99 deville engine knock

[Akredneck]

I have a 99 deville with a engine knock i dont know what caused it for sure it has overheated once because of a crack in my coolant resivour and had low oil pressure light come on when knock started as i was driving down the interstate so i parked it added oil and still knocked so i changed oil and cleaned valve covers etc and it still knocks i dont know if it could be the headgasket problem or just something small. If anyone could help give advice or things to try it would be much appreciated as i do not know much about northstar engines thanks.

[Cadillac Jim]

Sometimes if you never drive on the highway, carbon can accumulate on the piston and cause a knock. The solution is a can of Techroline and, preferably, a 250-mile ride at highway speeds. The dealer can offer a solution in the shop but it's expensive.

There's something called the WOT treatment, otherwise known as an Italian tune-up, where you find a clear road with a 60 mph or higher speed limit and repeatedly accelerate from 20 mph to near redline in 2nd gear, then decelerate in 2nd gear (the deceleration part might not be necessary for carbon buildup and is hard on the pistons). I prefer a road trip because the scenery changes and a road trip is always fun in a Cadillac.

[rockfangd]

Welcome to Caddyinfo.

Does this sound like a top end knock or a low end knock?

I have yet to hear a northstar actually knock.

When you added oil how much did you have to add?

Would like to figure out if it has carbon tick, IE piston slap or if you have something more major going on

[Akredneck]

It sounds like more of a top end. I added about 4 quarts to it and it only brought it up to about half.

Welcome to Caddyinfo.

Does this sound like a top end knock or a low end knock?

I have yet to hear a northstar actually knock.

When you added oil how much did you have to add?

Would like to figure out if it has carbon tick, IE piston slap or if you have something more major going on

[rockfangd]

About half in the hatched area?

4 quarts should not hurt the engine.

The guru used to state that they could safely run with as low as 4 quarts,

the higher oil level is mainly to help any starvation possibilities on high G force turns and what not

[winterset]

Can you video the engine and try to get a good sound of the knock by moving closer to where you think the source. Rev the engine to about 1100 rpm, record for a minute, and post to youtube? We have had others post some sounds there.

[BodybyFisher]

It is possible that your oil has been trashed by overheating.

Change it and use Rotella 10W30 it is hard to find but worth the search. Your 99 has rubbing element lifters that cause significant oil shear, SN star burst oils have 800ppm zinc, Rotella has at least 1200ppm which is needed for our rubbing element engines and what the oils had in 1996.

If you can not find it, use an SN oil and add a pint of GM EOS (engine oil supplement) to boost the oils zinc level. You must protect those 32 lifters.

[Akredneck]

https://youtu.be/xnTljD0BZzU video of engine running hope to get some help thanks

[airmike]

i dont think it is oiling. does it have oil pressure?

[BodybyFisher]

I listened to the video. A few questions:

It overheated, the oil light came on and it began knocking? Correct?

How far did you drive with the oil light on? Did you drive highway speeds with the oil light on?

Is the oil light out now?

What viscosity oil are you using?

Are you using synthetic?

Does the engine idle rough?

[Akredneck]

I listened to the video. A few questions:

It overheated, the oil light came on and it began knocking? Correct?

How far did you drive with the oil light on? Did you drive highway speeds with the oil light on?

Is the oil light out now?

What viscosity oil are you using?

Are you using synthetic?

Does the engine idle rough?

Yes that is correct. I had to drive about 1/2 mile as i was comin off the interstate i was maybe goin 25 at most because it started losing power. Oil lights off now since i changed oil i run valeline high milege 10-30 synthetic in it and it doesnt really idle rough it just the ticking noise stays constant i havent ran it over 2 minutes so i dont know if itd go away as i dont wanna risk doing any further damage.

[BodybyFisher]

Did you see a message on the dash regarding LIMP MODE?

You said you added 4 quarts and you were only half way up the range on the dip stick, typically when the oil is that low you will get an add oil message, did you see an add oil message?

It sounded like the noise was coming from the front head or cam cover yes?

The engine knock you now have was spontaneous at highway speeds on the interstate, timed to the low oil that caused no oil pressure as signified by the oil pressure light. You continued to drive about a 1/2 mile at 25 mph with the oil pressure light on.

You had no oil pressure, your lifters no longer got oil pressure and collapsed its possible that you have one or more lifters that did not refill and that is causing the knock you hear. The collapsed lifters are probably why you lost power also. It is possible that one or more lifters have not refilled yet.

Change the oil, before running the engine again,

When you refill do not use synthetic, use either Rotella ot DelVac 10W30 diesel oil. Those oils have the zinc (an anti-wear compound ZDDP) that the NS needs of at least 1200 ppm whereas the current SN spec of oils have only 800 ppm of zddp. Stay away from synthetic oil with the 93 to 99 aging NorthStar due to synthetics known characteristic of superior flow. Because it flows 7 times better than mineral oil, it tends to reduce oil pressure. One thing you do not need is reduced oil pressure at the top of this engine with 32, 33mm lifters leaking oil. The tops of the lifters are lubricated via splash lubrication and you want the oil pressure that the designers intended using mineral oil that does not flow so easy thereby providing higher oil pressure and better splash lubrication to the lifter faces. The only time synthetic makes sense is extreme cold, like chicago in january where I have been in -15 degrees. But the manual specifies a drop to 5w30 in low temps but still mineral oil. See the owners manual.

