More likely the factory clamps. They only work for the first few years or till you touch it. You can put a normal one on without loosing your coolant they come apart

I was just going to say, your hose clamps are too far to the end of the housing. You need to move it back towards the housing.

ya Thanks Guys...
I installed a ring clamp on the rad side, closer the rad and it seemed to help.
Going to to try to do the same today on the thermostat side and see if it stops.
The hose at end though is still bulged out...Cant wait for new hose to get here....

The New Delco Top Hose arrived..!! (finally) from Michigan, Got 2 Stainless Gear Clamps!

Also while at dealership going to try a new Delco 195F thermostat. NO gasket included, I guess I can use the left over one..??
William looks like the OEM one has no hole in it for bleeding air.
Can you please tell me..do I drill it at the blue mark on photo for the 12 o-clock position or ...??

That is a fine location to drill a small hole.

Thanks!
There'* a hole in my.........thermostat..dear Liza, ...Mike & William.....LOL..

Also replacing the aging front ceramic pads into semi-metallic tomorrow..post 589
https://www.gmforum.com/lounge-99/wh...9/#post1603812
Time to get er done...Sat under hood with tires off again....

What size hole did you go with 3/32"?

You made sure to install it with that drilled hole in the 12'oclock position right?

Yes William 3/32 and then a slight bit of sides reaming to just under 7/64.
Will install it in the 12 O'clock position..not done yet..2 am here now, however in 7 hours will start on it all...

Ok So the new Delco Hose was a perfect fit. Gear clamps not leaking now!

Even with the hole in the thermostat, it is like starting from scratch again.
This cooling system holds enough air to fly a 737 though it.
Filled it started engine, refill after slight rev at 197F then cap on, bleed air valve etc....
Took for 40 mile hwy boogie with interior heat on then let system cool, remove cap, refill it, bleed air again..getting there..some now in top rad hose..repeat in another 40 miles...
So far used about 3/4 of a gallon.
I think you get the idea....Going to let it cool for 10 hours now and open cap & top it up. Went through the same thing after LIM job.
Took 3 days before the upper rad hose was rock hard...fun!
I will have to also post something later once I get some shut eye on the front brakes..what a day...

Ya after work tonight I notice a nice puddle of clean fresh coolant below the car on passenger side...great...
Pop the hood and gave a look..tell me it'* now not the lower rad hose ... Was wet all around there and I thought the worse...
So I fire up the car and am looking all around and below and see a drip and smell coolant. Remember that new Delco rad cap I bought 2 weeks ago...ya luckily it is leaking from around the seal pretty good.....
Another band Aid of paper towel now exist around the cap until I can swap it out with my old one that does not leak. Back to dealer soon to try another Delco cap...
I hope it is only the cap..It seems ever since I tightened the system up by new UIM /LIM, now that it is pressurizing better, it is one thing after another..

While I was under the car, I also noticed an oil leak....
Remember that nice new fel-pro oil pan gasket I installed a year ago...well
I think I may need another gasket kit. Wont know for sure until I can get it on the lift for further inspection...
Old Gm'* do run and leak good !