Yesterday I wrote an article about how my 1989 Chevy K1500 Silverado’s motor blew up. I had tried starting it, the engine revved high, and then it locked up. Thereafter, cranking the mighty 350 V8 yielded a horrible noise that sounded like internal damage. Well, last night I charged my battery, and while the Chevy still made that awful noise while cranking, it fired up! And once it was running, it sounded OK. And yet… now it’s overheating. Someone please help me understand.
For the most part, if something doesn’t pass the laugh-test, you should always be wary, which is why I maintained cautious optimism when I chucked my newly-charged battery into what I thought was a blown-up truck. You see, motors don’t just throw rods for no reason, and certainly not two seconds after startup.
With the new battery in, I turned the key and listened to the horrible mechanical grinding noise still present, and I thought it was over. The truck sounded like it was filled with marbles. But after enough cranking, and a bit of pedal, the motor fired up and started idling nicely! Listen to this thing:
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I drove the truck around, filled it up at the gas station, and marveled at the wonder that is the Chevy V8 — never doubt a 350! America’s unstoppable powerplaint! And then I noticed the temperature needle climbing, so I shut her down.
What the heck?
I haven’t driven enough to categorize the overheat-condition; does it happen only under load? What about at idle? But what I do know is that I’m not leaking any coolant, my oil looks nice and clean, and… hmm, does the heater work? I did try to turn the heater on on my way back to the house to help the truck stay cool; it cranks hot so that tells me that it’s probably not the water pump?
I mean, maybe the pump broke apart?
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The pulley still feels reasonably tight (then again, I still have the belt on there)… I’m confused. What do we think might have caused this horrible noise, and how is it related to my overheat condition?
I was getting a stuck ignition switch issue, which I suspected might have caused the starter to hang up, creating that awful noise. And when you turn the ignition, the temperature does max out on the gauge until you let off the key, but while I was driving, the temp wasn’t at max, it was at 3/4, so I don’t think the ignition hanging up is the issue.
The truck now seems to take quite a few cranks to start. Don’t see any white smoke. Water pump doesn’t sound loud at idle… hmm.
Does anyone have any ideas? This is a strange one.
I once bought a Nissan Sentra at a good price that turned out to have a broken tooth on the flywheel. As it was stick, I learned to park on a hill after replacing the starter 3 times.
I would honestly replace the thermostat to address the temp issue and then look at the flywheel and water pump. That surge of revs though…check vacuum lines.
One thing probably lead to another. The high rev could have been caused by some vacuum leak or MAF sensor type thing that caused the engine to rev high. That in turn caused something else to break.
The horrible noise cranking is likely a chewed up flywheel or an iffy starter. Not sure how this could be related to a high RPM starting condition unless the starter somehow got hung up and spun up too high.
The over temp needs to be confirmed by some other means. The stock gauge was probably only a “somewhere around” reading when it actually works. On a truck that old, I’m surprised it is working at all.
When I was a kid, my job was to hold the flashlight while dad wrenched on the old Jeep.
David might as well start the new baby on flashlight training as soon as possible
I’d pay good money to see a photo of the kid.
Wearing DT’s forehead flashlight, and duct taped to the fender looking into the engine bay… really.
“I’d pay good money to see a photo of the kid”
And that is how you end up on a list you very much do not want to be on.
I tried giving my sister’s husband that job when I would work on their cars. He always managed to shine the light directly into my eyes. He didn’t, doesn’t know anything about cars.
I’ve seen some weird things with various tbi. Sometimes it’s a simple as the air cleaner not on right or grounding out something. Those GM interiors are awful sticky and the plastic components aren’t so great over time. I’ve had those gmt400 ignitions switch fail in weird ways but I’ve also seen where everything has been cut off and it works well for basically ever. So maybe just start unplugging stuff and see if it gets better.
I’m not some sort of expert mechanic by any means, but do you know if the engine is actually overheating, or if the temp gauge just says it is? Could be something as simple as a faulty gauge/thermostat, with the faultiness brought on by whatever happened yesterday. You said coolant is flowing just fine through the radiator, so that leads me to believe that the water pump is fine and there’s no leak in the radiator or hoses, so it really sounds like it shouldn’t be overheating.
Carefully touching the radiator should give you an idea of how hot it’s actually getting. Or David might have an infrared thermometer somewhere (I’ve seen them advertised for new parents)
We just bought an infrared thermo meter for humans and interestingly it has “food mode” sold as a feature to test a baby’s formula or other food, but also for cooking purposes. However David should have one intended for general use all things considered since they are so cheap now. Under $25 at Horror Fraught “compare to Klien” at $59.
