Rep Power: 271

alright guys.. today i put everything in the car today, the motor turbo and everything. engine starts up, got a cel but right now thats irellavant. when i was pouring coolant into the radiator after about 10 seconds a lot of coolant leaks from the back of the block, seems to be coming from somewhere from above the oil filter. the car was off while i filled it up. i tightened the coolant bolt on the back of the block and the leak is still there. i dont really have enough visibility to see where the leak is coming from and it is very hard to pinpoint the exact location of the leak because it splashes everywhere/drips everywhere. is there any coolant hoses that connect to the back of the block? maybe i missed something but i double checked mostly everything. thanks for any help.

 
Rep Power: 0

You've got your main water line back there that runs from the water neck (hard line) does a 3" rubber hose transition and then switches back to a hard line to run into the water pump. I would check the crappy stock clamps on that hose transition first. There should also be a heater that goes in back there too.

 
Rep Power: 271

sweet, thanks foos. anyone else got pointers?

 
Rep Power: 271

okay well i checked out where the leak is coming from. it wasnt from the rubber hose. it is actually to top left of the oil filter above this small black thing attached to the block. say this...

( )( )( )( ) <--- intake mani
_________ <--- water neck hard hose
???? <----- leaking somewhere?
[ ] <----black box looking thing
O <--- oil filter

the black box has a small rubber hose hooked up to it and i have no idea what it is. anyone know of anything coolant wise that could be leaking from there? i hope i dont have to take my motor out and put it back in again. that would be a bitch. is it possible that the block is cracked? the member that i bought the motor from packaged the block very VERY poorly. it was a cardboard box with newspaper and the block. insane huh. can cracked blocks be repaired if this is a possibility. grrr this is pissin me off

 
Rep Power: 237

nope...cracked block = reaches in wallet
but id make damn sure it wasnt just somethin else first, like a hose cracked, etc...

good luck

 
Rep Power: 350

I doubt very seriously that anything is cracked. The black box that you're referring to is the oil/air separator, it allows air to vent from the crankcase and that little rubber hose is a vacuum line. No, you aren't leaking coolant from there.

However, that big bronze water pipe that's at the top of the block hooks into the water pump outlet on the driver's side of the motor. Guess what? It has a big o-ring that seals it into that position. My suggestion, pick up a new o-ring for that pipe and install it. I bet you will solve your leak issue.

The part you need is #21 in the pic.

 
Rep Power: 0

Ah, there you go Andy. Good stuff.

 
Rep Power: 350

Yeah well, I know where every seal, nook and cranny is on this motor. I've had it apart soooo many times, I think the only person who knows this motor better than I do is Gery.

 
Rep Power: 237

so basically this black box is hondas effed up PCV valve?

wow

 
Rep Power: 343

its always been. and it obv works. my b18a1 has it. its a black box that connects into the block and it has one hose into the head than one that goes through the i/m into the valve cover... i would HATE to have to work on it when the motor is in tho because its behind the i.m bracket....for me anyway.

 
Rep Power: 237

my 8th gen has a hose from the CAI pipe to the valve cover, so i dont think my FG1 has this so called black box??

 
Rep Power: 343

yeaaa thats something completly diffrent. ALL cars have that. well all cars i have ever seen anyway. its called a breather tube.
and i went out to the 8th gen to see if it had a box. man that bay is small.. i didnt feel like getting into it. if anything it prob would be in the back of the motor. where you cant see very easy.

 
Rep Power: 271

sweet thanks for the help andyman. thinking about what you said im pretty sure the leak is coming from there now. looks pretty hard to replace the o-ring from under the motor. what should be the easiest way to get at it? probably remove the intake mani? i never removed the intake mani with the head on in the car, i always left the intake mani on. any pointers?

 
Rep Power: 0

Just remove bolts 24 and 26, the heater hose, and pull the whole thing out. You shouldn't have to pull the IM to get it out. Start with the piece of hard line that you can see first and pull the one from the back of the block after you get the first one out.

 
Rep Power: 271

^^ very nice. i feel so n00b. lol thanks foos.

 
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I had a similar leak from the back of the block. It turned out to be a tiny hole in the coolant pipe. I have removed it by taking off the breather box and disconnecting the two pipes (and rubber joining hose) from there. There were a couple of brackets on the two pipes and when they were removed I was able to pull it out of the back of the water pump. Make sure you disconnect the wires on it before you pull!

 
Rep Power: 253

Thanks for contributing and helping, but you need to check the date of the thread. This thread is 5 years old.

 
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Sorry. I had this problem last week, googled it and this thread came up. I thought others might find it the same way and would appreciate the info. I am new to this so I don't understand - is there a concern with adding to an old, but useful, thread? Was there a better way for me to have gotten (and added) newer, better info?

 
Rep Power: 253

No its fine, just since this thread is so old op does no longer need help.

Adding info is fine, just try to refrain from opening older threads when its no longer needed.

If you have a problem you cant find any info on or not enough info, dont be scared to make your own thread.

Have fun.

 
Rep Power: 0

I know this is an old post, but it came up in my search. I have the same problem with an 04 Civic, a leak from just above and to the left of the oil filter. Did you confirm what the problem was?

 
Rep Power: 118

Aye it’s a old thread, but I suspect more and more owners will be encountering this problem as those oring harden and leak.

 
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Thanks Slumpertcivic. This was my daughter's car, and she got a newer one, so this sat outside last winter. I don't know if there was water in the engine, or antifreeze, so I thought maybe something was damaged from freezing. Maybe the o-ring dried up from sitting. So this is where the water pipe connects to the water pump? Someone referenced part #21 in the picture, but I don't see a picture.

 
Rep Power: 223

Here's a pic. This probably won't be easy to replace.

 
Rep Power: 0

Hey guys!!!! I have the exact same leak. My 2003 ex civic coupe 1.7l vtech 5 speed manual. I just got done doing a timing belt and head gasket, water pump, radiator and hoses, t stat. Upon filling up, coolant leaking out of the back of the block, drivers side top, just under the head. Theres a machined hole the size of a pencil eraser, not threaded from what I can see. Just dumping out of there once i have about a gallon of coolant poured in. WHAT DO I DO!?!?!

 
Rep Power: 125

Did you even read the thread?

 
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Yeah, guy, i read the entire thread. Then just now, again, thinking i missed something. The leak im experiencing doesnt have a hose, hardline, or anything that plugs into the hole. I was hoping to receive help... thanks.

 
Rep Power: 223

Can you get a picture of where the leak is coming from?

 
Rep Power: 125

Then it’s obviously not the “exact same leak”, is it?

 
Rep Power: 0

Good afternoon. I have the same exact problem. Were you able to figure out how to fix this leaking coolant? Thanks in advance!

 
Rep Power: 118

Glad you know you have the exact same leak.

Without pictures of your leak, your just going to be getting guesses...