Unstoppable Coolant Leak

[Charlesvolare]

I have a la 360 with Magnum heads. Block is bored .060" over, stock crank, eagle rods, KB flattops. Custom grind Comp roller cam , retrofit roller lifters with matching springs. The past few times I've had the heads off for various reasons, there's been a slight coolant leak but only to the outside- Front/rear drivers, front passenger. Usually a bottle of Bar's block sealer stops the leak and it's all good to go.
Example A -video was made about a year ago:


Beginning of the month I blew a head gasket (thread Piston Failure ). Blew out into the lifter valley, so no coolant leak or overheating. Since it was all apart, I went ahead and got the heads flat-milled (.010"), hoping to fixed the ever-present coolant leak that is always there upon re-installation. Cleaned everything with scotchbrite and acetone, wiped with clean rags, same procedure as always. Start it idle to temp, small leak. figured the block deck itself is a little off wack. Bar's block sealer goes in, followed directions and then let cool. Leak stopped. Drove it, got on the the throttle pretty good. Got home and leak was there again. Retorqued the intake and another test drive. Got home and this:

Looked like maybe it was leaking where the intake meets the block, so took the intake off and regakseted it (edlebrock 7277). Used rtv around the coolant ports and put it back together. Spent the day Saturday driving it, taking it easy, temp saw maybe 200* max (kept off the highway, rpm's never saw above 2600) No leaks. Pulled the valve covers today and checked the head bolt torque, tightened the intake torque back to spec, and tightened a few hose clamps. Took a spirited drive to Kroger and this is what I see:

Both heads, Drivers side looked like it was coming more from the top

Doesn't leak at all at idle or easy throttle, up to 200 maybe more degrees. Leaks under hard throttle no matter how hot. Used to be cured with a bottle of block sealer, milled the heads to remedy that and now cant seal at all.

Heads are flat, Brand-new gaskets all around. Is there anything I can try? Or is my block deck done for and need to be milled flat? How easy is it to warp a block? Haven't overheated any at all, MAYBE 220* max on this block at one time last summer.

 

[tonysrt]

I thought if you milled heads may also have to mill the intake because now heads are sitting lower on block and intake will sit a little high. If it looks like the leak is predominately at intake and head you may have to mill intake. There is a rule of thumb for the mill of the intake, but it's not my forte, so someone that knows will hopefully chime in.

 

[Charlesvolare]

I thought if you milled heads may also have to mill the intake because now heads are sitting lower on block and intake will sit a little high. If it looks like the leak is predominately at intake and head you may have to mill intake. There is a rule of thumb for the mill of the intake, but it's not my forte, so someone that knows will hopefully chime in.

I looked a little into that, only milled the heads .010" and I was told the intake should be fine. But it leaked very slightly before, just not nearly as bad and I was able to stop it. Part of the reasoning in getting the heads milled was so I didn't have to worry about it anymore.

 

[tonysrt]

Do you know if block was ever milled when it was bored? If it was milled and now with heads being milled it's more than a .010 drop.

 

[Charlesvolare]

Do you know if block was ever milled when it was bored? If it was milled and now with heads being milled it's more than a .010 drop.

I bought the block off a guy with the machine work already done. He said the deck hadn't been touched, but all I have on that is his word. That could also caused detonation problems as well couldn't it? I was thinking maybe having iron heads was playing a huge role in it but more compression than what I thought could as well...

 

[RustyRatRod]

You gave us info we didn't need for a coolant leak the cam lifters and all that. What intake does it have on it? I would be highly suspecting a mismatched angle between the intake and heads.

 

[Red63440]

Aluminum intake, possible crack in the manifold?

 

[604B1duster]

You need to borrow or buy a pressure tester.
Like Rusty said, something is out of wack.
Could even be the intake bolts are wrong, shoulder too long, not enough thread. Maybe add a washer and retighten.

 

[Charlesvolare]

You gave us info we didn't need for a coolant leak the cam lifters and all that.

Figured it wouldn't hurt anyone, better to have it and not need it than to need it and not have it. Got a little carried away, I at least think it's a pretty trick setup. If anything it'll help someone understand it's not a boat anchor smog motor but a hot small block that sees some more stress than normal. You can skip over it if you want, I don't mind

What intake does it have on it? I would be highly suspecting a mismatched angle between the intake and heads.

Here's the intake:
55026 - Small Block Mopar V8 Crosswind Intake Manifold Satin
At what point would would one have to take off for it normally start to affect the intake angle?

 

[RustyRatRod]

Figured it wouldn't hurt anyone, better to have it and not need it than to need it and not have it. Got a little carried away, I at least think it's a pretty trick setup. If anything it'll help someone understand it's not a boat anchor smog motor but a hot small block that sees some more stress than normal. You can skip over it if you want, I don't mind

Here's the intake:
55026 - Small Block Mopar V8 Crosswind Intake Manifold Satin
At what point would would one have to take off for it normally start to affect the intake angle?

