99 Yukon Engine Knock

[rell_ent]

i bought a very clean 99 Yukon SLT 4wd had 69k on the dash and was clean as a whistle..
I had replaced the shocks, fuel pump, brakes, new dual exhaust, installed hids, radiator, compressor, and did a tuneup. Well i had a manifold that was leaking took it up to the local gas station for repair and the next day when i started up i heard something bouncing around like popcorn in the engine when i got up their to let them hear it went away. Know a few weeks later i have a loud knock in my engine.

So what i wanna ask is was the best thing to do i paid a nice penny for this truck.. should i sell the way it is? try and fix it? put on ebay? i really dont want to put a used high mileage engine in this truck that i bought with 69k miles..and at the same im tired of putting money in to it...

 

[OR VietVet]

Whether you don't want to put money in to it or not, you need to find out the source of noise and location. You are talking about a knock that that you heard once and then went away and now back a few weeks later. Does not sound catastrophic. Random knock may not even be the engine. You need to be specific as to when you hear it, engine speed, engine load, cold or hot, accel or decal, how often.....etc. Did you get paperwork verifying the actual mileage?

 

[rell_ent]

Whether you don't want to put money in to it or not, you need to find out the source of noise and location. You are talking about a knock that that you heard once and then went away and now back a few weeks later. Does not sound catastrophic. Random knock may not even be the engine. You need to be specific as to when you hear it, engine speed, engine load, cold or hot, accel or decal, how often.....etc. Did you get paperwork verifying the actual mileage?

i been letting it sit, but drove it yesterday to get a oil change, when i started it up the noise wasn't their, but came back as i was driving and do believe it gets a little louder under load, the source seems to be from the bottom left side of the engine. i purchased the vehicle with 69k and it has about 77k now. I checked the carfax when purchased and didn't notice any thing strange..

 

[OR VietVet]

When engine is at idle the knock may be less loud, but there. Get a mechanics stethoscope, very inexpensive, and see if can hear it with that tool at idle. If can then while running remove the plug wires one at a time and if noise stops then you located which cylinder and then do a compression test. As a matter of fact do a compression test of the entire engine. The noise may also be from the flexplate being loose at the torque convertor inside the bellhousing cover. Remove that cover and check all bolts for tight and look for any cracks radiating out from the center bolt area at back of crank.

 

[rell_ent]

When engine is at idle the knock may be less loud, but there. Get a mechanics stethoscope, very inexpensive, and see if can hear it with that tool at idle. If can then while running remove the plug wires one at a time and if noise stops then you located which cylinder and then do a compression test. As a matter of fact do a compression test of the entire engine. The noise may also be from the flexplate being loose at the torque convertor inside the bellhousing cover. Remove that cover and check all bolts for tight and look for any cracks radiating out from the center bolt area at back of crank.

well i took it up to the mechanic he said it probably will need a new engine, and to try some lucas..also said i could possibly get another 5 yrs out of it but it sounded like a rod

 

[ccapehartusarmyINF.(ret)]

check and make sure all your manifold bolts are there
because mine sounded the same way and it was the exhuast leak from the missing manifold bolt

 

[rell_ent]

check and make sure all your manifold bolts are there
because mine sounded the same way and it was the exhuast leak from the missing manifold bolt

ok ill check did urs knock all the time ot only after warmup?

 

[ccapehartusarmyINF.(ret)]

if wasnt so much a knock it was more like a ticking noise sounded kinda like a stuck lifter
and i even went through my entire valve train nothing
then i finally stumbled onto this broken bolt and couldnt beleive a tiny exhuast leak could cause all that extra noise