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How to repair leaking oil cooler

Discussion in 'How-To' started by Yellow_rag, May 10, 2011.

  1. Yellow_rag

    Yellow_rag Few SVT Poster Established Member

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    How to repair a leaking oil cooler

    So, I’m changing my oil the other day and I see coolant dripping from the oil cooler. After I freak out for a while I dig in and here’s what I find out: First the good news – there are 2 gaskets separating coolant from oil, with a weep hole in the no man’s land between them, so chances of getting oil in your water or vice versa are almost zero. The bad news I found out is a new oil cooler costs $309 online at Silver State Ford. The other good news is it’s actually pretty easy to repair if necessary.
    [​IMG]
    [​IMG]

    There are several places you can have a leak, so you should confirm exactly where before you pull this stuff apart. Starting at the block, there’s a gasket between the block and the cooler adapter. Both oil and water go through this. AutoZone carries a $5 Fel-Pro gasket for this, but mine wasn’t leaking there, so movin on. Next there are 2 o-rings between the adapter and the cooler as shown in the FordParts.com exploded view. My local dealer sold me these o-rings for $17 and $11 (I was robbed btw). If the big o-ring is bad you’ll leak oil from between the adapter and cooler, if the little one is bad you’ll leak coolant.
    [​IMG]

    Next is the cooler itself. Ford sells this as a non-serviceable unit but you CAN take it apart and replace the o-rings. This is what I had to do after wasting time confirming it wasn’t the other 2 I just bought. The cooler is an aluminum housing with a heat exchanger inside, which can be removed. There are 3 o-rings in this unit plus one on the stud. There is a small weep hole on the bottom, so if oil or water is coming out of the weep hole then one of the rear o-rings inside the cooler is bad. If water is leaking out around the oil filter then the outer o-ring inside the cooler is bad. This is where mine leaked coolant from this groove, see finger in picture.
    [​IMG]
    Put car on jackstands with plenty of room underneath, and remove driver’s front wheel for better access. Drain all the coolant – I take the 2 10mm bolts out of the thermostat housing. Also drain the oil and remove the filter. Remove the coolant hose going to the cooler – I had to drop the sway bar ½ inch to reach mine but I think if you jack up the front wheel it will drop too. To take the cooler off you need a 1/2in hex head on the oil filter stud. The upper coolant passage o-ring will hold the cooler in place. The best way I found to break it free is to put the oil filter stud about halfway in and use as a handle for leverage. Pull down on stud while pushing on the bottom of the cooler with your other hand. You can then maneuver the cooler out past the steering lines and such – it will fit. Make sure your alternator has the rubber cover protecting the hot lead or disconnect your battery btw.

    If your leak is oil or water from between the adapter and cooler, then just get the $17 oil o-ring or $11 coolant one and reassemble, and hope you didn’t cause another leak. If you have oil or coolant coming out the weep hole or coolant from around the oil filter keep going. The cooler is only held together by o-ring friction and some RTV. You can probably insert a flat screw driver through the center hole in the rear and pry the heat exchanger from the case – I think this will work. I separated it the hard way: I stuck rubber stoppers in the big water passages, and held in place with clamps, and filled the cooler with water. One stopper had a hollow bolt which I put air into and blew the heat exch out. (I thought was pressed in but after getting apart I saw nothing holding in but o-rings).
    [​IMG]

    If you got this far you may as well replace all 3 o-rings. I went to a place that sells seals (Austin Seal) and bought two Viton o-rings for each of the 3 plus the stud o-ring - 8 pcs for $10. They matched size of my old silicon rings with a chart – something you cant do on the internet very well. There is one ring on the rear face of the cooler – see picture. This holds in oil. There are 2 rings, one on each end of the heat exchanger. These hold in water of course. The small o-ring on the stud just separates cool filtered oil from hot dirty oil so probably not crucial.
    [​IMG]

    Here are the Viton sizes I used – NOTE: these may not be exactly correct but are apparently close enough. You can just google Viton –xxx and get the details.
    -237 (3 5/8 in OD)
    - 233 (3 1/8 in OD)
    - 019 (15/16 in OD)
    - 234 (3 ¼ in OD)

    Before you reassemble you should scrape off all the old RTV and then sand the lands smooth. I used 1200 grit which took a while. 800 is probably plenty fine for aluminum if you have it. Note there is an axial surface AND a redial surface at the back of the cooler. Don’t forget to clean the adapter still bolted to the block.
    [​IMG]

    Once cooler is clean and dry you’ll want to tack the rear o-ring in place since it just sits in a shallow groove. I used black RTV since that ring holds oil. Not sure if that is best thing. You have to align the 2 pieces carefully to slide them together – definitely use some silicone grease or some kind of lube on the other o-rings, but be careful not to mess up your RTV.

    Now the cooler is assembled use some Silicone grease or RTV to hold the o-ring on the back side and maneuver into place. Don’t forget to replace & lube the ring on the coolant adapter. Torque spec for filter stud is 41-53 ft-lbs – I used 50 fwiw. Now you can refill the coolant while the oil ring RTV sets to insure no major leaks. Next day I filled with oil and burped the cooling system. Been several days and just checked and its completely dry. Hope this is helpful.
     
    jmsa540 likes this.
  2. P49Y-CY

    P49Y-CY selfie deaths ftw Established Member

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    nice write up - when i took mine out to repair i didnt think it was a serviceable unit
     
  3. Cobra-Gobra

    Cobra-Gobra New Member Established Member

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    Had to replace mine and it was an SOB to get out. Ohwell, all is good now.
     
