Ok so my car is making noise when I start it. About half the time hot or cold it "bangs", basically sounds like someone took between 1 and 3 marbles and dropped them on top of the engine. Quiets down immediately after this initial noise. I am fairly certain it is the supercharger. I took off the belt and started it 5 times in a row without the sound. I am going to do it a few more times to confirm.

As far as the snout goes there was a little bit of play in the pulley a month ago when I changed the belt, now that play is doubled - probably a quarter inch play at the edge (diameter) of the pulley. Given this I am pretty certain the snount needs a rebuild. However the banging noise seems to come from the other end of the engine making me wonder if the roller bearing are bad too (or perhaps my ears are bad and I am imagining it is coming from the back of the engine).

I am an engineer by trade with a ton of tools and a lot of mechanical knowlege so I am not intimidated but this is my first time dealing with a supercharger. So a few questions:

1. I obviously need to take off the thermostat housing, if I do that and move the cooling hoses aside can I get the snout off without taking the whole supercharger or intercooler out?

2. Is the "banging" consistent with a snout issue or does it indicate a roller bearing problem or the rotors hitting the case?

3. From looking online rebuilding the snout rebuild looks pretty straightforward and I have all the tools I would need for that. However there is almost nothing online about replacing the rotors and roller bearings. Has anyone done this? Do the rotors have to be sized/fitted in any fashion? Is there any literature or rebuild manual available (I have not found one)?

4. It looks like the pulley is coming off no matter what. I am thinking of replacing it with a smaller one from Eurotoys or somewhere to get a little more power. Is this worth it with no tuning or intercooler mods? Also I will be doing the primary timing tensioners in the winter (secondary already done), would it be better to just wait and get a larger crank pulley instead? I probably don't need/want both replaced.

Any other recommendations? I am not adverse to speding a bit for better performance in the process but I don't want a new tune nor to spend more than $1k total on this.

Thanks for any help.

 

When you replace the pulley you have to do a hard reset on the ECU but that's it. It will run hotter but short of a Chiller Killer there really isn't much I've found that works well. I've done the intake relocation and the larger front heat exchanger/radiator but I don't think either change is worth the effort. If had to do it over again I'd have just done a Chiller Killer or water injection and called it a day (I understand if you do both you can have an ice problem). The pulley does noticeably improve your power at lower RPMs. You do have to trim the snout if you want the smallest pulley which is what I did. There is an outfit that will rebuild the supercharger with lower gearing (Snake Bite) but you have to send them the supercharger and I was never able to find a cheap spare that I could use for this or I likely would have gone that route because they also improve the oil cooling for the bearings. You have a 4.0 engine so you can also do the lower pulley (I understand the 4.2 already has a larger lower pulley stock so it isn't worth it on my car). Stiegemeier Porting Service » SnakeBite Kit

 

The play might be the coupler, which can wear out and get sloppy.

1) I have not done it, but the snout is integrated with the front cover so I think you will have to take the supercharger out to get at the snout.

The charge coolers stay on, but the intake elbow has to come off and the S/C slides out the front. IMHO this is a lot easier to do with the bonnet off so you can stand in front of the car.

2) The marbles sort of noise you describe is more consistent with the rear bearings that the front.

3) It's a bit of a specialist job as I understand, as you there are setup tools and you have to get the lobs of the rotors fit together the right way. I imagine it's similar to installing a camshaft, but I've never seen any documentation on how to do it properly.

If it comes down to having the blower off for repair, I would go ahead and get it ported and have the pulley installed on the bench.