'98 Chevy 5.7 Vortec Knocking

Discussion in 'Chevy C/K Truck Forum' started by MJ4NOLES, Feb 4, 2014.


    MJ4NOLES New Member

    I Have a 1998 chevy silverado with a crate motor in it with approximately 40,000 miles on it. It has recently started to knock when the motor is cold. It does not knock at idle, it only knocks when in gear and moving. The knock eventually goes away once the motor reaches running temperature. I don't think that it is associated with the ambient outside temp as the knocking still occurs, just as long as the motor is cold. I'm not completely sure it is a result of the outside temp since it has only started occurring this winter. I am running Mobil 1 10w-30 synthetic oil in it now. I feel like this is the correct weight. I have read of oil draining back to the sump after sitting for a while due to a crappy oil filter or some kind of valve associated with the lifter lubrication. I am not very knowledgeable of this kind of thing.

    Does anyone have any thoughts?

    If you need to know more about what I am dealing with I will try to answer all of your questions to the best of my knowledge.

    Sent from my iPhone using Forum Runner
  2. edsmagichands

    edsmagichands Member 2 Years 100 Posts

    are you sure its the engine making the noise? If so, knock/bang low in the engine or click/clack higher up? auto or manual trans? 5/30W is a better choice especially in the winter. doesn't it say 5/30 on the oil filler cap? when did you buy the engine? if it is a GM crate engine it might be under warranty.

    MJ4NOLES New Member

    I am currently in the process of trying to upload a youtube video of the problem so you can hear it. The engine was purchased about three years ago, It had a 100,000 mile warranty on it, I will have to dig up the paper work regarding that. As far as the knock, it sounds like it is high up in the motor, as if it is a lifter or something of that nature. The transmission is an automatic transmission. As far as what the oil filler cap says, it may say 5w-30, however I didn't think there would be such a significant difference between that and a 10 weight.

    - - - Updated - - -


    Here is a video of the knocking. Listen closely, you may have to be in a quiet area and turn you speakers up. The knock is only occuring when I am applying the throttle.
  4. edsmagichands

    edsmagichands Member 2 Years 100 Posts

    there is not a huge difference. however, oil does become thicker in the cold. i prefer the 5/30W. let us know about the warranty.

    MJ4NOLES New Member

    I found the invoice of the engine installation. Thats really all that I have. According to the below form is should have a 3 year 100,000 mile warranty transferrable to any GM dealer. The engine was installed 04/05/2011, so in other words I now have until 04/05/2014 to get this figured out.

    If all that I need for a warranty replacement/fix is what is in this form then I should be good.

    Last edited by a moderator: Aug 20, 2014

    MJ4NOLES New Member

    Whats the deal? I made a post 2 hours ago about my findings and it said it was waiting on moderator approval...

    - - - Updated - - -

    I found the below form online about the GM engine warranty. All I have from my engine installation is the invoice from the GM mechanic who did it along with a part number for the crate motor. I think I can fill out this entire form with what I have. Has anyone gone through this? Is this the correct form?

    I have also discovered that my engine was installed on 04/05/2011 with a 3 year 100,000 mile warranty, which gives me about 2 months to figure this out.

    Problem is, I would have to drive to a dealership, let the truck sit for who knows how long, to cool down then crank it and drive it showing the mechanics the knocking.

    Will I be charged for a diagnosis given the warranty? Considering it may take some serious digging to find out what is wrong.

  7. edsmagichands

    edsmagichands Member 2 Years 100 Posts

    I think i can help you here. last year i installed a GM GOODWRENCH crate engine with 3yr/100,000 in my sons truck and did some preventive research in case i ever needed to warranty it. the form at the website you gave looks identical to the one i got when i purchased mine. except my form also shows a GM parts engine with only a 12/12 warranty. don't remember how i got the number, it wasn't on any paperwork. however i spoke to them about possible future issues. if i remember correctly you will not be charged if it is a warranty issue. any GM dealer can perform the repairs. i believe a authorized independent can also do it, i would prefer dealer,less hoops to jump through. they also told me they could start a claim immediately over the phone so it will be on record. i recommend you do this immediately!! here's the number. 866) 453-4123. i believe they answer PCC(don't remember what that stands for) they should be able to answer all your questions. GOOD LUCK, AND PLEASE KEEP ME INFORMED!!![TABLE="width: 361"]
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  8. Scrufdog

    Scrufdog New Member

    is that a check engine light on? if so what is the code?

    MJ4NOLES New Member

    The check engine light is for a heater core in the second O2 sensor. I had oreilys auto parts check on the code.

    Sent from my iPhone using Forum Runner
  10. edsmagichands

    edsmagichands Member 2 Years 100 Posts

    Have you called that number i gave you, if so, were they any help?

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