Mild coolant leak

[melloh]

Hello FOlks.  About 3 years ago, I did a pretty much complete rebuild of the coolant system (and did the intake/plenum delete).  All new hoses, pump, clamps, etc.  

Ever since then, there has been a slow leak as evidenced by a periodic small pool of coolant towards the front of the block (in that 'valley' under the intake and injectors).  First evidence was the squealing belts.  The leak has been very slow, but annoying.  The car was parked for  about 2 years, now driven a few thousand miles (3-4k.. the odo isn't working even with new gears..  another problem another day) and I'm just having to top off now.

When I first did the job I went crazy and redid everything... took it apart and put it together again - evey hose is SNUG.  I've narrowedit down to the one place I cannot tighten it - where the "water pipe connector" (http://preview.tinyurl.com/7clvxu5) joins with the block.  I intend to take out the pipe, use a dremel with a wire brush attachment to clean out the openning at the block, and reattach.  

The question is this - any recommendation on a sealant??? I didn't use sealant the first 2 times b/c I didn't see it mentioned in the manuals I have or online. Obviously it needs to be high-temp, but it will also need to resist corrosion from the water.

Thanks in advance, folks.

[keflaman]

When you rebuilt your cooling system did you install a new water pipe with O-ring?

[Geoff]

not only does the pipe require an o-ring, as previously noted, it also is made of plastic and will crack.   if you think you have narrowed it down to that area,  replace the pipe and the o-ring.
                                                         Geoff

[jetteman]

Replace the pipe. Just fixed the coolant leak on the new beater. The pipe was deteriorated at the o ring. It was only $16 from the dealer.

[DesktopDave]

Don't get the Uro part if specified.  It doesn't fit, the mouth was formed improperly and it won't sit flush on the block..  The OEM part is the way to go.  Get a new o-ring too, it's cheap insurance.

$18.95 at BMW of South Atlanta.

[melloh]

Sorry for the delayed reply.  I forgot to "subscribe" to the thread (I wish it would auto-subscribe, honeslty...)

The pipe is/was new when I installed it.  I only buy oem unless otherwise recomended to buy OE or superior parts by group consensi from sources such as here, r3vlimited, etc.. For reassurance, however, I have no problem buying another new one if I suspect the pipe itself is the problem.  However, at this time I don't feel there is enough evidence suggesting that the pipe is the problem (yet).

It was so long ago, I cannot recall with 100% certainty that the o-ring was replaced.  If it came with a new o-ring, then I am pretty sure I used it.  I'll have to check that when the weather allows me to work on the car (I don't have a garage).

I do recall I had a heck of a time shoving that part in.  IF I do have a new o-ring in and I still suspect its the source of the leak, is it ok for me to use some sort of sealant to reassure me that its water-tight?

[DesktopDave]

I'd avoid using a sealant on that ring.  I'm not sure what the seal is made of and some sealants attack synthetic rubber.  The o-ring should be more than adequate by itself.

[melloh]

What if I use something like this?

http://www.amazon.com/Hondabond-High-Temp-Silicone-Liquid-Gasket/dp/B006YTTV4W/ref=sr_1_25?s=automotive&ie=UTF8&qid=1334825320&sr=1-25

This website suggests it's designed for "metal-metal, metal-plastic, and plastic-plastic" - 3rd from bottom of page. Amazon page also indicates it won't corrode aluminum (makes sense since Hondas use a lot of aluminum)
http://handa-accessories.com/civmaint01.html


Or, what about Hylomar "Blue" or "Racing Formula"?
http://www.newmantools.com/chemicals/hylomar.htm
http://www.hylomarsealant.com/_resources/_html/products.html

[Geoff]

I'd tend to agree with Dave,  the part should be clean, the block should be clean, the o-ring should be new-and thats it.    I dont have any experience with that honda stuff,  so cant really comment.   However,  I have used hylomar products in the past and I have to say..they aint really all that..
                                                 Geoff

[bmwman91]

I ended up having to use some silicone assembly grease to get my new pipe & O-ring in. Dry, it just wouldn't go into the hole, and I actually ended up damaging it (so I had to run to the dealer mid-project!). As far as I am aware, silicone lube (the kind in a tube, NOT the spray stuff) is totally benign and should be fine. Don't use anything oil-based or that has solvents in it.

Alternatively, since antifreeze is sort of slippery, you might be able to put some pure antifreeze onto the ring & slip it in with that. I assume that is fine since the O-ring is designed to be exposed to it.

With all that said, there should be NO need for sealant on there. If it is leaking, it was either damaged upon installation, or the mating area in the block casting was dirty. Pop it out, and clean the heck out of the counterbore where the O-ring sits. Make sure that there is NO dirt or grit in there. O-rings really only work on smooth surfaces.

[melloh]

Cool.  Thanks for all the input.  Yeah, then it looks like I need to pull it apart and really clean the heck out of it.  I think just for kicks I'll buy a new one w/ new 0-ring.  I'll go w/o the sealant.  

Any tips on cleaning it?  I'm thinking of getting a soft wire wheel attachment for my dremel and getting that on it.  (Going to fill the hole w/ a heavy plastic to minimuze bits getting in there.)  I tried just regular engine cleaner and a towel when I first did the job and I could feel that the mating surfaces were not smooth.  I'm just afraid of going too far and boaring it out a bit.