$3.39 for a T400 (max reading 400C) from AliExpress less than a year ago. I suppose less, now that they’re making them in the USA. /s
David, if you open up that parking ticket you will see that you were actually written up for an incorrect diagnosis, $75 fine. Thrown rod would have likely left a puddle of oil and/or coolant which would clearly be seen by the parking officer and result in no fine. .
That’s fair. Part of my made the diagnosis so as to ensure I had no hope. Best to expect the worst-case, nahmean?
Ha, I can totally understand that mindset! And I should talk, I’ve probably racked up thousands in faulty diagnosis fines by now.
It’s California. You definitely don’t want a puddle of anything. The abatement fines would be more than college for baby Tracy.
My ex’s Kia Soul threw a rod without any oil/coolant leak. She just turned up the radio and drove another 20 miles until she got home.
Back in the day my friend’s uncle had a Chevy Citation that threw a rod with no leaks. Since we were young and stupid he let my friend drive it around for a while.I also drove it a few times and can never forget the sound.
That’s interesting. I guess it depends on how it throws. If the bearing cap failed it might just chuck the piston and rod up into the head and stay there.
The only one I saw was at an engine testing lab where a 14L Cummins threw a rod out the side of the block. It took out the oil line to the turbo and the whole thing caught on fire. There was a CO2 fire suppression system in the room so the fire didn’t last long.
David, do you believe the average parking enforcement officer knows what throwing a rod means? I’m pretty certain they didn’t in your case.
I might have tried something like, ‘Car Broken. Waiting for Tow Truck. Reported to Dispatch at 3:45 PM. Please don’t Ticket. Thanks’
I’ve found that phone call and note works better than just a note.
Yup. The car nerdyness of law enforcement officers is far below the standard I’d hoped for when I started more than a decade ago. I’ve now found a couple of us, but still not many and my department is rather massive.
Have you tried therapy sessions?
It is the baby, they have strange abilities, they can turn milk into that stuff. make rational people say blubble blubble. destroy sleep patterns and rational thought, change your shopping patterns and make cats wierd.
This is but a small list of the things that babies can do, screwing up a V8 from a distance, easy stuff, the big stuff is still waiting.
This is easily the most rational and scientific answer…
“If only he’d had Car Shield.” /s
Good luck with this DT….
I would definitely start with a water pump and starter as likely culprits of the noise and overheating. I would also check the thermostat as well.
The grinding sound and the anguish you are experiencing are simply the realities of grown-ass adulthood. Shoot it with the parts canon. Replace the water pump, hoses, thermostat, and starter. Then sell it and get a Camry, or a lovely Mazda CX-90, or some other reliable car. Play time is over, my car loving friend. On the birth of my second, I had to let go of the 73 MGB and the 83 300ZX. I feel your pain. When the kids get older, get them interesting cars to drive. Until then, you are a family man. Learn to love it, because it is lovely.
Why in the world would he buy a Camry or Mazda, he has a daily driver and this is his truck for doing the occasional truck things.
Not sure about the Camry suggestion, but “MazdaLove” gonna Mazda all the things I would think.
It’s still idling WAY too high. If that clip you posted is anything to go off of, it’s at like 3000+ Hard to start, high idle, big surge when you started it the first time indicate a big ol vac leak somewhere, and considering the high temp, I still think the intake gasket might be a good place to start your diagnosis. Don’t drive it/run it too much without doing some diagnosis.
As an aside, these TBI trucks can be…surprisingly hard to diagnose. Primitive ECU combined with aging gaskets and electrics can make them do all sorts of weird stuff. ASK ME HOW I KNOW. I’d take it to a place that is familiar with these trucks, modern GM techs will probably just blast it with the parts cannon.
If it isn’t an intake issue, there is a possibility that (since it was a Cali/Desert Truck and the PO may have just put water in it) the impeller has rusted to pieces without the actual seal going bad.
Agreed – I had a neighbor with one that ran bog rich. Barely ran or idled and stunk of gas.
It took us quite a while to figure out the TBI injector went bad. (OBD1 is not very helpful in diagnosis). He had driven it for a while like that and I was convinced he would need a new cat, but replacing the TB unit fixed it. He didn’t even replace the plugs. Nothing runs as bad as a GM for as long as a GM.
Codes are not very helpful in diagnosis, especially where there are so few. However the GM system is super simple to diagnose since they will give you access to a wide range of what we now call PIDs, IF you have the right tool, or cable and laptop with the right software.
