Pop N Wood

iTrader: (1)

I have antifreeze coming out of my exhaust when I start the car after sitting awhile. Pretty sure I need pull a head and replace a head gasket.

Anyway to tell which head has the problem, or should I just go ahead and replace both sides? I tried pulling plugs and didn't see anything obvious. I also tried an inspection camera in the spark plug hole, but couldn't see much of anything with that. I might try looking in the intake/exhaust port once I get the manifolds off.

Doug G

Usually a clean cylinder or discolored plug gives it away ?

Can you pressure test the cooling system at home ?

Jakes LS1

Always change both sides! Why take one off and change it and then have to take the other off in the future and change it when you can do both now while you have everything off.

Pop N Wood

iTrader: (1)

I pulled the intake and saw some coolant on top of one of the closed intake valves. Pulled the head and can't say I see anything obvious. Everything is nice and dirty, no pitting of the aluminum and no errosion marks from a water jacket to a cylinder. Need to finish cleaning off the gasket material but a quick check with straight edge on the head looked dead flat. Didn't get to the block yet.

Will try and post pics later today and will pull the other head later this week.

Autozone and Advanced Auto Parts were having pretty good sales yesterday. Got 20% off a set of felpro gaskets and head bolts, free shipping and a $50 gift card.

man, sure glad i went carb'd. Head was super easy to pull.

ZONES89RS

iTrader: (25)

I would have pulled the exhaust, see which side had coolant come out on start up.

speedtigger

iTrader: (16)

This is pretty typical. The cylinder with the popped gasket will usually have a clean piston and combustion chamber in the head if the engine has been run for a bit like that.

This is a really "out there" possibility, but there is always a chance of a crack in the head through the exhaust or intake port.

Doug G

HHhhmmmmm, I'd maybe get that head checked. These are "dry" intake motors (unless running a stock set-up with the coolant lines at the TB)...maybe a loose bolt or no thread sealant ???

Pop N Wood

iTrader: (1)

Pulled the passenger side head last night. The cylinders on that side were definitely less dirty than the port side, but IDK, can't say I see anything obvious. Checked the head for warpage with an 18" flat edge and a 0.002 feeler gauge and nada. Heads and block decks both look flat. Looked in all the intake and exhaust ports checking for cracks and again, nothing.

Think I will run the heads past a local machine shop and have an expert give them a once over. if they don't find anything then I will just put in the new gaskets and put everything back together. I was kinda hoping to find the smoking gun.

Amazing how easy these cars are to work on. Having a carb'd alternator only motor in a spacious engine bay doesn't hurt.

When I put it back together I will probably add a slug of stop leak. I say this because that is what GM does when they ship their new crate motors, put a slug of stop leak in a water pump passage.

Opinions on that?

toxic99

Engine builder/installer I know would always put a bottle of BARS copper stop leak in all his engines. He swore by it.

3pedals

iTrader: (3)

Anti-freeze on top of a closed intake valve sounds like a cracked head - cracked into the intake runner

Pop N Wood

iTrader: (1)

Yeah, short of it splashing up out of the cylinder as the intake valve closed I can't think of another way for it to get there. It was on #1 cylinder, where I have my alternator bolted up, so I checked super careful to make sure I didn't seat an alternator bolt too deep. But nothing, all looks good.

I'm starting to wonder if it was just some gasoline from when I tilted the intake with carb off in that direction.

TX_Z28

Once you have it back together I would do like previously stated and pressure test the cooling system before you fire it up and cause more damage.

Pop N Wood

iTrader: (1)

Not a bad idea. Should be pretty easy to T a mityvac into a steam line. I probably should have done that before I tore everything apart. That and run it with the headers disconnected to check for fluids.

It doesn't look like anything is damaged.

3pedals

iTrader: (3)

an engine rebuilding place should be able to pressure test the heads separately, so you dont have to assemble the engine before knowing if they are good.

The stunningman

iTrader: (47)

What casting heads do you have? If they have the cas-tech symbol. They could be some of the pourus (SIC) heads they produced. Replaced a engine that had some on it for a guy a few years back. I try to avoid the cas-tech heads altogether if possible.

Pop N Wood

iTrader: (1)

Just got a call back from the machine shop. They did the pressure test and said no cracks or casting issues (243 heads). He said one of them was warped 1 1/2 thou end to end while the other was 2 thousands side to side.

Doesn't seem like much to me but he resurfaced them anyway so should be good to go.

He also told me if I could have found a problem looking at the head gasket he would have hired me on the spot. Says the MLS gaskets pretty much kill that idea.

fast89stang

iTrader: (2)

I would have ran it, pulled the plugs and let it sit over night. Then when its spun over, you could have seen which cylinder it was coming from. I know the plugs are kinda hard to get to in a f body, but If it had coolant getting in a cylinder you would see it when you spun it over, it would blow a mist out of that hole.

fox12303

iTrader: (7)

Only 706 4.8/5.3 heads from Castech were faulty per GM tech bullitin #06-06-01-019B. Not all castechs were faulty. Doesn;t sound like warpage was the issue and yes the MLS gaskets are pretty bullet proof. Not sure but are the rocker bolt holes blind on GM heads? Maybe use thread sealant on them when you put it back together. Wish I could give you other ideas but everybody pretty much covered it. What LS are you running?

Pop N Wood

iTrader: (1)

The machine shop guy was aware which heads had bad castings and said this wasn't one of them. Not sure about sealant, haven't gotten around to looking up the reinstall in a manual. This is a few year old crate motor so any problem like that came from the factory that way. Besides, I don't think the rocker bolts go through the head. I will follow the manual.

When I took the heads in you could feel and see the machining pattern in the head mating surface. That's all gone now, all smooth and shiny.

I'm hoping it is related to the time I threw the belt and puked up half the contents of the radiator.