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Hey everyone like the title says my car is leaking coolant from the backside of the engine. I took it in about about week ago for its regular oil change at my local dealer and they had me come back to take a look at this leak. Coolant was leaking off of the transmission housing and seems to be originating from the backside of the engine. The only thing that I know of on the back side that carries coolant is the heater core hoses but cannot find the leak on either of them. Any one hear of this happening? I have previously replaced the water pump around 100k miles for a coolant leak and car is at 128k now. I am working on getting a pressure tester currently to help hunt down the leak. Any other tips or tricks I can do to remedy the situation? If you want more pics Ill be glad to go take some.
The lower intake manfold contains the heater core 'through pipe'. http://iihs.net/fsm/?d=814&f=Engine.pdf&p=6
You can see how the thermostat housing connects to the pipe on the intake manifold, and then in the back is the connector for the heater core hose. If this has cracked in some way, it'll drip in the valley and then exit out the back. So maybe that's it. And you'd sorta wanna hope that is because...
There's a coolant jacket surrounding each cylinder. And there's four other ports on the lower side of the heads. These all connect from the block to the head to provide cooling of all things. http://iihs.net/fsm/?d=179&f=Engine%20Cooling.pdf&p=2
If the head gasket's let go on the left side (as it appears in this picture) on the rear, the rear cylinder jacket would be leaking. If it's at the lower rear corner, that passage would leak. Then this might be a result. It could also be a problem with the head bolts, but I'd highly doubt that, you'd probably have WAY more issues than a little coolant leaking. Of course, this is a head removal thing to fix... not sure what the cost to repair vs a new/'new' engine dropped in is... Can't be worse than the water pump replacement, nearly same procedure to a point, all the same stuff has to come off to get to either...
Past that... yeah, there's not many more places for coolant to come out. I agree with the pressure tester, but I'd also say that if you got the engine warmed up you'd probably see it that way too, so...
Hope that helps ya out anyway. Good dang luck! And welcome to the forums!
Hi I have right now what it seems to be the same problem.
The coolant is dropping very fast from the top/back of the engine when I turn it ON. I can see the leakage goes through the clutch system to the floor but can not see very well were in the top/back engine it comes from due to narrow space.
Ya I got you. The guy who originally replied was on the right track and helped me focus my trouble shooting.
So after a lot of watching the car and tracing the leak I narrowed it down to the seal between the lower intake manifold and the engine block. I had some issues with corrosion in the cooling system from the original owner he must have mixed coolants or added something he shouldn't have. (See the part about how I had to replace the water pump.) All I did when I replaced the water pump was force the leak to the next weakest or most susceptible part of the car. Bunch of sediment and corrosion got up between the lower intake manifold and block pushed a seal just barely enough out of the way and caused the leak.
I got a pressure tester for the cooling system and pressurized it and that was the biggest help in finding the leak as I would see the pressure dropped and I would go looking for it. Eventually I resorted cleaning the back of the engine as good as I could so when I went in with a white paper towel I would see if there was any red coolant on it.
It was quite the fix to be honest, upper intake manifold had to come off then the fuel rail and some other stuff that I am drawing a blank on. I ordered a whole new lower intake manifold and reinstalled and did the best I could keeping everything clean and did a coolant flush to the best of my ability. And I have had zero issues with it since and I have on an additional 40k miles since this post and fix.
I don't know if this will help you with your issue since mine leaked slowly while running and when it was off but I hope this helps!
8/6/20 | 02:56 PM
And welcome to the forums! 