  4. JohnC96cobra

    JohnC96cobra New Member Established Member

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    What's the easiest way to pull the cooler off?
     
  5. Yellow_rag

    Yellow_rag Few SVT Poster Established Member

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    The way you pull the cooler all spelled out in my original post below.

    Btw, my car is lowered and has a tremendous sway bar previous owner installed. The sway bar was hitting the bottom of the oit cooler and pinching the hose. Probably cause my leak too. You may want to make sure when there is no weight on the wheels there's still plenty of clearance from the sway bar. Also, adding weight to the wheels will pivot the sway bar out of the way so its easier to remove the coolant hose.
     
  6. 01cobravortech

    01cobravortech Banned

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    subs for future reference
     
  7. mpm

    mpm Member Established Member

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    There is no point in starting a new thread, so I'll ask in here. How many bolts hold the actual oil filter adapter to the engine block? I was under the impression there should be 4. I was under my '04 Cobra yesterday trying to replace the oil filter adapter gasket, but for the life of me couldn't figure out how the hell to remove the bolt that is 2nd from the top on the side of the adapter facing the radiator. Am I over-complicating this?
     
  8. Yellow_rag

    Yellow_rag Few SVT Poster Established Member

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    did you pull the cooler off first? I never tried to take the flange off cause mine wasnt leaking there, but I'm sure it would be easier to remove the flange with the cooler off. Hope that helps.
     
  9. rudycobra

    rudycobra New Member Established Member

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    I don't think it's possible wothout taking some of the front accessories off. I bought a whole rebuild kit but when looked at it closely there was no way it was coming off , think the other bolt is hiding up top .
     
  10. rudycobra

    rudycobra New Member Established Member

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    Hmm that may b true , I just realized that u can pull the cooler off first , then maybe the flange ? Gonna have to chk that out because mine is always a little oily around flange .
     
  11. mpm

    mpm Member Established Member

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    That was the same conclusion that I came to. I wish I would have known that before wasting my time on frustration. I eventually gave up and tightened the allen key oil filter bolt. If that doesn't work I will just have to live with the leak until I have time to remove accessories.
     
  12. Lonnie

    Lonnie New Member

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    Good info, thanks a lot
     
  13. SilverNotch

    SilverNotch Member Established Member

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    I went to check my fluids on my 01 cobra today and found that there is oil in the coolant. First off, I freaked out thinking that it was head gasket then I calmed down and thought about the oil cooler as the car has been running healthy and there is no coolant in the oil. So, after looking at the very high prices of the oil coolers I stumbled on this thread. How long will this take from start to finish and will it cure my problems most likely? I'd like to save money but, I don't wan't to waste my time if its not going to cure my issue. Can I pick up the gaskets and o rings at local places because I need my car back on the road as soon as possible? I'm just trying to weigh my options on getting this fixed I'm very mechanically inclined so I can do the majority of things myself on my car.
     
  14. SilverNotch

    SilverNotch Member Established Member

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    So, I talked to Ken at Speed Concepts and he was extremely nice and informative and willing to answer any questions about the kit. I hope its the solution to all my oil cooler problems as I dont want to spend 400 dollars on a new unit. He assured me that this is what I need and assured me he sells quite a lot of these units. I should receive it on Sat. then I'll do it either then or on Sunday.
     
  15. Phil'scobra

    Phil'scobra Member Established Member

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    I changed my oil about two weeks ago. Drove it for the first time yesterday, had oil leaking, I checked the filter for the top and it was tight. I am guessing my cooler is leaking. I have a tub k-member and had to kind of force my filter on, while doing so the housing would move around. I did not think much of it and it did not leak at startup so I figured it to be Ok. I will be checking the bolts to make sure it is tight today, if so I will be pulling the cooler to rebuild, replace O-rings.
     
  16. Anabolic

    Anabolic Banned

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    is there anyone who sells replacement sets for these coolers?



    i installed gasket # 70415 duralast in place of 6840 up top (block > housing gasket)

    is this ^ a problem?
     
  17. SilverNotch

    SilverNotch Member Established Member

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  18. Anabolic

    Anabolic Banned

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    thanks, i reinstalled everything. gasket isnt leaking at the block anymore. the duralast i installed is fine..
    NOW it's leaking where the cooler pushes in the housing at the coolant passage, the o ring keeps melting/destroying itself when it reaches optimal temp? what's going on?

    i put alittle grease around the o ring/housing so it slips in easier, no rtv or anything.... could that be it? what's happening?!?! it's frustrating..
     
    Last edited: May 15, 2012
  19. Anabolic

    Anabolic Banned

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    what size is o ring HR1?
     
  20. SilverNotch

    SilverNotch Member Established Member

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    Hey Ken
    Finally got all the oil out the cooling system for sure now and everything is tight and no oil lose anymore. Thanks for all your help and a great product and a huge money saver so I can spend money on performance and not repairs.
     

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