So I have an '86 n/a automatic with low miles. It has been sitting for quite a long time and I just started to work on it again. The engine ran perfectly before it sat. I started it up for the first time since it started sitting and I am getting a pretty loud knocking of sorts, almost more of a loud ticking from the head . I have had it running twice for only a minute or two. I changed the oil and still get the noise. I know I should have changed the oil first before starting it but I didn't even think about it... Is this most likely lifter noise? And if so what can I do to cure it? What type/weight of oil is best for this sort of thing?

 

totally possible it's lifter noise. or it could just be the injectors. they're pretty loud too. 20w50. what brand of snakeoil...that's up to u. i've used castrol and mobil among the commonly avail brands.

 

let it run and the lifters will pump up.

 

AT IDLE.

It's entirely possible for the noise to go on for 15 or 20 minutes if they are bone dry. After having my top end apart and not keeping the lifters in oil, it took a good 10 minutes (they were out for 3 months or so).

 

i have had a couple that would not shut up even after alot of idling and going for a drive. One good stab at the throttle and they shut up. The little tiny oil ports that allow the oil into the lifters sometimes make it hard for the lifters to pump up w/o some oil pressure.

 

Good point. I've had old pushrod V8s do that as well after rebuilds.

That's not going to hurt anything unless you're trying to drive it around before it stops, which is what I probably should have said.

 

Thanks guys i appreciate it. I am pretty certain it is not injectors because of the type of noise it is. I'm guessing since it sat for so long that the lifters are more than likely dry. I have heard that marvel mystery oil helps? Can anyone attest to that? I am going to let it run for 10 or 15 minutes and see if that clears them up. Why is 20w 50 the way to go? I have read a bunch of threads about oil types and I have noticed that a lot of people say a lot of different weights like 10w 50, 10w 30, 20w 50 etc. I have just always wondered what is actually the Correct one to use (in the mid west, so we both hot and cold weather extremes...)

 

It isn't "the way to go", if you want my opinion. All of this depends on what shape your oil pump and bearings are in. You want to have sufficient oil pressure, but not excessive (if you're hitting the pressure relief valve at 2k RPMs when hot, you have too much pressure and aren't flowing enough volume to lubricate properly).

I think the type of oil is as important - the things making noise are flat tappets. Most cars don't have them anymore, and the additive that keeps them from galling is ZDDP, which can cause emissions issues and cat damage on newer cars. So it's getting hard to find oils that have sufficient amounts.

I've been running Rotella 15w-40 in both my 944 (I have more than sufficient hot oil pressure even in the summer on this, but your experience may be different depending on your motor) and my Rover (also flat tappet) for years. It is easy to find, had a reasonable ZDDP content (it was recently lowered, but there is still a reasonable amount in there) and had a lot of detergents (it's speced as a diesel oil as well).

If you're partial to some other brand of oil and it doesn't have enough ZDDP, you can use any of a number of common ZDDP additive packages to correct that. GM EOS is one of the popular ones but has been getting harder and harder to find.

Bottom line: if you have 1-2 bars of oil pressure at hot idle, aren't topping out at 5 bars before 4000 RPMs, and change it regularly you'll be fine. Bonus points for ZDDP content if you can get it.

Cue the inevitable oil holy war.

 

I'd go with the numbers in the manual for the temperature ranges that dictate the lower number oil to use. Here in florida, I always go with 20W50. For the lifter problem, keep in mind that when you're idling the engine, the oil pressure is low also. I'd run the engine at idle till up to normal operating temp and then run the rpm's up to where the oil is around 4 bar. That should then run the warmed up oil into those little ports on the lifters. Keeping it at idle with the low oil pressure will take a lot longer to cure the noise.

 

So 10w 30 is probably not the best way to go at this point in time? I have some lucas additive sitting around in my garage, could that help at all?...I might just head to autozone and see what kinds of additives they have with ZDDP in them. So I just started it up again and let it run for maybe 5 minutes. Noise never went away but I did just find out that my oil pressure sending unit is bad...gauge is tapped out all the way up...fantastic, its always something isn't it? I guess I will have to get that replaced to be able to accurately determine what is going on with my oil and what pressure it is running at. I just did an oil change with roughly 6.5 quarts. It had been awhile since I had done an oil change on a 944 since I sold my 87 and obviously had touched this one in awhile...ha. I would what the trans oil is like after sitting for that long...the cars and automatic with 60,000 miles.

 

I run 20w50 year round with temps in winter being no lower than the teens. The "oil cooler" heats the oil up quickly in cool/cold weather, so worries about it being too thick like with most engines are not a big concern. If it goes to 20 below, then you can use something lower to spare your starter.

 

I run 10w-40 in the severe of winter, and 20w-50 in the summer. Get a high zinc oil (this is most of the diesel oils, motorcycle oils, VR1 Valvoline, Royal Purple etc). I've also run 15w-40 (common diesel weight) with no problems. 944's and 928's really like the thicker oils.

 

Current spec Diesel oils no longer have the high ZDDP formulation, you need to get "legacy" diesel oils, which NAPA and farm/fleet stores carry.

 

Update: Did some more work on it today and started it up again. Lifters were loud again so I let it run for a good 15 minutes with the last minute or so at 2500 rpm and what do you know! It suddenly completely quited down and ran like it was new! So I checked the trans fluid level, all the lights, brakes, and suspension work I did a few months back, then took it for a quick spin for the first time in 3 years! I can not believe how well it ran. The trans shifted perfectly the engine revved completely smoothly and the steering and ride were superb. These cars are truly amazing. Now to find a buyer for this gem... Thanks to all you guys for your input in this thread. I do really appreciate it!

Cheers,
Spencer