I took in my car to a MB Indy to do the following:

1. Change Engine cover gaskets which had been leaking for sometime.
2. Install new spark plugs
3. Install new air filter
4. Flush SBC
5. Install Akebono dust free pads, front and back

He told me engine cover was very dirty with a lot of build up inside and so were the 1" hoses on top, were also brittle, which he changed.

As I drove car and came to first stop sign, I felt car was shaking lightly. I put in it neutral and same thing happened. I assumed that a vacuum hose was loose or possibly he had not tightened a spark plug. So, I called him and he had me drive back to the shop. He was able to duplicate the problem. He hooked it up to STAR, but all looked fine. He then removed engine air filters cover and squeezed one of the new hoses he had just replaced, this caused car to run very smoothly, but as soon as he let go, a slight rattle would come back.

He told me that because of the work done, car is "breathing" differently, but that car's computer had previously compensated for what was clogging good air flow. He added computer should make up for this change in air flow in about a couple of weeks.

Your feedback would be appreciated.

 

EGR valve clogged maybe??? Or something went wrong when changing spark plugs. Make sure both hoses on, 2 left and 1 right, valve covers are going to the correct locations-especially the big one that goes to the Mass Air flow sensor on the left valve cover when sitting in the car. Make sure the vacuum line coming from the purge valve is all the way seated behind the intake manifold in front of the mass air flow sensor. If he re-traces his steps he should be able to decipher where he went wrong. If it was running fine before, valve cover re-seal-spark plugs-and engine air filter replacement, these things should not cause running characteristics to change....

Does it rattle at idle or under a load?

 

At idle too.

 

Sorry, I don't buy it. If the car previously had a defect, it would have shown a failure code. Even if it did, fixing things that were wrong should result in the engine running properly if nothing else is wrong.


Might be time for a second opinion.

 

Post a video, clear one if possible, of this rattle.

What sucks is everything you just paid this clown to do, is DIY and quite simple. Even if you have amateur mechanic skills.

 

The rattle is not that strong that it could be seen on a video, but it's certainly felt when you're inside car.

No, I could not have done cover gaskets or change plugs. My skill level is limited, but hey, I did change the air filters myself

I'm gonna give that mechanic another week just to prove his theory is full of nothing but hot air, and I'll go back and demand that he fix what he did. Car was nice and smooth before I took it in.

 

If you can change air filters you can do spark plugs-and use a silicone gun. Same concept different idea. Take pictures before you take stuff apart. Anyways, make sure he installed all your plug wires correctly. If you have a 112 or 113 motor which i'm assuming you do due to the leaking valve covers, the bottom wire on each coil pack starting at the rear of the motor goes in the spark plug port closest to the firewall. So if you are looking at the engine from the front, take each bottom wire of the rearward most coil pack, near firewall, and put the bottom wire in the first port-then the top wire in the next port-next coil pack-bottom wire first, then top and so on until you have installed your last wire, which would be the top wire on the frontward most coil pack.

The only things that he did that could change running characteristics if all he did was what you told him to do, is, spark plug repair gone wrong some where, or a breather tube or vacuum line leaking/not installed correctly.

If this genius has DAS or HHT- he should look at smooth running characteristics.... That might be a little too tough for this fella though!

Don't give him another week as he wont spend any time on it till the last day of the week and hit you with the, Stealership remark.....

 

Thanks for the feedback and brief tutorial. I'm giving mechanic a week so as to show him that car computer did not reset itself, as he claimed.

 

Believe It Or Not, Problem Discovered!

This is an update to engine rattling after repairs. Per mechanic's recommendations, I waited 2 weeks to see if car's computer would compensate for new changes with "increased air flow." It did not happen. I went back to him and he decided to restrict air flow in one of the crankcase hoses. It did not work. He ran another scan using a large hand-held device and results showed cylinder #4 was operating at lower voltage. He then suggested that I change spark plug wires, and said it would cost me $40/piece. I declined, but went and bought an entire set for $90. A couple of days ago, I installed the 12 wires. That did not resolve the problem. I called him today, and he suggested changing coil pack#4, as it was associated with cylinder #4.

Earlier tonight, I decided to reinspect the plug wires I had installed a couple of days ago. As I tried to feel how tight and snug spark plug wires were, I noticed spark plug wire on driver side nearest to radiator, would that be #7, was not that nice and snug. So, I pulled out wire, and decided to test spark plug using old wires, thinking probably spark plug head was damaged some how. As I tested old wires, there continued to be some play. I then decided to remove spark plug and inspect it. As I deployed 5/8 spark plug socket, it would not engage properly, and when I pulled it out, I found half of the spark plug stuck in the socket's rubber. I then realized that was a broken spark plug inside the engine block. After releasing the half stuck in the 5/8 rubber part, I proceeded to remove the other half stuck inside engine block. Luckily it came off without trouble. Now, I had a spark plug that was broken in 2. I took it down to a local auto parts store and bought a new one. The parts guy told me mechanic had over torqued that spark plug, the reason it got compromised.

I came back home and installed new spark plug. Car was tested and all is smooth and sound. Tomorrow, I'm calling mechanic and requesting compensation for all my headache and expenses.

 

I think I should call my doctor and ask him for compensation for all fever I had after he had prescribe me wrong antibiotic.
Good to hear the car is running well without big investment.
Thinking about it, I had similar issue with first generation of Bosch Platinum about 20 years ago.