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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For those of you anti-Instagrammers, here it is:
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’m more knowledgeable about the 96-99 vortec engines than the tbi variants, but I’ll take a stab.
These trucks are rife with ignition issues at this age. The distributor gears are usually well worn between 100 and 120 thousand miles. When it gets sharp and shiny, it allows a lot of slip in the ignition, and under load it will drift quite a bit.
The distributor caps available now are rubbish. The plastics are cheap, and the guts are aluminium. They corrode badly, especially when the truck sits, or is driven infrequently. The track for cylinder 3 ignition likes to arc out as well. GM has a few tsbs but never really figured it out, and ultimately adjusted the replacement interval. Even if your cap and rotor are low milage, I’d throw a fresh set at it.
Aftermarket ICMs are common, and all of them are junk. There is potential to gain power by lengthening the dwell as many of the aftermarket “high-performance” ones do, but non of them last any length of time. Only buy the genuine GM/AC Delco one.
Take 20 minutes and swap the thermostat and then do more troubleshooting from there. My old K2500 shot the temp gauge to the moon one day after never having had any problems at all. Limped it home, swapped the t-stat and it was sorted.
I don’t think the 2 problems are related at all, just an old truck being an old truck.
Maybe even a borescope down the thermostat neck – you should be able to look at the impeller on that SBC. Pull each plug and borescope as well to check the pistons.
You can buy a borescope for your iPhone for a few bucks.
New strange sounds, now overheating. Menopause.
^This^ Very common for trucks entering their mid to late 30’s
Your starter is in more than once piece and you have a loose axel, and a bad tie rod, or at least this is what my buddies GTI did when all these sounds happened lol.
Blew up or didn’t, doesn’t matter, you got some page views for the site out of it 🙁
The explanation, reduced to condensed prose, and the solution to the problem will soon appear in a Rock Auto Newsletter “Repair Mistakes and Blunders”.
All we wanted was recognition, thank you.
Glad to hear the engine didn’t blow up! I mean, it’s not a Fix Or Repair Daily/Found On Road Dead
It’s just a Gross Malfunction.
I much prefer a Free Of Ridiculous Defects to a Generally Mediocre.
Jason’s OBS will probably outlast this thing if he doesn’t neglect it.
Oh, sure, because a cruise control deactivation switch on the master cylinder that catches fire wasn’t a ridiculous defect.
Entirely fair play
Jason’s benign neglect vs David’s obsessive maintenance. Ford 300 vs SBC. Two trucks enter, one truck leaves.
I am more impressed by the dial design in the cluster
Uuhhhhhh….yay! This has gone from devastating disaster to interesting project! (Right?!) There’s clearly a lot going on here but it can’t hurt to start with the cooling system…that thermostat seems wonky, and I wouldn’t trust that water pump.
I’ve had water pumps fail with no obvious leakage until the moment of failure (parking on just enough of an incline can cause leaked fluids to pool in the bumper fascia instead of on the ground). And I’ve also had one fail spectacularly after I noticed it occasionally sounded like BBs rattling in a can, but kept driving anyway.
Heating problem = fan clutch
Starting problem = who fucking cares, it’s a 5 speed. Always park on a small incline and pop the clutch.
Isn’t this the very definition of GM? It runs like crap, but it still runs.
Fortunately the classic 350 is easy to access and work on. I changed the water pump, alternator, and starter motor all in my driveway on my ’95 C1500. I didn’t need a jack, ramps or stands to get under it. The work didn’t require any special tools and it was a great entry point into wrenching. Good luck David! And congrats on the new family!
Sounds like the impeller came off of the water pump a very common problem for chevy small blocks
Broken flywheel teeth was my initial guess, but that doesn’t explain the overheating issue.
I think you are on the right track, Robert. That is what I was thinking. Something screwy with the water pump.
Totally possible – I recommend removing the belt and running the engine. If the noise persists, you can eliminate alternator, water pump, steering pump, and AC compressor.
If I was a betting man, this is what I’d put my money on.
Based on personal experience with these trucks, it sounds like you have an injector stuck open in the throttle body. Sometimes just pulling it out and smacking the side with a screwdriver handle will fix it. I accidentally fixed mine by dropping it while trying to bench test the problem. The first incident may have been caused by hydrolocking the engine. You may have a cylinder that is low on compression now, or not, those things are tough. The overheat could be the cat clogging up from excessive rich mixture. No saving the cat if that’s the problem, but a cheap aftermarket on from the parts store got mine running right after getting the injector sorted.
I’d say that’s a good guess. I’d also do the water pump & thermostat, and make sure the timing set is still intact.
IIRC (going back a while) Ford’s TBI injectors were finicky and subject to sticking. Good fuel and regular treatments of fuel injector cleaner helped.
I think I’ll just come back to this topic when you actually get it figured out.
This feels like an interim NTSB assessment of an airplane crash and a year later, we get something useful to learn from.
I don’t even fly anymore. But I do find the final assessment interesting. Maybe thankful that I didn’t end up in one of those situations.
And this site’s spelling checker is absolutely useless at the moment. Not offering suggestions how to fix typos. Fix it!
This is a “it’s not the worst-case scenario I rocketed to from baby-induced sleep deprivation” diagnosis.
“Baby-induced sleep deprivation!” Ha! I remember that, but it’s been 30 years. BISD is real.
He had better fix it quick, or the Mrs. will insist on selling the damn thing and buying a Toyota Sequoia.
Only if she hasn’t driven one. There is almost no use case a Sequoia is the answer. My buddy bought one and I drove it. It was horrible. We had an ’18 MDX and it was so, so, so much better.
It’s not legal to sell newborns though
Take the belt off and try again. See if the noise goes away with the belt.
…and it starts. May the “My Unkillable Chevy that Almost Works” series commence!
I think you’d have gotten a bit more grace with the meter maid if you had wrote engine blew up will move asap or something instead of engine threw a rod. We know what you mean but if you asked 10 people on the street what that means I bet at least 7 of them don’t.
Not to get too far ahead of ourselves but this is good news, a strange noise and overheating seems much more repairable than the other alternative! Before you mentioned that the heat still worked I suspected a water pump, and it could still be but I don’t know my way around these pickups so I’m eager to hear what you ultimately find.