98 Z71 350 Vortec Problems

[HondaMartin]

Hi all, My truck just all of a sudden quit running. There is gas in the airbox, and its steaming, the exhaust is steaming and there looks to be like coolant in the oil. The dipstick is covered in a mud type mess. It runs after it sits for a while, but it soon starts to sputter and will not run for its life. Is it a blown head gasket, cracked head, cracked block, or a intake manifold gasket. Thanks

[killthewabbit]

I don't think you're going to be able to tell which of those is definitively the problem without yanking the engine and tearing it down, or at least removing the heads.

[68C15]

It probably started with the intake leaking. Then it over heated and cracked the head(s). The blocks are pretty strong, unlike the heads. I would advise against having them fixed. New aftermarket is the way to go.

[rickpilgrim]

I'd really guess head gasket with what you have described. Compression is leaked into the cooling system and blows the coolant out the overflow and or radiator cap and the engine fan blows it everywhere. Worse yet because there's air instead of coolant where the temp sensor is your guage is slow or unable to display engine temp. My 98 K3500 did this to me and yes it got so hot that the o-ring on the pressurized fuel connection disintegrated and sprayed fuel everywhere. Everything below the heads was ok.
If you decide to repair the engine I'll x2 the aftermarket heads. My machinest won't touch Vortec 5.0-5.7 heads, he uses the Summit Racing Vortec heads for his rebuilds.
The bottom end on the 5.7 is strong, even though it got really hot at 155,643 mi bores were nice and bearings were within spec. Yours should be similar.

[HondaMartin]

Thank yall. I dont think it ever got HOT but it did get a tad bit warmer than normal. I found a 350 with only 16k for $1k. Im just gonna swap them and beef up the old 350 and experiment with efi in a play truck. 86 4x4. 6inch lift and 37s. after I buy new heads, small cam, and headers.

[rickpilgrim]

If you need some shorty headers(from 98 5.7, 1/4 of new + ship) for your play toy PM me

[68C15]

"Don't think it got hot"

I've heard that before. Usually while I'm replacing the engine. Worst one was a motor home going from factory to dealer. It lost coolant so the gauge was reading air temp in engine. The driver also said it was. "A little warm"

[HondaMartin]

Originally Posted by 68C15

"Don't think it got hot"

I've heard that before. Usually while I'm replacing the engine. Worst one was a motor home going from factory to dealer. It lost coolant so the gauge was reading air temp in engine. The driver also said it was. "A little warm"

The Engine still had coolant. But it never got to 210. maybe 175, 180.