I have a severe knocking sound in the front of my engine. on 1998 GMC Sonoma

My truck is a 98 GMC Sonoma and last night I was turning into a parking lot when the knock started, its been getting progressively worse and now just 15 miles later its horrible. I was curious if i could get someone who had the same problem describe their symptoms? Maybe then I can narrow it down to the timing gears with out digging into it. Thanks so much.

by in Tamworth, NH on July 25, 2014
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2 answers 7 comments
ANSWER by , July 25, 2014
Take the belt off and see if noise stops.
COMMENT by , July 25, 2014
I did this morning and it persisted, what are your thoughts on the timing chain tensioner? could that make that loud of a smacking sound?
COMMENT by , July 25, 2014
Probably not the chain on this engine.. Most likely deeper, sorry... Have a mechanic listen to it.
ANSWER by , December 12, 2015
91sonoma same prob ,timing gear on mine, its made of some synthetic material not metal and they have to drop oil pan raise motor, pull valve cover side cover for lifters, get into cam its pressed on so once they get it out it has to b pressed back on. My est $450-$700
COMMENT by , December 12, 2015
NOPE .. NOT REALLY!... Different engine options in the 1998...4.3L & 2.2L.. both have timing 'chains' .. BTW: 'IF' one know how it's done... On the 2.5L (like in your truck) timing gear CAN be replaced WITHOUT doing all that work!! .. *Have done several of them*... No need to remove camshaft! .. Just thought you.. and other readers .. should be aware of that. .. Interesting how there is NO mention of engine size posted by the vehicle owners here... Go figure.
COMMENT by , December 15, 2015
Mines the 91sonoma, 2.5 Have found out i have gears no belt or chain..since. Im out the truck anyway because i wont pay that much to have it fixed I have a couple friends telling me they think they can do the job. They do work on vehicles but i just dont know that they can do this job. They have tools and the puller and im gonna let them try it.. really not out anything except tbe money for parts which the napa store says about $100. Thats for the gears gaskets and sealer. I think thats a bit high so i will call around but wish us luck on this fix and hopefully it is a fix. I will post as to how it goes...
COMMENT by , December 15, 2015
Yes I know... I am very familiar with that engine.... Just replace the CAMSHAFT GEAR and the FRONT SEAL.. Can use RTV gasket maker (silicone) for gaskets... Crankshaft gear is STEEL and has been mated up with the fiber camshaft gear so it should be in good shape! .. Camshaft has a hole already in it and it can be threaded so the cam gear can be pushed onto the cam using the proper bolt... New cam gear needs to be heated up in say a toaster oven before install.. Clean as much of the old cam gear fiber from oil pan as possible.. Let me know if more help is needed ... Check YouTube for a video... Might be something there that helps.
COMMENT by , December 15, 2015
Thank you for your help. I have checked you tube and dont find what i really need so maybe you can enlighten me some. What all exactlly has to come off to get to the gears. Looks like the fan shroud serpentine possibly water pump(i think) then can get to the cam, am i close..and why do the shops say all the other has to come out if it doesnt? More money i assume. Thats terrible they do that to folks.thank you so much i may yet be driving my truck again.i am walking right now and dont have enough to even get a dif vehicle and working at night its cold coming home at 11at night. Its only 5blocks but still cold.
COMMENT by , December 15, 2015
It's pretty straight forward for someone that's really auto repair savvy... The recommended proceedure is to tear it all apart, according to the repair manuals... MOST don't know how to do it any other way... However it CAN be done without ALL that work... Removing fan shroud, fan and timing cover is required... Water pump is optional but will make the job easier if removed... Keep in mind that I've been doing this for 42 years so it's a little easier for me I guess... Used to race a Chevy Nova in the late model limited division in which we used the older in-line six cylinder,, 'modified extensively' ... That engine IS the same .. Just has 2 cylinders removed! .. What I'm telling you to do absolutely can be done if the tools and talent are available... That's about all that I can help you with except wish you good luck with it..