Coolant Leak, rear of engine

Hey Guys. I have a persistant small coolant leak that is coming from somewhere at the rear of the motor on my LS1. I originally thought the coolant blanking plugs were the culprit (and they were leaking). I have since replaced the o rings on them, but am still getting drops of coolant on the shed floor. Is their anything else, other than a head gasket :( that might be the culprit? I have just given the motor a good wash with hot water to eliminate any prior coolant from the blanking plugs that may have been dripping down, so fingers crossed.
Any advice appreciated :)

I had the same issue when a I got the SS, with coolant around the the blanking plugs at the back of the motor. In my case it was coming from the front of the motor and finding its way back under the intake, making it look like a head gasket leak.
They can also have porosity in the block, but that's probably unlikely.

Have you inspected all of the heater hoses where they join the firewall?

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Originally Posted by BLACK 346

Hey Guys. I have a persistant small coolant leak that is coming from somewhere at the rear of the motor on my LS1. I originally thought the coolant blanking plugs were the culprit (and they were leaking). I have since replaced the o rings on them, but am still getting drops of coolant on the shed floor. Is their anything else, other than a head gasket :( that might be the culprit? I have just given the motor a good wash with hot water to eliminate any prior coolant from the blanking plugs that may have been dripping down, so fingers crossed.
Any advice appreciated :)

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Head gasket is unlikely there are a few possibilities
Heater hoses rubbing on back of drivers side head causing a leak
Welsh plug on back of head
A coolant leak from up front of engine transferring making you think it is from the rear.

I had my heater hose rubbing at the back cause my leak.

Good luck with it rob, Id look at heater hoses first. before anything else, I remember finding one on my mates car, thinking it was leak near the exhaust manifold (had no idea why it would be leaking there apart from a cracked head) after a few hours of pulling the engine down to get to it all, by coincidence ran my hand on the underside of a heater hose only to find a small hole :doh:

it was then spraying onto the engine and looked like the leak was from the engine

I just replaced all my hoses and noticed one of the new heater hoses touches the back of the drivers side rocker, but cant remember if the old one did as well :confused:

Hope you find the leak mate, and its a simple fix!

best bet is to pressure test the system and then you can see where its leaking from. a little mirror helps to see in the places that are hard to get at

Thanks for all the replies fellas, some very helpful info in all of them. Will investigate further tomorrow :)

Cheers
Rod

Hey Guys,

Rather than start a new thread thought I would add to this one. Where is the best place to source the upper and lower radiator hoses for an LS1 M6 Commodore? Whilst searching for the leak that started this thread I found a nasty leak from the bottom radiator hose where it connects with the pump. I also want to replace those OEM clamps with some decent ones. Should I just grab OEM hoses from Holden, or are their good aftermarket ones I can source?

Cheers
Rod

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Originally Posted by BLACK 346

Hey Guys,

Rather than start a new thread thought I would add to this one. Where is the best place to source the upper and lower radiator hoses for an LS1 M6 Commodore? Whilst searching for the leak that started this thread I found a nasty leak from the bottom radiator hose where it connects with the pump. I also want to replace those OEM clamps with some decent ones. Should I just grab OEM hoses from Holden, or are their good aftermarket ones I can source?

Cheers
Rod

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Rod,

i had similiar ages ago and it turned out to be fine crack in the headder tank that ran along chassis rails etc then dropping out near back of motor, took weeks to find.

OEM hoses arent expensive from Holden, about $20 each for the main ones. Wouldnt mind betting they are cheaper than Repco or SC sell them for.

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Originally Posted by aratic

OEM hoses arent expensive from Holden, about $20 each for the main ones. Wouldnt mind betting they are cheaper than Repco or SC sell them for.

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Cheers mate, will just grab them from Holden then :)

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Originally Posted by klink

Rod,

i had similiar ages ago and it turned out to be fine crack in the headder tank that ran along chassis rails etc then dropping out near back of motor, took weeks to find.

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Hey Paul,

My leak is driver side mate, hopefully it is just a heater hose or something similare.

Cheers
Rod

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Originally Posted by BLACK 346

Hey Paul,

My leak is driver side mate, hopefully it is just a heater hose or something similare.

Cheers
Rod

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thats the sidde my tank split

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Originally Posted by klink

thats the sidde my tank split

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Radiator is only a couple of hundred k's old, should have done the hoses at the same time. Got a new top and bottom for the drivers side today and have fitted them, will see how it goes leak wise over the next couple of days.

I had a bad leak but couldnt work out why it was comming from the rear of the motor, I lifted it up and sure enough it was leaking from the radiator and dribbling along the rail and dripping down the back, it was only a hair line fracture as well but couldnt see it untill the car got hot and the crack expanded from the heat.

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Originally Posted by Arrow420

I had a bad leak but couldnt work out why it was comming from the rear of the motor, I lifted it up and sure enough it was leaking from the radiator and dribbling along the rail and dripping down the back, it was only a hair line fracture as well but couldnt see it untill the car got hot and the crack expanded from the heat.

