I Have a 2000 gmc jimmy 4x2 engine code w. I have done a intake gasket on the engine because of a vaccume leak and oil leak in the front of the engine started making a ticking noise. also replaced plugs, wires, cap, rotor button, fuel pump and fuel filter at same time. did the fuel stuff because of low fuel preasure but thats fine now. All parts where from dealer so are ac delco. I have everything back together and have a tick/knock noise from what seems to be the crank rear when under the car butalso a tick in the upper area too. Oil pressure is 30-40 at idle and goes to 40-45 when going down the road. I pulled the oil pan to look at the bearings on the crank and everything looks fine and did a wax gap test on them and everything is in spec by dealer spec. checked lifter/ rocker arms and everything is fine there too. I have a p0301 code that keeps coming back but on compression test is 115-118 on driver side and 114-118 on passenger side. I have replaced plugs 4 times and have checked for cracks each time but always fine. I was thinking bad valve or lifter on cylinder 1 but have swapped lifters/rockers with cylinder 3 and back again with no change in code or running. The truck has plenty of power even up hill. transmission shifts fine. I have even had the computer flashed twice. once by the part store that does it local put back in and did same problem then by dealer with same problem. Dealer says they havent seen this problem so thought I'd ask on here. I use a Syn blind from mobil one (5w30 summer 10w30 winter) as far as oil goes. I have around 180k on engine and problem has started about 100 miles ago. I'm just out of ideas on what will fix the noise problem. I'm thinking burnt valves as far as the miss fire code on cylinder 1. The injector is new and working on the cylinder. Sorry for got to say about replacing that too. The knock/tick is always in the engine even after warm up and speeds up with rev of the engine. thanks for any help or Ideas anyone may have at this point.

 

Bump
Similar problem here, on my 96 ext cab. 4.3 V6. Around 126,000 mi.. Ticking sound that speeds up with RPMs. But no code or check engine light. It gets faster and quieter when engine revvs up, and gets louder when you take foot off gas as it goes from almost a chatter back down to a ticking. It seems to be in the back of the engine/firewall area. I can hear it clearly from inside the cab when all is quiet. The engine runs fine otherwise, but the ticking is unsettling. Friends with more mechanic experience than me are at a loss. They say its not a lifter or a knock... and that its really wierd. Only suggestion has been that it was coming from somewhere in the HVAC deep in the dash, but I can hear it with a long screwdriver pressed against the engine and handle to my ear and it sounds like its in there towards the back...
I read somewhere that someone had a sparkplug that wasn't tight enough and it caused a similar ticking. And that tiny exhaust leaks can have similar effects. I will be torking all my plugs tomorrow, but I dont expect it too work because it really sounds mechanical, like a little dry bearing at low RPMs that starts to chatter at higher RPMs.
Also thanks to everyone on the forum, it has been a huge and constant help... I think this is my first post because so much has been covered here already I havn't had to yet, but I am an avid reader.
And thanks in advance for any replies.

 

hows the oil?

 

TimC2000, if you have a #1 misfire, you need to get that figured out first. It could be a problem with the distributor cap/rotor or even a bad wire causing that cylinder to misfire.

Bitrunner, A ticking noise at the back of the engine could be caused by a cracked flex plate. But really, if you want to discuss things further, you should consider following along in this thread and creating a thread of your own. Your problem sounds different from Tim's and it wouldn't be good to take off in a different direction in Tim's thread.