454 coolant leak FIXED

[MTBLAZER89]

I have a fairly large coolant leak somewhere on the back of my 1989 454. When I got home yesterday I noticed the puddle so i started it back up. Its draining down the driver side of the bellhousing/inspection cover. I stuck my head in the fender and looked up under the inner fender, and I could see it running down the area with the casting numbers, but does not appear to be coming from that head.

What could it be? I know the freeze plugs are lower than that right?

Intake gasket?

Coolant lines? Not sure if there are any that go into the back of the intake?

The truck never got over 190* on the drive home so it just happened out of nowhere

 

[udy2554]

Heater hoses at the firewall? Hope I don't sound like too much of an idiot!

 

[sweetk30]

there is freeze plugs in the back of the block in the bell housing area. look up inside the bell area also.

ends of the heads have a huge pipe thread plug in them so i bet its not that but ya never know.

if you dont have a pressure pump/tester you can pump up by hand get 1 it will let you build pressure in the system to help find the leak.

we just had a head gasket job at the shop . cold motor held 15 psi all night. as soon as it was up to temp she would run out. so check if yours is a cold or hot leak . also helps pin point the leak.

 

[MTBLAZER89]

Ok a few updates today.

I gotta get this thing fixed so I can stop DDing my K5

I checked the coolant and it was a little low and it started to drip with the motor off??

Ideas?

I got a better look with the flashlight today, and the back of the head is dry, and the plug in the back of the head isn't leaking.

I can still see the small stream running over where the casting number there so it is coming from above that area so that should rule out any freeze plugs right?

There is no steam in the exhaust, or water in the oil so I am hoping that rules out any head issues.

After it sat and idled for about 10 min dripping about 5-10 drops per second it quit leaking Motor was up to temp, and the area near the casting numbers was dry. I took it for a drive around the block and when i came back it was dripping about the same again

After it idled for a few minutes it quit leaking again.

The leak is not as bad as I thought, but the weird part is that it leaked when I topped off the radiator with the motor off, and then it quit leaking after it idled for a few minutes?

Ideas?

 

[Thunder]

The 454 TBIs have a heated adapter for the TB that coolant runs thru. There is a fitting in the front and back for coolant lines. Maybe the rear fitting or hose is leaking.

 

[80' 427]

Intake gasket? Where do the cooling lines go to on a 454? On a 350 there is a rear elbow that goes in the intake and rots off.

 

[MTBLAZER89]

The 454 TBIs have a heated adapter for the TB that coolant runs thru. There is a fitting in the front and back for coolant lines. Maybe the rear fitting or hose is leaking.

Intake gasket? Where do the cooling lines go to on a 454? On a 350 there is a rear elbow that goes in the intake and rots off.

I will check both of those. I don't think its leaking from anywhere on top of the intake though because there is nothing wet up there.

Drove it back and forth to work today..NO leaks

I suspect an intake gasket at the rear edge, but its weird it stopped leaking.

 

[MTBLAZER89]

Started leaking again today...weird two months almost with no leaks at all. Even towed with it a couple times.

Recap

Will leak when its running.

Will leak with a full Rad if the cap is off. When I put the cap on it stops.

 

[MTBLAZER89]

Now it stopped again..I think it's an intake gasket, but its weird that it goes away I also think this is related to my TBI 454 runs like crap when its hot thread problem...intake leak?

http://coloradok5.com/forums/showthread.php?t=260562

 

[MTBLAZER89]

Intake gasket fixed it It was leaking on the driver side where the block/head/intake meet. Replaced the coolant temp sensor and fixed a couple bad vacuum lines as well, but still have the running bad after it gets to operating temp problem in this thread.
http://coloradok5.com/forums/showthread.php?t=260562

One problem at a time right