cold miss and water loss

[kenh]

Well, I think I have a problem that is not going away on it's own.

On start up I have a cold miss for a "period" of time. It goes away pretty quick especially if you get out on the highway right away. I'm also losing water, slowly, but don't have any obvious leaks.

One of two or possibly both things. Bad head gasket or cracked head.

Another clue is I was going to flush the cooling system at some point because I thought the coolant looked "rusty". I think the PO dumped a bunch of radiator sealer in it to hide the problem. It worked for a while but now I have the issue to contend with......

Ken

 

[RawbDidIt]

Well, I think I have a problem that is not going away on it's own.

On start up I have a cold miss for a "period" of time. It goes away pretty quick especially if you get out on the highway right away. I'm also losing water, slowly, but don't have any obvious leaks.

One of two or possibly both things. Bad head gasket or cracked head.

Another clue is I was going to flush the cooling system at some point because I thought the coolant looked "rusty". I think the PO dumped a bunch of radiator sealer in it to hide the problem. It worked for a while but now I have the issue to contend with......

Ken

What year?

Sent from my SM-N976V using Tapatalk

 

[stutaeng]

If a Vortec, then perhaps an intake manifold gasket leak? I think those swell after reaching operating temperature and "seal up."

Any codes?

Not sure what it would be if TBI, but I don't think a head gasket or cracked head would cause it to run fine after warmup.

 

[alpinecrick]

The TBI's manifolds leaked too, although the Vortecs were more prone. If the leak is at the back of the manifold (majority of the time it is) the coolant seems to rarely hit the ground, it apparently boils off at the back of the motor. Do you smell coolant?

On occasion the leak will be to the inside. Check the color of your oil closely.

 

[SUBURBAN5]

Well, I think I have a problem that is not going away on it's own.

On start up I have a cold miss for a "period" of time. It goes away pretty quick especially if you get out on the highway right away. I'm also losing water, slowly, but don't have any obvious leaks.

One of two or possibly both things. Bad head gasket or cracked head.

Another clue is I was going to flush the cooling system at some point because I thought the coolant looked "rusty". I think the PO dumped a bunch of radiator sealer in it to hide the problem. It worked for a while but now I have the issue to contend with......

Ken

Silverado?

 

[frito-bandito]

What year / engine?

 

[kenh]

Sorry for the lack of info. It's a 1990, C1500, 5.7 (350). As said I'm slowly losing water. The engine will miss for 30??? seconds or until it gets a few revs to flush the (what I assume) is water out of the cylinder. It is what I have always been told is a classic symptom of a bad head gasket or cracked head.

I just changed the oil a couple days ago and so nothing unusual. I never smell coolant so doubt there is a leak to the outside of the engine. Engine runs like a top except for the cold miss.

I'm going to pull the plugs tomorrow and see if I can find one that is wet.

Ken

 

[brian c lindsey]

yes that is a cold manifold leak and miss , quite common on those engines , new intake manifold will cure that

 

[Schurkey]

yes that is a cold manifold leak and miss , quite common on those engines , new intake manifold will cure that

New MANIFOLD?





Here's a thought. Go to a parts-store that rents cooling system pressure testers. Pressurize the cooling system overnight. Next morning, pull the plugs, have someone crank the engine, and see which cylinder spews coolant. Look for traces of leaked coolant on the ends of the intake manifold gaskets--front and rear.

For the record, you're saying head gasket or cylinder head, but don't forget that the engine block itself could be cracked.

 

[kenh]

New MANIFOLD?




For the record, you're saying head gasket or cylinder head, but don't forget that the engine block itself could be cracked.

Yes a cracked block did come to mind but is not common. Not saying it can't happen. I think the 400's had more issues with cracks due to the siamese cylinders.