:
    Gosford
    I would stop taking advice from your mate, did you test the thermostat to see if it was working, and never ever ever put shit like seal up in your cooling system. It is now busy clogging your radiator and any other area it decides to settle in. What was he trying to seal if you never had coolant loss.
     
    hairyman and syncro like this.
  5. syncro

    syncro Well-Known Member

    Messages:
    10,368
    Location:
    Southern Highlands
    Temp sensor is only for gauge and light. No connection to ECU.
     
  6. grumble

    grumble Well-Known Member

    Messages:
    1,384
    Location:
    Taree

    Assuming that the radiator has been cleaned as great stuff like Bars leaks,sealers etc block the tubes restricting flow,also assuming the cooling fan is working.
     
  7. nils

    nils Well-Known Member

    Messages:
    1,523
    Location:
    newcastle
    Sounds like you have some electrical gremlins there too. Cleaning all your earth points is cheap and will help keep your sensors accurate.

    The braided earth strap at the engine and nose of the gearbox should be replaced too.
     
  8. syncro

    syncro Well-Known Member

    Messages:
    10,368
    Location:
    Southern Highlands
    Why?

    They only fail due to mechanical damage and it is very hard to buy good quality earth straps.
     
    Last edited: Jan 24, 2017
  9. Wolf River

    Wolf River Member

    Messages:
    95
    Location:
    Gold coast
    No idea if he tested the thermostat before he drilled the holes into it. I assume he did but going on his advice for SealUp when I don't have a coolant leak, then telling me to leave it in when the bottle instructions say to flush it, who knows?
    The chap was a genius when it came to working on my T2 Kombis 20 years ago. Maybe he's losing it in his old age... :confused:
    Despite his advice I will be flushing it and putting coolant in as soon as the new thermostat arrives.
     
  10. Wolf River

    Wolf River Member

    Messages:
    95
    Location:
    Gold coast
    Only cleaning the radiator has been through was 'accidental' flushing from blown hoses. I am tempted to take it to a radiator specialist but will they do anything more than what I can do at home with a hose?
     
  11. Wolf River

    Wolf River Member

    Messages:
    95
    Location:
    Gold coast
    I suspected as much, thanks.
    I will add a sensor to the thermostat order from JustKampers.
    Is this the right one? http://www.justkampers.com.au/025-9...5-1985-1992-2-1-only-vw-t4-1990-2003-all.html
     
    Last edited: Jan 24, 2017
  12. syncro

    syncro Well-Known Member

    Messages:
    10,368
    Location:
    Southern Highlands
    I cannot remember but I think that is the temp sensor for the ECU. Phil should know.
     
  13. hairyman

    hairyman Active Member

    Messages:
    411
    Location:
    Sydney, NSW
    Correct, there are two, the blue one for the Temp 2 input for the ecu and the black on for the temperature gauge. I had a look on Brickwerks and they list two types, a single pin and dual pin on the sensor so pull off the plug and check which you have before ordering.

    It could well be worth replacing the Temp 2 sensor at the same time because if they go it causes all sorts of strange faults while driving
     
  14. Luckyphil

    Luckyphil Well-Known Member

    Messages:
    7,076
    Location:
    Gosford
    Go to Natrad or another reputable radiator business and get the radiator reverse flushed & pressure tested, should cost about $80.
     
  15. Luckyphil

    Luckyphil Well-Known Member

    Messages:
    7,076
    Location:
    Gosford
    Phil is correct that is what is known as the "temp2" sensor, however as yours is a syncro it is the wrong one anyway. Syncro Temp2 screws in sow when you specify what you need ensure you are ordering sensors for s Syncro. I would replace both sensors as suggested by the hairyman.
     
  16. Wolf River

    Wolf River Member

    Messages:
    95
    Location:
    Gold coast
    Thanks guys
     
  17. syncro

    syncro Well-Known Member

    Messages:
    10,368
    Location:
    Southern Highlands
    You may be causing more problems as a lot of the replacement ones are faulty. If it is working good then leave it. The one in it may last another 20 years and the replacement 12 months.
     
  18. nils

    nils Well-Known Member

    Messages:
    1,523
    Location:
    newcastle
    Those old braided ones harbour alot of corrosion by now. I used to clean them, but even after they are still hit and miss.
     
    Dapom likes this.
  19. gazman

    gazman Well-Known Member

    Messages:
    1,914
    Location:
    Perth WA
    OK... The gauge and light working on and off like that is possibly a loose wire/connection somewhere. If it was a sensor failure it would normally just stop working/keep flashing all the time - check all the wiring and plugs etc before spending any money as its easy (and pretty common) for a mechanic to accidentally knock things loose while working on it. Also absolutely no idea how a 'screwy fan' could have anything to do with this problem?

    Dont stress about the sealup, just drain the system and refill with good coolant. I've only seen blocked radiators from this stuff after repeated use ie. people trying to 'bandaid' fix blown headgaskets etc. (Although if you really feel the radiator needs cleaning then get it done).

    Drilling holes in the thermostat is pointless, if its faulty they are cheap and easy to replace.
     
    syncro likes this.
  20. syncro

    syncro Well-Known Member

    Messages:
    10,368
    Location:
    Southern Highlands
    Visual check. If they are going to cause an electrical fault they would have to look pretty bad. If want reliability, put a second one for redundancy. Most of the problems that I have seen has been incorrect fitting by mechanics.
     

Share This Page