How did low 4WD kill the engine?



My blazer was stuck in snow, so I put it on low 4WD and 1st gear, having my wife stepping on the gas while I was pushing it. Then all of the sudden the engine died and I couldn’t get it running again. Towed it to a shop, and the owner said it was the high rev that killed the engine. they could not get any compression, and I need to replace it (costly).

I did some searching online but didn’t find any references about low 4WD killing the engine. What do you think? Was it the engine or something else?


What is the model year and mileage (odometer reading) of this Blazer?

If it has no rev limiter, yes, revving the engine into the red zone can destroy it.


its an '02 4door 4.3L, and barely 60,000.


Hard to believe an '02 doesn’t have a rev limiter. Also hard to believe she was revving it that high.


It is certainly possible to overrev a motor when in 1st gear and in 4WD Low range. With the wheels spinning it is pretty much like reving it in neutral. I’d would think the noise of a rapidly rev’d motor would have raised some alarm in either the driver or pusher. If there is a tach in the SUV the driver should be told to not go over 3,000 rpm and shown where the needle on the tach would be at 3K rpm.

If there is no compression it seems that something in the value timing must be off. Perhaps it is repairable without a complete motor replacement.


In that case, I recommend you get a second opinion. It sounds like this shop may be assuming replacing the engine will fix the problem without doing the proper diagnostic work first.

This diagnosis fails my sniff test. Something smells like bull____.


“Killed the engine” does not give us much to work with…We need to know (and so do you) what exactly happened to the motor…That engine, a Small Block Chevy with two cylinders removed, is very tough and durable. It IS possible to damage it by over-reving, but it would have made A LOT Of NOISE during its final moments.

The ONLY time you would need 4WD low range would be to pull a heavy boat up a steep ramp.

Sounds like frustration, ignorance and ego results in a blown engine. I was going to suggest checking the timing chain, but at 60,000 miles, that is a long shot. Does the engine turn over normally and SOUND normal when it’s turning over??


It probably was making a lot of noise, however, as I was pushing from the back of the car, the wheel spinning on the ice covered other noise. Now the engine doesn’t try to crank when I put the key into ignition. It is just quiet. The battery light goes on, but it is certainly not the battery.


1st gear on transmission + 4wd low is about 3 MPH max speed when not stuck. 4wd Lo and top gear(drive) is about 25mph on most vehicles.

You over revved the engine causing internal damage.


Is the motor seized up, frozen in place, will not turn at all? If so, sounds like a new engine needed. You likely threw a rod, which is essentially the insides of the motor flew apart. Is there oil leaking out underneath the SUV?


It could be, but with the engine dead, I don’t have too much choice. It is sitting on at their shop, and getting a second opinion is difficult. Believe it or not, at least the shop is friendlier than the AAA.


there was no fluid leaking, but according to the shop, the engine was most likely in a state where the pistons overshot their normal position and got stuck… since I don’t know much about mechanics, I don’t even know if this is possible or not, and can only take their words


The STARTER should still engage and TRY to turn the motor over…You should hear a loud “clank” sound as the starter engages. If you hear NOTHING, then you have a starter problem, not a blown engine…All we can hope for is that you have a competent and honest mechanic working on it…


there might be some quiet clicks or hums, but definitely not LOUD. I did ask the shop about the possibility of other parts being damaged, but they said they tried a few different ways and determined it was the engine.


Common problem. Stuck+4WD+frustration=blown engine. I’ve seen it a hundred times.


Unless you were running the thing at the redline for a long time and it overheated, I don’t think it’s a direct result.

It is not possible to overrev a modern electronic fuel injected engine just using the gas pedal. Even if the engine isn’t intentionally limited, the engine computer does not have data for engine speeds beyond the redline and the engine will cut out. The only way you can go past the redline is if you’re in a low gear and the momentum of the car raises the engine speed past the line (like if you shift to 1st at highway speeds, but maybe rolling down a hill in 1st and 4lo would do the trick).

If you can provide more information about your engine’s demise that would help, but even putting it in low 4 and spinning the tires as fast as they’ll go shouldn’t (instantly) kill the engines.


Seems like I am getting conflicting opinions here. You say it is difficult to kill an engine like that while the guy above you said he’d seen it hundreds of times…

Well, I asked my wife who was in the driver seat at the time and she said she didn’t hear any funny noise before the car died.

Incidentally my car just got out of the shop two days ago for a leaking coolant problem. they fixed an intake valve gasket. Could that have anything to do with it?


You can damage an engine by holding the accelerator and letting it bounce off the rev limiter. The engine will jump between redline and slightly below if you hold the pedal and basically engine will scream in a jerky motion due to fuel turned on-off.


Still, going a bit over the redline won’t mean instant death for the engine. Especially with the new piece of information about the coolant issue, I’ll bet it was just overheating and either the temp gauge/light was not working or was ignored.

I suspect missleman’s equation should be
overheating+time (possibly not very much time)=blown engine


Do you mean “Intake Manifold Gasket”? This was replaced on my 2000 S-10 Blazer (4.3, 4wd) in Feb 04 at 48k miles. After I changed the antifreeze, I noticed the coolant level in the overflow tank was dropping slowly (~1 pint/month).

At the next oil change my mechanic noticed a small amount of coolant in the drained oil. He stated to get the intake manifold gasket replaced as soon as possible. Any coolant in the crankcase displaces the oil from the main bearings and will damage the engine in short order.

If your intake gasket had been leaking for any length of time the engine may already have been damaged goods and the 4-Lo incident was enough to kill the engine.

Ed B.