I have a 93 Allaqnte with 10K miles on it with a noise in the engine on cold starts. Sounds like a lifter and lasts about 3-4 minutes. The Cad. dealer in little rock told me I would have to change the Pistons, rings and llifters. I then got a 2nd opinion in Idaho Falls and they said the same so I went a head. Noise is still present. Any one have any suggestions? The car sat for about 11 years.

 

Some startup noise is normal for the northstar.
They have covered the known issues for a cold start noise.
It's possible they installed a new part that is the problem.
Diaging a noise over the net is tough and even more so when the best solutions have been covered.
A noise that only lasts 3-4 minutes could be very troublesome even with a complete engine teardown.

My suggestion:
If the car is no better than the day you brought it in for repair,
leave the car at the dealer and tell them you have paid to have a specific concern corrected.
It has not been repaired yet. Please repair the concern i paid to have corrected or refund my money.
The service director can handle this issue.
The dealers GM would be the next person to talk to, then the owner.


P.S. Ever try using synthetic oil?

 

Maybe try out an Italian Tune up? And toss a bottle of good injector cleaner in there? (IE Gunmount Regane (the clear looking one) or Chevron Techron (the expensive one))







Make sure to do it on a HOT engine (not when your coolant gauge reaches the middle, that just means the coolant is hot, not the oil) make sure its been running 15+minutes, you can down shift too to keep the revs up (pull the tranny down to the gear you want before it shifts to a higher one, downshifting an auto isnt the best thing to do) and run it hard for a few minutes, obviously if your car is falling apart i wouldnt reccomend this, so be careful, but it can have great results.
Heres what the cadillac forums guys reccomend for N* owners, but it works on any engine:

"There are many advantages to occasional full throttle accelerations with a Northstar and any engine.

It keeps the carbon cleaned out of the combustion chamber. This is maybe a little more important with the Northstar than some other engines due to the tight squish volumes between the piston and the cylinder head. It's designed this way to promote good in-cylinder mixture motion (good combustion) but it has the down side of providing a ready place for carbon build-up to touch the piston - causing noise. Ever heard of the Northstar "cold carbon rap" problem?? Simply put you'll hear a rythmic, piston slap-like noise when the engine is cold. Very prominent and very annoying. Cause: excessive carbon build up causing the the piston to contact the carbon on the head - causing it to rock in the bore and "slap" Much more evident when the engine is cold and the pistons haven't expanded to full diameter yet. Simplest and easiest "fix" for this: A few good WOT (wide open throttle) accelerations to clear the carbon out. That is all it takes to eliminate the problem and prevent it from re-occurring.

Occasional WOT accelerations also help seat the rings to the ring lands and exercise the rings and keep them mobile and from becoming stuck in carbon in the ring lands. At high RPM and WOT the rings move around on the piston - they actually rotate on the piston and will polish away any carbon and seat themselves to the sides of the ring grooves. This is especially important on the 2000 and later Northstars which had hard anodized top ring lands on the pistons. Very hard and wear resistant - also harder to break-in and seat the rings to the sides of the ring-lands to promote the best possible seal. Many oil consumption complaints on the 2000 and later engines are related, to some extent, with the rings never seating to the sides of the ring-grooves due to lack of load as the engine was babied around forever. Even engines with rings stuck in the ring-grooves due to carbon build up can eventually be freed up with enough high RPM operation.

WOTs warm up the engine thoroughly and clean out the exhaust due to temperature in the exhaust and high flow rates blasting particles, rust and such out of the system.

Frequent WOT operation will not hurt the engine or the transmission. They're designed for that. The healthiest engines that I have seen at high miles are always the ones that are run the hardest. Rings are free on the pistons and sealing; no carbon buildup.

The exercise that I think works best for many things is to select manual 2nd gear on an isolated stretch of expressway. This takes the transmission shifting out of the question if you are worried about hurting it. Start at 55 MPH or so and go to WOT in 2nd gear and hold it until the RPM reaches near the normal shift point - i.e. 6500 for an L37 and 6000 for an LD8. Hold the throttle wide open until the engine reaches, say, 6200 for an STS and then just let completely off the throttle. Leave the transmission in 2nd so that the engine brakes the car and creates some pretty heavy over-run conditions at high vacuum levels. Let it slow until it is about 55 or so and then go to WOT again and repeat. This exercise really loads the rings, allows variable RPM operation at WOT for several seconds continuously, creates heavy over-run which tends to unload the rings and make them move and thus exercise them in the ring grooves and it will blow-out carbon and the exhaust - all without creating a spectical of yourself and attracting the attention of cops. You can do it on most any freeway and stay within the 70-75 MPH range allowable. Once a week like this will keep the engine cleaned out and healthy and is DEFINITELY recommended for the Northstar in particular.

The Northstar engine was designed/developed/validated to be run hard. It was expected that people would use the performance of the engine - which few people seem to do. The biggest single problem that many issues stem from is lack of use at full throttle by the owners. It just doesn't like to be babied around. The rings are low-tension by design for good high RPM operating characteristics and low friction/good power. They work best if "used" and kept free.

In every conversation with owners I have had, once the owner started doing the WOTs and using the power of the engine they report no more carbon rap, better oil economy, no "smoke" when they do light it up (keep the exhaust cleaned out. If you notice a "cloud" at WOT then you are not doing enough WOTs...) etc... A bit of judicious use of the other end of the throttle travel is a GOOD thing..."




original author KC

 

We had the same thing with a 93 with 14k on it.. We change the oil with moble 1.
No more noise..
johnny
www.CadillacAllanteClub.com

 

gummy deposits on a garage queen?

 

I was also thinking that this was an oiling problem, especially because it only last for a few minutes. In cold climates this is a common problem so we go to a low viscocity oil and do frequent oil changes. In an engine that is not used much all the oil is allowed to drain down into the pan so it takes a while to circulate up through the motor and into the valve train etc...Hard to believe the dealer even suggested changing pistons on a 10K car imo.

 

i received a email from D.Hussey (www.allantesource.com) that concurs
with some of the postings above.
i will let him post the rest when he is able to do so.
"A lot of'93's do that after they have been sitting for a while .... "

 

With the vin # we can determine whether it's an early 93 (oil leak) or later 93 N*. My 93 in Pa. can go a while without being started, but after the first crank I don't hear anything. Also remember my engine was replaced under warranty in 2k, that could make a difference.