Upper radiator hose popped at the radiator side

Hi guys,

Today I arrived home at night, as usual, and after a minute of parking the car and turning off the engine, there's a LOUD pop and lots of steam start coming out from under the hood; I let it alone a few minutes so I wouldn't get burned with hot coolant.

I go to open the hood and find out the upper radiator hose came off at the radiator side, radiator seems to be intact as well as the hose. It has a worm type clamp on it.

A little background of the cooling system:

- Heater core developed a leak a long time ago so it's been by-passed.
- Engine was apart due to a cracked head, "mechanic" used lots of RTV on the plastic coolant elbow.
- Water pump replaced back in late 2009
- Replaced the radiator and upper hose in january 2010 because the radiator had a leak under the fill tube, the hose burst down the road.
- Installed a new radiator cap at the same time the radiator was replaced, used one from autozone (motorad) with an external pressure relief valve. 16PSI. Like the one in the following link: RADIATOR CAP (http://www.autozone.com/autozone/parts/CST-Radiator-Cap/1997-Pontiac-Grand-Prix/_/N-j8uzbZ8gcwj?itemIdentifier=4443_167256_4559_)
- Thermostat was replaced around september 2012 with one from the dealer.
EDIT - Coolant is the regular green one, no DEX-COOL stuff.

Fast forward to last week
Tensioner assembly came apart and left me stranded at the side of the road so I had to replace it on the run; used a Gates replacement, came with a new plastic coolant elbow. Since it was getting dark I used RTV on the nipples to the heater hoses (had to transfer both from the old unit); it was dark and I didn't notice if they are a different size or have any difference on them, don't think so, so I just installed them at random (put some RTV around the edges, o-rings were toast). Car hasn't overheated since and had been running fine, temp gauge reads around 212 it might go slightly higher than that but comes down after a few seconds, there were no leaks; all normal behavior.

I noticed a little black build-up on the radiator cap. When the heater core started to leak, I used some stop leak product; this might be some leftovers, although I remember flushing the coolant when I replaced the radiator.

I don't know what to think, if the clamp wasn't tight, why did it happen after 3 years of replacing the hose?. What caused the pressure to build up high enough to pop the hose? Do you think the tensioner replacement could have something to so with it? Air in the system?

I'll take a better look tomorrow when things are cold and there's enough light.

I'll appreciate any comments,

Oscar.

Clamp was not tight enough---hoses can pop off or stay on with little or no clamp force- depends on angle, friction etc- it was just its time to pop off- put it back on- tighten clamp- make sure clamp is not stripped..

Thank you brcidd,

I took a look at it this morning and everything seemed fine; I'm sure it was the clamp, just like you said. I tried putting it back on with the clamp and went half way in, then I seated it properly with the clamp tightened the same to see if pulling it would cause it to come off and it sure did. I must have forgotten to fully tighten it when I replaced the hose, space is tight there and, today, I had to remove the airbox to make sure the clamp is tight; I don't remember doing such thing the last time...

I took some pics during the process, just in case I'm missing something. I will appreciate if you or anyone else have any comments on them.

This is the sludge on the radiator cap. Maybe the stop leak stuff?
http://imageshack.us/scaled/thumb/202/img2013012900521.jpg (http://imageshack.us/photo/my-images/202/img2013012900521.jpg/)

The inside of the hose, doesn't looks damaged at all.
http://imageshack.us/scaled/thumb/248/img2013012900524.jpg (http://imageshack.us/photo/my-images/248/img2013012900524.jpg/)

Here you can see that the clamp was barely tight on the hose. Almost as straight as new.
http://imageshack.us/scaled/thumb/543/img2013012900525.jpg (http://imageshack.us/photo/my-images/543/img2013012900525.jpg/) http://imageshack.us/scaled/thumb/842/img2013012900526.jpg (http://imageshack.us/photo/my-images/842/img2013012900526.jpg/)

And this is the radiator, plastic is OK and there are no cracks. It has the bigger diameter at the tip, which is what made it last that long.
http://imageshack.us/scaled/thumb/441/img2013012900528.jpg (http://imageshack.us/photo/my-images/441/img2013012900528.jpg/) http://imageshack.us/scaled/thumb/651/img2013012900529.jpg (http://imageshack.us/photo/my-images/651/img2013012900529.jpg/)

I have a theory that there was some sort of leak at the tensioner assembly (the "mechanic" who fixed the cracked head RTV'ed all of the fittings but did not replace the o-rings) and replacing it, took care of such leak. The normal build-up in pressure is what caused the loose clamp and hose to pop off.

Don't know if some air in the system could have aggravated the situation, I made sure to purge as much air out as possible by jacking the front passenger side wheel, opening the bleeder bolt on top of the thermostat housing and poured it in that way. Could listen to lots of it escaping through.

Oscar.

If he put some RTV on the rad neck, the hose will never seal and probably pop off.

No RTV on the hoses, just on the tensioner assembly fittings as I said above, but thanks.

Oscar.

Your radiator cap has to be able to open to relieve pressure into your overflow tank. The fact that it is all gummed up makes me wonder if it is relieving pressure properly.

Thank you man.

I was thinking that there might be a problem with the cap. I cleaned it and seemed to be OK but didn't want to take the risk and decided to get a new one from Gates early this morning; for $3 I'm just not risking it.

I drove the car today until it reached normal temp, cruised around the city and everything seemed OK; temp goes to the center of the gauge, goes up 1 or 2 notches and comes down other 1 or 2 notches from the middle line; pretty much normal.

Later I decided to turn the blower on so outside air would get into the cabin and I could smell any antifreeze and I noticed a little smell from time to time when coming to a stop, keep in mind that the heater core has no coolant flowing through, it's bypassed. I parked and took a look at the fittings and everything looked OK; I'm thinking that there might be still some antifreeze evaporating from somewhere in the engine compartment, there were lots of it inside the airbox when I removed it to fully tighten the upper radiator hose.

