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Thread: 300tdi oil leak FL engine bay : possibilities please.

  1. #1
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    300tdi oil leak FL engine bay : possibilities please.

    My 300tdi has about 400,000 km on the clock. This leak was present when I got the vehicle about 3 years ago. It doesn't keep me off the road but it needs addressing now. It never seems to drip on the road but the whole front half of the underbody has a good coating at any time. When I get home it will drip a finite amount while cooling, always in the same place FL of the engine bay, and a bit a bit further back although this may only be where the blowback happens to drip from.

    I know tdi oil leaks is a big topic but I want to make a list of only about 6 prime suspects to start with. I'll learn how to eliminate them starting with the simplest. Maybe there are specific smallish areas I can clean just with brake cleaner and brush/rags then drive and watch?

    Possibilities please and your own experiences and suggestions :-)

    DSC_1098.jpg

  2. #2
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    Could be so many possibilities ... where to start.

    You really need to clean the engine bay well get all oil staining off and watch like a hawk.

    Question that first comes to mind is, is it engine oil? If the drip is directly from above, then it most likely isn't engine oil and more likely power steering fluid.
    Learn to differentiate oils.

    Engine oil will be black .. as in sooty inky black as black. Trans fluid(if auto) is dark red, fresh will be more translucent red. power steering is same/similar to trans.

    And don't assume that just because it's dripping there that the leak is from directly above .. oil leaks can 'travel' along a line before they fall to earth.
    This is why you need to give it a good pressure clean and degrease and then watch where the fresh leak starts to come from.

    But! .. assuming it is from directly above the oil stain spot, about the only oily components directly above that location could be power steering reservoir(and hose to and from) to pump .. or auto trans joint at the trans cooler, also the trans temp sensor .. if it's an auto.
    If manual, I dunno about any possible transmission cooler gear on that side.

    Also note that it if is actually engine oil(the black as black stuff) it could have built up in the intercooler and hoses(happens!) and then oozing out of the lower hose, if the clamp is a tad loose.

    Mine did this a few years back. Pulled I/C out cleaned out hoses(small pools of it in hoses) threw in petrol and brake cleaner into I/C sloshed around hosed out, more brake cleaner(primarily to help disperse water and more cleaning, blew out with air back into car and no build up for quite a while. Mine didn't have that drip tho, it just oiled up the chassis area heaps and looked ugly as, and hands got mucky for no reason if I was working in that area too.
    Arthur.

    '99 D1 300Tdi Auto
    '03 D2 Td5 Auto

  3. #3
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    Quote Originally Posted by AK83 View Post
    Could be so many possibilities ... where to start.

    You really need to clean the engine bay well get all oil staining off and watch like a hawk.

    Question that first comes to mind is, is it engine oil? If the drip is directly from above, then it most likely isn't engine oil and more likely power steering fluid.
    Learn to differentiate oils.

    Engine oil will be black .. as in sooty inky black as black. Trans fluid(if auto) is dark red, fresh will be more translucent red. power steering is same/similar to trans.

    And don't assume that just because it's dripping there that the leak is from directly above .. oil leaks can 'travel' along a line before they fall to earth.
    This is why you need to give it a good pressure clean and degrease and then watch where the fresh leak starts to come from.

    But! .. assuming it is from directly above the oil stain spot, about the only oily components directly above that location could be power steering reservoir(and hose to and from) to pump .. or auto trans joint at the trans cooler, also the trans temp sensor .. if it's an auto.
    If manual, I dunno about any possible transmission cooler gear on that side.

    Also note that it if is actually engine oil(the black as black stuff) it could have built up in the intercooler and hoses(happens!) and then oozing out of the lower hose, if the clamp is a tad loose.

    Mine did this a few years back. Pulled I/C out cleaned out hoses(small pools of it in hoses) threw in petrol and brake cleaner into I/C sloshed around hosed out, more brake cleaner(primarily to help disperse water and more cleaning, blew out with air back into car and no build up for quite a while. Mine didn't have that drip tho, it just oiled up the chassis area heaps and looked ugly as, and hands got mucky for no reason if I was working in that area too.
    Thanks. Manual transmission. It really looks like engine oil to me and I often have to top up the engine. I'll check the intercooler and hoses. For the cleaning what is the best option? A mechanic mentioned steam cleaning to me - is that any good? How do you do the pressure clean at home?

  4. #4
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    Don't pressure clean.
    Add some degreaser agent of some kind inside the IC. block ends up and slosh around by hand.
    I just did it a few times till the solvent came out clean.

    Same with hoses .. spray a solvent through them, run a rag through and cleaned.

    I only used air 'pressure' to clean out the residual water when I flushed it all again with garden hose to be sure no more blacky muck in there.
    Just a std compressor with a blow tip rags at the ends, fill with air pressure then release the other end to force out the air/vapour.
    Then let it sit to be sure it's dry. You don't need the air pressure even if you do rinse with water at the end.. just let it dry longer in the sun or something.
    Or just don't rinse with water and use more brake clean, as brake clean dries up faster than degreaser does.

