2001 Cad Deville - Engine Noise

[protraxrptr17]

Customer complaint of an intermittent noise from right front wheelwell.

He brought the car by last week and I did a quick walk around and heard a real faint tapping. I was real busy so I made him an appointment for a few days later. I got the car now and I can hear a real faint noise that sounds like maybe piston noise. I can hear it better if I am standing about ten feet from the car. Every once in a while the light tapping comes back for just a couple seconds.

Theres a TSB on replacing the pistons Any suggestions?

[Tim Martin]

I am assuming that you got a 4.6L engine. Yes, they did have some piston issues and from what you are describing it could be, and I stress, it could be piston related. It could also be timing chain related. You may end up doing exploratory surgery before you find the source of the noise.

[steven kiser]

how many miles on this mill? if it's a lot the customer should be made aware that this may become a nightmare. if a butterfly flutters is wings in africa.............................. a call to jasper may be in line.

[protraxrptr17]

Its right around 100K. Its a really nice car. Inside of the engine is really clean. I hate chasing noises.

[Tim Martin]

[quote="protraxrptr17"I hate chasing noises.[/quote]
Can't say that I do either. That's why I have this electronic ears stethescope that has halped me in many situations. Noise can travel but this thing will get you real close to the source of the noise. I got mine from the MAC tool truck but I expect that other brands also carry something similar.

[a&mauto]

I have a customer with an 02 DeVille with only 40k on it. We ran some SeaFoam thru the injectors and some in the tank and the noise went right away. We had suspected carbon and got lucky. 40k was too early to have something major. 100k might be a different story.

[steven kiser]

Its right around 100K. Its a really nice car. Inside of the engine is really clean. I hate chasing noises.

at 100k i would put some thought into this. would also make the customer part of it. these mills, when they're running right are top notch. my experience is when they start the down hill slide it's a train wreck. i try not to be a conductor on this train. i make my customer aware of once we start on this road it's going to be long and expensive. if this car is a treasure it will be beneficial for the customer to bite the bullet and replace it now. the other choice is that this noise may not get any worse and a change of oil viscosity will make a difference.

[protraxrptr17]

I did the seafoam thing but I let it suck straight out of the bottle thru a vacuum hose. It smoked something fierce, so it had to have cleaned something out of somewhere. I told him to go try it. He hasnt picked the car up yet, so I cant label this one fixed just yet.

[Goose]

I have seen throttle body gaskets leak and caused a lean condition that has caused a knock.

[steven kiser]

i agree with the vac leak causing a lean pop but i think in this case there would be a huge drive ability issue. i'm thinking that the carbon cleaning may have solved the issue.

[MarionB2BAuto]

I know this is lateafter the original post, but I worked for Cadillac for 10 years and this was actually a very common issue on the Northstar engine. The biggest problem is locating the location of the ticking. Carbon build up on the pistons was VERY common, as was piston slap and lifter noise(the lifters on this engine are actually upside down) The decarbon, as you have done is a great way to help clean up the faces of the pistons. It is also a very inexpensive way to atleast TRY to correct a noise. GM has a product called "EOS" for engine oil supliment, that we added to oil changes. This additive help REDUCE piston slap, and pretty much eliminated lifter noise. I hope this is acceptable to post here, but theG part number for the EOS is 1052367. Remember that when chasing down ANY noise, be it engine, transmission, suspension, etc., letting the customer know in ADVANCE of the difficulty and time involved in locating and/or correcting noises is high, will go a long way. Customers like to be kept in the loop. My service writer knows that she is to call EVERY customer with an open RO each day to touch bases and let them know the status of their vehicle.
I will offer this: If anyone has problems with a GM vehicle, I would be happy to provide my experience and knowledge. I may not always be able to come up with the answer, but I will try. I like this forum, where shop owners and technicians even, can talk shop!