Coolant leak

Worktruck · March 7, 2005

Posted this in Compact and Light Duty as well.

My son has a 98 S-10 4wd with the 4.3. This truck has developed a coolant leak and I'm having a hard time finding it. Appears to be at the left front of the motor. At first thought I it was the water pump but removed and inspected, re-installed with new gaskets and still leaking. Next I checked the upper radiator hose and that wasn't it. Next I removed the intake ducting and noticed a puddle of coolant where the intake and the rocker cover meet. I can't find a obvious leak there so I cleaned it all off and ran the engine again and the coolant is back. It's a pretty good leak, drips off the bottom side of the motor at a pretty good rate. Are these 4.3's known to develop manifold leaks, is there something I should check before tearing the top off this thing? Any help would be appreciated.

firstruck · March 8, 2005

I don't claim to be an authority on this but, I'm guessing its the throttle body coolant loop conections. There are two small coolant hoses that run up to the TB and actually keep it warm in winter(and summer) to keep it from freezing up. I know my Land rover has them and they leak, but what doesn't leak on it?

Haulin' 8.1 · March 9, 2005

At this point I'd suspect the intake manifold gaskets, it's common. Coolant passes through the intake from the head corners on the way to the thermostat.

See if you can borrow or rent a cooling system pressure checking set. Then you install it where the radiator cap fits and pump it up to operating pressure. Where ever coolant comes out is where you need to work.

Vernon

dougmac · March 9, 2005

Are these 4.3's known to develop manifold leaks, is there something I should check before tearing the top off this thing? Any help would be appreciated.

<{POST_SNAPBACK}>

Yes, 4.3 manifold leaks are very common. We have a large fleet of vehicles with 4.3 GM engines and replace a lot of intake gaskets. We also have replaced a few engines when the coolant has leaked into the crankcase, contaminated the oil and taken the bearings out.

Glycol rapidly destroys bearing material. My advice is to get it repaired as soon as possible to prevent a complete engine replacement due to failed rod and main bearings.

Doug

Worktruck · March 9, 2005

All done. Turned out to be the manifold gasket. Didn't leak into the crankcase though, but what a PITA.

griphon · March 23, 2005

I just got done this weekend changing out the intake gasket on my 98 K1500 Ext cab. It ended up taking about 5 to 6 hours. This was the biggest PITA mainly due to having to take everything off the top of the engine to get at the intake. Then after doing so find that some brillinat engineer decided that the bracket for the air conditioning compressor would be OK to allow to hang over the front drivers side bolt of the manifold. Other than that everything went well.

After talking to a couple of local shops I also decided to flush out all of the Deathcool and put green back in it. Coolant level is the most consistent (right where it should be) that it has been in 3 months. I will also be changing the oil this evening when I get home from work.

Anyone with basic ability and a lot of patience can do this procedure. Just make sure to hold off on the beer until after you are finished working on the vehicle.