Coolant leak...need help diagnosing/finding the problem

[munly]

98 k1500, 5.7 vortec, 4L60e.
Hi guys. I need some help. My truck started leaking coolant yesterday. I drive, the motor warms up to operating temp, I shut it off and the coolant will begin to leak. About 50 ml or so. Then it will stop. I assume it leaks because the system is pressured up...which means it's probably leaking while driving as well. I tried to trace the leak back to its source but I can't seem to pinpoint it. I think it's coming from the front area of the block/passager side. It may be where the water pump mates to the block...I also think I may be the head gasket. Is it possible that it's the head gasket? I'm think this because there may be coolant leaking somewhere at the back of the block as well (but I'm not sure, it could be the way the coolant is making its way to the lowest point of the motor before it drips to the ground).
Either way, I have all the parts to do the intake gasket replacement (because it's leaking also, this was happening before the external leak) and the mpfi upgrade. So I'm just wondering if I should be prepared to tackle something else.

Ps...I haven't had any over heating issue, but I haven't drove it more than 10km since I noticed this leak.

Any help would be greatly appreciated. Thanks.

 

[great white]

Likely the watter pump is going out by your description.

There is weep hole in the bottom of the water pump snout. When the wp seals are failing or the bearing is wobbling it will leak from this hole.

This is what I would check first.

If that is the problem, replacement of the wp is the cure....

 

[munly]

Ok thanks. I'll have a look. If it was the intake or head gasket would it leak externally like I described above. Previous to this I have had dropping coolant levels but no external leak and white smoke on start up. From the research I've done these are the symptoms of a leaking intake gasket. Any info appreciated...thx.

 

[SAATR]

I've never seen a SBC head gasket blow to the outside, or leak to the outside. Generally they blow into the cylinder or between cylinders. The intake gaskets can certainly leak externally, and I have personally seen it happen on Vortecs and older SBC's. Best way to check it is to clean the area around the head to intake surface and apply pressure with a cooling system pressure tester. You'll see your leak, if one exists. It's much safer than working on a hot engine. If you lose pressure and can find no external leak, then it's best to crack the oil drain plug and see if you get coolant drops. That would generally indicate an internally blown intake or cracked block. The danger is that a blown head gasket will allow a cylinder to fill with coolant, which can hydro lock the cylinder and cause all kinds of havoc when you try to start the engine.

Sent from my XT912 using Tapatalk

 

[great white]

Ok thanks. I'll have a look. If it was the intake or head gasket would it leak externally like I described above. Previous to this I have had dropping coolant levels but no external leak and white smoke on start up. From the research I've done these are the symptoms of a leaking intake gasket. Any info appreciated...thx.

Nope. Head gasket is an internal leak.

It either goes into the crankcase or into the exhaust as steam.

Leaking itake gasket is a possibility. It can either leak out or it can also go into the intake stream and out the exhaust as steam.

It is possible you have 1 or more problems happening simultaneously.

I have seen a failed head gasket leak combustion pressure into the coolant system and also cause the water pump shaft seal to fail. This causes you to loose coolant, experience high coolant temps (sometimes overheating) and it the over pressure caused already weak pump seals (high mileage pump) to fail.

X2 on the suggestion above to use a coolant system pressure tester.

You can buy one or usually rent one at a local parts store..

 

[Scrufdog]

Check those coolant line quick connects too

 

[JollyGreen]

Everything above is spot on by GW and SAATR. Is it running hot?

 

[munly]

It's not running hot. But then again I haven't been driving it since I noticed the external leak. However I was loosing coolant prior to this. I'm assuming it is the intake gaskets as i have white smoke/steam when I start the truck, until it warms up and no external leak.
Where is this quick connect you're referring to. Is it behind the alternator? That's where it seems to be coming from. I'm just hoping it's not a head gasket or a cracked block. Like I said in an earlier post I'm going to do the intake gaskets when I get a chance and I'm hoping that's all that it is (and the water pump too).

 

[semperfi]

It's not running hot. But then again I haven't been driving it since I noticed the external leak. However I was loosing coolant prior to this. I'm assuming it is the intake gaskets as i have white smoke/steam when I start the truck, until it warms up and no external leak.
Where is this quick connect you're referring to. Is it behind the alternator? That's where it seems to be coming from. I'm just hoping it's not a head gasket or a cracked block. Like I said in an earlier post I'm going to do the intake gaskets when I get a chance and I'm hoping that's all that it is (and the water pump too).

Munly....This engine has a common coolant leak problem from the intake manifold, usually the back end. I have had my '96 5.7l Z71 since new & had this issue for the last 10 years. I would lose a small amount each week and never could find where it was coming from until last year when it got worse. BTW, I only have 61k miles on it now, so you can see I don't drive it much. I bit the bullet last summer & pulled the intake & sure enough, the gasket was bad on the rear passenger side. They make a updated gasket with a "steel" core if I remember correctly. This would also be a good time to replace the "spider injection" with the updated version, valve cover gaskets, heater lines, and all other rubber hoses.
Let me know if this is something you can do yourself & I can direct you to a couple sites. A good place to start is search YouTube for the GM 5.7l V-8 water leak, you'll be surprised at the number of videos for this & the comments on how frequent the issue is