350 Vortec loosing coolant?

[Vortec 350]

I just purchased a 1998 c2500 with a 350 Vortec with a 4l80e. It's a decent truck except that it uses coolant. When I first got it I changed the oil and drove it for a while. I noticed it was burning some oil so I was adding a 1/4 quart in 500 miles. My stupid self forgot to look at the coolant level, so when I looked the resevoir tank saw empty and the radiator was like 1/2 full. Anyway I added a gallon and a half to get it to the cold line. I've been driving it turning the heat on and off to try to get the level to settle. It's been about 200 miles since I added the coolant and it is still got a coolant drinking problem. I know the intake manifold gaskets are a common problem, but I don't know what the symptoms are and she seams to run good. Also I don't see it leaking anywhere, and no it's not ending up in the transmition. Thanks for reading any help would be appreciated.

 

[Gearheadmike]

There's only so many places it can go. I'd check oil for milky-ness if not going in oil then it is either leaking or burning it. Did you check to see if heater core is leaking?
Also did you top off using antifreeze or water?

 

[Vortec 350]

There's only so many places it can go. I'd check oil for milky-ness if not going in oil then it is either leaking or burning it. Did you check to see if heater core is leaking?
Also did you top off using antifreeze or water?

The oil doesn't look milky but after I topped of the coolant with 50/50 the oil level isn't going down. But the oil doesn't look milky. It doesn't leak a drop of any fluid either.

 

[Gearheadmike]

so no leaking from reservoir tank or the line from it to the radiator? my buddy's tank had a crack so when engine gets hot while driving and tank filled up some would leak it out going down the road when it cooled and pulled antifreeze back to radiator it wouldn't leak.

 

[east302]

Also check the bottom of the radiator, particularly at the drain valve on the driver side. Look down into the fan shroud, see if the radiator support at the bottom is wet.

A coolant pressure test would probably be in order. You can rent a gauge set at a parts store (check to see that the gauge needle rests at zero before you leave with it). Pressurize to around 15-psi and see if it holds.

An intake gasket leak is sometimes visible where the manifold meets the block at the back.




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[grampadirt]

X2 on the intake manifold to head leak...driver's side,rear,happened to wifey's Burb last year.

 

[Pychokenny]

Check the heater hose on the right rear of the intake the one on my 93 snapped

 

[n8pu]

Mine had an intake gasket leak, very slow but a leak none the less. On mine in the front where I could see (without a lift) it looked like it was 'weeping', you could see a spot on the front that was constantly wet, also the over flow tank would never hold its level. I had that repair done for me, I'm mechanically inclined but not to the level of taking an engine apart. Anyway when I went to get it the mechanic said it looked like some of that coolant had also been getting into a couple of the cylinders in the front two pistons on the driver side. Now the coolant level stays right it should, if I take the radiator cap off it is right at the top and the level in the over flow varies very little, AND no more weeping either. This picture is of the gaskets, good luck with yours.

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[Steve A]

Check the front lower corners of the intake where they meet the head and block. Could be leaking into the intake ports also. Stock vortec heads are known to crack when they get hot as well. If you change the intake gaskets don't mess with the stock type plastic/rubber ones. Use Fel-Pro MS98000T, no more leaks!

 

[big_mike]

Check the front lower corners of the intake where they meet the head and block. Could be leaking into the intake ports also. Stock vortec heads are known to crack when they get hot as well. If you change the intake gaskets don't mess with the stock type plastic/rubber ones. Use Fel-Pro MS98000T, no more leaks!

That's where I just found my leak and I have been chasing a missing coolant issue since installing a new radiator. Now she will have fresh lower gaskets, fresh pump, hoses and new thermostat to go with the new radiator. Here is what mine looked like, I didn't see it until the alternator bracket was removed.

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