Vortec 4.3L V-6 -- Opinions Wanted.

It always bothers me to see the post of yet another victim of GM's poorly designed 4.3 Vortec V-6. (See the post entitled "99066F: Is this
GM recall real??") With the exception of the GM passenger car diesels, I feel that the 4.3L Vortec V-6 is possibly the biggest lemon that any vehicle manufacturer has ever palmed off its unsuspecting customers. I am offering my negative experience and negative opinions of the 4.3 Vortec V-6, but I would welcome any feedback.
The 4.3 Vortec V-6 is often referred to as a "Baby 350", when in fact, it is nothing more than a bastard child. Two cylinders were cut off of the 5.7L (350 cubic inch) V-8, to create a 4.3L (265 cubic inch) V-6. But the problem with this design is that the 5.7 V-8 is a balanced engine (two pistons up/two pistons down -- two piston up/two pistons down), but the 4.3 V-6 is an unbalanced engine (two pistons up/one piston down -- two pistons down/one piston up). This V-6 imbalance is made worse due to the massive size and huge displacement of the 5.7L pistons and GM has been unsuccessful in its attempts to get the 4.3 engine to stop shaking. The inherent failure of the 4.3 engine design was addressed by GM when it released its smaller 4.8L (295 cubic inch) V-8 engine. The 4.8L V-8 is 30 cubic inches (11%) larger than the 4.3L V-6, but it has 33% more cylinders. As a result, the operation of the 4.8L V-8 is smooth and quiet, while the 4.3L V-6 is rough and noisy.
Around 1990, GM was very concerned with producing a low-priced, full-size pickup which would deliver unusually-high gas mileage. This gas miser would then be used to offset GM's extremely profitable gas hogs. In order to accomplish its goal, GM introduced a C1500 pickup which would actually deliver its 18/24 MPG rating. This gas-saving, loss-leader was built around a 160 HP 4.3 Vortec V-6, with a Getrag 5-speed manual transmission and a standard 3.08 differential. The key to higher gas mileage figures, for all GM truck engines, was the Getrag 5-speed manual transmission, which delivered 15-20% higher gas mileage than trucks with automatic transmissions. GM was so anxious to produce this gas-saving, manual transmission vehicle that it offered a $1500 "Manual Transmission Bonus Package" incentive, which lured in suckers, such as myself, who bought the atrocious 4.3 Vortec V-6.
For some reason, my 1990 Chevrolet C1500 California 4.3 truck came with a smog pump, while other 1990 C1500 models with 5.0 and 5.7 V-8 engines did not have smog pumps. This smog pump robbed the 4.3 of power that it couldn't spare. My original 4.3 was the epitome of the old joke that GMC stands for Garage Man's Companion. My first complaint of constant 5th gear pinging was remedied by the dealer by retarding the spark. The pinging didn't go away and retarding the spark made the truck feel like it was pulling a trailer. I endured the pinging and low power for a month. Then, through a stroke of luck, a mechanic discovered a service bulletin which revealed that GM had released a new PROM for my vehicle which was designed to correct an engine flare that occurred when shifting between gears with a manual transmission. Even though my truck didn't have this shifting problem, the service manager reasoned that the new PROM might have other re-designed features which could fix the pinging. Fortunately, he was right.
My 4.3 was mechanically-noisy, especially so after a cold start, when the engine would race uncontrollably at a high idle until it warmed up. The engine also vibrated badly, particularly in the 1200 to 2000 RPM range. To my dismay, a GM service bulletin revealed that this was a "1200 RPM Shake" and that this severe vibration was considered to be normal operation for the 4.3. The engine speed compensation never worked when the air conditioner was operating, so the engine would buck and jerk when shifting gears when the compressor was engaged. When the truck was stopped in traffic, the compressor would drag RPMs down to the point of nearly killing the engine. I would either have to speed up the engine by pressing down on the gas pedal or turn off the AC when stopped in traffic. The dealer was never able to fix this problem.
