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[Astra Mk4/G] [98-04] Replacing Oil Cooler or O Rings?

Discussion in 'Astra, Corsa, Zafira, Meriva, Adam, Agila, Tigra & Nova [Includes AstraVan & ComboVan] owners forum' started by Sierra Charlie, Oct 4, 2011.

  1. Sierra Charlie

    Sierra Charlie Member

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    Location:
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    Just wondering if anyone could help me with some advice please.

    I`ve bypassed my oil cooler due to having oil in the expansion tank and I`ve flushed the cooling system a couple of times. The problem hasn`t got any worse and the contamination of the cooling system appears to be gradually clearing up.

    I understand and appreciate I might have to replace the oil cooler, however, I have read somewhere that the oil cooler has some O rings fitted to the rear.

    Does anyone know for sure why the oil coolers usually fail (are they a sealed unit?) and start to leak oil into the coolant? Would it be possible to remove the oil cooler and just replace the O rings?

    Many thanks in advance for all replies
  2. paul.spencer

    paul.spencer Well-Known Member

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    Location:
    Waiwhetu, New Zealand
    Drives:
    96 Astra Estate X17DTL
    Hi there and welcome to the VXON forum.

    Was that you on the astra forum asking this question a couple fo days ago? Maybe just a coincidence.

    I reckon if it was just a matter of replacing the o-rings surely people would be doing that - however, I have never even seen one of those oil coolers first hand, only heard of people replacing or bypassing the unit.

    I'll be interested to see whether anybody has inspected their faulty oil cooler and can describe exactly how they fail/where they leak... might have to cut one open to see corroded pipes or something...
  3. Sierra Charlie

    Sierra Charlie Member

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    Hi Paul,
    Yes, it was me on the Astra forum a couple of days ago. I joined this forum as well, my thinking being perhaps some people prefer to visit this site whereas some others prefer the other site for whatever reason/s, I hope you are not offended or annoyed at my duplicate postings.

    You are the only person to answer my post on this forum and the Astra forum at the moment, I was hoping I might get some others to contribute to this discussion to help me decide the best outcome both time and cost wise. I didn`t want to go to the expense of replacing the oil cooler ( especially as it seems a regular occurance to have to replace these with some people suggesting replacements can sometimes last or fail again within 12 months??) if I could get away with just replacing the O rings.

    Many thanks again in advance for all replies
  4. paul.spencer

    paul.spencer Well-Known Member

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    Location:
    Waiwhetu, New Zealand
    Drives:
    96 Astra Estate X17DTL
    That's a larf, me offended by you posting here as well? No, the few times I had questions I posted on several forums hoping to get answers.

    Anyway, about the leaky oil cooler (TIS 2000 calls it a heat exchanger) I might be wrong, but looking at pictures of the oil cooler and where the o-rings are situated, I think the o-rings must be there to prevent oil leaking out over the crankcase. So I can't see how changing the o-rings would do anything to prevent oil getting mixed with the coolant.

    I think the pipes inside must get corroded at some point(s) and oil gets through to the coolant. Hey if you want to be the one to confirm it yourself I guess you could remove your oil cooler clean and dry it thoroughly and try putting some solution in (coloured solution might help), possibly under some pressure, and see if it bleeds through into the coolant side and out through the coolant pipes. That would be good info...

    Cheers, Paul
  5. Sierra Charlie

    Sierra Charlie Member

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    I think I will leave the oil cooler bypassed for a short while longer as I am able to use the vehicle at the moment without too many adverse effects. During the meantime I`ll look out for a cheap second hand one if possible ( they seem to vary from around £40 for a second hand one to around £80 for new one, as far as I am concerned its a no brainer I`d go for the new one every time at those prices!) and put your theory to the test.

    I`ll report back when I`ve either found a second hand one or whether I`ve had to fit a brand new one.
  6. threelander

    threelander Member

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    Location:
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    hi sierra i,m in the same boat mate.i,m just wondering wether to bypass the cooler as i too have oil in header tank.i see you allready by passed yours.now the question is is there any oil leaking from the cooler pipes at all and it does not look a easy bypass as there is not a lot of give in the two pipes to be connected.itlooks to me like you have to join them together with like a u bend piece of pipe rather than straight piece m8.allso pauls bin a great help to me too
  7. Sierra Charlie

    Sierra Charlie Member

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    Hi threelander,
    I managed to get away using a 90 degree copper elbow as a temporary bypass, not ideal as it leaves a slight kink in one of the rubber hoses but it does the job. Where I`ve taken the pipes off the oil cooler I`ve placed a plastic cap on each together with a jubilee clip.
    The header tank is staying reasonably clear but obviously the warmer the engine gets the more chance there is of the old oil sludge and gunge becoming diluted and settling in the header tank.
    I am toying with the idea of removing the radiator and flushing it out with white spirit as I am sure this is where all the thicker sludge and gunge has settled previously.

    Hope this helps.
  8. paul.spencer

    paul.spencer Well-Known Member

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    Location:
    Waiwhetu, New Zealand
    Drives:
    96 Astra Estate X17DTL
    I have to admit that last year I went to great lengths to clean out a fouled up Rover cooling system and among other things I use a spray can of engine surface degreaser sprayed into the radiator. Sparyed, swished and flushed with blasts of water several times. It was amazing how much emulsion crap that treatment got out of the radiator.

    I guess white gas might do about about the same although I thinkthe degreaser is more of a detergent rinses out easily with water. Whatever, the emulsion does get everywhere and it takes much effort to get it all out - sounds like you are getting there...
  9. Sierra Charlie

    Sierra Charlie Member

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    Location:
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    Just a quick update. I removed the bumper to gain access to the radiator today. I poured some "Gunk" degreaser into the radiator and gently shook it swishing the "Gunk" about inside before pouring it out again ( blacker side of greyish liquid came out). I repeated this two more times before satisfying myself that the radiator was now relatively clear and clean.
    I then placed a small hose from a garden sprayer into the top and bottom hose pipes before spraying the insides of the pipes with another degreaser product I wanted to try. This produced more greyish liquid. I carried on until I was satisfied that I had cleared all there was to clear.
    I refitted the radiator, top and bottom hoses and bumper, filled the cooling system with water before running engine until warm. I removed the bottom hose and although the water was slightly dis-coloured there was hardly any sign of oil. I refitted the bottom hose and refilled the cooling system with fresh water.
    I am going to continue to monitor the header tank for traces of oil over the next few days. If I am satisfied that the majority of the oil contamination has now been cleared I am going to leave the oil cooler permantly bypassed ( although I am going to carry out a better modification on the pipe work by getting rid of the present "kinks" that exist) as this seems reasonably standard practice.

    Hope this information helps others in the same boat.
    R9ORE likes this.

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