I have a Olds Silhouette with the 3.4...rebuild the top end when the head gaskets blew...just rebuilt the heads and replaced the top gaskets and such..no cam work or timing chain stuff..worked great for a while, then the van quit making heat but still ran fine.

Now, the thing runs hot in stop and go, but get it on the highway at crusining speed, the temp of engine stays in check....the top rad hose is cold with no water running thru...I am thinking vacuum leak since when I open the bleeder on the gooseneck the air comes out in spurts.

Question is, I have heard of water pump impellers breaking with no visible evidence without yankin it apart...would this be the prob or do I have a major vacuum leak and where to look?

Appreciate any help before I dive into this...these GM vans are not easy to get into...I hate all these sensors and crap...I guess I am a 34 year old backyard mechanic with hating these newer cars..

Sounds like it still has air in the system. Keep the bleeder open until just coolant comes out.

Sounds like it still has air in the system. Keep the bleeder open until just coolant comes out.

First thing I thought of too.

There are 2 bleeders, one on the thermostat housing, and one on the hard line above the water pump.

I am assuming you are talking about the newer 3400 motor and not the 3.4 DOHC from the early 90s.

Yes, its the newer one...I get no air from the water pump side, and get air spurts but no coolant, seems if there is no coolant running thru the top hose.....

There must be a ton of air in the system yet. Is the radiator full? Leave that screw on top of the thermostat open and rev up the throttle at the throttle body, otherwise it could take a while to see anything.

I have seen a few of those with cracks in the engine block radiating out from around the head bolt holes.:sad:

I will try that, ty...I was even told if worse copmes to worse, replace the intake gasket...I did that before but you have to use sealant and the ends instead of gaskets so maybe the selant spread wrong over the ends of the block......