Can the LT5 experts fill me in on..... - ZR-1 Net Registry Forums

Roadster · 08-31-2014

Ok, I think I have an idea why, but am not really sure, so can the LT5 experts who have the knowledge and understanding of this engine explain the following to me....
Why is it that if you let the Z sit for a week or even two weeks before you start the engine, that there is not any chain rattle upon first start-up???
I understand why there is chain rattle during some restarts, and that there is a kit available (which I have) that once installed, eliminates that problem or almost completely eliminates the problem.

We had the Z out today, and first start-up, no noise, most restarts after that the dreaded chain rattle.....
Just trying to learn more about the system......thanks for any info........

We Gone · 08-31-2014

No expert here but it sounds like you have a good check valve in your oil filter.

I have no chain rattle on my 91 or 93 even if they set many weeks. Both have Blue GM filters.

Roadster · 08-31-2014

Quote:

Originally Posted by We Gone

No expert here but it sounds like you have a good check valve in your oil filter.

I have no chain rattle on my 91 or 93 even if they set many weeks. Both have Blue GM filters.

That would seem to be true, but its on the restarts that it appears the check valve isn't working as it should, only that it appears to work better when the engine is cold as opposed to when the engine has been running and is hot!!!???
I also have a Blue GM filter. Hopefully over the winter I will attempt to install the kit for this, just have to see what the time factor allows me to do....as there is always something going on........

Jim Nolan · 09-01-2014

Mine went away years ago after my second synthetic oil change. I use the blue PF970.

Kevin · 09-01-2014

chain rattle is annoying but not harmful. I don't even notice it anymore

Karl · 09-01-2014

I barely notice it and that is only if the car sits for a long time. Also the car starts quicker (or at least seems to) if I turn on the ignition first wait about 3 seconds then start.

Roadster · 09-01-2014

Quote:

Originally Posted by Karl

I barely notice it and that is only if the car sits for a long time. Also the car starts quicker (or at least seems to) if I turn on the ignition first wait about 3 seconds then start.

Quote:

Originally Posted by Kevin

chain rattle is annoying but not harmful. I don't even notice it anymore

I hear you on that. ...if mine sits for day or longer no rattle on startup. ...as mentioned earlier, its just those hot or warm restarts that bug me.....I am using Mobil 1 , might switch to Amsoil next time around and hopefully get that kit installed

spork2367 · 09-02-2014

I've been using the white "Napa Gold" filters that are made by Wix and they have a great anti drain back valve. Zero rattle.

secondchance · 09-02-2014

Quote:

Originally Posted by Roadster

I hear you on that. ...if mine sits for day or longer no rattle on startup. ...as mentioned earlier, its just those hot or warm restarts that bug me.....I am using Mobil , might switch to Amsoil next time around and hopefully get that kit

I am not a mechanical engineer so my guess may be wrong. Having said that, from what you are saying, it seems, when oil is fully warmed up and engine start is initiated oil draining out of hydraulic tensioner is faster then the oil system pressure build up to feed the tensioner. Whereas, when the oil is cold (perhaps due to higher viscosity) oil is being held in the hydraulic tensioner longer and pressure build up is seemless.
I noticed that if I turn the key without starting 2-3 times (did it to intentionally to move the pulleys a bit) when I actually start chain rattle was severe which never happens on daily normal start. I concluded that when I ran the motor w/o starting oil in the tensiners were being drained and w/o actually running were not replenished w/ system pressure. Just my theory.

Roadster · 09-02-2014

Quote:

Originally Posted by spork2367

I've been using the white "Napa Gold" filters that are made by Wix and they have a great anti drain back valve. Zero rattle.

I also have a Mobil 1 filter, along with the Bosch oil filter to use in the future, but just might try the Napa Gold, like you have....

Quote:

Originally Posted by secondchance

I am not a mechanical engineer so my guess may be wrong. Having said that, from what you are saying, it seems, when oil is fully warmed up and engine start is initiated oil draining out of hydraulic tensioner is faster then the oil system pressure build up to feed the tensioner. Whereas, when the oil is cold (perhaps due to higher viscosity) oil is being held in the hydraulic tensioner longer and pressure build up is seemless.
I noticed that if I turn the key without starting 2-3 times (did it to intentionally to move the pulleys a bit) when I actually start chain rattle was severe which never happens on daily normal start. I concluded that when I ran the motor w/o starting oil in the tensiners were being drained and w/o actually running were not replenished w/ system pressure. Just my theory.

Either am I, but what you are saying makes sense to me. I have to go out soon and will take the Z to run my errands. Will report back later. The Z has sat for 2 days, so we shall see!!!

08-31-2014	#1
Roadster Join Date: Mar 2014 Location: Warrington PA Posts: 1,914	Can the LT5 experts fill me in on..... Ok, I think I have an idea why, but am not really sure, so can the LT5 experts who have the knowledge and understanding of this engine explain the following to me.... Why is it that if you let the Z sit for a week or even two weeks before you start the engine, that there is not any chain rattle upon first start-up??? I understand why there is chain rattle during some restarts, and that there is a kit available (which I have) that once installed, eliminates that problem or almost completely eliminates the problem. We had the Z out today, and first start-up, no noise, most restarts after that the dreaded chain rattle..... Just trying to learn more about the system......thanks for any info........ __________________ Tom 1994 ZR-1 #009 "captured test fleet car" 1974 LS4 454 Vert 1974 L-82 355 Vert. 1982 L83 CFI...now a retired "dd"....Sold WAZOO Member

08-31-2014	#2
We Gone Join Date: Apr 2004 Location: ATL. GA. Posts: 2,170	Re: Can the LT5 experts fill me in on..... No expert here but it sounds like you have a good check valve in your oil filter. I have no chain rattle on my 91 or 93 even if they set many weeks. Both have Blue GM filters. __________________ Steve 1990 Steel Blue/Black #2355 1990 Red/Red #1473 1991 Quasar /Black #118 Sold 1991 Turquoise/Black #766 Parted Out 1993 Yellow/White #179 Sold 1990 Black/Gray #1361 Headers/4:10s Sold

09-01-2014	#4
Jim Nolan Join Date: Jan 2007 Location: Florida Posts: 241	Re: Can the LT5 experts fill me in on..... Mine went away years ago after my second synthetic oil change. I use the blue PF970.

09-01-2014	#5
Kevin Join Date: Jun 2005 Location: pittsburgh Posts: 4,632	Re: Can the LT5 experts fill me in on..... chain rattle is annoying but not harmful. I don't even notice it anymore __________________ It's not the car, it's the people - Doug Johnson 90 r/r "KEYS ON" nick named "T.L.B"

09-01-2014	#6
Karl Join Date: May 2013 Location: Chicago Posts: 980	Re: Can the LT5 experts fill me in on..... I barely notice it and that is only if the car sits for a long time. Also the car starts quicker (or at least seems to) if I turn on the ignition first wait about 3 seconds then start. __________________ 1993 ZR-1 #211 Yellow On Beige Beast #2 1992 ZR-1 #427 Black On Black Sold 1985 L98 Blue On Blue Sold

09-02-2014	#8
spork2367 Join Date: Jun 2013 Location: PA Posts: 879	Re: Can the LT5 experts fill me in on..... I've been using the white "Napa Gold" filters that are made by Wix and they have a great anti drain back valve. Zero rattle.