Coolant Leak 1999 5.7

[Modoyadney]

Hello guys,

For some time I've noticed a very slight loss of coolant. Today I decided to take a closer look and I noticed a drop of coolant on the starter motor.
I took a closer look with a mirror and I suspect a little leak between the cylinder head and the block right above the starter motor.

Could there be any another source of coolant in this area?
Or is it probably the head gasket?

I was worried that there might be a bigger problem with the head gasket. But as far as I can tell there was no visible oil in the coolant nor any sludge on the oil cap and the oil on the dipstick looks fine.

 

[Hoesgottaeat2]

Known areas are head gasket and intake manifold gasket. If it's not too significant and you don't want to do a tear down just yet, I personally have used stop leak. Stay away from the pelletized type as that has a tendency of clogging the overflow tank orifice. I've had very good luck with this product in (2) of my 5.7 Vortecs for small head gasket leaks and also in another GM 6-cylinder sedan we have that had an intake manifold gasket leak. Virtually all are drip free to this day as a result. Just follow the directions.

 

[strutaeng]

I vote for intake manifold gasket as well.

I think you can rent a pressure test kit from the local parts store to confirm.

 

[OR VietVet]

On the passenger side of the engine and on top of the engine, there is a PITA heater hose connection at the passenger side front top area. Known for leaking coolant and then can puddle enough to run back along top area and drain off at the back, when driving and the coolant moves. Or the intake. You can rent a cooling system pressure tester and do a proper basics test and see what happens. Do it with a cold engine.

 

[Hoesgottaeat2]

On the passenger side of the engine and on top of the engine, there is a PITA heater hose connection at the passenger side front top area. Known for leaking coolant and then can puddle enough to run back along top area and drain off at the back, when driving and the coolant moves. Or the intake. You can rent a cooling system pressure tester and do a proper basics test and see what happens. Do it with a cold engine.

Right on @OR VietVet. That plastic tee fitting in that area is a known culprit for cracking.

 

[east302]

Whenever that heater hose fitting leaked on mine, it ran down the valve cover valley and dripped from the starter bolts.

 

[Hoesgottaeat2]

Whenever that heater hose fitting leaked on mine, it ran down the valve cover valley and dripped from the starter bolts.

View attachment 407458

Never had that one fail on me. But I’ll be watching mine now that you mention it.

 

[OR VietVet]

I have dealt with fixing that over the years, approximately a dozen times. Half the time the pot metal snorkle, where the hose snaps in, would not unthread and would break off. Some guys just said, needs a new intake. I had to do a new intake one time but the other times I was able to get a sharp small chisel and a hammer and coming at it from the side, was able to break off chunks and dig them out till I had a whole side out and then the rest would vibrate loose and collapse on itself. We always had one guy in the shop that had a thread chaser/tap to use and clean the threads and then gobs of anti-seize on the threads for reinstall of a new snorkle/fitting. PITFA! Worth every dollar I charged for the labor time to do that.

 

[east302]

Never had that one fail on me. But I’ll be watching mine now that you mention it.

Haven’t had one break in the intake during removal, but I’m sure that’d be worth a few dozen cuss words. Mine usually just end up leaking from inside the fitting where the end of the hose meets and overflowing a bit of coolant.

 

[the 18th letter]

I have dealt with fixing that over the years, approximately a dozen times. Half the time the pot metal snorkle, where the hose snaps in, would not unthread and would break off. Some guys just said, needs a new intake. I had to do a new intake one time but the other times I was able to get a sharp small chisel and a hammer and coming at it from the side, was able to break off chunks and dig them out till I had a whole side out and then the rest would vibrate loose and collapse on itself. We always had one guy in the shop that had a thread chaser/tap to use and clean the threads and then gobs of anti-seize on the threads for reinstall of a new snorkle/fitting. PITFA! Worth every dollar I charged for the labor time to do that.

https://www.amazon.com/Lisle-62200-...ocphy=9060351&hvtargid=pla-568792428374&psc=1 saved me a couple times.