Oscar.

Maybe some residual coolant in heater core leaking out, and you smell it with blower on?

Otherwise pressure test....see if it drops and look for a leak....

Thanks Tech II,

I don't think there's any residue in the heater core, it's been 4 or more years since it was bypassed and I would find it real strange to start having any smell until this moment.

I have checked several times around hoses, new radiator cap, etc. to see if there's any fluid leaking out after engine has reached normal temp and is parked but have found nothing. I'm thinking that there might be a very small leak at the nipples on the rear side of the tensioner assembly, since I only used RTV around them and the O-rings were in bad condition. I'll replace them as soon as I can; having to replace the entire assembly and now the ignition switch has left my wallet empty at the moment.

Problems don't seem to end as I started hearing a metal against metal noise during the first 100 yards I drive in the morning (distance between my house and the main street) after that it will be OK for the rest of the day.

There's also a weird noise coming from the engine bay also during the first 30 seconds of starting the engine in the morning (it seems to go away with RPM's), nothing else after that. I really don't know any term for that noise, but I would describe it as dragging a wooden chair over ceramic tiles, I hope you get the idea. I'll see if removing the serpentine belt makes any difference. I must say that this noise happened from before replacing the tensioner, in fact I thought it was coming from it but now I know it didn't.

Oscar.

Noise could be the brake pads making a grinding noise(rust on rotors)....this usually goes away after a few brake applications.....

The other noise could be the air pump coming on on startup....it's "on" time varies depending on the temp of the coolant on startup(doesn't run on a warmed up vehicle on startup)....

Thank you very much buddy,

About the smell, I was thinking that since part of the padding on the hood got soaked in coolant, that might be were the smell is coming from. I didn't think of rinsing it with tap water. Might take it to the car wash and ask them to do it along with the underside of the car and engine.

I don't think it's brake noise, it doesn't comes or goes away when tapping the brakes, it happens when going over bumps. Rear struts and mounts were replaced 10k or a little more miles ago and it puzzles me the fact that it only happens during the first yards and never again during the day.

Air pump, huh? Never heard or read about one on GP's. Where would that be located at and is there any way to test it?

Oscar.

Metal on metal noise could be the a/c compressor clutch rubbing due to corrosion--only when a/c is off (compressor no commanded on)

Thank you for your input brcidd; the A/C compressor is fine, system works and blows cool air as it should. In fact, after replacing the tensioner assembly, it blows even cooler air than before and that rumbling sensation that I used to think was coming from it (noticeable only at idle with A/C engaged) turned out to be coming from the tensioner assembly or pulley. My steering wheel is back to soft at all times and car seems to have more power. That tensioner assembly coming apart turned out to be a good thing after all!

I checked today both fuse blocks and found no fuse or relay for the AIR system, also my car does not shows RPO codes NC1 or NC8 (according to a post in the forum) listed in the label on the trunk lid. The exhaust system does not has any ports other than those for the O2 sensors; I'm sure there is no AIR system mounted on my car.

It's funny that today it was a little warmer and the metal to metal noise did not appear at all; the other suspicious noise (I'll call it a bad bearing noise) was barely noticeable when I tried to listen to it.

I'll see if I can take a video of it, only if it happens again.

Please keep those ideas coming, I really appreciate them!

Oscar.

It's been a few days and I haven't noticed any coolant smell so I guess it was all the remaining coolant on the underhood padding that was evaporating and causing the smell. Will still keep a close eye on it, just in case.

Today I started the engine and was kneeling next to the driver side front fender, where the AIR pump is located according to other users, and it's not coming from there. It rather seems to be coming from the upper intake manifold close to the alternator. At this point I would describe it as kind of a howling noise. I'm pretty sure the MAP sensor has the rubber seal on it and it's in good condition; don't know if a sticking PCV valve would cause that noise.

I replaced the alternator around 2 or 3 years ago with a new unit (can't remember the brand) and I noticed a slight chirping noise when I removed the serpentine belt to replace the tensioner assembly, but I don't think that chirping would turn into a howling noise at higher RPM's. I guess I'll try removing the belt and see if it still makes the noise.

I'll appreciate any input.

Oscar.

Today, I removed the serpentine belt and started the engine, no noise. However, when I tried to turn the pulleys, I noticed the alternator pulley was kinda seized.

I find it very odd since it's a couple of years old. I used both hands and it started turning, I kept doing a few more tries and was OK. Then I decided to re-install the serpentine belt and there were no noises. Voltage output is OK, neither undercharging or overcharging.

Looks like I'll be needing a new alternator soon... DAMN!

Oscar.

Hello people,

Today I found out that the howling noise is actually coming from the water pump and not alternator as I said before. I find it very weird for it to happen since it only has around 10k miles on it (maybe even less). It might have been some manufacturing defect.

I don't know if a slightly shorter belt could have caused it. When I got it, the computer at autozone listed two belts with only 1/2" difference. I got the shorter one because they didn't have the other in stock. The tensioner has about 1" of play when releasing the tension so I really don't think it's putting too much stress on the bearings.

Even when I haven't had any responses lately, I will appreciate if anybody has anything to say on this matter, I want to find other possible causes before the new pump fails again. Thanks in advance.

Oscar.

I replaced the pump yesterday and drove the car today, no noises.

Upon inspection of the old pump, I found some corrosion where the shaft meets the impeller which is very odd since it's supposed to be submerged in coolant. It must have been a manufacturing defect for sure. The bleed hole also had traces of coolant leaking from it; I don't now how I missed it, I used to think that the lose of coolant was caused by a faulty rad cap...

Oscar.