71Camaro-Norway

Hi there. Sorry that I do not have a problem with my Camaro, but I am desperate looking for help on my Silverado Pickup 4x4 with a TBI V8 350cid engine.

The last owner told me that I needed to change the thermostat in the engine and it was running without that now. Tried to install a new thermostat, but then the engine overheated at once.

Then I changed the water pump, did not help. Installed a new radiator, did not help. Took the car down to a local garage, they checked if the head gasket was gone, but no… Installed a new cap on the radiator, still not any change… When the thermostat opens, the radiator host are getting flat???

The engine runs like a clock without the thermostat, and do not use any water… I have used the truck for a while, and since the engine is not running with the right temp, it uses a lot of gas! I want to convert it to run on Propane, but need to fix this problem first.

Can any one help out???

UDLooz

have you had the system pressure tested at the radiator shop? could be a cracked head/block or a pinhole leak somewhere. Trucks with their large grilles, huge radiators and HD fans usually cool very well.

71Camaro-Norway

Yes, I have had the system pressure tested at the radiator shop. But if there is a cracked head/block, can you really just use the truck without any problems? At the radiator shop, they also tested if there is a broken head gasket, but there is not broken.

I have used the truck for 5 months now…

UDLooz

if the hoses are going flat, check for air in the lines and get hoses with built in springs to keep them from collapsing (should be available at the parts store)

it really sounds like a flow problem, if the hoses are collapsing I don't think the pressure is high enough. how did they test for the blown head gasket?

71Camaro-Norway

They had a device that they put in to the radiatorwater while the engine was running. And they told me that the liquide inside this device will turn green if the headgasket was gone...

UDLooz

that just looks for exhaust gasses in the coolant, not 100% accurate

Vader

A system pressure test would be vey helpful. That still does not explain the difference in cooling capability with the thermostat installed or removed.

If the hose (especially the lower radiator hose) goes flat when the thermostat opens, the problem is not the thermostat, nor the system flow. The problem could be that the reinforcement wire (spring coil) is missing from the lower hose. When this occurs, pump suction can flatten the hose and effectively stop any coolant flow from the radiator.

I'm speculating that the phenomenon does not occur with the thermostat removed because there is no restriction in the upper radiator hose in that situation, and pump pressure helps keep the radiator slightly pressurized and lower hose therefore "inflated" enough to allow coolant flow.

In short, drain the system, verify the spring wire reinforcement is intact inside the lower radiator hose, and have fun with the propane conversion.

ZEEYAA

Crazy question, are you sure you installed the thermostat in the correct flow pattern, number two, are you sure they gave you the right waterpump with the correct flow direction. If it is a serpentine belt they may have given you one that is flowing the water the wrong way causing a vaccume instead of pressure, and the other member is correct you need to make sure all the air is out of the system and get some new hoses, sometimes after they get old they get soft and will collaps very easy, you need to make sure that they have the spings in them. Good luck.

jstrdn90rs

I own a 90 chevy 4x4 with TBi and had the same problem..The thermostat was stuck open or the previous owner made it that way.Anyway..after installing a two thermostats, I still got air pockets and overheating.I ended up removing the valve covers gaskets and at the rear of the heads was about an inch of sludge covering the oil drain holes for the rear of the heads.I was scraping sludge out of this engine for days,had tracked it in the house... in the carpet it was a mess.After adjusting the valves cause they were are out of specs, she runs great.Gets a little warm on the freeway but never overheats..that problems lies in the radiator itself.So with the thermostat stuck open ,the oil never reaches temp... forms sludge..idle never goes down cause computer thinks its cold and dumps additional fuel to warm the engine up and to top it off ,the previous owner took off the anti-lock stuff cause he couldnt stop the truck with his boat behind it..WELL DUH, maybe cause the computer kept the idle too high..thinking the engine was cold.All I have left is install the anti-lock stuff back on and the radiator.