406HDi leaking intercooler
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  1. #1
    Gus
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    Default 406HDi leaking intercooler

    My intercooler has had a slow leak for at least the past six months. Oil weeps out somewhere close to the join with the bottom end tank, which is plastic.

    I know my next step is to take it out and try and bubble air from the exact leak spot (ala bicycle tyre.) I'm not really sure what I should do after that though.

    If it is the seal between core and end tank, is there anything I can do to fix it?

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    Should I just find another intercooler from a wrecker or UK ebay? Does anyone do aftermarket intercoolers to suit 406es?

    Any tips?

  2. #2
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    the intercooler split on my 806 HDI but I think that it's a different design
    the 806 has something that looks like an extra radiator that goes right across the front of the car, whereas I think the 406 as vertical one just on one side?
    Anyway on the 806 the metal had split where it was folded over the plastic end tanks and there was no way to repair it
    I had a custom solid aluminium intercooler made which is also higher capacity

  3. #3
    Tadpole
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    A leak is understandable - if undesirable. These things happen.

    I would be wondering why there is oil leaking out? Does your engine have a lot of blow-by? Perhaps an air/oil seperator is required to stop the oil getting into the air intake system.

    Anyone else experienced this?

    Regards,
    Wallaby

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    Gus
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    Quote Originally Posted by dieselnutjob View Post
    the 806 has something that looks like an extra radiator that goes right across the front of the car, whereas I think the 406 as vertical one just on one side?
    Sounds like 806 is "front mount" and mine is "side mount", as you describe.

    Quote Originally Posted by dieselnutjob View Post
    Anyway on the 806 the metal had split where it was folded over the plastic end tanks and there was no way to repair it
    I think this is where mine has split as well, although as I say I have yet to verify it.

    I might have a go at finding something (epoxy?) and gumming it up over the split. Can't hurt, as long as I don't let anything get sucked into the engine.

    Quote Originally Posted by dieselnutjob View Post
    I had a custom solid aluminium intercooler made which is also higher capacity
    I should take a look and see if I have a chance at higher capacity as well, thanks.

    I saw some photos on a UK forum of people fitting large front-mounts to Xantia HDis and the like, but it looked fairly invasive.

  5. #5
    Gus
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    Quote Originally Posted by Wallaby View Post
    I would be wondering why there is oil leaking out? Does your engine have a lot of blow-by? Perhaps an air/oil seperator is required to stop the oil getting into the air intake system.
    Hey Wallaby,

    That's a reasonable question. Motor has a bit of blow-by, I don't think a lot though. I was told by a Peugeot mechanic I know that some blow-by is something to expect on diesels. It certainly doesn't consume any measurable amount of oil between oil changes (10,000km), though.

    One of the reasons why it's taken me 8(?) months to diagnose the leak is the small amount of oil - I cleaned the intercooler and then reinstalled it, and there was no immediate re-oiling but it is clearly reappearing over time. I'm 99% sure it's coming from inside, as well.

    When I get a chance I'll pull it off and do the "bicycle tube" test, to be sure.

    Cheers,

    - Angus

  6. #6
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    Icon7 I know this one!!

    I have the same problem with by 406 HDi... And I am saving up for an engine rebuild.....

    It is your turbo.... unless it is your rear-main seal leaking past the join you mentioned.

    There should be no oil in the intake system, regardless of whether you have blow-by or other engine problems.

    As you said, the air intake pipe runs under the engine to the intercooler. it runs right below the join between the engine and the bell housing. If oil is dripping from here, it might be oil running over the pipe, but actually coming from the rear of the engine within the bell housing.

    If it is the turbo, oil will be all over your intake pipes. The easiest way to check is to remove the hose running from the intercooler to the intake manifold. Or you can remove the top half of the intake manifold. It is just four bolts and comes away easily. You might find that cleaning out the manifold removes a lot of built up crap....

    Unfortunately, if you have worn oil seals in your turbo, you have to pull the engine out just to remove it all... Same if it is a rear main seal.

    If you are getting lots of oil in your intake, be careful about ruining your catalytic converter. Unburnt oil on that will quickly destroy it..

