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GM ENGINE KNOCK
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Anyone have a good answer for their attempt to explain away the noises by comparing to another defective engine??
around 34,000 miles they replaced the motor. All was well for a while until the new motor did the same thing. The dealer tried several different updated oil filters to no avail. Finally they said that GM said to run it the way it was and that if it failed that they would replace the motor even after the warranty ran out.(I had and extended warranty on this truck) They even wrote it on the repair receipt so I would have the documentation. I drove the truck for a couple of more years and finally traded it. As far as I know it still is running today.
Happy New Year!
I also mentioned: if this is normal, why don't they all do this from the factory?
-Eric
-Eric
Start several of them; find some that do knock and some that don't. Write down the VINs of those that do and those that don't. Take that to the meeting. Tell the arbitrator that you sampled several trucks with the same engine, some had the noise and some didn't. Provide him with the name of the dealer, the VINs of the trucks you sampled, the name of the salesman you spoke to and the date and time you were there.
NOTHING speaks louder than verifyable evidence! If necessary, invite the arbitrator to temporarily stop the meeting, go to the dealer, start the trucks you have listed and hear the noise for himself. Then let him hear the trucks that DON'T make the noise.
BTW, be sure and go into the meeting knowing what you want. For example, do you want a new engine in your present truck? Do you want new pistons and rings in your current engine? Do you want all of your money back? Do you want to swap even for a new truck?
Good luck. Let us know what happens.
Joe
2. Be sure and ask the GM rep how many trucks he had to sample before he found one that knocked!! I'm sure the arbitrator would be VERY interested in hearing his answer to that question.
How 'bout it, guys; anyone want to load up allchevy with data that GM won't be able to ignore?
Joe
www.tundrasolutions.com
Seems like a bunch of toy boys are
having fun with their engines and
cold start knock !!!!!!!!
AFAIK, Chevys have it on every start-up. At least some of the people in this thread have posted that.
from toy owners....Over the GM knock
you would have to as confused as I am !
I wish i could say that
2. If it WAS normal, why, then, is GM offering to replace engines, give away free extended warranties, and working on a new piston/ring kit to eliminate the noise?
3. DO NOT settle for a noisy engine! Insist, IN WRITING, that Chevrolet and General Motors fix your engine to YOUR satisfaction!
Joe
I took a trip between Christmas and New Years 2,700 miles - about 1,000 of them were at 80 MPH or more. I changed to Mobile 1 a week before the trip, also changed the air filter and wipper blades.
When I got to Colorado the knock was gone!!
The first few days I was in Colorado the temp got down to 0 degrees over night. I expected the knock to be worse, but it was gone. I am back in Houston now - and the knock is still gone. I hope it stays away - but my guess is it will be back in a few thousand miles.
Or maybe the solution to the knock is to change your wipper blades!
The new engine is now makes a noise, but not when completely cold nor when first started. The knock occurs shortly after startup and lasts for a few minutes during the warmup cycle. I heard the same sound with the old engine. After some close listening with a stethoscope, I am beginning to think that this noise is coming from an injector since the noise is coming from the same location as the noise in the old engine. (They reused the fuel rail and injectors from the old engine). Just wondering if anyone else has had a similar experience.
By the way, I found out this week that a used 2000 Sierra is about worthless, at least in Texas. I tried to make a trade for a 2002 F-150, but the trade-in value was so low that I decided to keep my Sierra.
The theory on the pinging motors was to get rid of build up on the tops of pistons that may have been causing hot spots. I can't imagine how a "soak" could help a knock that's caused by a clearance issue.
The engines they are replacing the knocking ones with, have the same pistons as the ones already
knocking. This then sets the vehicle up for
a lemon law buyback. GM is aware of the problem
and from what I understand is working on a fix.
Who knows
Ray T
Thanks
dash board rises with defrosters on. Rear springs are sagging ,goes in on tuesday for rear end problems. Junk Junk Junk.
Ray T.
- Reduced Main Bearing Tolerances
- Two-Point Coolant Vapor Vents
- Revised Intake Manifold
- Improved Catalytic Converters
- Improved Mass Air Flow Sensor with Temperature Sensor
- Extended Oil Change Interval
- Sleeveless Coolant Sensor
Reduced Main Bearing Tolerances
Two-Point Coolant Vapor Vents
Revised Intake Manifold
Improved Catalytic Converters
Improved Mass Air Flow Sensor with Temperature Sensor
Extended Oil Change Interval
Sleeveless Coolant Sensor
CUSTOMER BENEFITS
MORE PRECISE BEARING FIT
Smaller tolerances in the crankshaft main bearings mean a more precise fit. The result is an increase in long-term durability and, just as importantly, a reduction in something known to engineers as "cold knock"--a slight slapping noise from the engine before it reaches full operating temperature.
FEWER VENTS
The number of water pump vapor vents has been reduced from four to two, thereby reducing cost. The vents are located in the cylinder heads, and release gas from localized coolant boiling around the combustion chambers, preventing air pockets that restrict coolant flow. Experience with has shown that two vents are sufficient.
REVISED INTAKE MANIFOLD
The intake manifold has an improved purge isolator--the rubber device used to mount the solenoid that manages fuel injection-to reduce noise and vibration. The new manifold also has a new, more durable injector director plate, with two large holes rather than four smaller one to reduce potential for clogging.
BETTER CATS
Both the 4800 and 5300 have 74-ci primary converters that are manufactured with less precious
metal, at considerably lower cost. A new catalytic coating and thin-wall catalyst substrate--the source of the catalytic reaction that turns exhaust emissions to harmless vapor--allow improved performance with less platinum, palladium and other precious metals in the converter.
