99 Silverado Overheating

[mcbassin]

I know this is the LSx swap section but I figured it would be the best place to ask.
My daughter drive s 99 Silverado, 5.3 engine. Yesterday she calls me and tells me a hose popped and it was spraying stuff (coolant).
She sent me a pic, I told her it was the heater hose. I told her, see if you can lock it back on and get some premixed coolant. Long story short, my son filled the coolant back up through the top radiator hose once the truck cooled down.
By the time I get off work, they call me and said it went about 1/2 mile and got hot again.
I drive there, and fill it up again through the top radiator hose. It appears to be completely full of coolant. I gave her my car and drove her truck home (about 7 miles). I had to stop to let it cool down a few times.
It's really weird to me, almost like the water pump is not circulating the coolant.
I changed the thermostat last night, just because it's a quick fix. But it didn't fix it. I let the truck idle up to temp, it seemed fine but as soon as I drove it about 1/2 mile the temp shoots up again. I had to let it cool down then return home.
The truck is a high miler (235k+) and all stock, the thermostat had been changed before. i.e. the goop job for make a gasket they used. The motor has tons of power and runs great. Doesn't consume oil or anything. There is no sign of head gasket or cracked head, no steam from the exhaust and the oil is clean.
I'm not into just throwing money at experimentation.
Has anyone experienced a water pump impeller failure or similar?
The coolant looked really clean and it doesn't appear the engine could be stopped up.
Suggestions?

[ls1nova71]

How far did she drive it after the hose came off? Maybe could have done damage if it was driven until it quit running, I only say this because ive seen people at my work do it believe it or not. Other than that, I have heard of impellers coming loose from the pump shaft, but it would be a strange coincidence if it happened after the hose came off.

[mcbassin]

Originally Posted by ls1nova71

How far did she drive it after the hose came off? Maybe could have done damage if it was driven until it quit running, I only say this because ive seen people at my work do it believe it or not. Other than that, I have heard of impellers coming loose from the pump shaft, but it would be a strange coincidence if it happened after the hose came off.

No she didn't drive it at all when the hose came off. As you can imagine steam probably bellowed out pretty good. I don't think the engine is damaged but I have been wrong before.
I know it gets hot super fast, almost like when you lose a serp belt.

[BR3W CITY]

Do you get heat from the heater?

99 Silverado's IIRC had the early car-style press fit waterpump pully which can gouge and freewheel on the shaft. Pulley turns, shaft doesnt, or does so less.

[mcbassin]

Originally Posted by BR3W CITY

Do you get heat from the heater?

99 Silverado's IIRC had the early car-style press fit waterpump pully which can gouge and freewheel on the shaft. Pulley turns, shaft doesnt, or does so less.

I'm thinking the heat was working but I'm not 100% sure because the temp was warm out.

[mcbassin]

Yesterday, I spent a bunch of time trying to remove air from the system. From research I was thinking there's still air in there. I think I burped it all out. It never overheated while idling but as soon as I drive a 1/4 mile the temp shoots up. I think the clutch fan isn't working properly but I just don't see it heating up that fast even without the fan.

[homemade87]

Originally Posted by mcbassin

Yesterday, I spent a bunch of time trying to remove air from the system. From research I was thinking there's still air in there. I think I burped it all out. It never overheated while idling but as soon as I drive a 1/4 mile the temp shoots up. I think the clutch fan isn't working properly but I just don't see it heating up that fast even without the fan.

Remove the hose on the steam line and finish filling it at the upper radiator hose and see if it takes the rest of the air out. Is seems like you still have air trapped.

Something else to consider is it could have been doing this before the hose blow out . It could have been the reason for the hose coming off. These are low pressure systems . With the added heat and pressure the hose could have come off . I have never heard of a hose coming off of one of these systems . Something to think about .

[ls1nova71]

If the clutch fan was bad, it would get hot idling and when you drove it it would cool down.

[mcbassin]

Originally Posted by homemade87

Remove the hose on the steam line and finish filling it at the upper radiator hose and see if it takes the rest of the air out. Is seems like you still have air trapped.

Something else to consider is it could have been doing this before the hose blow out . It could have been the reason for the hose coming off. These are low pressure systems . With the added heat and pressure the hose could have come off . I have never heard of a hose coming off of one of these systems . Something to think about .

I have no idea of what the symptoms were leading up to the hose popping off. I have asked my daughter what the temp was, but obviously she didn't monitor it. It sucks she has to drive an over the hill beater but I have never had any issues with the cooling system until the other day. I do all the maintenance on this truck, I've never noticed anything out of the ordinary.
I did get a bunch of air out of the system but I suppose there could be more trapped in it. I will try filling it again at the hose.