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I have my fingers crossed that this is what mine is :)

Hey guys,

Can anyone tell me off the top of their head what diameter the heater hoses are on the LS1 (the ones in the engine bay that run over the drivers side chassis rail). I have found several leaks from what I assume is heater related hoses. It is the small device right next to the headers with 3 pipes running into it. Hoping some decent worm drive clamps will fix it, otherwise it might need some new hoses.

* goes out to measure*

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Originally Posted by Toddler78

* goes out to measure*

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lol, I did think of that, but thought maybe someone might know the exact pipe size :)

Rob, The one closet to the front is 27mm OD (approx 24mm ID) this goes into a tee about 100 from the water pum then goes back to 23mm OD
the other one is also 23mm OD (assuming same wall thickness then about 20mm ID)

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Originally Posted by Toddler78

Rob, The one closet to the front is 27mm OD (approx 24mm ID) this goes into a tee about 100 from the water pum then goes back to 23mm OD
the other one is also 23mm OD (assuming same wall thickness then about 20mm ID)

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Thanks mate, much appreciated :bow:

Rob, you'll probably find that its the heater tap leaking. they're not expensive

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Originally Posted by sikss

Rob, you'll probably find that its the heater tap leaking. they're not expensive

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If you're changing hoses and haven't done the heater tap recently I'd definitely change that too. They turn really brittle and leak, then when you go to pull the hoses off they break into a few pieces lol.

Thanks for the heads up on the heater tap guys, will grab one before I change the clamps :cheers:

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Originally Posted by BLACK 346

Thanks for the heads up on the heater tap guys, will grab one before I change the clamps :cheers:

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Hey BLACK346 everyone seems to be calling you "Rob" & I thought your name is "Rod". :confused:
Which one is it? :jester:

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Originally Posted by whitels1ss

Hey BLACK346 everyone seems to be calling you "Rob" & I thought your name is "Rod". :confused:
Which one is it? :jester:

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yes Ed it is Rod.

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Originally Posted by klink

yes Ed it is Rod.

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Okay Paul, thanks. ;)

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Originally Posted by whitels1ss

Okay Paul, thanks. ;)

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Bobgen3 is Rob

After my radiator blew about a month ago I decided to replace every hose, clamp and the heater tap. Not that expensive exercise really and easily done in a few hours. Good peace of mind will summer on its way too.

Loving the fact that I no longer have a coolant smell when I open the bonnet too

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Originally Posted by whitels1ss

Hey BLACK346 everyone seems to be calling you "Rob" & I thought your name is "Rod". :confused:
Which one is it? :jester:

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Hey Ed, yeah as Paul said, it is Rod, but I get called Rob that often I don't even notice anymore :)

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Originally Posted by aratic

After my radiator blew about a month ago I decided to replace every hose, clamp and the heater tap. Not that expensive exercise really and easily done in a few hours. Good peace of mind will summer on its way too.

Loving the fact that I no longer have a coolant smell when I open the bonnet too

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Wise move, think I might do the same. Might have to let the skin grow back on my hands from this last job before I tackle it though.

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Originally Posted by klink

Bobgen3 is Rob

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Yep thats me. lol

You guys were dead right, parts of the heater tap were more like cardboard than plastic. Probably something I would replace every few years as preventative maintenance now I am aware of it. Thanks again for the heads up. I am hoping that the coolant running down the chassis rail from this is what I was seeing on the floor, fingers are crossed.

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Originally Posted by BLACK 346

You guys were dead right, parts of the heater tap were more like cardboard than plastic. Probably something I would replace every few years as preventative maintenance now I am aware of it. Thanks again for the heads up. I am hoping that the coolant running down the chassis rail from this is what I was seeing on the floor, fingers are crossed.

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Rod,

i cant believe you jinxed me, lol

passengers floor carpet is saturated my system let go on the way home last night by the looks

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Originally Posted by BLACK 346

Hey Ed, yeah as Paul said, it is Rod, but I get called Rob that often I don't even notice anymore :)

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I think it's a national past-time to call people named Rod, "Rob" :) (even when responding to emails with "rod" in the name!!??)

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Originally Posted by OzJavelin

I think it's a national past-time to call people named Rod, "Rob" :) (even when responding to emails with "rod" in the name!!??)

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How true is this, i get return emails just about daily calling me Rob, when I have Rod in my sig block in big f-off bold font lol

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Originally Posted by klink

Rod,

i cant believe you jinxed me, lol

passengers floor carpet is saturated my system let go on the way home last night by the looks

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Damn, that sounds nasty mate. Hope it is not too hard to fix.

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Originally Posted by BLACK 346

Damn, that sounds nasty mate. Hope it is not too hard to fix.

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feel free to come around for a swim. Contemplating buying a wet and dry vacum cleaner at the moment. then i'll need a 40 degree day to dry it properly. and i have 4 days to sort it all out.