Beerman

I have a coolant loss mystery that I think I solved on my 2008 Si. I found the source of the leak and hope someone here has either dealt with the same issue or can offer some advice on how to fix it.

It is difficult to see, but the leak is coming from the front of the engine, looks like where the black coolant hardline that runs under the intake and meets the thermostat housing.

Between number 6 and the thermostat housing, they call it the heater pipe:



I tried to wedge my phone in there to get video and tried to get an inspection mirror back there to see more. Didn’t work well. So I guess it could be the housing itself or the rubber hose (number 3)

A few questions:
- The end of the black pipe looks a bit rusty, should I go ahead and order that pipe?
- Do you think it is just the O-ring? (number 12)
- If anyone has attempted this fix (or similar), did you have to remove the intake manifold to get some space in there? Any tips to access this part of the engine?

I did replace the thermostat itself last week (kind of a bitch), thinking that was the cause of my overheat, but turns out it is a leak.

Thanks in advance!

06 EX Mild Mods

Send a private message to Ezone he is a very knowledgeable long term Honda Mechanic who has helped me a few times. If the black pipe looks structurally sound painting it with a high temp rust resistant paint is probably cheaper. I wouldn't be surprised if the intake manifold has to come off, nothing seems to be easy working on a shoe horned in front wheel drive engine. Like your posting name, having a few of those now.

ezone

Replace O ring #12 and see if that stops the leak? Sometimes just disturbing one of those aged seals is enough to make it start seeping.

On the pipe, if the area of that O ring is rusted, smear a bit of RTV in the groove to help aid in sealing?