max's dad

Just buttoned up a head /cam install (not my first) and I'm getting a steady coolant leak toward the header collector and oil filter. I can't really see where it's coming from. Any suggestion would be greatly appreciated.

ss rally red

iTrader: (8)

Sounds like you left out one on the plugs that need to be transfered from the removed heads.

foff667

iTrader: (2)

coolant plug?

pdd

iTrader: (3)

yup. i did the same thing. had coolant all over the place

max's dad

I can see that for the passanger side. The driver side has the temp sensor. Both are in place.
Hypothetical questions: Say I had some serious gashes( a 1" by 2" area) on the block between cyliders 3 and 5 just above the bores, could this be the issue?

max's dad

Leaking was not immediate. Drove the car for about 40 miles and it seemed fine. Came home after dinner to find coolant trail under the car.

LS1 Power Plant

iTrader: (7)

How about the two back ones?

fbodysetc

iTrader: (5)

I had a similar problem It happened after a few hard passes. The dowl pins should be replaced everytime the heads are taken off. If not they have a chance of getting crooked and not letting the head set all the way down on the block. This happened to me so I learned the hard way

1999_SS_M6

FWIW, I can't see driving 40 miles with a coolant plug out and not noticing. with a hole that size gushing coolant from your cylinder head, you would pump the system dry enough to overheat in a matter of a couple miles... unless maybe you live in the arctic.

Just for grins, you could check and see... The coolant plug is (or should be) toward the top of the cylinder head, almost directly above the back spark plug on the passenger side.

max's dad

Coolant plugs are in. They are both dry, so it must be something else.

2xLS1

iTrader: (25)

What is the casting # on the heads and what type of head gaskets were used?

jmX

There are extra bolt holes cast into LS1 heads, and sometimes they are tapped/drilled in too far and will cause a coolant leak. They are right near the header flange on both heads.

I once got a set of heads from a sponsor and coolant was pouring out one of these extra holes. Strange stuff, but its at least something to check

DaleMX

iTrader: (4)

The wrong head gasket could cause a leak.

tuff

iTrader: (15)

I say head gaskets are leaking . A possible f up

max's dad

Heads are 5.3s. This was my first time using Felpro gaskets and ARP bolts. Everything was torqued to spec. Is 75ft lbs enough? It seems as if it took more muscle with the t-t-y oem bolts.

fbodysetc

iTrader: (5)

Where is the leak coming from exactly ?

highgear

Head gaskets should specific to your year model. Verify the part# thru your dealer.

BADDLS1SS

iTrader: (22)

Yeah sounds like the Infamous " U notch" strikes again...

Had the same exact problem, my car is an 01' and didnt have notched heads to begin with, but i put the Patriot 5.3's on and they are 99-00 style castings that have the notch and didnt even think about it and i looked at the deck a 1,000 times before i installed them, but its a simple honest mistake but i tried using the MLS GM head gaskets and it pissed coolant from the notch on both sides. Replaced them with the graphites, problem solved!

jsnone1

iTrader: (11)

What are the "2 back ones" I have a leak after putting my 243s on, coming from the back of the engine