Mazda 323,Mazda 626 & Mazda 929 Whether the compact 323, the mid sized 626, or the full sized 929, these vehicles remain very popular even though production has stopped.

Coolant leak - 1992 929

  #1  
Old 04-11-2016, 12:36 PM
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Default Coolant leak - 1992 929

Hi group, I have a coolant leak coming from somewhere between the firewall and the intake manifold...right in the middle it seems like. I can't see it from above nor below. I tried using a mirror and no luck. It only leaks once the thermostat opens or at least it seems that way because it doesn't leak for 15 minutes or so when cold. Any idea of any hoses back there? I can see the heater core hoses and they look nice and dry. There is one in the corner of the intake manifold by the ABS system and looks good too. I also checked the one under the intake manifold by the brake fluid reservoir, and the one by the thermostat and they all look fine. Upper and lower large hoses are fine. I really don't want to remove the intake manifold since I just did it a couple of weeks ago to replace the Fuel Damper. Not too complicated but it does take some time and I would need a new plenum gasket. I don't recall seeing any coolant hoses back there but I wasn't really looking for one at the time. I only need this car to last another month or so. It is my son's and he is saving up for another car. Thank you for any help you can give me.
 
  #2  
Old 04-11-2016, 06:02 PM
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I remember your damper issue. Still starting in the rain I assume. Do you have a coolant line to the throttle body on your car? If so, possible clamp didn't get tight enough or small hole in the line.
 
  #3  
Old 04-12-2016, 09:28 AM
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Sparky, thank you for helping again. Yes, still starting fine in the rain...and we keep getting plenty of it.
I do have a coolant line to the throttle body and it looks fine. I was able to check all the hoses that I touched and they all look fine/dry, with no cracks. Looking at the heater core diagram, there is a metal tube by the firewall. See part 61-230A in the attached picture.
Unfortunately the Intake manifold would have to come off to get to it. I'll try to do it today. I am not planning to replace the plenum gasket again...I hope this doesn't create a problem. Nobody has it in stock and I can't wait a week to get it. I'll report back.
 
Attached Thumbnails Coolant leak - 1992  929-heater.png  
  #4  
Old 04-12-2016, 03:46 PM
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Well, I just removed the intake manifold and still can't find the leak. It is very tight and hard to see. I might have to start removing more stuff like injectors' wire harness, and other hoses. Anything I should be looking for back there?
 
  #5  
Old 04-12-2016, 04:25 PM
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I can see some coolant on the valley under the intake manifold. I think I'll remove it since I can't find anything else wrong. Shouldn't be too hard. FYI, what I had removed before was the "upper" intake manifold.
 
  #6  
Old 04-13-2016, 06:16 AM
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It is not very easy after all to remove the intake manifold. Instructions say to remove each injector but I am pulling really hard and they don't come off. I am afraid I'll break one. Do they really need to come off or can I just pull the fuel rail with the injectors still attached?
Also, looking at the diagrams for the water cooling, I don't see any water hoses underneath. See attached. I am afraid I'll remove it for no reason.
 
Attached Thumbnails Coolant leak - 1992  929-cooling-diagram.jpg  
  #7  
Old 04-13-2016, 06:31 AM
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Is this a V6?

Ive seen a few of the old V6's have a coolant pipe that runs thru the valley thats rusted thru, or split a o-ring.
 
  #8  
Old 04-13-2016, 06:38 AM
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Yes, it is a V6. What year V6 are you talking about? I am tempted to pull the intake manifold but want to make sure there is a pipe or a hose there. Thank you for your help.
 
  #9  
Old 04-13-2016, 06:58 PM
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Grim_reaper, you were right. It is a hose that goes from the end of the passenger side head, on the firewall side, to the EGR valve. The only way to get to it was by removing upper and lower intake manifolds. It looked worse than it was. I just ordered a manifold gasket kit from Rock Auto for $16. The only other part I need is the hose. The old one had a small crack right where it meets the fitting by the head. I might replace some vacuum hoses but surprisingly they don't look brittle and are still flexible. Looks like this 929 will stay on the road for a while longer. I almost gave up. Thank you everyone for your help.
 
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