Usually the accepted maximum is .030" off the heads before the intake needs to be cut. It varies of course. At this point, IMO, I think you should remove the intake and double check the angle. Those intakes have a reputation for not being "so good" regarding details........but I have to admit, this would be the first one I've seen that didn't seal coolant. Most have problems regarding rough castings, crooked port windows, and things of that nature. There's always a first. That's what "I" would do.

 

[RustyRatRod]

Also, what kind of intake gaskets are you using and are you using RTV sealant around the water ports?

 

[Charlesvolare]

Aluminum intake, possible crack in the manifold?

Yes aluminum. I took it to work and cleaned it pretty good. I wasn't looking specifically for cracks, but if something looked strange I'm sure I would've seen it.

You need to borrow or buy a pressure tester.
Like Rusty said, something is out of wack.
Could even be the intake bolts are wrong, shoulder too long, not enough thread. Maybe add a washer and retighten.

I have one sitting in the back seat. They're oem magnum bolts w/ their washers. In the video you can see the bottom of the bolt sticking through.

Just remembered that I saved the old gaskets, here's pictures. There's indention's at the bottom where it sealed:

I though I was in focus better, I can grab better pictures in better light if I need to

 

[Charlesvolare]

Also, what kind of intake gaskets are you using and are you using RTV sealant around the water ports?

Edelbrock 7277

First time I used ACDelco RTV- My favorite hands down, never had any problems ACDelco 88864346
Second time I used black rtv stuff from the autoparts store. I'd have to go dig it up to see what brand.

Both times around coolant ports (only on one side, the other has a ring thing in the gasket), the second time I was extra careful in making sure sealing the valley wall didn't interfere with the coolant port in any way.

 

[604B1duster]

Yes aluminum. I took it to work and cleaned it pretty good. I wasn't looking specifically for cracks, but if something looked strange I'm sure I would've seen it.

I have one sitting in the back seat. They're oem magnum bolts w/ their washers. In the video you can see the bottom of the bolt sticking through.

Just remembered that I saved the old gaskets, here's pictures. There's indention's at the bottom where it sealed:
View attachment 1715371463 View attachment 1715371464

I though I was in focus better, I can grab better pictures in better light if I need to

Put some red rtv around the coolant passages on both sides of the gaskets and try again

 

[AJ/FormS]

Pressure test it.
But here's my nickle; Let her cool off.Pull the radcap off, top up the coolant, and warm her up. If it still behaves the same way, with zero psi in the cooling system, then I bet the head gasket let go. But I have never seen a gasket blow cylinder pressure in that direction. So that then points to a failed cooling system transfer. And that would most likely mean the intake gasket, most likely..

As others have suggested; it is much more likely that the intake is not pulling down properly; and that is relatively easy to prove.
As the heads move down they narrow the valley, forcing the intake higher. As the intake floats up, eventually the bolt holes don't line up. But if you manage to get them just barely in there, then there is no room for the bolts to draw the intake down. So the bolts tighten up reasonably fine cuz the torque spec is not that much, and so it feels Ok. But the fact is that it's not tight were it counts and out flows the water. The proof for this will be right on the gasket when you take it apart; there will be little or no clamp imprint on it or it will have a heavy imprint on perhaps the top, and no imprint on the bottom; or such like. That is your proof. That proof may already exist on the old gaskets if you still have them and if they were FelPros. Cheaper gaskets, or gaskets that were glued down, will usually/often be destroyed at teardown. I've had good success with dry FellPros.
The solution for this situation is not to elongate the holes. That mighta worked with a small misalignment, but IMO, your situation may be past that. Check out the previous gasket and the evidence may be right there on it.

 

[RustyRatRod]

Edelbrock 7277

First time I used ACDelco RTV- My favorite hands down, never had any problems ACDelco 88864346
Second time I used black rtv stuff from the autoparts store. I'd have to go dig it up to see what brand.

Both times around coolant ports (only on one side, the other has a ring thing in the gasket), the second time I was extra careful in making sure sealing the valley wall didn't interfere with the coolant port in any way.

Sealant on both the head side and the intake side of the gasket around the ports I assume? I know stupid questions, but we gotta start somewhere. Sounds like you're doin it all right so to "ME" that leaves "something" you ain't found yet such as a craptastically machined intake. At this point, I would be taking it off and literally.......and I mean LITERALLY looking at it with a magnifying glass. You'd be surprised what might jump out at you. From there if you find nothing, it's time to check the intake angle against the angle of the heads. I believe you will find the problem if you do those two things.

Now......one last stupid question. Did you remove the dowel pins from the china walls in the block where the intake ends meet the block?

