Hey All,

Brand new to this Forum! I recently just bought a 2002 ZR2 Blazer V6 4.3L. with 107k miles. Only a few months after I purchased it I noticed a strange ticking sound coming from the engine just before the engine would shift (The sound is fastest at this point). As soon as I heard it I said to myself "that doesnt sound right" I pulled over and noticed the engine was ticking at idle as well. The ticking is very Rhythmic and is dependent on the RPMS of the engine. When at Idle it can be timed like clock work....tick...tick...tick...tick and as I give the engine more throttle the ticking is faster but not much louder. I decided to limp my way home and let it sit while I did some research about what would cause this sort of ticking sound that is RPM dependent. (I should note that I don't know very much about cars but I am very technically and mechanically inclined). After doing some research I decided to take it over to a shop down the road for a diagnostic. I went and started my bitchin blazer....thats her name....and she fired right up with no ticking noise at all. I hopped in and drove it around the block.. as the engine warmed up the sound started to come back stronger and again, fastest just before the engine shifts. (At cruising speeds on the freeway there is no sound...that I can hear anyways) I stopped the truck and popped the hood... there it was again...tick tick...tick...tick...tick.... It seems as if the noise is ONLY there after the engine has warmed up. So I turned off the car, and did the first thing that came to mind... checked the oil..... oil was fine and clean. I had it replaced a a few weeks after I bought it. It wasn't dirty and I still had another 1,000 miles roughly before I was due for another change.

After I took the truck into the shop, they said "it sounds like a classic chevy lifter collapsing tick" and that they would need to be replace. Again, I dont know much about cars but I know from life experiences to get more advise. I took it to another shop that my uncle recommended... they said the same thing. I looked all over online for suggestions and tried a few things myself to possibly fix. I replaced all spark plugs with Bosh Plat (verified gap), replaced and routed all spark plug wires the correct way, replaced the distributor cap and rotor. ( All these things I wanted to do anyways since i just bought it). The plugs didnt look fouled or messed up real bad other than a little brownish and some light carbon. The distributor cap didnt look to bad but the Rotor did look a little brown. The boot at the ignition port on the distributor cap had some corrosion on it too. oh, and I also replaced the Serpentine Belt and the check engine light has never come on nor have any codes been sent.

I cant pinpoint the ticking sound anywhere on the engine. If the hood is shut, it sounds like its coming from the very front of the engine. If the hood is open its a little louder on the drivers side in between the air filter box and the exhaust manifold. I went and bought a stethoscope and still had a hard time pinpointing where exactly the noise is. It was loudest near the exhaust manifold where the number 1 and 3 plugs are but again, at various different points. I would place the rod on certain bolts and it sounded louder there but then would move near the manifold and would sound just as loud. I checked under the car around the same area and it all sounded the same in intensity.

I took the truck to a 3rd mechanic and he said that it definitely sounds like a lifter. and to replace they wanted close to 1,000! At that point I decided to get my hands dirty and do the job myself. I replaced the lifters, and rolled all the push rods on a plate of glass. 1 push rod seemed to wobble a little bit so I decided that at only 2.50 a piece and while I was in there I would replace them all. The roller lifters didn't look warn at all and the cam didn't show many signs of uneven spots or even burn/wear marks. All in all, they looked pretty good. I did however find that one of my injectors on the #4 cylinder was melted back and was exposing the tip more than the others. I decided to replace that one injector and dipped the other nozzles in some lucas injector cleaner while I had them out. I reassembled everything down to torque, replaced all gaskets and o rings and also replaced the PCV Valve and t-stat. (might as well right?....thats what I said until my wife saw the charges :P ) All in all I spent around 400 in parts so I was feeling pretty good about it. I set the timing correctly at TDC #1 and lined the marks up...dropped it in....checked all my connections and started her up.....VVRROOOOMM! No problem..... I was feeling really good about the whole thing. I let the engine warm up and periodically gave it a few good revs. ....and again.....the ticking sound came back! SAME EXACT SOUND! still acts up after shifting. I shut down the truck......let it cool down and tried again.. VROOOOM! no ticking..... as soon as it warms up it comes back and its fastest / loudest just before shifting. The odd thing is that I can put her in gear... press the brake and rev the engine and the ticking noise stops but once I let off the throttle.... it comes right back... it slows down with the RPMs and ticks like a watch.

I am really hoping for some help from this forum. Out of all of them out there, this was the most helpful during my investigations. Could it be an exhaust manifold leak? Why does it only start after the engine is warm? Im at a loss.