“You see, motors don’t just throw rods for no reason, and certainly not two seconds after startup.”
Clearly you’ve never owned an ICE BMW.
Some BMW owners consider that standard maintenance.
M539 Restorations!
For me I’d slow down and take things methodically one at a time:
I would honestly start with the water pump. sounds like it seized and then broke up. now it starts but gets hot. all the signs lead to the water pump. I would say the easiest first thing to do would be removed the belt/belts and start it with no accessories. it should start and if the noise still persists, then the issue is likely not the water pump. a good ACDelco water pump for this is only 35ish dollars though, so even if you parts cannon this, it would still be something good to do while in there. along with the T-stat I suppose.
This is the best piece of advice start with so far. Pull the belts and run it to isolate the noise. Belts are very easy to pull. Step 2 would be pull the plugs.
it would be a good way to also check the ac clutch and smog pump at the same time, though I am not sure how either of those might affect cooling really.
You felt the upper radiator hose right at the end of your video, but didn’t tell us what you found. Was it hot? If the starter was jammed in the flywheel, I would expect the cranking to sound fine, but the sound of disaster after it started. My guess is that the water pump seized somewhere, and you eventually snapped the impeller off.
The thing is: The heat works great! And I can see coolant circulating nicely in the rad.
Convection is a thing. The heat would work well with a busted water pump.
It’d take a damn while of running though…
Yeah, the heat wouldn’t work WELL with a bad water pump.
You can check pressure on the cooling system by pinching the hose going to the radiator with your hand. If the pump is working you’ll feel it flowing in the pinched section of hose. “Convection” you won’t feel at all and will stop if you pinch the hose completely. Partially failed pumps or partial obstruction in the cooling system somehwere else (like thermostat) will feel a weak flow. Old school.
No it won’t, at least not more than a second or so, convection takes way to long to make it through a heater hose.
Welp, ‘spose the next step is to fire ‘er up and observe. BTW, congrats on the kiddo. Definitely has mom’s smile!
You mentioned you use a fuse as an anti theft mechanism, maybe you’ve knocked a critical fuse just loose enough to cause a problem, or imones partially blown. You might want to check or replace all your fuses. Especially since a lot of other comments think it could be an electrical issue.
You could have a problem with the water pump impeller.
I’m not sure how that would cause an over-rev at startup, but if a vane fell off in the water pump housing it could certainly cause some noise.
This was my thought as well. Potentially the damaged parts have now lodged in the thermostat, restricting flow. Isn’t the thermostat right over the pump on the small block? (I haven’t owned one in years)
The impellers are pressed onto the water pump shaft. There’s almost no force applied to it that would cause it to separate. I think I’ve only seen it once in 40 years. The impellers on SBC pumps are also steel, so I suppose it could have rusted away but I haven’t seen that much either.
There’s a weep hole in the pump; when the seals on the shaft start to go bad the coolant comes out the weep hole. That’s your signal it’s time to replace the pump. If David’s not seen any coolant leaks it highly unlikely the impeller just spontaneously decided to separate.
There’s always the caveat that anything’s possible of course. He should check for flow first and go from there.
I have seen a lot of drastically rusted impellers online, but haven’t experienced one in person.
It’s the only water pump related cause I can think of that could leave the shaft in place without anything dripping from the weep hole.
With potentially 300k miles and a southern California vehicle that runs straight water as coolant I guess it’s possible.
It is possible, and for that reason I certainly wouldn’t be running straight water in it without at minimum an anti-corrosion additive. Even then, I’m not sure I trust it too much; I did that for many years in my track car only to ruin a $500 aluminum radiator that was packed with rust gunk.
I bet it still looked pretty on the outside, though.
I was thinking corrosion, not just blowing apart but I do agree seems unusual given that, as you say, the impeller is basically just a block of steel. Perhaps something else was shaken lose by the high revs and only lodged in the pump before being eventually dislodged and moving further downstream to restrict flow there.
It’s flowing well.
We had an impeller erode away to a throwing star looking item on a ’99 Cherokee around fall of ’04. Wasn’t that old, and likely still on original coolant (we hadn’t touched it, having bought it in ’03). I think we still have the photo, if we could post them here…
We still had the appearance of water flow in the radiator when we popped the cap off after it cooled down, but it definitely wasn’t adequately cooling the motor. Never saw where the missing blades went though, unsure if they broke off in pieces or literally eroded away over time. Fixed it though once we replaced it!