For 2001, the 4800 and 5300 are National Low Emissions Vehicle (NLEV) certified. Vortec 5300s built for California Suburbans are fitted with a pair of "pipe converters," or an extra pair of small catalytic converters in the takedown pipes from the exhaust manifold. As a result, the 5300 is Ultra Low Emissions Vehicle (ULEV) certified for California--the current most stringent emissions standard.
BETTER MAF
A new Mass AirFlow (MAF) sensor features an integral inlet air temperature sensor, which allows the Powertrain Control Module to adjust for optimal performance at a given air temperature. The result is more efficient combustion and fewer emissions in all operating conditions.
LONGER OIL CHANGE INTERVAL
New computer algorithms extend the maximum oil change interval from 7,500 to 10,000 miles. The Powertrain Control Module records engine temperature and length of operation at a given temperature, then indicates an oil change when it's actually needed, rather than according to a predetermined interval. With new data on real-world customer use, Powertrain engineers have adjusted the software to allow the longer maximum oil-change interval.
COOLANT SENSOR
The new coolant temperature sensor uses a plastic insulator to protect electrical leads inside the brass housing, rather than a rubber sleeve, and reduces the possibility of assembly rejection or shorting in operation.
It is caused when the hydraulic lifters don't have enough oil in them at start-up, and continues until the oil volume in the top of the engine builds up. This is often caused by using a too-light weight of oil such as 0W20, 0W30 or 5W30, or by using a straight-weight oil, such as 30W or 40W. The too-light oil flows down into the crankcase too easily; the straight-weight oil is too thick at start-up, and it takes longer for the oil pump to get it moving.
If you are concerned about it, you can use some engine flush just before your next oil change, and step up the weight of your oil one grade, or go back to using a multi-grade. Virtually all modern engines are designed to use multi-weight oil anyway, but there are some out there that started on 30W fifty years ago, and will never change.
The knock that many users in this forum are trying to have addressed is a knock that occurs once the engine is warm. It is likely caused by excessive spacing in the ring grooves on the pistons, allowing the rings to make a rattling sound when the piston changes direction.
The fact that some engines do it and some don't suggests that either GM or its suppliers allowed too wide of an acceptable range in the size of the rings or the pistons, or both, or the engine was designed with rings and pistons the wrong size. For example, if the rings in your engine are a few thousandths of an inch larger than the ideal size, and the grooves in the piston are slightly narrower than the engineer intended, your engine probably doesn't knock. However, if you go to the opposite extreme--narrow rings in a piston with wider than normal grooves--you get the knock.
While the jury is still out on whether it affects engine durability, it is annoying at best, and a sign of sloppy quality control at worst. Some have even suggested that GM knew some engines would knock, but thought they could pass the noise off as normal. Guess they under estimated the devotion owners of nearly all brands of trucks have for their personal vehicles.
While I don't have one of the affected engines, I hope those of you that do keep the fire under GM's butt to cover the engines that are on the street, and design a fix for future engines. One thing you can take to the bank--the ONLY way GM will care about this problem is if it costs them enough money--either by paying to fix existing engines, or potentially loosing sales of new trucks. When the bean counters take notice, it is amazing how quickly things get done!
As for the owners of other brands that love to troll through here making immature remarks about GM trucks--so what? EVERY manufacturer has let vehicles go out the door that were not perfect. Yes, EVERY single one of them!
Joe
I don't know why bamatundra would say that 5W30 and 10W30 oils are the same. There are specific and measurable differences between 10W30 and 5W30 oils, whether they are synthetic or non-synthetic. Please keep in mind that the standards for oil are set by the SAE, the Society of Automotive Engineers, and NOT by the oil's manufacturer. If Mobil were selling the same oil as two different weights, it would seem that they are setting themselves up for a ton of lawsuits, both from individual users and various state attorneys general offices for consumer fraud.
For more information about oil standards, go to their web site at www.sae.org
Joe
More misinformation
First the pictures and now this!!!!
Oil...........................VI......Flash......Pour
Mobil 1 10W-30........160......450.......-65
Mobil 1 5W-30..........165......445.......-65
Sure look like the same oil to me! Although the Viscosity Index is slightly higher, this number is only comparable within the same viscosity class of oils. An oil with a smaller viscosity range would be expected to have a higher viscosity index. The Flash Point and Pour are nearly identical as would be expected with the SAME oil.
is not the same as
"exact same "
Ryan
Mobil 1 Tri-Synthetic 0W-30 5W-30 10W-30 15W-50
Product Number 48116-8 48111-9 48117-6 48120-0
API Service Classification
Gravity, API 33.0 32.8 32.0 30.2
Specific Gravity 0.860 0.862 0.866 0.875
Pour Point,°F -65 -65 -65 -55
Flash Point,ASTM D 92,°F
460 455 470 473
Flash Point, ASTM D 93,°F
412 410 430 433
Viscosity Index 176 162 147 160
This is not all of the data they have posted; if you want to see their entire spread sheet, go to this link, then click on the product data sheet:
http://www.mobil1.com/index.jsp
Like I said before, there are distinctive, measurable differences in the two different weights of oil. Even if you only look at the data that bamatundra quoted, there are still notable differences in Viscosity Index (VI) and flash points.
Joe
>You have shown very good proof that Mobil 1 5W-30 is actually different oil than 10W-30. Someone posted on another website that they were the same and when I checked the properties on yet another website they appeared identical. I should have checked at Mobil 1 website as you did.<
You just admitted the information you posted earlier from someone on another website was erroneous. Now you cite the same misinformation as PROOF! ROFLMAO!!!!!!!!!!!!!