After 106 thousand miles, the 4.3 Vortec V-6 developed a loud knocking noise and removal of the valve covers revealed that the engine had a dry side. One side of the engine was clean and gleaming with oil, while the other side was charred and blacked due to oil depravation. I had religiously changed the oil and filter every 2500 miles, but to no avail. The engine was ruined and would have to be replaced.
I decided to go with a Goodwrench rebuilt engine, however, the dealer told me that the original 1990 4.3 had been replaced with an "improved" 200 HP version. I think he mentioned something about a "roller cam", but I'm not sure. In any event, the new engine did have more power, but it used more gas. Then, after 6000 miles, the Goodwrench engine spun a bearing and needed to be replaced under warranty.
The next Goodwrench engine ran well enough for 110 miles, but it was starting to use oil. The "1200 RPM Shake" and air conditioning problems continued to plague this engine, as well. Finally, in February 2004, the vehicle was branded as a "Gross Polluter" and I was only able to get $1000 for it from a wholesaler. I disclosed this SMOG problem to the man who bought my truck, but because the truck scored well in the hydrocarbon section and had only failed one of the NOX tests, he thought that the problem would be relatively simple to fix -- maybe a loose vacuum hose or a bad catalytic converter. It turned out that he needed to spend over $1300 to get the truck smogged. Fortunately, he was still able to sell the truck for a modest profit.
While I see others who have gotten 200 thousand miles of trouble-free miles from their 5.7 (350) engines, I had to suffer through three 4.3 V-6 engines to obtain the same mileage. The money I saved on gas was more than offset by the downtime and expenses that I incurred while dealing with the deplorable 4.3 Vortec V-6.
My overall feeling is that the 4.3 Vortec V-6 is a piece of crap. I would be interested in hearing from anyone who has a 4.3 Vortec V-6 story to tell.
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Anyone buying a full-sized truck with a mid-sized motor gets what they deserve. I have a S-10 with the 4.3L and it is a great combo. Yes they shake because they are unbalance, but it's a truck. Pull your tampon out. Trade it in and get the Toyota you've been really wanting.
Big Chris
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<<Anyone buying a full-sized truck with a mid-sized motor gets what they deserve. I have a S-10 with the 4.3L and it is a great combo. Yes they shake because they are unbalance, but it's a truck. Pull your tampon out. Trade it in and get the Toyota you've been really wanting. Big Chris>>
Although my original 160HP 1990 4.3 lacked jackrabbit power, it was adequate, particularly with the 5-speed as opposed to an automatic. The two replacement 200HP 4.3 engines had more than enough power and required shifting from overdrive down to 4th gear only on steeper grades. My complaint is that I had mechanical problems with the first two 4.3s and the third 4.3 was on the verge of going bad when I sold it.
And it's funny that you should mention my getting a Toyota. My 1978 20R Toyota HiLux pickup had 185 thousand nearly trouble free miles on it when I sold it in 1990. I never did any work on the engine, the 5-speed transmission needed only one clutch, and I required no rear end or suspension repairs. The problem with the Toyota was that the truck just wasn't big enough. Even the new "full size" Toyota Tundra does not have a full size bed.
Yes, I would really rather have a Toyota. However, I am -- so far -- very happy with my 2004 Silverado Work Truck, which has a 4.8L V-8 and 4-speed automatic transmission. On the downside, the gas mileage that I have gotten with this truck has been hovering between 15.3 and 18.4 MPG, even with the standard 3.42 differential. I am inclined to think that this truck would actually deliver its 20 MPG highway rating if I ever took it on an extended trip.
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On Sunday, 11 July 2004 14:37:29 UTC-4, Big Chris wrote:

Your reply made me spew my coffee all over my screen...Ah, nothing like a good morning chuckle! Cheers and thanks for the memories!
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snipped-for-privacy@gmail.com wrote:

I've had around 10 different 4.3 powered vehicles. Haven't had one that didn't make it well past 150K still going strong. The chassis were usually well rotted by the time I replaced the vehicle. I did sell one still road worthy, it's still on the road at 250K My current 02 has 191K on it. Still runs great. Has an emissions issue with the EVAP but not engine related.
FYI the 4.3 is a 5.7 with 2 cylinders missing.
--
Steve W.

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On 9/21/2014 2:36 PM, Steve W. wrote:

Lost my last 98 Blazer to a traffic wreck about 260k, and driving another one, at 253 or so K. A bit sluggish in the morning, I suspect it needs sparks and some fuel injector cleaner.
My Tradesman work van is powered by a 4.3 with two cylinders added.
. Christopher A. Young Learn about Jesus www.lds.org .
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Yes I too am disappointed with my 4.3L moter it only has 315,000 miles on i t and now I have to do a tune up I mean its only going on 22years old the d ealer lied to me when I bought this thing he said it would probly outlive m e and that was a lie because if I don't do this tune up it might not run up to par and I may very well out live the vehicle so I just don't know I was wanting a good 50 years out of this thing so I am upset.
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Sorry to hear of One-Shot's problems with the 4.3. I have a 2003 Savana (7,200 lb GVW) van with the 4.3. I only have had it for 18 mos., but it has been a great engine and great vehicle so far. I have had zero problems with it, it has never been back to the dealer, though there is a recall to replace the rear license plate light (since when does a rear license plate light merit a recall?).
Most of my driving is in Los Angeles traffic, but I did monitor my gas mileage on a 1,000 mile round trip on the freeway, and it averaged 20.3 MPG with less than 2,000 miles on the odometer at the time. I have not checked it since, but I have to think it probably is even better now that the engine is broken in.
The 2003 4.3 passes smog here in California as an ultra low emission vehicle (ULEV) even without an EGR valve, which should stand a testament to its efficiency. Here are a couple sites with some info/specs on this engine:
http://www.gm.com/automotive/gmpowertrain/engines/vortec/apps/vehicle/4300.htm
http://media.gm.com:8221/division/2004_prodinfo/powertrain/truck/index.html
What sold me on this particular engine is that it basically is the rugged iron 350 V8 with a pair of cylinders removed from the center. As noted, it is a large bore and stroke engine (like the old V8), is made of iron, does not seem to have a lot of the cylinder head and intake manifold leaks that many of the aluminum head engines seem to have, GM has made millions of them and appears to have refined it.
My engine is very smooth (balance shaft and enhanced mounts). But what sold me on the engine was that it ought to be rugged, it can get 20 mpg in a cargo van, and it develops peak torque (260 ft lb) at an incredibly low 2,800 rpm. Right off idle, this engine has great torque, feels like a large V8, just what I wanted in a truck. I believe the large bore and stroke, combined with a cam profile, make this engine exceptionally "torquey" for it's displacement and fuel economy. As a comparison, the 4.8L V8 produces slightly more torque (285 lb ft), but only at 4,000 RPM.. The 4.3 has great "grunt" off the line with no fuss, no muss.
Now climbing in the mountains with a load, it only has 200 HP, so the four-speed automatic will downshift more than if it had 6.0 litter V8, but it has never been unable to hold the speed set on the cruise control.
It has roller rockers and roller lifters, a cast aluminum oil pan that bolts into the transmission as well, very sophisticated fuel injection and computer engine management systems, no noticeable noise or vibration, and great drivability and economy.
One-Shot, I am not trying to dismiss anything you experienced with your engines, but just wanted to offer up that I could not be happier with the 2003 4.3L in my GMC cargo van.
old bonehead
One-Shot Scot wrote:

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<<Sorry to hear of One-Shot's problems with the 4.3. I have a 2003 Savana (7,200 lb GVW) van with the 4.3. I only have had it for 18 mos., but it has been a great engine and great vehicle so far.>>
<<My engine is very smooth (balance shaft and enhanced mounts).>>
I'm glad to hear that GM has refined its 2003 4.3 V-6. The one that they sold me in 1990 as well as the two Goodwrench rebuilts from the 1992-1995 era were not nearly as sophisticated as yours. I still feel cheated that GM learned from its early 4.3 V-6 design mistakes while I had to pay for them.
<<But what sold me on the engine was that it ought to be rugged, it can get 20 mpg in a cargo van, and it develops peak torque (260 ft lb) at an incredibly low 2,800 rpm. Right off idle, this engine has great torque, feels like a large V8, just what I wanted in a truck. I believe the large bore and stroke, combined with a cam profile, make this engine exceptionally "torquey" for it's displacement and fuel economy. As a comparison, the 4.8L V8 produces slightly more torque (285 lb ft), but only at 4,000 RPM. The 4.3 has great "grunt" off the line with no fuss, no muss.>>
And all this from the "standard" engine! I sincerely hope that you continue to get good service from your 4.3.
I was so disgusted with my 4.3 V-6 experience that I gladly paid the additional $945 to get the Vortec 4800 V-8 in my 2004 Silverado.
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One-Shot Scot wrote:

Hi Scot,
Regardless of your previous poor experience with the 4.3L, you turned around and bought a GM 4.8L -- I think that says something.
I do think GM is building some very good machines these days. The 4.8L you have has a higher compression ratio (more efficient) than the 4.3L, is balanced "naturally" (does not need a balance shaft), has aluminum heads (better thermal transfer), shorter stroke, smaller bore, etc. It is the next generation smaller truck engine, and I think you will like it.
I was torn between it and the 4.3L, but the 4.8L for cargo vans only came with the higher GVW and did not have rack and pinion steering. It was more "truckish",but when I did the balance sheet for my usage, the 4.3 with the higher axle ratio (MPG) just made more sense for me.
I think GM offers more engine/axle ratio combinations for the pick ups than for the vans. For the vans, you can get the 4.3L with a high ratio rear axle and rack and pinion steering, but if you go to the 4.8L, you get R/B steering, lower rear axle ratios and higher GVW. It depends on what you are doing with the truck,
Good luck with your new truck. I do think you will be happy. GM is making some mighty fine trucks these days.
bonehead
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One-Shot Scot wrote:

<<Hi Scot, Regardless of your previous poor experience with the 4.3L, you turned around and bought a GM 4.8L -- I think that says something.
Yes, I did buy another GM truck. I had only three choices for a full size pickup: Dodge, Ford or Chevrolet/GMC. In spite of all the trouble that I had with my 1990 Chevrolet C1500, I still prefer the ride and handling characteristics of GM trucks.
<<I do think GM is building some very good machines these days. The 4.8L you have has a higher compression ratio (more efficient) than the 4.3L, is balanced "naturally" (does not need a balance shaft), has aluminum heads (better thermal transfer), shorter stroke, smaller bore, etc. It is the next generation smaller truck engine, and I think you will like it.>>
I appreciate your telling me this. My decision to buy a new truck was forced on me rather suddenly. In February, my 1990 4.3L V-6 failed smog and was declared a gross polluter and I decided not to fix it. This gave me until the end of April to find another truck before my registration came due. A local Chevrolet dealer had a Silverado Work Truck with a 4.8L V-8, 4-speed automatic and 3.42 axle in stock and he was willing to sell it at invoice price plus throw in a $500 loyalty certificate and a bed liner. My credit was approved and I was able to drive the truck home with nothing down and get a 60 month 0% GMAC loan.
Now, I am doing my research on the 4.8L V-8 after buying it.
<<I was torn between it and the 4.3L, but the 4.8L for cargo vans only came with the higher GVW and did not have rack and pinion steering. It was more "truckish",but when I did the balance sheet for my usage, the 4.3 with the higher axle ratio (MPG) just made more sense for me.>>
<<I think GM offers more engine/axle ratio combinations for the pick ups than for the vans. For the vans, you can get the 4.3L with a high ratio rear axle and rack and pinion steering, but if you go to the 4.8L, you get R/B steering, lower rear axle ratios and higher GVW. It depends on what you are doing with the truck,>>
<<Good luck with your new truck. I do think you will be happy. GM is making some mighty fine trucks these days. bonehead>>
I think you're right. So far, the new truck is running great and I have not had to take it back to the dealer for anything other than an oil change.
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Must be bad luck, as I have a 1993 Chevy Astro with the 4.3 V6 and over 130,000 miles on it. I have done two tune ups and regular oil changes and I have not had nary one problem out of it. The joker never has failed to start, except for dead batteries and forgetting to put the ignition interrupting plug in before starting. Oh yea and no 1200 rpm shake either to speak of. 90% of my miles are highway miles.
JMHO and Experience TM

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Just so you know I have a 88 S10 with a 4.3 and a 700R4 tranny. Yesterday it just passed 197,000. I have done all the maintenance on it like the manual says. I have had to replace the alt. twice and the water pump once, thats it besides the maint. items. Never had to do a thing to the tranny eather other than regular service. I wish they would put one in the Colorado/Canyon then I would seriously consider buying one.
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One-Shot Scot wrote:

