ablewaker

ablewaker

Recently bought 1992 Chevy G30 5.7L V8. with 77k miles. . . . I am a newbie at DIY mechanical fixes / maintenance. Records indicate Previous owners seemed to do all schedule maintenance and take good care of her. She runs choppy and variably at idle and lower speeds (I'm told that's fairly normal for these generation?)
The main issue right now: She is overheating and I'm not sure why or what order of fixes, checks, etc I should try to go in.
It takes her less and less time to become VERY hot. Even though the temp gauge is reading all normal engine temps, the heat is noticeable and almost unbearable in the dash area. Warning Light comes on coinciding with the overheating, and goes off once she's cooled down and operating normally for a short while at lower speeds. Within about 4-5 mins of driving over 50mph she begins to overheat quickly.
Coolant levels checked and are good. Fan seems to be operating normally. One kid doing a battery test (confirmed battery and alternator are good) suggested its running rich, and also needs a tune up and that would fix the overheating problem? I'm fearing worse (aka manifold or gasket leaks or worse) but want to stay positive. ANY advice or discussion is very welcome. thanks all!

Rednucleus

Welcome to chevy - IMO a normal cooling system would maintain proper tem pseven if running poorly. You say you're a newbie - are you handy with tools and comfortable following a troubleshoot list? This could be as easy as changing a thermostat or other cooling system maintenance items. Any previous recordson history of coolant changes, thermostat, water pump etc

ablewaker

Hi and thanks Rednucleus !
nO i DON'T SEE ANYTHING RELATING TO RECORDS FOR PREVIOUS FIXESAROUND THESE TYPE OF ISSUES. OOPS SORRY FR ALL CAPS MY PHONE IS DOING ITW OWN THING....
yes
I am handy enough with tools. No expert but I can turn wrenches, etc. And I can follow guidance or instructions very gratefully! Any help or advice or steps to instruct are appreciated!

Derrick71

It sounds like it's not circulating the coolant. At 50MPH you don't need the fan and there's no "tune up" issue that would cause this. My first thought would be thermostat or water pump. I would open the radiator cap (with the vehicle cool), start it and let it get up to operating temp where the thermostat would open. See if the coolant flows as you rev the motor by moving the throttle body with your hand. You could also pull the thermostat and see if you have water flow without having to let it heat up.

If you don't have flow it's probably the thermostat, pump or a clogged up radiator.

Does the hearer blow hot? Also, what does the coolant look like?

jfmorris

I'm with @Derrick71 on the thermostat and water pump being likely suspects. I would start with the thermostat, as that is a quick and cheap fix. When those water pumps go bad, they tend to start leaking water through a "weep hole" as my dad called it, right where the shaft comes out for the fan, and you start seeing water run down the front lower part of the water pump. I would inspect that area as well.

ablewaker

[QUOTE=Derrick71;506377]”It sounds like it's not circulating”

hey thanks! Man I hope you guys are right! I’m cooking it all the way down now to perform first check on thermostat and then I’ll lyk how it went! Really means a lot to have some solid focused specific input. Really is priceless y’all share experience kbowlrdte and knowhow🙏💪🏽

ablewaker

Checking back in here. . . the coolant looked good. I wasn't sure if I did it right but I boiled some water and tried that test on the thermostat and got no result so I changed the thermostat. Amazing what a mess of such an easy job a new guy like me can make. Lol. I thought I'd wathed every video i could find but none of them mentioned prob be better to dsiconnect battery (esp in case of live wire spaghetti from the early 90' under doghouse) nor to drain coolant first (to prevent being "that guy" and making a hazardous cat killing mess on the ground).
Anyways, I got it swapped. The results are mixed....
I have ran it pretty good for a bit and the Check Engine Light didnt' come on (or at least not as soon as it was) but I didn't do a long drive test (gas and new tools are expensive af !$!$!)
Temp Guage remained normal and actually seemed more responsive (testament to one of Derrick's possible prediction that things were remaining at a constant as to coolant/water)
These are all a win....
However....She is STILL running hot as hell. I mean HOT.
To me it feels and seems like the check engine and overheat should be signaling almost immediately upon reaching normal operating temp on the guage.
I'm trying not to be dramatic and there's no real way to mark ambient temp (also dramatic) to somehow confirm or deny there's a probelm but I'm telling you it;s HOT.
Especially in test with the doghouse off, if that is how it's supposed to run it's amazing to me this whole front end hasn't caught fire under that little hood. already.
So is it still possible its the Water Pump? Simple test for that? What's the possbiliity of multiple issue and the heats from loose / bad gasket somewhere?


Here are some Pics. . . for proof of the masssacre really, nearly sliced my finger open trying to reach and untighten. Lesson learned about the coolant drain and capture and disconnecting battery. Forgot to mention air filter was very dirty imo, so I did change that as well. I feel like theres' an improvement in performance, less choky at idle/low speeds, smoother, etc, but that could just be me wanting to feel cool about accomplising the thermo swap (major operation for my XP level) but there's no denying it's still a problem how hot she still gets.
Its like iti's overheating, but not.


ThaNKs Everyone for help.



DAY ONE (July) 24)

overheating, fan below running on power by Onan Emarald Plus 40000, (prob made god laugh)

jfmorris

Ok, so the thermostat has been swapped, and you still are running hot. You've told us the fan is spinning properly. That leads us to the next suspects:

1. Water pump. Usually on these type engines and water pumps, if they fail, they start leaking, but who knows.... if the water pump is NOT spinning, no coolant will be moving through the engine, and it will certainly overheat quick!

2. Clogged radiator. Are the fins of the radiator clean of debris and dust build up? If not, air can't flow freely through them. Second.... if it's an old radiator, I guess there is some possibility of the tubes the liquid runs though becoming clogged...

3. Air pockets in coolant? We know you lost some coolant when replacing the thermostat. Are we sure the air has left the system?

4. Low oil? A low oil level might lead to a hot running engine?

5. Gunk/rust buildup in the cooling system. By this, I am wondering if you could have a bunch of crud in the cooling system causing a blockage somewhere, even in the engine block... maybe it's time to flush the cooling system?

Sorry to not have a definitive answer for you here - I am just brain storming. I've had to replace the water pump at least twice over the decades on my 1996 C1500, and had to replace it once while I owned the 2003 Yukon. I've yet to replace it, knock on wood, on the 2006 Silverado.

Derrick71

If you're just talking about under hood / doghouse temps they can get really hot. Any motor and exhaust naturally put off a lot of heat. I've noticed that lifting the hood on my van while running feels a lot hotter than a car or truck even though it's running at the proper temp. It probably has to do with the heat all being funneled from the tight fitting doghouse to the small hood area while the van isn't moving. Running it with the doghouse off will cook the interior really quick. All the heat from the exhaust manifolds rises straight up.

If the gauge is saying it isn't overheating then it probably isn't. There's nothing that's going to cause the engine to put out more heat if it's not overheating. Any exhaust leak that big would be obvious. Maybe if it's missing heat shields on the exhaust but I'm not familiar with what shielding that van has.

You also have to remember that it's the middle of summer and the air entering the radiator is already hot and gets hotter passing through it. For the most part, air passing through a heating element (like a radiator) will pick up a certain % increase. Basically, the hotter the air going into the front of the radiator the hotter the air blowing under the hood will be.

I don't know what the underhood air temps are supposed to be but they could easily be checked by keeping an oven thermometer under there. You can also get a cheap laser thermometer to check the temp of the radiator, top hose, block, thermostat housing etc... to confirm the basic accuracy of the gauge.

From what you're describing, it sounds like the cooling system is working properly now.