Coolant leak 81 308 GTSi

When warm, the rubber components soften and seal better. Also, metals expand so cracks and gasketed joints can seal better when warm (even though the pressure is higher when warm). The tool you need to buy or borrow is a small hand pump made by Stant (Stant 12270) -- it mounts to the coolant filler neck, and allows you pressurize the system when cold:

http://www.sjdiscounttools.com/sta12270.html

 

I just finished chasing down a similar leak; it was fine when hot and under pressure and didn’t leak until after being driven then parked for a few days. Most of it seemed to be coming the front (timing cover area) but I couldn’t see where it was coming from. Since it acted like a hose connection I checked the hose clamps that I could see and reach easily. Some had signs of leakage between the hose and pipe so I tightened the clamps, but none were in the area I was finding the majority of the drops (hanging from the bottom of the engine).

I knew there were coolant tubes/hoses on top of the engine block and under the intake plenum. The only service invoice that came with the car showed “replaced hoses under manifold” with no part numbers, so I’d hoped they were good. I couldn’t be sure what was actually done.

I bought a $30 wifi endoscope (brand = Nidage) in hopes of diagnosing the problem. I stuck it under the plenum and sure enough I could see leakage between one clamp and the hose and there was a small puddle underneath.

I removed the intake plenum and continued to investigate with the endoscope. Believe it or not, removing the plenum didn’t allow me to see a whole lot more, but I was able to scope each end of each hose and isolate the leaks. The bottom-most hose turned out to be the culprit. I tightened the clamps on each end and reassembled. Now I just need to wait for a few days to see if it’s fixed. If not I’ll just plan to pull the plenum again and replace the hoses.
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Replace them all on the entire system. If one goes they are all due for a change. Just saying......

 

Must be the ethanol in the coolant.

 

If those photos are showing green coolant leaking from the hoses I would ask if that coolant is specifically for aluminum engines? I am not aware of one that is green and is recommended for our cars. As for the hose, I agree, if one is getting weak or leaking, there are 10 others that should be replaced at the same time. It takes a good weekend to do it all right but its worth the effort and not too expensive.

 

"I would ask if that coolant is specifically for aluminum engines? I am not aware of one that is green and is recommended for our cars."

Any brand of coolant made today is suitable for aluminum engines. The various colors USED to indicate longer-lived coolants of various lengths but nowadays that's not really accurate anymore. IOW, the colors don't matter; any antifreeze you buy is fine for the engine. Standard (green) ethylene glycol antifreeze was typically scheduled to be changed every two years/50k miles; there are coolants now that are designed to be changed every 10 years/300k miles and different brands use different colors for the same spec product.

Hmm...installing some 10 year coolant will probably be the last time you'd ever have to do it...In 10 years ICE cars will probably be banned from public roads!

 

I have seen that "leak while sitting" problem on 308. It's normally the old water pump, or the hose connections around the water pump area. The amount of torque needed on those hose clamps makes me feel uncomfortable but that is what it takes.

 

Not quite true ... there *are* types of coolant that are not cross-compatible; they shouldn't be mixed.

 

Good point that I should have mentioned! I was just (incorrectly) focused only on the "OK for aluminum" aspect. Thanks for adding the very important point that although they all may be compatible with aluminum, they may NOT be compatible with each other!