    You can run the car without the pipe from the turbo to the intercooler, and you might be able to clean any oil off and see if it is running out of the pipe or from within the bell housing... This is what I did..... Only to discover that by 406 has BOTH oil leaks..... joy... So as she has 300,000 on the clock, I thought I'd do the rings, clutch, belts and seals all in one...... oh and probably the drive shafts....

  7. #7
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    As it is an air to air intercooler there should be no fluids contained within.

    So IF the oil is actually leaking OUT of the Intercooler, then you must find out how the oil got INTO the intercooler.... Most probable cause would be past the turbine shaft seals in the Turbo charging unit.

    Having said that a 'little' oil, passing thru the turbine shaft seals into the intake side, is a GOOD thing , as it provides some upper cylinder lubrication.... The positive pressure within a forced induction engine, prevents engine oil from passing the top piston ring (Whereas the vacuum, within a normally asperated engine, will draw oil up past the top piston ring)... hence a turbo engine, when working under load can result from a lack of lubrication at the upper end of the bore.

    In fact, as an Automotive Engineer, I advise owners of turbo or spercharged vehicles to add some upper cylinder lube to their fuel tank.

    So, if the amount of oil passing your turbo seals is NOT excessive I would not worry about it.
    Last edited by Rod Slater; 17th November 2010 at 11:55 PM.

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    the intercooler on all my turbo diesels is quite oily and I don't think it's a problem
    it only takes a tiny, tiny amount of oil to get past the turbo oil seals and over 10 years, 100,000 miles it will gradually coat everything in its path
    If your oil consumption isn't excessive and you're not getting blue smoke in the exhaust then forget about it

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    Gus
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    Thanks everyone. It's certainly not a lot of oil, and the car certainly doesn't use any significant amount (no need yet to top up between 10,000km oil changes.)

    So I'll have to assume the turbo seal situation is in hand, for now (205,000km on the odo.)

    It does make me wonder if maybe the oil is arriving on the outside of the intercooler join from somewhere else, though. I couldn't see anything likely in the engine bay, but I'll need to have another thorough look.

  10. #10
    Tadpole
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    Sorry Gus to change the direction a little - but - I am interested in Rods comments about recommending "upper cylinder lube to their fuel tank.".

    Rod,

    What are your recommendations? I have read on other sites that some types of 2 stoke oils are effective. I did post a similar question a while back and the concensus was to leave it alone.

    Regards,
    Robert

  11. #11
    Gus
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    (Now Wallaby's gone O/T I'm going to go as well.)

    Quote Originally Posted by Rod Slater View Post
    The positive pressure within a forced induction engine, prevents engine oil from passing the top piston ring (Whereas the vacuum, within a normally asperated engine, will draw oil up past the top piston ring)... hence a turbo engine, when working under load can result from a lack of lubrication at the upper end of the bore.
    Rod, do you think this applies for diesel as much as petrol? I would think that diesel, being an oil already, would be kinder to these surfaces than petrol. I'm not basing that on anything, though, except I guess for the large numbers of turbo diesel engines out there with massive kms and good compression.

    To go right O/T, I've been toying with the idea of fitting a water injection kit, such as those sold by Devil's Own. They present some of the benefits as being reduced combustion chamber cleaning, which is a plus for diesels, as well as some very impressive before & after dyno charts on small diesel engines. Although I'd be after improved economy before massive power. Do you have any thoughts on whether you think the cavitation effect could make the effect that you describe much worse?

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    Gus
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    Quote Originally Posted by Gus View Post
    I know my next step is to take it out and try and bubble air from the exact leak spot (ala bicycle tyre.) I'm not really sure what I should do after that though.
    Boy, do I feel stupid. Intercooler doesn't seem to actually be leaking - it took it off last night and couldn't get air to bubble out anywhere. Also, what I thought was fresh oil reforming around the base may have just been old oil moving around, on closer inspection it was not so bad.

    Have taken some photos of the area's grubbiness now (after a clean) and will compare in a month or two's time, just to set my mind at rest.

    Pulling the intercooler revealed some oil in the intake ducts (enough to drip out, but not enough to flow out.) Doesn't seem any worse than any other car I've ever owned, though, so I'll wait optimistically before declaring my turbo seals unwell.

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