Click for Westport Click for Mulder Click for Cross Click for Mulder Click for Walker

CAT C12s loosing coolant

Discussion in 'Engines' started by xF_PP, Jun 5, 2022.

You need to be registered and signed in to view this content.
  1. xF_PP, Jun 5, 2022
    #1
    xF_PP

    xF_PP New Member

    Joined:
    Aug 3, 2013
    Messages:
    37
    Location:
    Moon
    We bought a trawler style boat with C12's/705HP/y2006/1.850h (my first Cat). No loss of coolant during or after the extensive sea trial.
    Had the boat sitting for 7 month for refits. No coolant issues during this period.

    We had a major service done by a official CAT dealer (2.000h). Part of the maintenance was cleaning and pressure test of the heat exchangers.
    After sea trial with dealer mechanics on board - doing RPM steps up to full load while diagnosting - one engine lost about 50% of the coolant of the external tank. They did a refill and I was told everything should be ok.

    Some days later without running the engines the coolant tank was empty. I called the dealer and they took one heat exchanger out, had it repaired by a 3rd party cooler company and installed it again.

    We did a 4h drive on quiet low RPM (1.050) and realised later, the external tank got empty again. I called the dealer and they did pressure check the fresh water cooling system. Their diagnosis: the heat exchanger is leaking.
    We decided not to have it repaired one more time and ordered a new one.

    Now, having one new heat exchanger, we were running again for 1,5h. Being back at the marina we realized we lost the coolant of the external tank. Plus 50% of the other side. Even without running the engines.

    No smoke, no temperature issues, clean bilge, clean oil.

    Before I call the dealer again: any helping ideas?
    Last edited: Jun 5, 2022
  2. Pascal, Jun 5, 2022
    #2
    Pascal

    Pascal Senior Member

    Joined:
    Feb 29, 2008
    Messages:
    8,166
    Location:
    Miami, FL
    Cat heat exchangers are usually pretty good, it s the aftercoolers that have been having issues starting around 2004/2006 and have been subject to recommended replacement every 6 years

    I ve never C12s but with 3412s and C32s I ve never had the HEs pulled and tested. descaled in place every 3 or 4 years yes.

    if your dealer can’t figure this out after they pulled the HE, tested it, repaired it and then replaced it, I can only suggest finding another Cat specialist that knows what they’re doing. Where are you located ?
  3. Capt Ralph, Jun 5, 2022
    #3
    Capt Ralph

    Capt Ralph Senior Member

    Joined:
    Sep 8, 2004
    Messages:
    12,747
    Location:
    Satsuma, FL
    Are the engines just getting the air out. If the air is not bled out correctly, it could take a while. Empty bottles cold would be a result from this. Fill the bottles half way and try it again.
    Dont open the cap as vacume developed is trying to work for you.
  4. wannapost50, Jun 5, 2022
    #4
    wannapost50

    wannapost50 New Member

    Joined:
    Sep 5, 2014
    Messages:
    17
    Location:
    Newport Beach, CA
    I had a similar problem on a 3196 (basically same motor) problem was the coolant rail o ring. With engine running and cooling system pressurized no leaks, engine cooling down and cooling system depressurized it would leak ? I spent $thousands figuring this out and I really cant point any fingers at CAT or my really great technicians. Expensive lesson but by god I know every inch of my cooling system now. Hope this helps, better yet hope this is your problem it's a cheap and easy fix.
  5. xF_PP, Jun 5, 2022
    #5
    xF_PP

    xF_PP New Member

    Joined:
    Aug 3, 2013
    Messages:
    37
    Location:
    Moon
    My observation is that the coolant loss does not appear to occur while the engines are running. I can't say yet whether it's in the cooling phase or while they are standing still. Anyway, the bilge is clean. It is noticeable that both engines lose coolant.

    And yes, my confidence in the Cat dealer is starting to wane even though they try hard.

    Where is the coolant rail o-ring located?
    I assume that this O-ring will always be replaced when a new heat exchanger is installed, right?
  6. Pascal, Jun 6, 2022
    #6
    Pascal

    Pascal Senior Member

    Joined:
    Feb 29, 2008
    Messages:
    8,166
    Location:
    Miami, FL
    I ll ask again… where are you? Your profile says “the moon”. That may be cute and witty but it makes it difficult to recommend alternative cat specialists!

    there is no excuse for a cat dealer to rebuild, re install then replace a heat exchanger and still be loosing coolant. Maybe be acceptable in some “you know what” hole but not in the civilized world
  7. xF_PP, Jun 6, 2022
    #7
    xF_PP

    xF_PP New Member

    Joined:
    Aug 3, 2013
    Messages:
    37
    Location:
    Moon
    Alicante/Spain heading to Cherbourg/France as soon as the boat will be ready to leave.
  8. Capt Ralph, Jun 6, 2022
    #8
    Capt Ralph

    Capt Ralph Senior Member

    Joined:
    Sep 8, 2004
    Messages:
    12,747
    Location:
    Satsuma, FL
    With a coolant recovery system, air / coolant is pushed out to the bottle until the coolant gets warm, then the cap closes.
    When the engine cools, it draws coolant back in from the bottle.
    The design is, after a while all the air has been pushed out of the system if you leave the cap alone and ad coolant mix to the bottle.
    Your engines require many gallons of coolant and when completely drained, it takes bleeding the system of air and patience for the last of the trapped air to work out.

    I am sure a coolant pressure pump has been used to look for leaks. Here, these are available in many part stores and may already be a part of your ships tool inventory.
    My next thought; with these pumps, some folk want to really pump things up.
    Pending your heat exchanger design, seals or gaskets can be deformed and cause leaking into the raw water side if over pressured.
    When testing with these hand pumps, 8 PSI (0.55 bar) max. This should hold well over night.
    Robertoman likes this.