3100 V6 cold knock

[Bens71442]

1996 Cutlass Supreme, with 3100 V6 mpfi 101,000 miles.

I have let (what I thought) was a minor intake leak (coolant) go for about a year.

Noticed that low coolant light comes on more frequently than it had in the past, as of recently.....

This is the 2nd time I have had a cold engine knock after a highway trip, (engine sat overnight) started this morning and had a knock with low engine power! Knock was just like someone was inside that engine with a hammer, smackin away on the side of the block!

Knock went away after about 2.5 miles......during this drive, (me sweating and feeling sick to my stomach at the thought of destroying this engine) noticed power loss, NO engine lights on, {oil pressure light is NOT on} either??????

engine oil is CLEAR but underneath oil filler cap is a little bit of the yellow goo.

Have I let this engine coolant leak (which was external) go too long?

Have I destroyed my 3100 because I let the intake leak go for too long?

Why does the engine knock (go away) after the engine got hot?

Engine did not knock yesterday morning......drove it about 150 miles yesterday with NO knocks whatsoever.....

How do you check engine oil pressure on, a 1996 3100 motor?

Anyone have a (crate engine) available for sale?

Again engine oil shows NO signs of coolant contamination......but noticed external coolant leak has slowed or stopped, at this time. Oil PSI light is Not on, and has never flickered since I owned this car. Oil changed EVERY 3000 miles, running a Fram oil filter, long filter not short one? Can my upgrade to the longer PH 3495? (can't remember pt# now) filter be causing this?

[Bens71442]

3100 cold knock

Started this engine cold again today, same knock!!! The knock sounds high as in valve train.

Are there KNOWN issues with ageing 3100 in regards to sticking lifters. Driving the car with the " knock in progress " has trouble getting up to speed, power loss, sluggishness. NO service engine soon lights on Oil press light is OFF.

Very loud knock at valve train speed. Knock is not low end, it sound high in side the motor.

How common is it for a ageing 3100 to get a stuck lifter. Reason I am suspecting this is the missing the engine seems to exhibit and loss of power.

After engine is hot knock goes away, power is ok ?????

I am realy stuck on this one guys can anyone help me?

its in a 1996 Cutlass Supreme SL coupe. Just turned 100,000 miles, was on trip last night with NO problems whatsoever. Started this morning and again today very loud cold engine knock, at all rpms....

[Bens71442]

3100 cold knock

60 Degree V6er's

My dad and I cold started the Cutlass this evening, and he is 95% sure its a lifter not pumping up.

The knock still goes away engine hot. I've been running Valvoline 10W-30 since my purchase of the car 3 years ago at 58K miles......and when this happend 3000 miles ago for the first time, I added 1 qrt of Lucas oil stabilizer.

After I had installed the Lucas I never noticed the knock getting worse until now.

What can I run to clear whatever is plugging this stuck lifter?

Also, do the 1996 3100 engines have a roller lifter valve train ?

Help me out this latest problem with this car is really makeing me sweat bullets here!!

[prophiseer]

Anyways, almost all gen3 60* motors tend to be prone to piston slap, which usually sounds similar to an engine knock (some are loud, some are a bit quieter) which is more prominent when cold and will usually go away once the motor warms up. In some instances, when the motor continues to make these sounds warm, a thorough decarb can sometimes clear it up. GM has issued a few TSB's for different applications where they've attributed the noise to carbon build-up inside the cylinders. Anyways, piston slap isn't anything to worry about, and doesn't typically result in any damage to the block.

I have seen these motors blow the LIM gasket in such a way that coolant will lightly spray on the closest rocker when it's under pressure (but not a large enough amount to show in the oil as it's usually burnt out by the heat of the motor), and after the motor is turned off it effectively "washes" the said rocker and lifter and they scream after a cold start.

Also, I've seen quite a few 3100 motors that are prone to lifter noise also, usually it's really loud. I've noticed it more on the motors that go LONG periods of time between oil changes. If you replace the LIM gasket, make sure you use a shop vacuum to remove any large chunks of carbon that might be built up on the tops of the heads, in the valley, under the valve covers, etc. Look for any rockers or pushrods that look unusually dry, most of the time it's one of the rockers closest to the coolant veins. Also, cleaning the pushrods out with pipe cleaners and compressed air with ensure there are no carbon blocks in the pushrods (good test is to look through them). You can also "soak" the rockers in Lucas oil stabilizer or full synthetic oil, and after the work is done some kind of half synthetic/half conventional blend would really be beneficial. If the problem lifter still taps it's ass off, throw some Lucas in with the crankcase and run the motor until the noise goes away.

Also visually inspect the sides of the rockers, paying special attention to the needle rollers. I've had too incidents where a needle bearing has somehow "dislodged" and ended up in the oil pan, in which case, the rocker was making a horrible noise to go along with it.

But all things aside, these motors tend to be extremelly resilient to punishment, whether it's over heating, low oil and/or oil pressure, etc. they tend to bounce back and keep running.

[AWeb80]

IMHO, i'd get rid of the fram filter.

i'd go w/ Delco or WIX.

there are numerous tests that show fram sucks compared to other filters.

I don't understand people that buy cheap filters.....$1.50 compared to $5...is is the extra $3.50 really gonna break ya? I'd rather pay the extra 3.50 to make sure i've got a quality filter for my engine.

I'm not jumping on you, just making a statement.

[PCGUY112887]

Can ya get a recording of the sound? Usually you can tell between a "oh shit wtf" knock and typical piston slapping "damn this thing sounds like a mack truck" knock.

[DEI37]

I find this interesting about the power loss, and what not. My Lumina is miserable that way, with shitloads of knock...I've even got a thread in here about that. I'd hate to think I had bad lifters.

[ihatemygrandamg]

I have been leaking coolant from my gasket for a little while in my 3400, but Im fixing that very soon. Pretty much all 3x00's have a cold knock until warm oil starts flowing through the heads. Im not sure what kind of oil your using but Id suggest switching to something like mobil 1 or something.

Also maybe try running a can of seafoam to try and clear out some carbon buildup or anything like that. AND FIX THAT GASKET if its not already too late.
I have 131k on my 3400 and Im still modding

[bszopi]

I'm on my second 3x00 and I have never had a cold knock...

[PCGUY112887]

Even my moms 03 buick has the piston slap when it's cold.

[Tommy Boy]

This sounds like the problem I had. Mine sounded like lifter tick, was really loud. Sometimes went away, sometimes was there throughout my drive.

But what I did, maybe this will work for you, is I put in some Rislone oil additive. The knock went away completely and hasn't showed up since (2 months). Besides the normal valve train clatter, my engine runs great and is relatively quiet.