    If those oil stains(location) are anything to go by .. hard one to guess at whats leaking. Would like to think front main seal(quite possible), but I'd have thought that it'd fling the oil to the driver side, not the pass side.

    Mine had a front seal leak and did this.. more towards the steering box, but still some at the middle up front.
    Could be tappet cover leaking say up front and traveling down to the pass side???

    I'd say you really need to clean it up in there and take photos from top and bottom sides.
    Most Tdi's will be running quite black oil so will be easy to see leaks original source, if you catch it early enough before it lathers the entire engine bay that is.
    Arthur.

    '99 D1 300Tdi Auto
    '03 D2 Td5 Auto

  5. #5
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    Quote Originally Posted by AK83 View Post
    Don't pressure clean.
    Add some degreaser agent of some kind inside the IC. block ends up and slosh around by hand.
    I just did it a few times till the solvent came out clean.

    Same with hoses .. spray a solvent through them, run a rag through and cleaned.

    I only used air 'pressure' to clean out the residual water when I flushed it all again with garden hose to be sure no more blacky muck in there.
    Just a std compressor with a blow tip rags at the ends, fill with air pressure then release the other end to force out the air/vapour.
    Then let it sit to be sure it's dry. You don't need the air pressure even if you do rinse with water at the end.. just let it dry longer in the sun or something.
    Or just don't rinse with water and use more brake clean, as brake clean dries up faster than degreaser does.

    If those oil stains(location) are anything to go by .. hard one to guess at whats leaking. Would like to think front main seal(quite possible), but I'd have thought that it'd fling the oil to the driver side, not the pass side.

    Mine had a front seal leak and did this.. more towards the steering box, but still some at the middle up front.
    Could be tappet cover leaking say up front and traveling down to the pass side???

    I'd say you really need to clean it up in there and take photos from top and bottom sides.
    Most Tdi's will be running quite black oil so will be easy to see leaks original source, if you catch it early enough before it lathers the entire engine bay that is.
    Ta that gives me something to go on with. Getting some degreaser tomorrow
    at supercheap - the spray on, leave a while, hose off stuff.

  6. #6
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    From the picture my best guess would be intercooler hose connections.

  7. #7
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    give the area around the pwr str reservoir a good clean too. Check the colour of the fluid(whilst you check the level too). It's not expensive to flush it out and replace with fresh stuff.
    If darker than a mid toned browny colour, replace sooner rather than later. but in reality it should be clear/translucent red, like auto trans fluid.

    something to be 'aware' of, so what could be happening: the I/C and hose joints can build up with a greasy oily vapour like film on them. If the pwr str reservoir(or more likely hoses) are leaking, it could be migrating down onto the IC/hose greased up area and mixing up then dripping to the floor. So while the leak may be (say) pwr str fluid, if mixing with the greasy film around the I/C hoses it could look dark like engine oil.

    Not saying this IS the problem .. just a possibility that it could be.

    Unless you've moved the car a bit when lifting, it's a weird place to have an engine oil leak so far forward and kerbside.
    Arthur.

    '99 D1 300Tdi Auto
    '03 D2 Td5 Auto

  8. #8
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    Quote Originally Posted by AK83 View Post
    give the area around the pwr str reservoir a good clean too. Check the colour of the fluid(whilst you check the level too). It's not expensive to flush it out and replace with fresh stuff.
    If darker than a mid toned browny colour, replace sooner rather than later. but in reality it should be clear/translucent red, like auto trans fluid.

    something to be 'aware' of, so what could be happening: the I/C and hose joints can build up with a greasy oily vapour like film on them. If the pwr str reservoir(or more likely hoses) are leaking, it could be migrating down onto the IC/hose greased up area and mixing up then dripping to the floor. So while the leak may be (say) pwr str fluid, if mixing with the greasy film around the I/C hoses it could look dark like engine oil.

    Not saying this IS the problem .. just a possibility that it could be.

    Unless you've moved the car a bit when lifting, it's a weird place to have an engine oil leak so far forward and kerbside.
    Thanks. A mechanic did once write "power steering oil leak" on a sheet. He also told me to replace my rear brake discs which would have made no difference to the vacuum pressure problem. He was going by the location I reckon. My local diy mechanic (200tdi d1, lt77 reverse switch problem any takers?) has been underneath my truck and he's pretty sure if it was ps fluid I'd have had problems with the steering because of the sheer quantity of the black stuff. I've never had a steering issue but I frequently have to top up the engine. Still never a good idea to fix on one possibility. IC+hoses, p.streer, and front main seal all on the list, nothing eliminated yet.

    In the photo the ramps do make it harder to judge but it has always been pretty well forward.

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