External coolant leak- just started today

[super44]

94 Silverado, 5.7L, Auto

I just replaced the water pump 2 weeks ago.

Just noticed 15 min ago I've got another leak

Wasn't there yesterday and have only driven it 6 miles since yesterday.

The coolant is leaking from somewhere at the back of the engine, running down the outside of the starter around the starter bolts and a little down the BH. I've check the heater hoses, especially where it runs back into the intake manifold. (I'm at work so it was a quick check) and it seems ok. No leak anywhere around my new WP. It drips about 2 drops per second when the engine is turned on. Were could it be coming from??

Thanks

 

[Boomer]

My guess... intake manifold gasket. Happened to mine some years ago with the same symptoms. Or it cold be a head gasket. Also, don't overlook a loose hose clamp that allows cooant to seep out near the front of the block and run backwards toward the rear of the block.

 

[mechtech2]

When you fix a coolant leak, there is now more pressure to make the next weakest link go bad.
Try explaining that to customers. It sounds like you are giving excuses and [censored] about why another leak occurred after a fix.

 

[FL_Rob]

More than likely ,the lower Intake on passenger side, absolutely notorious on this engine.I've got great advise short term,although it has worked for me long term now.Those of you who hate additives, disclaimer: I know it's not the right way but it works,Bars leak liqiud copper (not the silver rad seal)block seal ,add to your radiator, not coolant tank you may need more than one application,and a lower pressure rad cap to assist with the sealing properties.It's too fine to block heater passages.If it's a freeze plug it'll seal that too.Again,not a permanent fix although it could be.Mine's a '93 it drove me nuts,same exact thing,not enough for me to justify pulling the I/M.Just make sure it's not something simple like the heater bypass.These are not sissy hypersensetive engines,they'll take the occasional coolant leak ,quicky fix, approach.By the time i would get to work ,it would be a third low IN THE RAD,coolant tank dry of course,until I found this stuff.Gaskets are cheap too, if you can afford down time.

 

[super44]

mechtech-
Yeah, I can understand that(new parts stressing old). The old WP was "intermittant" leak. It seemed to weep just a little over a week or so, so I decided to try and avoid the inevitable.
The system would pressurize when hot, or it seemed to when I would check the upper hose.

Boomer-
Haven't a clue on what all is "back there". I'll have to get it home to really look close.

 

[super44]

FL_Rob---

The block seal approach will probably be my 1st approach on it if I can't find anything else, I know- short term if it works. Its been years since I really opened up an engine, so it may be time for me to brush up!

thanks

 

[FL_Rob]

See,mine's a G20 van (same engine) thats the only reason I put mine off,It was meant to be short term,"I'll just wait till the weekend" "Dont wanna mess with the doghouse right now" excuse ,but it stopped leaking and hasn't been for months now,so.........?

 

[super44]

Just looked again, it's wet at the rear passinger head/manifold junction from what I can see, but I also seen a wet "strip" coming from the top & down the side of the IM. I'm crossing my fingers on the aluminum heater hose connection on the IM.

My dad had an 84 GMC custom van with a 305, and I understand about putting it off! Yep, why do something now, if I can put it off till tomorrow. Just call me redneck!

 

[super44]

Boomer: You guessed it!!!

Took it home, which is about 3 miles, and by that time the
pressure had built up enough to really do some searching.
I was still seeing it drip from the back of the engine, but I also noticed 1 drop of AF where the mechanical fuel pump used to be attached to the block for earlier models. So I backed it up my driveway (pretty good incline) and bingo! It's leaking
at my water pump gasket. I guess my cleaning and RTV didn't hold.

So this weekend I get to do a resealing job.

Thanks for the help guys. I was sweating this one, the manifold and head gaskets or a freeze plug was something I was dreading. This old engine has never been opened up!

 

[FL_Rob]

It's nice like that sometimes.I'm glad I was wrong

 

[super44]

Update:

Well, it turned out to be the IM gasket- passenger side front
corner. Funny thing is it was a intermittent leak. One afternoon I stepped out and smelled hot antifreeze, the thing was spraying coolant everywhere. After it cooled off I could squeeze the upper hose and hear the suction through the gasket!
I ran it a couple days with the cap loose (6 miles) then tightened the cap and it sealed back up and didn't leak a drop!
Glad that's over!