1994 K1500 Suburban: Antifreeze Leak..Freeze Plugs?

[Splat]

Over the past two weeks I've been noticing my coolant slowly disappearing on my 94 Suburban K1500. No noticeable puddles under the truck. I finally got the time today to look under her. The starter has coolant on it and in that general area, though not enough to puddle I guess so it must be burning off. Any ideas? I was wondering if there's a freeze plug somewhere above there but can't see it yet. Are there freeze plugs around there or can someone tell me where they're at on the back of these GMT400 350 5.7L engines? Thanks.

[BenJass]

Check your lower intake gaskets. Back corners. Front corners too while you're at it, but it sounds like your back left corner is leaking a little.

[Splat]

Check your lower intake gaskets. Back corners. Front corners too while you're at it, but it sounds like your back left corner is leaking a little.

 

I did manage to check them as best I could and they look dry. I will check again tomorrow.

[BenJass]

Lower intake gaskets, head gasket, check your heater hose connections that go into the firewall.I don't know if there are freeze plugs back there but the coolant has to be coming from somewhere

[thx1138v2]

I had a similar problem on a '94 C1500 but mine wasn't showing any coolant anywhere except the reservoir level would go down - none on the ground, on the bottom of the motor anywhere, or around hose connections, the heater core or the radiator. I was stumped for a while.

 

Once I started taking off parts to pull the intake manifold I found it. There was a cavity in the top of the water pump housing and the coolant was leaking at the front intake manifold water port and running down the end of the head onto the block and into this cavity and evaporating from there. That's why none ever got to the ground.

 

I'd bet on a manifold gasket.

 

BTW, depending on the mileage, I recommend rebuilding the TBI while the manifold is off. Mine as at around +200K miles at the time. It's a lot easier to rebuild the TBI while the manifold is off.

 

And replace the manifold heater hose connection if it is one of those pot metal ones. Mine broke off and I had to use a pipe ease-out to get it out. I don't remember now if it was for 1/2" or 3/4" galvanized pipe. Got it at Ace Hardware.