Originally Posted by ls1nova71

If the clutch fan was bad, it would get hot idling and when you drove it it would cool down.

This makes sense to me too, but I have read threads (internet has millions on this subject) that say just the opposite. It's hard to know what to know is good info. I've only had a similar problem once on these motors and it was on my red truck. I didn't know to fill the engine from the upper hose and it got pretty hot on my first test drive.
After I filled it correctly it cools normal.

[homemade87]

Originally Posted by ls1nova71

If the clutch fan was bad, it would get hot idling and when you drove it it would cool down.

There is a lot of truth to this . Most don't know this but the gm vehicles that came with electric fans shut off after about 35mph . At that point they are no longer needed for engine cooling . Once yours gets up to speed the forced air will cool the engine at that point . Thats also why the fan has a clutch . Just does it differently . Slower than 35 is when the fans come into play.

Don't forget to remove the steam line hose when filling . This is important . Watch for fluid to come out and reconnect and finish filling the upper radiator hose. Also part the truck on an incline to help move the air to the front of the engine.

[Hart_Rod]

If you take the cap off of the reservoir, can you see the water moving?

[mcbassin]

Originally Posted by Hart_Rod

If you take the cap off of the reservoir, can you see the water moving?

Yes whenever I throttle it up, it pushes coolant around in the tank. So, I'm thinking it can't be the water pump impellor at this point. Maybe a stopped up radiator or heater core or both. Not sure. I am going to replace the clutch fan tonight and see if that helps.
It's just weird to me that both of my other trucks have electric fans and they rarely ever come on in the winter and they don't run hot.
This 99 gets hot after just a few minutes after driving. It has me stumped but I don't need to just throw money at it.
I'm pretty certain the clutch fan isn't working properly so I will start there.

[BR3W CITY]

Might as well ask; the engine was installed with a downword angle, right? This goes hand in hand with steam line function, tho the steam lines themselves are more important.

[mcbassin]

Originally Posted by BR3W CITY

Might as well ask; the engine was installed with a downword angle, right? This goes hand in hand with steam line function, tho the steam lines themselves are more important.

The engine is in the stock position.

[BR3W CITY]

Originally Posted by mcbassin

The engine is in the stock position.

sorry forgot this wasn't a swap truck.

[mcbassin]

Well it turns out there was still a bunch of air in the system.
I filled the coolant through the upper radiator hose (steam line disconnected) with the truck on a steep incline.Then idled it while
watching the temp and coolant with the cap off the surge tank. It took about 20 minutes.
A lot of air bubbled out during this process.
I test drove it for about 4 miles up to 60 with no increase in temperature.
I will drive it a few more times before I put her back behind the wheel.
What about the heater hose quick connects? I wonder what caused it to pop off?
I guess it could have gotten too much pressure built up.
Should I remove it completely and just clamp the hose to the outlet? It seems like a poor design.

[homemade87]

Originally Posted by mcbassin

Well it turns out there was still a bunch of air in the system.
I filled the coolant through the upper radiator hose (steam line disconnected) with the truck on a steep incline.Then idled it while
watching the temp and coolant with the cap off the surge tank. It took about 20 minutes.
A lot of air bubbled out during this process.
I test drove it for about 4 miles up to 60 with no increase in temperature.
I will drive it a few more times before I put her back behind the wheel.
What about the heater hose quick connects? I wonder what caused it to pop off?
I guess it could have gotten too much pressure built up.
Should I remove it completely and just clamp the hose to the outlet? It seems like a poor design.

That's good news .I have never seen a fail of the quick connector . I would just keep the quick connector but I would order a new hose and replace it before I gave it back to your daughter . There seems to be something wrong with it . No need to go thru this again . Preventative maintenance .

[mcbassin]

Originally Posted by homemade87

That's good news .I have never seen a fail of the quick connector . I would just keep the quick connector but I would order a new hose and replace it before I gave it back to your daughter . There seems to be something wrong with it . No need to go thru this again . Preventative maintenance .

I'm going to replace all the hoses and I'll go ahead and get the connectors too.

[homemade87]

Originally Posted by mcbassin

I'm going to replace all the hoses and I'll go ahead and get the connectors too.

All the hoses I have see come with the new connectors for the heater core . Just have to pop them on . Not 100% on the 99 though .

[mcbassin]

Originally Posted by homemade87

All the hoses I have see come with the new connectors for the heater core . Just have to pop them on . Not 100% on the 99 though .

The pics on rockauto.com do not show the connectors and in fact they have them individually. I will call them to confirm before ordering.