Oh!, and I replaced the fuel filter and air filters, cleaned the MAF sensor as directed and made sure I never touched the sensor itself.


HELP PLEASE! THANKS IN ADVANCE FOR ANY ADVISE!

 

It can't be an exhaust tick, because it'd get louder the higher of a load you put on it. If it runs fine, it makes me think you have some crud stuck in your lifters. Next oil change, substitute a quart of oil with automatic trans fluid. Drive it around and change the filter every thousand miles. When you finally go to change the oil, it should come out black. ATF has certain detergents in it, and when its ran in the crankcase, it cleans all of the gunk and crap out of your engine. If that doesn't work, your rocker arms might be out of adjustment.

 

farley463- Thanks for the reply! Sorry if I didnt clarify. The sound DOES get louder and faster when I push on the throttle. Its loudest just before it shifts into second and also in 3rd. ..After that I cant hear it anymore when Im at cruising speed. If I rev the engine when in park it also gets louder and faster as if it is moving with the RPMS. I just replaced the lifters and lifter rods last night. They are the roller lifter style and I was sure to soak them in oil to prime them before installing. Also they are "NON ADJUSTABLE" so I ensured that they were tighten down to torque in the proper sequence. In trying to pinpoint the problem I have a hunch that its has something to do with only appearing after the engine has had a chance to warm up thus making me believe that there may be a leak at the exhaust manifold or gasket. the warmer the engine gets....the more apparent that the sound is. My oil pressure of course is higher (according to my gauge) when I first start the car which is around 60 and when its at idle its around 20. To my knowledge that is normal on these blazers. It doesnt seem to effect performance at all either. I intentionally back off on the throttle when the ticking starts just before shifting because I am afraid of damaging anything.

 

Try focusing on the front of the engine with those components driven by the serpentine belt. After all you have already done I'd look at the tensioner pulley first as it makes sense to me that as the bearing would heat up it would start to make noise.

I could be way off, and have been before, but this is where I would look next.

 

AJBert - I had thought of that because honest to god thats where the sound is loudest (with the hood shut) when I open the hood it sounds more on the drivers side. I ruled out the accessories by removing the serpentine belt after the engine had warmed up... dont worry I only let it go for 10 seconds or so I have it in my garage now and am trying to pinpoint where its coming from exactly. I cant believe how hard it is to pinpoint. I just put my stethescope near the bottom of the engine under the crank and it was pretty loud there... but then again it sounded the same near the exhaust manifold as well. Mind = Blown.

 

So for the not so many following this problem - UPDATE- It dawned on me last night that I have never seen my check engine light come on. I got out of bed, went down to my truck and turned the key to the ACC position....all of my dash lights illuminated... EXCEPT FOR THE CHECK ENGINE LIGHT!. I have no idea how I never noticed that it never lit up! Either the guy that sold it to me disabled it for one reason or another (Most Likely because of emissions, but it passed emissions the first time) or the bulb has burned out. Before I took apart my engine I went to Autozone to check for any codes but the guy had said that if the light has never come on then there wouldnt be any codes to report. Thus, I never connected a diag to my truck. I went in this morning to another Autozone and asked them to connect it anyways and sure enough " Camshaft Position Sensor Failure" shows up. I bought the part and will install it after work... Im praying to god that this is what has been my problem all along and what I am hearing is a spark knock of some sort. Can anyone else check in on this? Would a bad Camshaft Position Sensor cause any sort of Engine knock? If so, Im still confuse as to how it could only appear after the engine is warm. . . Or come to think about it... maybe its not happening when is warm but when I reach a certain RPM or speed? I havent ever just let the car "warm" up to operating temps before and listened to see if the ticking occurs then. If the Sensor is bad, can it cause a delay in the timing thus throwing spark knock? Who knows how long this has been bad for... I may have had it going for a while without knowing and its done more damage to a piston or rod. Any advice is welcome

 

i have the exact same issue with my 99 balzer with 205k changed the lifters tried cleaners and everything can figure it out its just everywhere but no where at the same time did you figure out anything with yours yet

 

I did actually. Unfortunately Spun a main bearing. Your right though that the sound sounds like it's coming from everywhere but nowhere at the same time. I just purchased a new engine and am pulling the old one today.

 

ok i heard similar issues and it being the balance shaft and distributor but i had a feeling it was the mains so looks like i am gonna be in the market for a new engine

 

I ended up finding out by finding some of the copper shavings in my oil after I tried using thicker oil thinking it was a bad oil pump.