coolant leak new heads

[RustyBuckets]

I had my 350 all back together and the last thing i had to do was fill the coolant before I turned key

Well I got to a certain point while filling and coolant starts coming out of somewhere near the back of the engine

I feel around and figure out that its between the block and the head...

Googled some things and was convinced I must have put my gasket on upside down, but I pulled my head off and it seemed to be the right way...

Anybody know what happened? it was the rear on cylinder 8
Oh and Im running felpro 1094

 

[jux]

Idk. If it came out while simply filling it, then it must have been a fairly large open area. Are you using all of the correct bolts for the head and intake? Everything torqued to spec? Might want to try another gasket.

 

[gpmorgan]

I had an experience similar to yours. My intake gasket started leaking a few months after I started driving it. It was leaking at the back of the intake by #8 cyl. After removing the intake there was no doubt that the gasket had slipped. I assembled the engine on an engine stand. Not sure how that happened.
Did you have your heads rebuilt? It's a little strange that a head gasket would be leaking that bad. While I had it off, I would take the head and have it magnefluxed or pressure tested before installing it back on the block. Seems if the gasket was that bad there would be some signs of damage on it. Take a good look at the intake and head gaskets for damage.

 

[RustyBuckets]

The head was rebuilt, I used the 1094 but it was just a metal shim gasket, should I have sprayed it with something?

I used all the same head bolts, and I chased the threads so I got proper torque. Was I suppose to put something on the threads of the bolts?

 

[gpmorgan]

Pre-Flattened Steel Wire Ring Head Gaskets
The strength of steel wire sealing with minimum brinelling of aluminum heads.
Pre-Flattened Copper Wire Ring Head Gaskets
Copper will not brinell aluminum heads, and these Fel-Pro gaskets also offer superior heat dissipation from combustion hot spots.

Loc Wire Ring Head Gaskets
Fel-Pro Loc Wire gaskets are engineered to provide the best sealing available for severe applications. They have oversized wire rings that lock into receiver grooves which must be machined into the cylinder heads. Precise machining is critical to the success of these gaskets.

I looked these gaskets up and noticed they recommend machining the heads to accept the loc-wire ring gasket. Not sure which one you have. Did you do just the one head? I always put some sealant on the head bolt threads before installing. It ensures no coolant will leak around the bolt threads. If this is an OEM style engine, I would use an OEM head gasket.

 

[jux]

If this is an OEM style engine, I would use an OEM head gasket.

Words to live by.

 

[RustyBuckets]

The engine isnt quite stock, but its just a daily driver truck.

I bought new gaskets and new bolts that have the sealant on them, already have one gasket swapped out, but its 20 degrees here so Im preparing myself to do the other tomorrow.
Thanks for the help guys.

 

[chengny]

The way you describe the flow of coolant - seems like a lot to explain as a leaky gasket. Subjected to only that tiny amount of head pressure, a properly torqued head (even with no gasket at all) should only kind of weep.

I don't mean to be insulting but, it wouldn't have been coming from a loose shipping/painting plug in the alternate location for the coolant temperature sensor, could it? That would be right above and just a little forward of #8 intake. Here is a photo showing where it is - maybe an 1" to an 1 1/2" above the head/block seam:

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BTW - I tried using that location for the coolant sender only once (in an attempt to re-route and clean up engine wiring).

It was a bad idea - don't use that hole. Due to its location way at the beginning of the coolant flow through the head, the coolant does not have sufficient time to pick up any heat. Consquently, the temp (as indicated on the dash) was inaccurate. It showed the engine to be running signifcantly cooler than it actually was.

If it is mounted between 1 & 3 as designed, the coolant has time to pick up the heat of combustion as it flows through the head.

IIRC the temperature difference of the coolant from back to front was something like 25 -30 degrees F.

 

[RustyBuckets]

Funny you mention it I didnt have that hole plugged when i started filling coolant. But I have since gotten brass plugs for it. the original leak was at the very back of the head.

Now whats not so funny is I filled up the coolant and oil today after putting the new gaskets in and now I have water in my oil. quite a bit of it.
Can anybody set me on a path of righteousness.
I was going to rent a cooling system pressure tester.

For infos sake these heads were bought off ebay as remanufactured.
Does it matter that my cylinders are bored 30 over, but the heads arent?

 

[gpmorgan]

The engine being 30 over shouldn't be the problem. Did you drain the oil after changing the gaskets? It could have gotten the coolant in the oil when you removed the heads. Get the casting number from the heads and look it up. Some of the GM castings were crack prone if they have ever been run hot.

 

[RustyBuckets]

They are 906 vortecs,
I replaced the heads
Drained the oil.(left the drain bolt off for about 3 days.)
filled up the coolant
then put the oil in with new filter(and lucas break in oil)
I was priming the oil pump when I noticed it turned creamy.
I let it sit for about 6 hours after that and the water was on the dipstick pretty high.
thanks

could this be bad intake gasket because the heads might be slightly different height?

 

[gpmorgan]

Yeah, it could be the intake gasket. It is pretty easy to let them slip while installing the intake when the engine is in the truck. Hate to hear your having such bad luck with it. Did it have any water in the oil when you had the old heads on it?

 

[chengny]

Have those heads been heavily milled (on either the block or intake manifold faces)? Has the block been decked?

Either one of these procedures, if done past a certain point, will increase the clearance between the intake manifold and cylinder head.

I recently thought I had that situation. Was making up an engine and the gap between the head and manifold was huge. The gasket would never have been able to seal. Luckily (for me), it turned out to be that the manifold-to-block end gaskets were too thick. Used a stock pair and the gap closed right up. Read my story and see some images here:

http://www.gmsquarebody.com/forum/showthread.php?t=7110&highlight=felpro

 

[RustyBuckets]

I had cream on the oil filler breather but the truck sat for a while. I dont think the block has been decked. I have no idea about the heads though.

 

[chengny]

I'd pull the intake manifold and check the gap between it and the cylinder heads.

If an engine block has been bored, there is a good chance it was decked as well. I good way to check is whether the block ID is still visible.

All engines are stamped with an engine ID code, consisting of assembly plant code, production date and suffix code. V8 codes are stamped on a pad just forward of the right side (passenger) cylinder head:

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If the ID stamping is still there, the engine has not been decked. If it is not - it probably was. Sometimes a good shop will actually stamp the amount of decking that was done (on the same pad - in place of the ID code).

But this isn't really helping you. You need to get a seal between those surfaces.

If the gap is too big for a flat gasket, try the Mr. Gasket Ultraseal 5820. They have raised sealing surfaces around the intake/coolant openings:

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