Engine knock after car has been sitting

[ninja771]

1991 Camry V6 with synth 5w-30 and oem oil filter.

I left it sitting (in somewhat cold temperatures, between 25-40 degrees F) for 8 days when I was on a trip.

When came back and started it up, it had pretty loud engine knock so I quickly turned it off, waited like 2 minutes then started it back up. The knock was still there for about 10-15 more seconds (though not as loud) then went away and the car continued to warm up and drove fine.

I've read about this on other forums about other cars and I believe it is due to the oil settling and not being in the engine after 8 days of sitting in freezing temperatures...but is there a way to fix this? I will be taking business trips and the Camry will be sitting at times during this winter and I dont want to put the old girl through this every time I return.

Any help is appreciated.

[Zembonez]

Most likely just valvetrain noise. Takes a few seconds for the oil to pump back up in the top of the engine. It happens when cars get cold and sit for a while. Very likely nothing to worry about.

[ninja771]

Originally Posted by Zembonez

Most likely just valvetrain noise. Takes a few seconds for the oil to pump back up in the top of the engine. It happens when cars get cold and sit for a while. Very likely nothing to worry about.

So it isnt bad for the car? Is there anything different i can do to stop it from settling?

[Zembonez]

Not really. It an old car with some wear (not knocking the car). It's rather normal actually. I'd only be concerned if it didn't go away!

Edit: My 97 Miata does the same thing if I let it sit for a week or two. Top end rattles for a few seconds and then everything is fine.

[71Corolla]

This is one thing I believe Lucas heavy duty oil stabilizer is good for. The stuff is incredibly sticky, and when cold it forms a film that doesn't go away. Try putting half a bottle or less of the stuff in and see if that cures your problem.

I'm not sure the valve train can make a loud knock though, these engines don't have solid lifters that depend on oil pressure, so if they are bone dry I'm not sure they would make much more noise than usual? Either way, give Lucas a try it won't hurt your engine, worst case is you will be out a few bucks.

[dem2757]

when they rebuilt your engine, did they use the old bottom end? did the rebore and use new pistons etc?

the reason why i ask is that my v6 has some piston slap in cold mornings. i just let it idle until it goes away and then i drive it like usual. Even the owners manual says to let the car sit for 5 minutes in 32 and lower temperatures.

Synthetic is great because it coats parts with more of a film than natural oil. The downside is that all oils get sludy with the cold. The mains are ALWAYS coated in oil however, so you should only be hearing top en noise.

[66conv6]

Synthetic oils don't get sludgy. At least in Alaska that's why they use Mobil 1. Also as far as I know synthetics don't stick when a car sits for long periods; i e top end. That's why they are so slippery and don't break down. Mobil 1 full synthetics for piston engine aircraft were discontinued due to camshaft wear on large bore engines that saw little use. (i e; sat around a lot.) Synthetics are fantastic for cars that get driven a lot especially taxis.

[dem2757]

i guess the word i was looking for was that they get more viscous as the temperature goes down. sludge is just when its filled with grime.

unfortunately gravity wins in the end and the top end is usually the loser. synthetics are thinner though, and will travel faster than natural oil. the difference is slight though.

[71Corolla]

I tried to find specific information that would point to the fact that a synthetic oil would drain away more readily versus conventional oil, but didn't find anything. I did find this though, which I thought was interesting.

To offset the higher cost of synthetic oil, some of the oil companies claim you can run the oil longer between changes. They say you do not have to change the oil every 3,000 miles. Valvoline does not make that claim. McClanahan says, "The additives in synthetics are superior but they still break down at the same rate and you need to replenish them often. We are unaware of any additive package that lasts longer than what the manufacturer recommends. Those 10,000-mile claims are ludicrous."
link

A whole bunch of other good info there as well regarding synthetic and conventional oils.

[66conv6]

Synthetics. Fantastic stuff. Been using it since the 1970's. Could tell many stories of saved engines because of them.

[Doctor J]

Could be the accessory belt noise