Why does it sound like detonation when I start my car in the morning?

[fawcett]

Every time I start my car up after not running it for a while, say overnight, it starts up sounding like detonation. I dont know what to make of it, but after it gets going the loud banging noise goes away. Its like a really hard cold start.

My stock oil gauge has been on the far low side and I have straight 50w synthetic in it right now with an extra half a quart. I know this isnt the best but I over did it on purpose for FFW a few weeks a go. I also know that somepeople call the stock gauges dummie lights but considering its MY engine I wanted as much protection as I could get before I beat on it going down the 1320.

An oil change is happening this week, its getting cold here in Ma. so I'm going to some sort of synthetic 30w. How much of a difference is there between 5-30w and 10-30w? I am going to get some sick gauges asap so I can really see whats going on.

So whats the deal with the detonation/hard start? It doesnt do it after I drive it, shut it off (even if its for a few hours) and start it back up again.
I'm kind of worried this sounds expensive.

 

[Don 95Vert]

It's not detonation, that only occurs when there is a higher cylinder pressure. What you are hearing is most likely valve clatter because the lifters are not pumped up yet. Could also be piston slap or rod knock.

 

[rockin_rick]

I agree with Don. Perhaps if the culprit is bled down (drained) lifters, you may have a cheap oil filter that has a malfunctioning, poorly engineered, or cheap anti-drainback valve (Fram is one of the worst).

Rick

 

[HISSIN50]

The possibly bad ADBV idea from Rick is a very good thing to consider. It's easy enough to swap filters and see.

The 50 weight could exacerbate/extend the period of noise (I couldnt tell ya what the pour point is on a synthetic 50 weight however. I havent run it since I had a turbocharged Porsche).

Good luck.

 

[fawcett]

I hope its not the filter- Mobil 1's are pretty top notch right?
I'm doing a oil change sometime this week, I know my motors been beat on. I've kicked its ass since after its break in period.
Any other ideas? Any way to fix it? Sounds like its going to hurt my engine even more.
Thank You,
-Freddie Fawcett

 

[mo_dingo]

you may want to get a true oil gauge on it and make sure you are getting good pressure at startup. The stock gauge is crap.
Scott

 

[final5-0]

you may want to get a true oil gauge on it and make sure you are getting good pressure at startup. The stock gauge is crap.
Scott

Some more info on the stock gauge ... as I understand it.

It does not have the ability to show subtle changes in pressure.

I've seen some say it can't show a pretty fair amount of change as well.

Grady

 

[HISSIN50]

I hope its not the filter- Mobil 1's are pretty top notch right?
I'm doing a oil change sometime this week, I know my motors been beat on. I've kicked its ass since after its break in period.
Any other ideas? Any way to fix it? Sounds like its going to hurt my engine even more.
Thank You,
-Freddie Fawcett

I had a bud with that particular brand of filter (on his mod motor) and a filter change (to a Motorcraft/Purolator) reportedly fixed things. Not every filter is 100% perfect - you coulda just got the one bad one in a zillion, if that is indeed the issue.

In the scheme of costs involved regarding the noise, the 10 bucks for the filter aint much. Seal the filter up and if it wasnt the issue, use it again later.

Good luck.

 

[Don 95Vert]

The stock gauge is basically an idiot light - it registers as OK when you have pressure and way low when it's below like 5-10#. The incremental changes you may see or think you see mean nothing. A real oil pressure gauge works best and I've had best luck with mechanical gauges.