 

[Hoesgottaeat2]

https://www.amazon.com/Lisle-62200-...ocphy=9060351&hvtargid=pla-568792428374&psc=1 saved me a couple times.View attachment 407483

Lisle, one of the few that still make good tools IMO.

 

[OR VietVet]

Haven’t had one break in the intake during removal, but I’m sure that’d be worth a few dozen cuss words. Mine usually just end up leaking from inside the fitting where the end of the hose meets and overflowing a bit of coolant.

When I dealt with them breaking, was when I was not prepping correctly. Lots of corrosion built up there and I did not let soak in PB Blaster. I was in a hurry and should not have been. The Lisle tool would have been nice to have, that @the 18th letter shows.

 

[Modoyadney]

I took a closer look on it again today. Everything around the intake and the heater hoses looked and felt dry.
It is just a little wet between the head and block.

I dried it off with some brake clean and a towel and check again after driving tomorrow.
If it gets worse, I might try a bottle of the stop leak that has been recommended.

Thanks for your help. I'll keep you updated.

 

[Capn Jack]

I had a similar heater hose connection leak issue around 200k on my 94 burb. I replaced the fitting in the intake with the GMC part (metal construction) and never looked back. Still dry at 385k. Several overheating episodes over the years lead to sucking coolant wound that I couldn’t cure. In the end I replaced the engine with a new crate one.

 

[Hoesgottaeat2]

@Capn Jack 385k!!!!

 

[Modoyadney]

After quite a while I have had finally time again, to take a closer look this this again.
I found one leak at the coolant reservior. This could be easily fixed by cutting a small piece of the hose and installing a new hose clamp.

Unfortunately this was not the leak that leads to the coolant dripping off the transmission bell housing.
If I also have a case of the infamous intake manifold leak, where exactly should I see the coolant comming out on the rear of the engine?

 

[exp500]

Small leaks that travel or evaporate are sometimes tough to find. Some toilet paper or even paper towel will soak it right up after wrapping, if paper is stained or destroyed you have found it.
One of the worst for me was rear heat tee leaking under pressure spraying on exhaust manifold.

 

[Eman85]

A flex head mirror and a good small flashlight are essential. Look at the back corners of the intake where the intake meets the head. It will not be easy as it's a long way back there. You'll need something to stand on and probably will end up laying across the motor, just be careful not to lean on anything breakable.

 

[Modoyadney]

I came to the conclusion, that there is definitely a waterleak between the cylinder head and engine block on the passenger side. I'm not sure if there something wrong with the intake manifold gasket, didn't find anything here.
I could take a look in one of the cylinders on the passenger side with a endoscope and found no sign of water coming into the cylinder. Additionally I have made a test with one of those CO2 head gasket leak testers - also negative.

Is this a thing that the head gasket only leaks coolant outside the engine?

Bought a bottle of Bar's liquid copper now and give it a try. If that doesn't help, I guess I'll have to repalce the head gasket and that also includes repalceing the intake manifold gaskets ...

 

[Hoesgottaeat2]

I came to the conclusion, that there is definitely a waterleak between the cylinder head and engine block on the passenger side. I'm not sure if there something wrong with the intake manifold gasket, didn't find anything here.
I could take a look in one of the cylinders on the passenger side with a endoscope and found no sign of water coming into the cylinder. Additionally I have made a test with one of those CO2 head gasket leak testers - also negative.

Is this a thing that the head gasket only leaks coolant outside the engine?

Bought a bottle of Bar's liquid copper now and give it a try. If that doesn't help, I guess I'll have to repalce the head gasket and that also includes repalceing the intake manifold gaskets ...

Follow the directions to a tee. I drain about a gallon out of the radiator, pour the solution in, start it and then top the radiator off with leftover antifreeze/coolant I drained out. Whatever antifreeze/coolant won’t go back in the radiator I pour into the overflow tank.
Then take it for a 15-20 minute drive to circulate.
Watch it over the next few days and top off as necessary.

Please circle back and let us know how you make out.