Places To Look For A Coolant Leak

[Graya25]

Lately my '97 Sierra has developed a coolant leak. It's never anything much, a few drops on the driveway here and there, but nevertheless annoying. The overflow tank is just about empty, so I'm definately loosing some. The engine temperature never reaches over 200 (I don't drive too far), but I can smell the coolant after I've shut the engine off.

 

I tried looking for the source of the leak, and it looks to be somewhere close to the firewall, it's definately not from the radiator. Are there any hoses in particular that are notorious for leaking?

 

I am also aware that the Vortec engines in my series truck are known to leak coolant through the intake manifold gasket, which I'm hoping is not the problem....

[Zembonez]

Intake manifold gasket or water pump. From your description, the water pump is not it. Intake gasket is not all that hard to replace, but do it now before it causes more problems.

[Squirrely]

Could also be a loose intake manifold bolt. But it's prolly the intake gasket.

And I'll post this again. If you have the universal block heater, they go bad and will leak slowly at first... when the engine is cold.

[rodram]

when I could smell hot coolant after shutting my truck off in my garage.... my mechanic confirmed that the Intake Manifold Gasket was leaking ... leaks coolant onto the top of the engine and then most evaporates, so you don't always see any drips/drops on your driveway or garage floor...

\

these are a known maintenance item on the Vortec engines ... when you replace it use the new FELPro gasket kit... don't use the GM gasket parts for this or you will be doing the replacement all over again someday....

[Z'06]

Check for gunk on the bottom of your oil filler cap and at the base of your dipstick. Pulling the intake manifold and valve covers will give you even more information.

[Graya25]

 

 

 

I think I found it. This heater hose that goes to the intake manifold (inlet) looks like it had a leak before and was glued by the shop that the previous owner brought it to. As you can see, the hose connection is broken, and yes, it is wet with coolant. When I was replacing the shock absorber on this side last week I must have nicked the hose somehow that it would break the hold of the glue. No gunk was on the oil cap or dipstick and it doesn't look like there is a gasket leak (yet). This is a 305 engine, which, at least from my research, seems to leak less from the intake manifold gasket than the 350.

 

I appreciate all of the suggestions. Thanks for the help!

[VRSCA1]

If that fitting does not come out in one piece sometimes it breaks off flush in the intake you will be pulling the intake anyway.Most common area for coolant leaks,that fitting,intake,water pump not necessarily in that order.

[jrod332]

I found a good way to find a slow leak thats hard to find is to pressurize the system. Should force coolant out wherever its leaking.

[SAATR]

 

 

 

I think I found it. This heater hose that goes to the intake manifold (inlet) looks like it had a leak before and was glued by the shop that the previous owner brought it to. As you can see, the hose connection is broken, and yes, it is wet with coolant. When I was replacing the shock absorber on this side last week I must have nicked the hose somehow that it would break the hold of the glue. No gunk was on the oil cap or dipstick and it doesn't look like there is a gasket leak (yet). This is a 305 engine, which, at least from my research, seems to leak less from the intake manifold gasket than the 350.

 

I appreciate all of the suggestions. Thanks for the help!

 

Glued ?!?! Wow, talk about shadetree mechanicing! Nothing against you, the previous owner, or the truck, but I would pay my bill and drive away as fast as possible from any shop that suggested gluing one of those fittings as a viable repair option. Those fittings most often shear off (usually flush with the manifold ) when you attempt to remove them. The best (though not the cheapest) way of taking care of it is to purchase a 1/2" pipe thread tap and a 29/64" drill bit (or one that will just miss the threads on the manifold). If the fitting breaks off, drill the broken portion out with the bit (liberally coated with grease to pick up any bits and shavings) and then chase it with the tap, also liberally coated with said grease. Install your replacement fitting of choice, be it a nipple type or one of the steel replacements for the pot metal OEM fitting, and be done with it. The cheaper route is the deft and CAREFUL use of a small cold chisel and a shop vac with a very small hose to remove the bits that fall in. I do recommend thoroughly flushing the system afterward, and perhaps taking the opportunity to dump the Dexcool.