NEED HELP Overheating 5.3L

[aaserv]

I bought an 03 Envoy with close to 185K on it. Paid to much and it wasnt long until I realized it had been poorly maintained. Got it March of 19. Drove it sparingly but 1 thing was obvious, it leaked oil from virtually every gasket on it. Started making plans to fix it but got busy during the summer and neglected it. Had a lot of front end problems and spent those months fixing those.
So I drove it to New Orleans 1 night, probably 100 miles round trip. On the way back I looked down and the temperature was rising. Stopped as soon as I could and prepared to find a busted hose or something. Found nothing. Filled the Coolant tank and took off again. Every few miles Id have to pull over and let it cool but made it home.
Cking it out I could find nothing obvious as to why it overheated. But when Id start it it would rapidly climb
to 240+ in maybe 4 -5 mins. For some reason I didnt think the coolant was flowing as it should and settled on a sticking T-Stat.
I had driven it a few hundred miles since purchasing it with no overheating problems and for it to start out of the blue seemed very strange.
In August I parked it , jacked it up and prepared to go thru it. Change all the gaskets top to bottom, new water pump and timing chain. That'll should do the trick. It didnt......Still having the exact same problem.
New Water Pump w T-stat, new Temp Sensor, new coolant tank, system flushed and new coolant . Still start it up , let it idle and within 4 -5 mins its at 240 and rising.
Today I concentrated on cking the clutch fan. Info I found says clutch fan doesnt actually even turn on to high speed until 1 of a few things happen. Engine hits 260d, Transmission hits 310d or head pressure in AC exceeds a certain number. Since none of those things are happening normally, Im thinking the clutch fan is not the issue. It should be able to maintain 210d with minimal effort from clutch fan while just idiling in the driveway. Ckd it for air lock today also but where did air lock come from that night coming home after having driven it all that day and nothing leaking. Doesnt make sense.
Ive never found oil in the water so im putting a blown head gasket at a low percentage of being the problem. Without a scan tool its hard to completely eliminate the clutch fan but I really dont think thats it. A plugged up radiator??????? Theres 1 I havent considered much. Not real sure how to determine that so research is coming.
Another possibility I see talked about often is worn out Rod/main bearings in the motor. Thats beginning to look like something to be investigated.
Guessing Ill start out by trying to get it scanned, wont be easy as I cant drive it anywhere and dont know anyone off hand with a scanner. Try to learn a bit this weekend on how to ck for a plugged radiator.
Anybody with any other ideas Id love to hear them........

 

[Mooseman]

For the fan clutch, this is the definitive thread on how to test it without a scan tool:
How to test the electro-viscous fan clutch
It may be noisy when you first start it but if it fails to engage, especially when the engine is getting HOT, it's done (and they do fail a lot)

You have to be sure that there is no air lock in the system. Either obtain or rent a vacuum coolant refill system like this one or use my method where you remove the top hose from the radiator and pour the coolant directly into the block/water pump while keeping the steam tube unplugged until you see a steady stream of coolant come out of that tube.

https://www.amazon.com/dp/B01BW39HJS/?tag=gmtnation-20

Just because you don't have oil in the coolant or vice-versa doesn't mean you don't have a blown head gasket. I have one on my snowmobile and no contamination in either. Just overheating and coolant getting blown out of the reservoir. The head gasket could act as a one way valve allowing combustion gases out but not letting in coolant. One way to check for that is to remove the rad cap cold and start it. Check for bubbles or if it pushes a lot of coolant out. A little is fine as it warms up but it shouldn't gush out. If this is the case, you can further confirm by a leakdown test or a coolant exhaust gas test.

 

[Reprise]

Not saying the head gasket is the original cause of your issue, but if the temp gauge (which is a real one, since you have the V8) climbed to => 240F multiple times... I'd say the odds are good that you'll need to replace one or both. If you start seeing big white clouds of exhaust -- you'll know for sure you have a bad head gasket. You'll probably smell coolant from the exhaust pipe, too. Generally, if you get above 225F for 5min or more, the head gaskets should be replaced.

I wouldn't worry about the bearings in the bottom end causing this. If those were bad, you'd probably hear a rod knock. Stick with the coolant system for now.

Mixture should be 50-50 coolant & distilled water (60-40 is ok, but if it's higher than that, remove some of the mixture & replace with distilled water, run & mix. Repeat as needed until you get closer to that 50-50 ratio).

If it's not orange, then someone has replaced the GM Dexcool with something else. You can potentially use something besides Dexcool, but don't intermix Dexcool with anything else (no top-offs, etc.) You can check the protection level with a cheap $2 tester - the number of floating balls will tell you how close you are to 50-50, and if protection has worn out (1 or no floating balls). If that's the case, there's a good chance you have some corrosion someplace in the system (Dexcool is rated for 5yr / 100K miles from new; it's then supposed to be replaced every 3yrs, minimum).

