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2G Coolant leak help

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88BB8B

Proven Member
179
18
Oct 14, 2016
Coldstream, BC_Canada
Hi guys. I've done some searching, and everybody with a coolant leak on their 4G63 seems to be getting it on the driver side, from the water pump or oil cooling lines. I have a coolant leak that seems to come from the passenger side of the engine, and will drip down the back of the transmission on flat, and down the front of the engine on a hill. A I sealed what I thought was the culprit (I think the thermostat housing) but it persists. Either I sealed it poorly (but I think I did it well) or it is leaking from somewhere else on that side. Coolant is totally clean and free of oil, so I doubt its a head gasket, but I have an extra if it is. You guys have any idea where this coolant may be leaking from? Another note, it leaks when the engine is turned off, and tends to leak when the car is slanted in particular ways (sometimes if I park right, it doesnt leak at all)
 
While running, wiggle all coolant hoses near any clamps to see if it leaks there (hoses cracked or clamps loose). Also radiator cap. If can't find it, buy or rent a coolant system pressurizer which attaches in place of the radiator cap. When you pump up the pressure it should leak at the spot. If not, wiggle hoses again when under pressure.
 
On the trans side of the engine, there's not much that can leak. BUT I've seen pinhole leaks form in the turbo's 90* rubber coolant return line that returns it to the lower thermostat housing... just replaced one the other day
 
I recently had to diagnose a coolant leak myself. Mine was at the overflow hose by the cap. One of the clamps, assuming it was factory, was just weak as heck and causing a noticeable drip with the car off usually. Wasn’t pouring on the floor like a waterfall, but I’m kind of OCD.

Made me thing it was coming from the actual radiator hose since when it would drip, it’d make its way around that area. Ended up removing the small hose, cleaned the ends, and putting a new set of clamps on it after a visit to ACE.
 
On the trans side of the engine, there's not much that can leak. BUT I've seen pinhole leaks form in the turbo's 90* rubber coolant return line that returns it to the lower thermostat housing... just replaced one the other day
On the contrary. Thermostat housing. Heater hoses, turbo feed, coolant temp sensors, rad hoses, coolant pipe. All possible culprits. On an aging car I replace all the hoses. Yes, every single one.
 
Thanks for the help guys, its been really hard to pin down what the cause is, but some development. I think I have a second leak now? And the other has stopped? I'm perplexed. Last night it was leakning waterfall style from behind the oil filter. Dripping off the coolant likes back there. Not sure if it is one of those lines, or the water pump, but its intermittent. It was going like crazy last night and today, anytime the car got up to temperature, but just now when I went to check... Not a drop... Coolant completely full, engine up to temperature.
 
So first it was on the passenger side and now it's on the driver side? And you have a 4g63t motor right?

Have you checked to see if its at the water pipe ends? One connects to the passenger side of the block to the thermostats housing with an o-ring to seal it and the other to the driver side of the block to the water pump with an o-ring to seal it as well.

Being that you get it at different sides and randomly, maybe those could be a good spots to check since coolant flows through there
 
When in doubt if you have no history of the hoses take them all off, clean and replace every one. Hoses fail. Pipes corrode. It takes longer to keep guessing than it does to take it apart and make sure every connection is good.
 
Thanks for all your helpful advice guys. I found that the drivers side leak is just a hole in what I believe is the turbo return line, as for the passenger side, it was leaking significantly less, and I havent seen any drops off of it for a couple days, maybe it resolved itself.
 
Thanks for all your helpful advice guys. I found that the drivers side leak is just a hole in what I believe is the turbo return line, as for the passenger side, it was leaking significantly less, and I havent seen any drops off of it for a couple days, maybe it resolved itself.
Leaks do not magically fix themselves. Investigate and repair. Ignore it and wait to be stranded or worse. Your choice
 
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