Well, if nothing else, you are certainly "un-informed" about the design of the 4.3 Vortec engine. They have had balance shafts for years now and are a good running, and smooth running engines. I wouldn't recommend one for a full size truck, though I have a few friends who have the 4.3 in the full size trucks, and for just blasting around town, or hauling a bit of a load, they work great. We do almost "no" mechanical work to these engines in the dealership. They have proven to be very reliable and trouble free. They do have the intake manifold gasket concern that the v-8's do, but even then, I've seen very few of these engines actually blow up due to the coolant getting into the oil.
The Buick 3800 engine also uses a balance shaft. Very nice, smooth, reliable engine (for the most part). Any 90 degree v-6 engine has to have a balance shaft to be smooth.
Ian
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One-Shot Scot wrote:

<<Well, if nothing else, you are certainly "un-informed" about the design of the 4.3 Vortec engine. They have had balance shafts for years now and are a good running, and smooth running engines.>>
I certainly didn't mean to imply that GM made no attempt to balance the 4.3 V-6 engine. However, in spite of GMs best efforts to balance the 1990-1995 versions of this engine, it still had a pronounced 1200 RPM shake, as well as a more moderate shake at 500 RPM. I used to watch the floor-mounted manual transmission shifter shake and shake when the truck was in neutral.
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That might be the case in your situation but personally I think you just got a bunch of bad engines if that is even possible because I have the 1995 version of this very engine it has a bunch of miles on it (160k to be exact) and it shows none of the symptoms you have described. Have had very little trouble with the truck itself at all and none with the engine.
Justin
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1200
all and

<<That might be the case in your situation but personally I think you just got a bunch of bad engines if that is even possible because I have the 1995 version of this very engine it has a bunch of miles on it (160k to be exact) and it shows none of the symptoms you have described. Have had very little trouble with the truck itself at all and none with the engine. Justin>>
I have been looking for the history of the 4.3L Vortec V-6 and their inherent vibrations. So far, I have turned up the following on an S-series page:
1988 Common: The 4.3l v6 engine was introduced.
1993 Common: The 4.3l v6 engine received an internal balance shaft to reduce vibration.
My original 4.3L Vortec V-6 was produced in 1990 and my two Goodwrench replacement engines were put in the truck in early 1996. My guess is that both of my rebuilt 4.3L Vortec V-6 engines were pre-1993 models because it is very unlikely that any later models would have needed to be rebuilt. Therefore, my problems with the 1200 RPM shake were probably inherent in all three engines.
http://www.mys10.com/downloads/s10_history.asp
Here is some information on GM's Vortec 4200 inline 6-cylinder engine:
"Sutter (Tom Sutter, Assistant Chief Engineer for GM's new Vortec 4200 Inline 6-cylinder engine) described the inherent smoothness of an inline 6-cylinder design. It has both primary and secondary balance. Primary balance is when the crankshaft counterweights offset the weight of the piston and rod. Secondary balance is when the movement of one piston balances the movement of another. V6's have a secondary imbalance that causes engine vibration. Adding a counter balance shaft can reduce this imbalance, but that adds weight and complexity. The inline design was a good choice. The new Vortec 4200 engine runs smoothly, quietly, and quickly all the way to its 6200-rpm redline."
http://www.canadiandriver.com/articles/jk/at_010424.htm
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snipped-for-privacy@satx.rr.com.com says...

My 4.3L is in a '92 S10 extended cab and has 187,000 miles on it. The distributor was replaced and that's it! Uses no oil and runs fine. I'd buy another one tomorrow...in fact, if I get the money I'm going to get another S10 and hopefully with a 4.3L.
Maybe it's the oil he uses.
--

Drum-

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I have a 95 astro van awd (with the 4.3 V6 vortec 190HP). Bought it used 2 years ago with about 220,000km on it. It ran great. Took it to smog and passes with flying colours. Today it still runs great. Smooth, quiet, no complaints with the engine whatsoever. Excellent power from stop (I was actually quite impressed how snappy it is). No oil burning, no smoke, no ticking, no drips. The mileage isn't the greatest at about 20mpg (canadian) but it was cheap and I needed the room (8 people). I know the RWD vans get better mileage. I have driven it about 60,000km. My vote gives a yeah to GM for the 'turn the key and it goes' worry free driving on this one (and on my 2.8L with 300,000km and on my 2.2L with 325,000km) I have own imports and had problems with burning oil at much less mileage and connectors corroding out.

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(canadian)
Huh? Is a mile in Canada a different distance than a mile in the US?
Karl Perry
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