BTW -- Since you replaced your water pump & t-stat, it takes about 3000mi for Dexcool to coat the internal metal surfaces with it's protective additives - it's often recommended to replace your coolant at that time, anyway, if it's been in the vehicle close to the 3yr interval.


To bleed your system (engine cold), disconnect the right-hand side (as you're facing it) small hose under your throttle body, then fill with coolant until you see coolant start coming out of that hose. That's the high point of your system, so when coolant starts coming out, you've eliminated air gap. Reconnect it when you start seeing the coolant come out of that hose.
BTW, that small hose is there on each side to preheat the throttle body.

Once you're full up on coolant, make sure you've got coolant in the reservoir up to the 'full cold' mark (the bottom of the two).

It probably wouldn't be a bad idea to rent a coolant pressure tester from your local auto parts store. You need to test two things with it - the radiator cap, to see if it holds 15 lbs of pressure (and releases pressure as well), as well as the radiator - put 15-18lbs of pressure into the system, and monitor it. If you see the needle move much lower than about 12lbs, within 20min (or steadily downward, even after repressurizing), you've got a leak, somewhere (and if you can't see it from any of the external points, it's probably seeping past the head gasket(s).

(also... if you tightened the water neck / t-stat housing to spec (about 9-10 ft/lb), the bolts can work themselves loose and leak coolant from there, especially if the engine is stressed (towing, etc.) It has happened to me, so I'm mentioning it here. Get some blue threadlocker and put it on the two bolts, then torque to 11-12 ft/lb. That problem will be solved. Of course, if you're having to do this, you'll need a new t-stat gasket, too, so make sure you have one on hand / replace it.)


Continuing on... With the engine still cold, and the radiator cap off, start up the engine, put the heat up to max / blower high (same for the rear heat, if you have the XL), and monitor the dash gauge as you look for the following: a) coolant cycling through the radiator (you won't see this until the thermostat opens), and, b) see if the lower radiator hose gets hot (when the thermostat opens, the now-hot coolant starts moving through there.

If you don't detect the hose has gotten hot by the time the gauge is at midpoint or higher (about 210F), then the t-stat likely isn't opening. Since yours is an '03, your new water pump is probably the "1st design", which has the t-stat in the water neck (you replace it as an assembly.) You can remove that neck, and place it in a pan of hot water on the stove - the 'pellet' in the t-stat should open up by the time the water is almost boiling. This may be a little difficult to see unless you take the neck out of the pot with some tongs & have a look.
Normally, the thermostat is fully open by about 185F. While new t-stats have turned out to be faulty, the fact that you replaced it makes me think this is not the cause of your issue, TBH - but it should be verified that it's opening.


If you don't have hot air out of your ducts front & rear, then I'd start looking at a possible heater core issue. And if you have the XL, you have two heater cores - the second one is behind the passenger side trim panel in the rear (after the 2nd row). The coolant gets there via a pair of hoses that run underneath, near the frame rail, then route up and into the vehicle, near the rear wheel. Check for coolant leakage along that run, as well, if you're losing coolant. The underhood coolant hoses should be checked to see if there's a blockage somewhere, as well (you can squeeze the hoses along their length. If you want to do preventative maintenance, replacing all of your hoses (upper / lower rad, heater, coolant overflow) wouldn't be a waste of $, since they're likely original and 17 years old now.

You can also feel the carpeting around the area of each heater core, to see if you find any wetness. But you'd likely be smelling the sweet, sickly smell of coolant, as well.

If NONE of these things reveal the problem, and you've worked through Mooseman's list as well - then I'm stumped, sorry to say. Good luck, and let us know how it turns out.

 

[TollKeeper]

One of the first things I would check is to be sure that the engine IS actually overheating. Temp sending units do go bad, and it should not be overheating in 4-5 minutes. The only way to really check that is with a laser thermometer, unless someone has a good idea. Maybe OHM check the sensor, but you would have to do that at both engine hot and cold, and have a reference chart to go off of.

Once the system has been burped of all air, you should not need to add coolant at all. if you do add coolant, it should be only to the overflow reservoir, and it should be minimal amounts. If your adding cooling more often than every once in a GrEAt while, or having to add it directly to the radiator, you have a leak of some sort, somewhere. Heater core, radiator, rear heat core, head gasket, heater hose, heater line, radiator hose, freeze plug, water jacket, etc.

On my V-8, I was loosing coolant for months, and I could not figure out where it was coming from. I got lucky in that I never over heated the truck, I just learned to check the fluid about once a week. Turned out it was a pin hole leak right where the radiator core met up with the radiator end tank. I was loosing about a gallon a month, and it was only leaking when the engine was hot and under pressure. I could smell it, but just couldnt find it. I was doing a oil change, and found it by it dripping on me.

 

[aaserv]

Ok so I did the test on the fan clutch today and it offered very little resistance. Barely touched it and it stopped and then just slowly got back up to speed. I was actually able to stop it with my hand with no problem. Made a video but it didnt come out as bright as I thought it would..

