Leaking anti-freeze/coolant...where?

[add|ct]

Alright, so I'm under the car this evening fixing a small oil leak at the Oil Pressure Sending Unit/Pressure Switch(just above the oil filter, next to the breather chamber where the PCV valve seats); on this Civic VX it's just a dummy light not an actual oil pressure gauge...

So, while I'm under the car I notice what 'appears' to be crusty white, milk-like substance coming from above the breather chamber, like a slow drip hardening over time.

I'll be posting a picture later of this area, it 'appears' to be intake manifold side next to the block right next to the breather chamber, closer to the passenger side/area where the larger coolant hoses tie together.

I did check my overflow reservoir, and it is in fact losing coolant. Down most of the way now(below the MIN), after having it at the MAX line this spring around April 1st. So, in 5 months, it has consumed 'nearly' the amount of coolant that was in the reservoir.

I have had Used Oil Analysis performed, and initially it read high for Sodium, but that was traced back to the use of Valvoline MaxLife, since it has 300 ppm or more of Sodium in it's formulation(anti-foaming additive package).

So, the subsequent UOA showed only 18 ppm of Sodium(first showed 66 ppm of Sodium, 1 oil change removed from Valvoline MaxLife)...the other contaminants would be Potassium(K) and Silicon(Si). Neither have been excessive, with K being relative just in the 'noise' range. Where as Si was 'worth observing', as the goal was to make sure the use of K&N drop-in replacement wasn't allowing in too much dust/fine particles of dirt/sand, etc.

So, wear particles in the UOA testing has looked normal compared to other Civics this gen, and so I don't think it has a blown head-gasket or anything like that I hope(as you may have read in my other posts/threads, clutch is needing replacement so power is lacking at times in 1st/2nd)...so my concern is the loss of coolant and I 'think' oil 'may' be mixing with it possibly, unless it's just silicates(?) depositing on the external engine from heat. If it is oil mixing with the coolant, it hasn't shown up as of yet. I will be getting a UOA again within the month.

[add|ct]

Well, upon further examination I can't confirm if it's a coolant leak. I remember the other day I pulled the radiator cap so that may have affected the pressurized system and caused some fluctuation between the main cooling system and the overflow reservoir.

The level is about where it settled when adding up to the max line this spring, so if it IS loosing coolant it is slowly. Not like previously, either way I don't believe the coolant leak is internal, per se. Perhaps by the part that the hoses connect to with the thermostat(the housing?), just beneath the VTEC solenoid/housing area.

I don't know if it is the breather chamber itself or something mounted to the block itself, then, but more like from above it.

I didn't have to remove the oil filter to replace the OP switch(aka OP sending unit), so I didn't remove the breather chamber this time, but will during the next oil change.

I'm still going to go ahead with another Used Oil Analysis to confirm there isn't coolant into the engine. The car started up great with the replacement sensor, I cleaned up the 1 wire connector with MAF sensor cleaner and let it dry while I picked up the replacement sensor, restarted right away after letting it 'set in' with Ultra Grey on the threads/seated into its location on the block for about an hour.

The oil light didn't stay on for 2-3 seconds like it used to, it came on and went off immediately once started. No hesitation, flickering etc, so I'm pleased. I'll monitor for leaks over time there.

Not sure what the goo is, I swiped some away with my finger and it 'seems' to trace back from the Intake Manifold(where it mounts at the block) somehow.

I've got some pics, from the bottom of the engine while replacing the sensor(notice connector dangling next to oil filter)

The breather chamber is somewhat in the background, center of pictures. Notice the crud on the right near some wire harnesses?

http://img402.imageshack.us/img402/6020/1003556z.jpg

http://img600.imageshack.us/img600/8220/1003557.jpg

Breather chamber up close, gunk caked on towards the right(behind bracket):

http://img69.imageshack.us/img69/9408/1003559b.jpg

http://img853.imageshack.us/img853/3486/1003562tk.jpg

So, I suspect the 'source' to be from the area above with the coolant hoses, if that is indeed coolant? Felt sorta like 'old' goop, hand cleaner if that helps?

[add|ct]

Shot at the IM, from the passenger side(notice the 'bump'?), it almost appeared like there was a hole in it to the naked eye, perhaps not quite, but also several on top of the IM itself looking down at the runners, are those normal? It almost looked like 'patches' that are coming 'undone'?

http://img571.imageshack.us/img571/7492/1003563r.jpg

Also, some of the residue in that area appears to be caking the underside of the IM as well. The manifold itself may be corroding away.

[GasSavers_Erik]

Those "patches" were made at the factory are likely covering the casting holes for the EGR passageways inside the intake manifold. There was a post a few years ago about how to drill them out and clean the individual passageways.

That goo puzzles me. Is there any hint of a milky substance/film on the top of the dipstick or on the underside of the oil filler cap.

[add|ct]

Interesting regarding the EGR passages routing like that, I didn't know about that.

No, there is no hint of even a slight film of milk to the oil, dipstick or fill cap.

It appears as though it's coming from the joint where the thermostat housing is next to, where the hose routes over to the water pump/post thermostat, which runs along the backside of the engine underneath the IM.

It's possible this is a previous coolant leak that has dried up(from past parts replacement, like a thermostat?), but I will probably try to make sure each of the clamps at the hoses are holding tight. It was hard to see the source for the substance underneath the vehicle.

As you can see in these pics, it could be from any one of the hoses above the oil filter location, I just hope the internal crossover pieces aren't going. I don't see a leak on the ground and I don't think it's losing much like I first feared when I pulled the car on ramps yesterday to replace the OPS/OPSU.

http://www.hondaautomotiveparts.com/...r301_e1510.png

http://www.hondaautomotiveparts.com/...3sr301_e15.png

[add|ct]

UPDATE: So, apparently that's a pipe from the t-stat housing/heater hose to cabin routing; which also routes from the water pump next to the block. I suppose it's possible there is a crack in this pipe at the joint near the t-stat housing OR perhaps a house clap in this location is weeping?

I remember 'slightly' overfilling the cooling system. I added about 2-3 ounces above the MAX line to an empty reservoir over-flow tank...but was it too much for the system to handle? It has settled nicely between the MIN/MAX lines since then(4-5 months have gone by)...is it possible that I in fact overfilled it slightly enough to cause a weak clamp at a hose to weep?

[GasSavers_Erik]

No- overfilling would not cause the leak. The spring loaded rad cap keeps any excess pressure from building.