Need advise, Some kind of engine noise that's not good

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  • I've had what I guessed was a valve train noise at idle,cold and it went away as engine warmed. Now the noise is getting worse. I have a low mileage Hahn setup with 7 psi. With the help of @funinthesun we pulled valve/cam cover and cams,rockers,springs and timing chain look good and tight, we pulled off the alternator drive belt
    to test bearing on assecories and noise still there.
    With some advise from DDM of a possibility of bent rod I did a compression test and 160/165 across all 4 pistons seems all is good there. Tested oil pressure at Turbo oil inlet and 55/60 psi steady.
    The engine pulls hard and seems to run great, the rattle,marble noise goes almost complete away when she warms up. The noise comes in load once I lift off gas and it's ideling down. I did recently change oil to Rotella and plan on changing back to Mobil 1 this week and strain oil to look for metal. After my crash last summer I was having and issue shifting from Thrid to Forth when under pressure by somebody who thought they were faster and a bent shifter hold down cover and I missed I few shifts pegging the rev limiter.
    Any advise would be aperciated.

  • Long ago, I remember trying to locate valve-like tapping noises on a different engine and it turned out to be a tiny exhaust leak from a faulty gasket. It often helps to poke around with an engine stethoscope or even just a tube held to one's ear. On the LE9, I seem to remember the EGR valve can also make some weird noises. I debugged the latter by listening to the engine while removing the oil fill cap.

  • That sounds like a connecting rod noise. If you hold the throttle at 2500 - 3000 RPM you will probably hear the noise constantly. Not 100% sure, but my guess is a connecting rod.

    Yeah....could be an early sign of a bad connecting rod or even a wrist pin. Hopefully not.....keep us updated!!!!!

    Those who will give up essential liberty to secure a little temporary safety deserve neither liberty nor safety


    2016 Slingshot SL Vin# 8855 (born in September 2015) w/ Alpha Stage 2 Turbo @ 7.5psi

  • Thanks for your responses, stethoscope is a great idea will get one today. We did do the old long screwdriver trick and the noise seemed to be coming from front of engine, that's why we pulled serpentine belt and tested that. What does removing the oil fill cap do?


    I will run again at 2500-3000 and see if noise is there. If it was a connecting rod would tempature change the sound?

  • After listening to the video again (sorry, when I first heard it over the weekend it was on @rabtech phone), another thing that you should check is the timing chain, timing chain guides and timing chain tensioner again. We have seen a decent amount of the timing chain tensioners go bad and also the timing chain guides in the front of the engine crack or break, although usually at higher mileage than you are reporting. Another thing I would pull and check is the VVT solenoids on the top of the engine (2 silver canisters sticking up on the front of the engine with electrical connectors on top). They come out pretty easily, just remove the single 10mm bolt and disconnect the electrical connector, twist and pull up and they will slide out of the engine. There are screens on those solenoids, look to see if you have any debris on those screens and clean the solenoids with some brake cleaner and re-install.


    Was the noise as bad with the Mobil 1 compared to the Rotella? Did you notice a definite increase associated with the timeframe that you changed oil also?


    What I hear in that video is sometimes what we will hear in Solstice/Sky 2.4L when the oil is left in for a long time and the VVT actuators can not work correctly. I have had people call and think that they blew up their engines because of that noise and then after cleaning the VVT solenoids and changing the oil the noise goes away. It is hard to diagnose anything long distance, but something to check for sure.


    Just some other things to check, keep us up to date on what you find.
    Hope that helps,
    Dave

  • Thanks Dave,
    The noise got worse with Rotella "But" big butt I also changes my exhaust at the same time to Welter rear exit from the Hahn side and of coasre any engine noise would sound loader. The timing chain and guides look good from the top but will need to remove guides and check it deeper. I will pull those solonoids first and check them. That would be a simple and cheap fix !!!!!! :thumbup:

  • Update, even more confused.
    I pulled the VVT Solnoids and they were pretty clean, small amount of metal on each. Cleaned them and reinstalled.
    The noise came back, now for the strange saga.
    When I started her up after cleaning valves the engine was nice and quiet and purring like I kitten, I was having thoughts of hugging and high five'n DDM Dave and then i hit the throttle and noise started again getting louder with each rev. Not sure what that means or if it means anything. After that disappointment I drained the Rotella and topped off with new Mobil 1. The old oil had about 300 miles on it seems really dirty and the magnet drain plug has a greasy graffite like coating on it. Next step is to dig back into timing chain.

  • Following because I like puzzles.

    I personally would look really hard for exhaust leaks.

    If one of the timing guides is bad and breaks, it is usually a mess. The outer chain tensioner can be purchased fairly cheap and installed without a ton of work.

    You could swap your top VVT solenoids with someone else pretty easily to rule them out.

    That oil does look pretty nasty. Very odd deal.

    Owner of Slingshot #263 that has some stock parts left on it. :D

  • 51,000 miles with oil changes every 3,000 miles and at oil change my oil does not look like that. Now the wifes Equinox 2.4 looks like that on the last 3 oil changes. She was having some shyster change the oil and when I checked it one day it looked like coal tar so now I do the oil changes still trying to clean it up every 3,000 miles. Mobil 1 in the SS and now also the Eq.

  • Most of the miles were on the Blue Ridge Parkway, I pushed hard on a few twisty roads but always let her cool down afterward.
    This is a dam puzzle and i have a bad feeling it's going to have a expensive conclusion.
    I change my own oil, the oil I dumped was Rotella 5/30 Synthetic.

  • The only time I've seen oil get that dark with low miles was because the vehicle was running stupid rich. Friend had some issues with his Harley, and I asked him when he put the exhaust on. At the last oil change, about 400 miles ago. Turned out he was running a performance 2 into 1 header that was designed for a 120 Inch engine, and he had only an 80 inch one. It was scavenging the exhaust so well, he was running 3 sizes larger low jet and 2 on the main jet. When I pulled the exhaust off, it had closed up some from the 1/4 of soot buildup in the pipe.


    Like @FunCycle, I change mine with Mobil 1 every 3-4K, depending on if it's been on a trip with lots of highway miles on it. I'll go farther on the oil then. Mine never looks more than a strong tea color. Wife's Equinox goes 5K, and looks about the same.

  • The only thing on the Sling running stupid rich are us owners with lots of mods.

    Just to clarify, I wasn't suggesting the oil from @Pascal s SS was running that way. I'm following this thread to find out what the issue is, and why that oil got so dirty in such a short time.


    I'm not stupid rich by any means, and if I keep going with mods I could end up rather poor.... :00008356:

  • That's a good thought being I changed to the Welter 2.5, but i have not had any exhaust smell issues so I don't think it's stupid rich, if it was stupid rich it would be a LS7 motor in there. I think I know a place close by to get a couple VVT valves to test but I will have to hear why I need to replace her with a Civic motor and paint my toenails before posting pic of my feet. :D

  • That's a good thought being I changed to the Welter 2.5, but i have not had any exhaust smell issues so I don't think it's stupid rich, if it was stupid rich it would be a LS7 motor in there. I think I know a place close by to get a couple VVT valves to test but I will have to hear why I need to replace her with a Civic motor and paint my toenails before posting pic of my feet. :D


    Checked with @StickerDick to see if he had any old blowed up Ecotech's to use for parts testing and he went full Honda and moved anything with a bowtie out of his garage. @funinthesun said he will let me use his VVT solnoids to test that and if not we gonna tear the top off and relook at timing chain and guides.