It’s exceptionally rare for a water pump to just come apart. If it was in bad enough shape to do that, it would have been leaking long before. Let it cool down completely, open the radiator cap and start it. Once the thermostat opens you should be able to see the coolant flowing in the radiator. If it is, the water pump isn’t your problem. Be sure to recap the radiator before you shut the engine off.
Coolant if slowing nicely through the rad, even when cold.
Could that mean the thermostat might have disintegrated?
It’s been a while, but should there be water flowing in the rad with the engine cold [and the thermo presumably shut]?
Maybe thermostat fragments broke off and sank to the water pump, creating an unpleasant amount of noise and reduced coolant flow (e.g. by breaking a vane or two on the impeller).
IIRC this was your area when you were an engineer, so apologies in advance if I’m talking nonsense. 🙂
Coolant temp sensors (or the wiring/connector going to it) can cause all sorts of weird issues. I’d check that out, since it’s going to determine how much fuel to give the motor before going closed-loop. Could also say the motor is overheating when it isn’t.
Should be located right next to the outlet of the upper radiator hose on the motor.
I wouldn’t be at all surprised if that’s the issue… and/or there is air trapped in the system causing the temp sensor to show very incorrect figures which could also be causing these issues.
It’s an 87 motor, but the TBI system is basically the same (pretty sure)
https://www.youtube.com/watch?v=UnxlygSLCyU&t=75s
Lastly… in my experience when there have been extremely weird problems, it has been due to bad grounds as well, so I’d also check all those if you can. The truck is certainly old enough to have this be a culprit as well, for all of this.
Thinking about this further now… my money on all of this is because of bad ground(s)… I’ll bet $1 on it. Starter issues engaging and disengaging, won’t restart, gauge issues…yep.
I agree with the temp sensor thing to a point, on the ’89 the gauge is driven by a separate sending unit. The coolant temp sensor for the computer is a distinct unit. If I recall correctly the gauge sender is on one of the cylinder heads.
You are correct! Which makes me think even more that all this shit is grounds, and not the first part of my message. Probably should have deleted it, but I’m lazy.
I’m trying to go back in my memory, because I learned on a GM donated 350 TBI suburban of the same era (1993 i believe it was) while I was in trade school last century lol.
Stuck T’stat on top of the issues with the starter?
I was thinking that. If the radiator hose on the top is flexible and not firm. Hit the thermostat with a hammer and see what happens.
Always step one on a SBC.
I’m glad the engine isn’t blown!
With a turn of the ignition, it sticks and causes the starter solenoid to stick…
So, at this point, I would get a laser based thermostat to verify that it is in fact getting hot. Check the coolant for signs of anything out of the ordinary, then replace the water pump, and go from there.
*Edit* I can’t watch the video due to being a work. Thanks for the non-Instagram video!
*Edit*Edit* I would change the thermostat first, then go to the water pump. Cheap to expensive is the best way
I’d check the water pump. I saw you touch the coolant hose there, I’m assuming it was warm but you only need a small trickle of coolant to give you that.
Might also not be related… thermostat might have just decided to fail for no good reason right then.
No real idea what you have going on there. HOWEVER, my old ’97 Dakota blew it’s first water pump around 80,000 miles. Every 40,000 miles after that, I would start to hear a rumbling noise under the hood, it would shuck the serpentine belt, and I would know it was time for a new water pump. I could usually get the belt to hang on long enough to get me home and swap the pump. Didn’t matter if I swapped it with new or rebuilt, at 40,000 miles or so I was going to have to change the water pump till I traded it in with well over 180,000 miles on it.
Maybe it’s the water pump? Pull the belt, give it a whirl, and see what you hear. Only take a minute to do that. Hopefully it didn’t ingest an impeller…
Smog pump!
Mine ceased, but that was a 1984 K10, had to find a shorter belt to bypass to get home from two states away.
It sounded like nuts and bolts in a dryer before it ceased, high resistance slows water pump, alternator.
I really like this answer! It accounts for the noise and the high-ish RPM. A hoarked smog pump could cause a vacuum leak.
Thanks, a T-shirt is acceptable as a boobie prize if I’m right.
That’s a 1/4 century aged memory, seems like a bargain.
I 2nd liking this answer. As mentioned above, pulling the belts first would isolate this failure immediately. Great suggestion.
Me too. Had one sieze on my ’74 buick. It actually forced the car to stall as my idle was always a bit iffy while it still had the rochester 2gc. Edelbrock 4bbl cured the idling issue, and installing a dummy pulley corrected the smog pump probblem. Buick 350 parts and accessories can be a bit tough to come by.
Seized! I must have been thinking about my parrot nailed to its perch.