Bad Thermostat? Cooling Issue

[brickwhite]

Car - 91 318is

Engine - m42

Issue-

I replaced the Waterpump, thermostat, fan clutch, new temp sensors, and cleaned up the mess under the intake, new hoses etc.

I bleed the system 3 times with the front of the car up in the air. I believe I got all the air out. Followed directions on different sites.

The car heats up and the heater on high, gets hot.

However when I warm up the car and take is for a 10/15 minute drive the passenger side radiator hose doesn't seem to get hot/warm. The temp gauge shows in the middle. But will move a little past there at idle, never higher.

My concern is that that Thermostat is not opening with the lower radiator hose not getting hot. And am a little affraid to drive much further in the car if it's not opening.

Should I be concerned?

And is there an easy way to tell if the thermostat is opening?

[jlevie]

Drive the car a bit longer, watching the temperature gauge. If the thermostat isn't opening, the temperature will start to increase while you are driving.

[CorvallisBMW]

If the return hose from the rad is not getting hot, then coolant isn't moving through the rad. It is definitely possible to get a defective thermostat straight out of the box.

[roguetoaster]

Perhaps you installed the thermostat backwards? Or if you used RTV on the thermostat housing gasket you may have blocked the bypass passageway.

[brickwhite]

I'm pretty sure I put it in right. It was Behr brand thermo.

I put a 1/16" hole in thermostat at 12 O'clock too.

Would the blocked bypass cause the thermostat not to open? I did use a smear of gasket sealer on the gasket but made sure I didn't cover that channel.

Used a little of the Brown Permatex

[kwill22]

You say passenger side hose? That's the lower hose and it's not supposed to be hot. The top hose is the hot one the lower is the fluid that's gone through the radiator and should be cooler than the top hose.

[brickwhite]

But it should get warm after 10/15 mins of driving. Right?

[TobyB]

the lower radiator hose not getting hot

That means your radiator is working well. The upper hose should be hot,
the lower one cool. In St Louis in April, it could very well be pretty darned cool.

If the temp rises a little when you stop moving, then drops as you pick up speed,
your thermostat is working. Your engine fan may not be.

t

[brickwhite]

Well, I drove it last night for about 30 mins , and got a speeding ticket while doing it. Sucks but my own fault. but never went above 12 o'clock even while idling waiting for the Cop giving me a ticket for 74 in a 55.

Guess I'm good to go.

But I think I have a header leak/ exhaust leak it's noisy from the engine bay.

[oldmann]

Just gettin into 3rd, good thing you hadn't wound it up yet.

Be careful with any exhaust hardware, studs in head and so on, If you don't have replacement hardware, gaskets and such, on hand. That stuff is usually seized, and breaks off, strips, shuts you down until you can source parts.

[brickwhite]

Any one use Seafoam to find exhaust leaks? Or have a better method to find those leaks?