Can Engine Run Well w/o SC Engaged?

[Spector]

GM 3800 Series II with Eaton MP90 SC on a 2000 Buick Regal. The SC appears to be going bad, will know results of diagnostics from dealer on Mon. A high pitched whine that gets louder as RPMs increase etc. Yes, SC do whistle but I have had this car a while, definitely a huge increase in the whine/whistle level. Also a check engine light that appears to be the Mass Air Flow Sensor. Not sure the two are connected as the whine started weeks before the light came on.

Anyway, question is, due to the cost of replacement can this engine function perfectly fine with a shorter drive belt and not engage the SC pulley ( actually not sure if the belt drives more then just the SC) if just the SC can the engine run fine without that belt and or a shorter one?

I would lose 40HP but I can live with that. Does anyone know if this is feasible? A rebuilt or used is a possibility as well but will it run fine without the pulley engaged.

thanks

 

[NHGUY]

I would think the SC would be a huge restriction to the airflow of the engine.That and the SC engine should be lower compression ratio than a regular 3800 (??),so that would mean a far weaker engine than a regular 3800 that didnt come with a SC to begin with.
There are a number of online sources that sell rebuilt 3800 SC units.

 

[55Test]

Surely it couldn't be all that hard to find a decent junkyard engine and pull the S/C off of it? Have you checked car-part.com?

 

[GMBoy]

They are all over ebay:

http://www.ebay.com/itm/3800-EATON-M90-S...1#ht_528wt_1396


http://www.ebay.com/itm/98-05-PONTIAC-BU...1#ht_910wt_1163


Priced from $200 on up to brand new for $1300

 

[sciphi]

A new nosedrive should set that whine back in place. Likely the whole supercharger doesn't need replacing.

And, it won't run fine without the SC spinning. The SC does drive air into the engine even when it's not providing positive pressure.

pontiacbonnevilleclub is a great 3800 resource. Also clubgp for W-body questions both engine and chassis.

 

[440Magnum]

An engine with a roots-type supercharger won't run without the supercharger turning and turning at the right speed. If its stopped it blocks the intake.

A centrifugal supercharger like a Paxton or McCulloch blower doesn't block airflow and so the engine can run at reduced power without the blower spinning.

 

[Drew99GT]

It might work if you were to permanently open the bypass valve in the blower, but even that wouldn't allow much airflow at higher rpms and wide open throttle.

Best bet is to get a new blower.

 

[MrCritical]

It will run far worse than the non supercharged one. Your chance of getting a good supercharger from a wrecking yard is well...not so good.

 

[sciphi]

It's likely not the whole blower that's bad. Probably the rotors are fine. My money is that the nosedrive is shot, and he needs only a new nosedrive. That can be replaced by itself for far less than the whole SC.

 

[teambeechstreet]

SC rebuild could be anywhere from $300-$1500. I was quoted about $700 to have the nose rebuilt (this included shipping both ways).

 

[artificialist]

In order to get your car to work without a supercharger, you would need to remove your entire intake manifold, and swap in one from a NA 3800 V6, and you would need your engine computer reprogrammed custom because several other items in the 3800 are different between the SC and NA version.

You would be better off seeing what a W-body specialist can do for your blower to repair it.

 

[Spector]

As it turns out the pulley was causing the whining noise so not too bad of an expense, 170 with labor. On the other note the check engine light was off when they took it in but the history did show a mass air flow sensor. So wait and see, they said to replace it if it comes back on but I thought they just cleaned this most of the time?

 

[01rangerxl]

Originally Posted By: Spector
So wait and see, they said to replace it if it comes back on but I thought they just cleaned this most of the time?


It depends. A lot of times a MAF sensor can be brought back to life with just a cleaning, but if there is the slightest bit of damage to the hot wire you're looking at a new MAF sensor. Most chain auto parts stores sell a MAF sensor cleaner from CRC that's around $5 or so. It is very important that only the cleaning chemical comes into contact with the hot wire...do not try to wipe it clean with q-tips or anything like that.

 

[Trav]

The intake is different. The SC injectors go in the head and on the non SC they go in the intake. The fuel rails and injectors themselves are different also.
basically it would need a non SC top end and a reprogrammed or non sc ecm.

Originally Posted By: spector
but the history did show a mass air flow sensor.

MAF sensors cause lots of problems with these engines, never use a rebuilt unit no matter who make it.
Use an OEM MAF on these things, i have had 3 bad ones in a row one time, two rebuilt units from Standard and a new cardone. The new GM unit cured the problem right away.

 

[sciphi]

If it needs a MAF, go search a junkyard for a numbers-matching one off of another 3800-powered car. It'll be better than the rebuilt.

 

[saberz]

You add/change the supercharger oil(yes it uses oil, separate from what you put in the engine, and it smells horrible). GM sold the supercharger oil in small tubes/vials. Friend used to do it once or twice a year on his car pending how many trips he took(97 GTP). Not many people know about it, and not sure if they kept it the same through the years.

Just suggesting.

 

[dailydriver]

Originally Posted By: Anies
You add/change the supercharger oil(yes it uses oil, separate from what you put in the engine, and it smells horrible). GM sold the supercharger oil in small tubes/vials. Friend used to do it once or twice a year on his car pending how many trips he took(97 GTP). Not many people know about it, and not sure if they kept it the same through the years.

Just suggesting.


Yup, it's the same putrid, bad-cheesy smelling stuff that was used in the T-Bird SC's Eaton nosedrive, and I changed it out once a year.