engine knock

[typhooey]

first I want to thank thank Adam for all his help with the new truck I have engine knock and he kept reasuring me that the dealer didnt know what they were talking about, so tomorrow im going to tell my mechanic to do a full tuneup and hopefully that should take care of the problem so thanks again Adam SY0237.

 

[gmcturbo]

a tune up might take care of some spark knock. not an engine knock though! is it a pinging when youre getting on it or a constant loud deeper knock that gets louder with rpm??

 

[Captain Morgan]

i think he meant spark knock.........i hope.

 

[SYO237]

slowly but surely.... trying to take things slow here, figure out whats wrong.


like i mentioned to you before, dont take anything that the dealer said to be worth anything.

Get the numbers from the compression test they said they performed and post the results. Even then, I would question the results and have someone else trustworthly to look at the truck for a second opinion...another SyTy owner would be nice.

You mentioned the dealer said 2 cylinders read low. Make sure you post which cylinders they were also.


If the truck is truely knocking, it could be from fueling, ignition, faulty knock sensor, bent rods....or any of the other combinations the trucks are famous for.

Do the classic ignition tuneup (plugs, wires, cap/rotor, possibly coil) along with a new fuel filter to start out with.


Seems odd that the dealer would know the truck is knocking just from doing a mild "tuneup" and compression test? I hardly doubt they were using any diagnostic equipment. Any dealer that straight off wants to replace a motor is questionable to me. Sounds like the classic dealer takes your money and bends you over story.

These trucks are almost impossible to diagnose without use of proper diagnostic tools...knock degree being the top of my personal list.



Your new to the trucks, and your in the right place to find your answers along with help.

 

[ghettosled]

a compression test isnt necessarily going to diagnose a knock. It will be an indication as to a problem in that particular cylinder in which case you need to do a leakdown to determine broken/bad rings, headgasket, valves etc.

The best way to diagnose a rod knock is take a really long pry bar or screwdriver and touch the oil pan with the engine running while holding you ear against the other end.

Typically rod knock will get louder as the motor warms up and the oil thins out. If you add some oil treatment and the sound goes away or lessens then you got some issues.

An ignition knock should only be noticebale under a load. An ignition miss or stumble will be noticebale at idle or off idle.

 

[typhooey]

when I do get on it it seems that it does get louder but also the truck seems very strong in power im going to tell my mechanic to do all of the things you guys told me to do plus a tuneup and ill post the compression test also and lets see what it is.

 

[typhooey]

when I picked up the truck from my mechanic he came up with the same compression that the dealer did around 70 now keep in mind he didnt know what the dealer came up with and it was # 3 and #4 cyl.

 

[typhooey]

and the dealer I bought it from offered to pay for the rebuild so what would you guys do?

 

[bezerk]

and the dealer I bought it from offered to pay for the rebuild so what would you guys do?

kinda difficult to say.....
most of the dealerships screw around on rebuilding SyTy engines.
they prolly get you an 4.3 non syty block out of a crate.
(wrong compresion, and wrong main caps)

try to get them to pay you 2K, you take the engine to a well known SyTy vendor, or somebody that knows what he is doing, and pay that money to someone else to rebuild it.

but than again, you never know what is wrong, could be a simple thing, or your block needs overbore, and than is gonna leave you with a set of new pistons.

i wish you alot of luck during this process.
if you let them rebuild, try to get a warranty for 20K miles on the engine.
Could be a high thing to ask... just search around on this board, and you will find alot of dealership horror storier.

 

[typhooey]

first I have a rebuilder that I know so I can trust them. second im getting a 1year warrantee and if I want a longer one like 3 year its extra $250 which I will get. luckily I know the right people in engine rebuild, im going to try to bring the truck to hooters this weekend.

 

[JSM]

first I have a rebuilder that I know so I can trust them. second im getting a 1year warrantee and if I want a longer one like 3 year its extra $250 which I will get. luckily I know the right people in engine rebuild, im going to try to bring the truck to hooters this weekend.

We have heard this story before, and the end isn't always what you think.

Be VERY cautious.

 

[typhooey]

I will be very cautious!!!!

 

[Sy769]

first I have a rebuilder that I know so I can trust them. second im getting a 1year warrantee and if I want a longer one like 3 year its extra $250 which I will get. luckily I know the right people in engine rebuild, im going to try to bring the truck to hooters this weekend.

We have heard this story before, and the end isn't always what you think.

Be VERY cautious.

What he said. Better be sure of what's going in the engine.

Sort of reminds me of the classis story of your local super trans builder. "Yeah my trans are holding behind some stout camaros,vettes etc...." Me: "That's nice, Bet my little V6 can break it"

 

[93ty475]

Did you buy this truck without inspecting it?? i would make the sob take it back...you have no idea what it takes to rebuild one of these motors...it's alot of shit, then when your done, there could be alot of bugs to work out...if he sold it to you knowing that it knocks, i highly doubt he's going to pay for a rebuild...can't you protest the charges on your CC? i know used cars are usually sold as is, but how the hell are you going to afford this? expect for this to cost more than $5000.00 if any effort is made to do it correctly...damn, what a nightmare...

if it's rod knock, it should go away if you pull the plug boot on the knocking cylinder...try that and hope it doesn't work...

 

[typhooey]

the dealer is paying for all cost because he does not want to give my money back and also to pay for my shipping cost and to ship it back its costing $3,500 and hes paying

 

[bezerk]

bring the car back to your salesman....NOW!

 

[typhooey]

easier said then done im in NY the dealer is in IOWA besides everything else on the truck is flawless. the people doing the work on the truck are close friends and im not paying a dime!!!

 

[typhooey]

also have blow by so that prob will be fixed also!

 

[typhooey]

I do have a question can I replace reg antifreeze with dex cool in the ty

 

[93ty475]

if you drive the truck around, this could get more expensive...if you have blowby and rod knock, i would suggest someone start tearing it down soon... i have a good assembled, used .030 syty shortblock i can sell you cheap BTW...not built for racing though...just stock rods, caps and trw's...