The photo is of a lifter that has been dished, I bought a used NS head and it had two lifters that were dished worse than that. Maintaining oil pressure at the top of this engine is important.

Do not idle it long when you restart it, start it and begin driving it immediately, you want the splash lubrication to begin immediately and that wont happen at idle, given that you had no oil pressure the lifter tops or faces became dry and you want oil up there pronto. Drive the car at highway speeds where the RPM stays around 2000 rpm for at least 30 minutes. No need to beat on it, just constant speed for 30 minutes. That will provide optimum oil pressure to provide splash lubrication to the tops of the lifters and full oil pressure to refill any collapsed lifters. After the ride, see if the knock you hear is better. Let us know what happens. Good luck

[BodybyFisher]

I edited the above post a bunch of times and changed my thinking, read it again to make sure you see the final version, I see you are reading it now

[winterset]

When you turn the key to the run position (Prior to starting) is the oil icon on the dash iluminated red? It does sound like you are not getting oil to the upper engine or have any oil pressure. I am doubting your oil pressure sensor is picking up on that. In addition to the info provided above about the oil type, i have heard good things about motor honey working well for noisy lifters, and improving compression. I had a oil light flicker that was cured by adding a bottle 2 years ago, and i never saw it again.

[Cadillac Jim]

The oil light should go off when you start the car. If the oil light does not go off when you start the car cold, shut it off to prevent further damage.

[BodybyFisher]

The oil light should go off when you start the car. If the oil light does not go off when you start the car cold, shut it off to prevent further damage.

From original posters last post at 9:10 pm last night:

"Yes that is correct. I had to drive about 1/2 mile as i was comin off the interstate i was maybe goin 25 at most because it started losing power. Oil lights off now since i changed oil i run valeline high milege 10-30 synthetic in it and it doesnt really idle rough it just the ticking noise stays constant i havent ran it over 2 minutes so i dont know if itd go away as i dont wanna risk doing any further damage."

[Cadillac Jim]

Your point being that the problem of the light going off is past; thank you, I did read the thread. My point being that there may be engine damage.

[barczy01]

Spun rod bearing.

[BodybyFisher]

Spun rod bearing.

You really think so? No oil pressure for 30 seconds will do that? Have you seen spun rod bearings on tear down? He did not run the engine long since the no oil pressure issue and it appears to turn over easily, I am hoping he needs to get the lifters filled again, Thanks for your insight.

[rockfangd]

Just a quick question, Where can rotella 10w30 be found.

I found one but it is labeled synthetic blend 10w30. It was at Walmart. Is this sufficient to what is recommended?

thank you. End hijack

[BodybyFisher]

Just a quick question, Where can rotella 10w30 be found.

I found one but it is labeled synthetic blend 10w30. It was at Walmart. Is this sufficient to what is recommended?

thank you. End hijack

Not a hijack at all, its a good question I have a friend asking the same question. Walmart carries it but you may need to order it.

http://www.walmart.com/ip/Shell-Rotella-T-10W-30-Heavy-Duty-Diesel-Oil-1-gal./14958462

[KHE]

Just a quick question, Where can rotella 10w30 be found.

I found one but it is labeled synthetic blend 10w30. It was at Walmart. Is this sufficient to what is recommended?

thank you. End hijack

I buy Rotella 10W-30 at Menards but I don't think they have a presence in NY.

[Cadillac Jim]

Spun rod bearing.

A possibility, but don't assume the worst.

A Blackstone oil analysis will tell the tale.

[airmike]

"Yes that is correct. I had to drive about 1/2 mile as i was comin off the interstate i was maybe goin 25 at most because it started losing power. Oil lights off now since i changed oil i run valeline high milege 10-30 synthetic in it and it doesnt really idle rough it just the ticking noise stays constant i havent ran it over 2 minutes so i dont know if itd go away as i dont wanna risk doing any further damage"

After listening to the video, I would think the rod is likely myself. There is way more than a tick going on there. My youngest daughter let her car get 4 quarts low and when I started it I heard all those crickets chirping. I filled it with oil and all was good, so i don't think the fact that it was 4 quarts means the engine is necessarily hurt. The video sounds way worse than ticks. Multiple ticks/clatters but also a solid knock. Has anyone on this forum heard an engine sound that bad and recover? He drove it 1/2 mile and it was losing power. That would indicate something seizing up to me. Way longer than 30 seconds. Since the pan can't be removed in the car, I would either send an oil sample off or just pull it if it was mine.

[BodybyFisher]

Interesting airmike. I hope its not that serious. It does take more than 30 sec to drive a half mile at 25. I am curious if the engine turns over freely or if its dragging.