 

[Charlesvolare]

Pressure test it.
But here's my nickle; Let her cool off.Pull the radcap off, top up the coolant, and warm her up. If it still behaves the same way, with zero psi in the cooling system, then I bet the head gasket let go. But I have never seen a gasket blow cylinder pressure in that direction. So that then points to a failed cooling system transfer. And that would most likely mean the intake gasket, most likely..

As others have suggested; it is much more likely that the intake is not pulling down properly; and that is relatively easy to prove.
As the heads move down they narrow the valley, forcing the intake higher. As the intake floats up, eventually the bolt holes don't line up. But if you manage to get them just barely in there, then there is no room for the bolts to draw the intake down. So the bolts tighten up reasonably fine cuz the torque spec is not that much, and so it feels Ok. But the fact is that it's not tight were it counts and out flows the water. The proof for this will be right on the gasket when you take it apart; there will be little or no clamp imprint on it or it will have a heavy imprint on perhaps the top, and no imprint on the bottom; or such like. That is your proof. That proof may already exist on the old gaskets if you still have them and if they were FelPros. Cheaper gaskets, or gaskets that were glued down, will usually/often be destroyed at teardown. I've had good success with dry FellPros.
The solution for this situation is not to elongate the holes. That mighta worked with a small misalignment, but IMO, your situation may be past that. Check out the previous gasket and the evidence may be right there on it.

The pictures in post 12 show indention at both the top and bottom of gaskets. I pressure tested it before this last gasket change and it held at ~18 psi with a cold engine. And again, it's fine at temp, with easy revving. Purposely drove it easy everywhere last Saturday and it was okay (up to ~200* haven't been able to get things hotter than that). It seems to be when it revs hard that it leaks. Whether it's rpm on the water pump causes a spike in pressure or the short spike in heat from cylinders, I don't know.

Tomorrow I'll do a more thorough test with the tester to see if I can figure out more.

Sealant on both the head side and the intake side of the gasket around the ports I assume? I know stupid questions, but we gotta start somewhere. Sounds like you're doin it all right so to "ME" that leaves "something" you ain't found yet such as a craptastically machined intake. At this point, I would be taking it off and literally.......and I mean LITERALLY looking at it with a magnifying glass. You'd be surprised what might jump out at you. From there if you find nothing, it's time to check the intake angle against the angle of the heads. I believe you will find the problem if you do those two things.

Now......one last stupid question. Did you remove the dowel pins from the china walls in the block where the intake ends meet the block?

I used sealer on gasket to block, gasket to intake has a silicon ring around it you can see in post 12. I used to not rtv this gasket at all and never had a problem with it. And yes, there are no dowels in the china walls.

 

[pishta]

Blue Devil sealer kicks ***. When your so F'n tired of chasing a leak only to find it come back....or its a sunday night and you got to drive to work monday morning.....

 

[Charlesvolare]

Blue Devil sealer kicks ***. When your so F'n tired of chasing a leak only to find it come back....or its a sunday night and you got to drive to work monday morning.....
View attachment 1715371487

I think I might've said Bar's block sealer, I meant Blue Devil. Stuff worked like magic up until now and that's the problem.

Haven't tried the headgasket stuff yet though. I'm not sure how much different it'd be formula-wise

 

[RustyRatRod]

The pictures in post 12 show indention at both the top and bottom of gaskets. I pressure tested it before this last gasket change and it held at ~18 psi with a cold engine. And again, it's fine at temp, with easy revving. Purposely drove it easy everywhere last Saturday and it was okay (up to ~200* haven't been able to get things hotter than that). It seems to be when it revs hard that it leaks. Whether it's rpm on the water pump causes a spike in pressure or the short spike in heat from cylinders, I don't know.

Tomorrow I'll do a more thorough test with the tester to see if I can figure out more.


I used sealer on gasket to block, gasket to intake has a silicon ring around it you can see in post 12. I used to not rtv this gasket at all and never had a problem with it. And yes, there are no dowels in the china walls.

Doesn't matter. RTV both sides of the gasket every time. That silicone that comes on the gasket is usually so dried out from extended shelf life it'll never seal.

 

[pishta]

IIRC the head gasket stuff wants you to drain the coolant, add the blue devil and top it off with water, run it for 5 minutes then pull all the plugs. let it sit overnight, drain and refill with coolant. Stuff turns into a varnish when it hits air?

 

[Krooser]

Try some thicker intake gaskets.

 

[Kendog 170]

Stop leak in my day, you put a piece of cardboard over the radiator and got the motor much hotter than it would ever get to normally. Then let motor cool. If the motor get any hotter than when you used it it will expand more and blow out the sealer. With that said IMO you need to find and fix not use a band aid. Good luck. Also did you buy the intake new or did it come with engine when you bought it?

 

[bbrroowwnn]

interesting

 

[dano]

What pressure cap are you running on the radiator? Are the factory roll pins removed from the blocks front and rear China Walls? Are you using end gaskets on the block?