i have a 99 tahoe with 84k miles 5.7 engine that i just bought from an older couple that were the original owners. yesterday i started and it started knocking hard at the top of the motor. so i changed the oil added lucus oil to. it still knocked for about 3 mins then went away what can i do to fix this problem
cold start
- Thread starter katamdust
- Start date
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clkelley
Moderator
First of all don't put lucas in it. If the oil isn't good enough, adding those types of additives only mask the real issue. A better full synthetic oil would help a LOT. The reason for the cold start is that most oils out there do not cling to the valves good enough to protect them during cold start before the oil has cycled through the engine. Of course I recommend Amsoil, I run it, and have run it in every vehicle I have owned now for almost 9 years and never had an issue with cold start knocking.
Another option is to install a Pre-Oiler Kit similar to this one http://www.autoenginelube.com/
Doing so will allow the oil to be pumped through the valve train before starting the engine eliminating the dry cold start you are experiencing.
Hope this helps.
Another option is to install a Pre-Oiler Kit similar to this one http://www.autoenginelube.com/
Doing so will allow the oil to be pumped through the valve train before starting the engine eliminating the dry cold start you are experiencing.
Hope this helps.
I have this same issue with my 2002 5.3 and was told by several sources that this is normal due to the aluminum pistons contracting when cold. Once you start the truck and it runs for about a minute the pistons expand and the slap stops. If this is incorrect info please let me know so I can research a fix for it.
clkelley
Moderator
This is not normal due to the pistons contracting. This is a known issue, yes. But it is not because of the pistons. It is lifter slap that you are hearing. The reason it goes away after 30 seconds to a minute is because that is how long it normally takes for the oil pump to begin getting oil to the lifters.
clkelley
Moderator
Yes Sir, that would be the best choice to solve the issue.
clkelley
Moderator
Sorry for the short answer there, installing the preoiler will ensure that you no longer have "Dry" starts. By pumping the oil to the valve train before starting, you are prolonging the life of the valves and lifters as well.
clkelley
Moderator
AMSOIL use to offer a GREAT preoiler, but they discontinued it for lack of sales. Funny thing is, I wish I had been sponsoring the Tahoe forum when they had them, I am confident they wouldn't have discontinued it if people just knew about them and what they do for the vehicles.
clkelley
Moderator
Oh, believe me, I am as pissed about it as you are. Tell you what, send me a private message here on the forum with your vehicle details and I will contact them personally this afternoon and find out if they have any more sitting in the warehouse. I might just take them all off their hands...
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