 

[aaserv]

So what do think MooseMan? Is it shot?? And would you know if the clutch fan from my 6cyl will work on this 1? They look the same but don't want to go to all that trouble if its different.

Another question for you on another topic. I downloaded all the service manuals. When I go to front suspension it keeps mentioning that such and such is covered under "wheel alignment" but I dont see wheel alignment anywhere. Any idea where it is , or if its there at all?

 

[Mooseman]

So what do think MooseMan? Is it shot??

Oh yes, she's TU. It's just freewheeling.

And would you know if the clutch fan from my 6cyl will work on this 1? They look the same but don't want to go to all that trouble if its different.

Yes, they're both the same. However, if looking at getting a used one, trust me, it's a real crapshoot unless it looks like it was replaced just before it was scrapped. If getting a new one, stay away from Dorman and other eBay no-name brands or even junk like Duralast as all have been reported with high failure rates. Hayden has been used a lot on here. You could also go for the non-electronic thermal type used in 08-09 TB's but you'd need to get the codes for the fan tuned out.

Another question for you on another topic. I downloaded all the service manuals. When I go to front suspension it keeps mentioning that such and such is covered under "wheel alignment" but I dont see wheel alignment anywhere. Any idea where it is , or if its there at all?

I honestly don't know as I don't use them.

 

[aaserv]

The fan off my 6cyl was working fine when I parked a couple years ago. If it doesnt put up to much of a fight Ill take it off and use it until I can afford the AC Delco OEM.
Im not driving it or anything but would like to make the block a few times at least as i get the other things it needs sorted out.

 

[aaserv]

Got the new fan clutch...1 question......Is this thing even worth the trouble to install?????? Totally free spinning out of the box. No resistance whatsoever..

 

[Blckshdw]

If you were holding the nut that attaches to the water pump, and the clutch body free spun like that, I'd be more concerned. Having resistance on the electrical connector, on a rotating housing, would mean much faster deterioration of that internal connection. Definitely don't want that.

 

[aaserv]

Oddly enough, after looking all over for info on what a new 1 should do I found a video from Scotty Kilmer where hes holding 1 identical to it and spinning it like a top and saying thats what we want....so on it goes i guess.....hope it works

 

[Mooseman]

You want that front wire/sensor portion to spin freely. You should be holding the nut and trying to spin the clutch itself. I'll bet you won't be able to or it will be stiff and that's fine. It will likely sound like a jet engine at first and then will calm down afterwards. Kilmer is an idiot.

What brand did you get?

 

[aaserv]

I just got the cheapest thing I could find on EBAY. $51...lol I just need to be able to run it while I finish everything I have left to do on it. For 1 thing if it needed something besides the Fan Clutch to cure the overheating then I was going to need to debate blowing the whole project off and finding another car or putting even more money into this project. Ive spent an ungodly amount of money on this thing and its still in pieces for the most part. Don't get me wrong its got a lot to do with me having to do everything 3 times before I get it right.....But still I got to draw the line somewhere.
However it worked like a charm!! Its been sitting running now for over 30 mins with A/C on high and the temp gauge hasnt cleared 185 yet. I could feel the difference in the amount of airflow through the radiator instantly.
That also goes to show what Im talking about. I could have changed that fan clutch last August and been driving it all this time while doing the other repairs 1 at a time. It probably took me 3 hours to get the fan clutch off and out the 1st time I did it, today it took me 30 mins . Its all about knowing what your doing. I thought all the work I did on my 6 cyl would carry over to this 1 but almost a completely different vehicle. And my learning curve has been steep to say the least....lol

I will say without this site and you guys help Id probably have given up by now. Lot easier knowing I got some Tech support behind me when I get in a jam.....everyday!!

 

[Blckshdw]

New Water Pump w T-stat, new Temp Sensor, new coolant tank, system flushed and new coolant . Still start it up , let it idle and within 4 -5 mins its at 240 and rising.

Its been sitting running now for over 30 mins with A/C on high and the temp gauge hasnt cleared 185 yet.

Did you change out more stuff between the fan clutch, and the other mentioned stuff? I find it hard to believe just the clutch alone would make your truck go from overheating in 5 minutes, to over cooling like that. Even if the clutch was stuck on, the closed t-stat should still allow the engine to come up to operating temp and stay there.

 

[aaserv]

No that was it the whole time. It was barely turning fast enough to blow a small breeze. The amount of air going thru the radiator has to be tripled at least. And you got to consider Im not moving or steering so there is hardly any heat being from the transmission and power steering. Im sure if I drove it it would come on up to operating temperature fairly quickly.

 

[Blckshdw]

FWIW, when I changed my stuck open t-stat, my truck only needed to idle for 10 minutes in my garage, and it got up to 195 and held steady. Since it's not overheating anymore, that's definitely a good thing, but I'd be wary with 30 minutes of idle time, and not getting up to temp.