Coolant Leak on LLY

[rebel7777]

I have a coolant leak on my 04.5, I know it's not the head gasket (I have Boreoscoped the whole outer engine). The leak is running down the back of the engine by the starter, it's funny that it only leaks when I fill the reservoir full, and parked.

If I leave it at the add line the truck doesn't appear to use anymore coolant and no more leak occurs, hot or cold.

I am thinking the turbo, does anyone else have any ideas and how worried should I be?

 

[IOWA LLY]

Do you have an LBZ mouthpiece? If so, I would look at the fitting going into the egr cooler that you have to bend to install the LBZ mouthpiece. I have seen a couple break after being bent.

 

[rebel7777]

No EGR, with LBZ mouthpiece. Checked all hoses and no leaks found.

 

[custom8726]

Intermediate plate is a decent possibility, but there is also a weep hole near the turbo oil drane that would let any antifreeze leaking up in the valley of the engine drip down the back side of the engine and bellhousing.. I am assuming you checked the lines going into your heater core already?

 

[rebel7777]

Heater core lines good, there isn't any in the valley of the engine. Where is the intermediate plate?

 

[custom8726]

Between the block and bellhousing, The starter bolt's to it.. There is a coolant passage that runs through it. Not a very common problem but they have been known to crack and leak..

 

[ripmf666]

Between the block and bellhousing, The starter bolt's to it.. There is a coolant passage that runs through it. Not a very common problem but they have been known to crack and leak..

Not common for the adapter. But on that rear adapter on the pass side there is a blocker plate. That plate is a coolant opening like used on the driver side for the oil cooler. They sometime blow the gasket or sometimes when so get trans work done if a longer bolt is installed around this it will hit it and make it leak. Kinda werd that it doesn't leak when you only fill it to the line why are you trying to over fill? Tank could also be cracked.

 

[rebel7777]

Between the block and bellhousing, The starter bolt's to it.. There is a coolant passage that runs through it. Not a very common problem but they have been known to crack and leak..

I don't see a crack, but this location makes sense, this is where the leak appears to be coming from. Do I have to remove the starter to see it better. If so how do you fix if no crack exists?

 

[rebel7777]

Not common for the adapter. But on that rear adapter on the pass side there is a blocker plate. That plate is a coolant opening like used on the driver side for the oil cooler. They sometime blow the gasket or sometimes when so get trans work done if a longer bolt is installed around this it will hit it and make it leak. Kinda werd that it doesn't leak when you only fill it to the line why are you trying to over fill? Tank could also be cracked.

I had changed the engine out in Jan, so the longer bolt could make sense. Is this the plate on the housing with 2 bolts, right next to the passenger head and right between the engine and tranny?

I only say about the level in the tank, as it has 2 lines, full when cold and fill when cold. I have been filling when at the bottom line, fill when cold and only noticed that the more I put in the more the leak occured, now I'll run until the DIC comes on. I carry (2) jugs now as this problem has been bugging me for about a month now.

Tank is new, so it doesn't have a crack and the antifreeze isn't coming from there.

Thanks for all the suggestions, I've been scratching my head on this on, and I don't have much hair left. As mentioned I have a small boreoscope and have checked every were on the engine and the last place I couldn't look was under the turbo, so I thought maybe.

 

[ripmf666]

Yes the plate has 2 bolt. Also on the back of the head there is 2 freeze plugs. When you did the motor did you install the rear adapter? If it's leaking from between that and the block you will need to remove the trans. And lower oil pan to remove the rear cover. Along with the flywheel that would need new flywheel bolts. If you end up having to do this replace the rear main seal. Then some Gm sealer and 2 rear adapter o rings. Could try adding die to the coolant and use a black light to trace it.

 

[rebel7777]

Not common for the adapter. But on that rear adapter on the pass side there is a blocker plate. That plate is a coolant opening like used on the driver side for the oil cooler. They sometime blow the gasket or sometimes when so get trans work done if a longer bolt is installed around this it will hit it and make it leak. Kinda werd that it doesn't leak when you only fill it to the line why are you trying to over fill? Tank could also be cracked.

I think you nailed it with the plate, I just went and tightened the 2 bolts. Got about 1/2 a turn out of both, so they were loose. How do I go about changing the gasket if it still leaks? Do I have to drain the anitfreeze?

 

[rebel7777]

Yes the plate has 2 bolt. Also on the back of the head there is 2 freeze plugs. When you did the motor did you install the rear adapter? If it's leaking from between that and the block you will need to remove the trans. And lower oil pan to remove the rear cover. Along with the flywheel that would need new flywheel bolts. If you end up having to do this replace the rear main seal. Then some Gm sealer and 2 rear adapter o rings. Could try adding die to the coolant and use a black light to trace it.

Never touched the adaptor plate, still installed from when I bought the used engine.

That sounds like a big job, if it comes to that, I may just opt to wait (keep putting in coolant)and put in my engine I'm building right now.

 

[ripmf666]

I think you nailed it with the plate, I just went and tightened the 2 bolts. Got about 1/2 a turn out of both, so they were loose. How do I go about changing the gasket if it still leaks? Do I have to drain the anitfreeze?

it's a steel shim gasket. If it still leaks pull it off clean it and add some sealer and put her back on. You can drain it from the raditor drain then refill when done just make sure when feeling to remove the burping bolt fro
the therostat housing to get all the air out.

 

[rebel7777]

it's a steel shim gasket. If it still leaks pull it off clean it and add some sealer and put her back on. You can drain it from the raditor drain then refill when done just make sure when feeling to remove the burping bolt fro
the therostat housing to get all the air out.

Thanks for all your help, I will advise if anything changes.

 

[rebel7777]

Yah, after tightening it is leaking more than before, I have to remove now and seal.

 

[TransporterGuy]

Did this fix it? What kind of sealer did you use mine is leaking bad did you remove the up pipe? and down pipe