This "winter" in Ohio I have had the pleasure of putting on Long Tube headers and getting to do a few pulls to attempt to tune it. While doing so I noticed a sort of "grinding" noise coming from the rear end of the Vette. This occurred when turning the steering wheel Counterclockwise while in the throttle, when I would coast and turn it wouldn't make noise and am rather puzzled as to what it could be. The "Active Handling Warm Up" also appears very frequently now, not sure if it is related but want to give as much info as possible. After crawling under the rear end I noticed a decent amount of fluid on the passenger side of the differential...any ideas as to what may be causing these problems? Any ideas on how to solve them?

 

The first thing that I would check would be the rear wheel bearings. Make SURE that there is little or no lost motion in the vertical or horizontal

The leak is a whole different story most likely not related to the noise UNLESS,, the rear is LOW on fluid!!

 

Thanks Bill, I will check the wheel bearings, as for the Low fluid, I put new fluid in it just before Winter, do you think it would have leaked out something say the vent and be on the passenger side of the differential? Is there a way to check fluid levels in there?

 

Yes theres a VENT on the drivers side on the TOP



If the rear end is over filled, it can and will exit the vent


If you level the car and open the fill plug, the proper level is just below the fill plug opening. (basically just let any excess drain out when the fill plug is removed)

 

when you changed the rear end fluid did you add anti friction additive to it???i believe your suppose to
Steve

 

Not sure I have heard of that, so therefore no I haven't...do you know what brands/anti friction additives I need to add as I will most likely do a change again??

 

Great thanks for the info Bill...I'm assuming the vent is the brass looking "post" sticking up on top correct?

I will surely check the level! Have you heard of the anti friction steve is talking about?

Any indication of the proper fluid that the differential needs?

 

Yes,,,, thats the vent. AutoZone and Advance sells a friction modifer. What fluid did you use to fill the Diff??????????? Some GL5 fluids have modifier already in it but if there is still grinding you may need to add some. DO NOT add tooooo much.
Go a 1/4 tube at a time and do figure eights in a parking lot to work it into the clutches.

BC

 

Regarding the Active Handling, pull codes to see if you get one for the IAT. The active handling system uses the IAT to tell it how cold it is outside so it knows what kind of weather conditions it's dealing with. When the IAT connection is dead the active handling system thinks it's -38 degree's outside. There's nothing to 'warm up' on the active handling system, it's just waiting for all of the data to determine it's mode of operation for the current weather conditions. Since it can't see the IAT (one of the parameters it needs) it's simply telling you it's not ready to activate, or 'warming up'.

There are really only three problems that it could be. A bad connection at the connector that plugs into the IAT sensor, a bad ground, or a bad connection at the PCM. My symptoms appeared after I installed my Callaway Honker. Did you disconnect it to install the headers? My car is in storage, but it's right near the TB and the sensor goes into the intake horizontally from the drivers side.

Your GM dealer sells this IAT connection for about $28. It's a new connection with a 10 inch lead wire on it. Part Number 12102620. My local dealer had one. Cut the wire to the IAT sensor an inch or so from the end of connection and splice and solder this new piece in. I put shrink wrap over the soldered connection and then electrical tape over it and it looks like stock. I started the car and went for a drive. No warm up and no CE light. After about 3,000 miles of driving I am code free and CE light free.

Pull your codes. I'll bet you have P0113 and P1111 stored.

Questions, let me know. This should be everything you need. If you want more, search on codes P0113H and P1111H.

Kurt

 

Kurt

Fitt's Vette is a 2001. I’m pretty sure that he has the newer MAF with the IAT incorporated into the MAF sensor.

Fitt's Vette

If you have a 6 pin connector on your MAF, it is the newer version and the IAT sensor is inside the MAF housing.

Kurt’s IAT fits into the plastic air duct that connects the MAF to the TB

You can also get a WARMING UP message if the SWPS is not properly Zeroed. The EBTCM examines the value of the SWPS and compensates for any minor misalignments. You will see the message if you have the steering wheel turned, start the engine and drive off. The EBTCM is just waiting for an opportunity to run the ZEROING routine. I’ve also seen the message if the cars alignment is significantly off the steering wheel has to be turned slightly LEFT or RIGHT when the car is going straight down the road.


IF the message appears and does not go away, it indicates an issue with the SWPS and you will also see the DTCs mentioned

 

Bill, I used DEX3/M Auto fluid, is that the correct fluid? Any to recommend for the new change? Any brand of modifier in particular or will any do?

As far as the new sensor, that is correct the MAF and IAT's are built in together...I currently have it unplugged for tuning so if I understand you correctly, the active handling message is from that? Thanks so much for your help so far!

 

That is not the correct fluid for the differential, DEXRON 3 is the fluid for the transmission. The correct differential lubricant is SAE 75W-90 synthetic axle lube meeting GM specification 9986115.
You will also need to add approximately 4 oz. of limited slip differetial fluid additive (GM part nr. 12345579 or equivalent). I would not drive it with ATF in the differential.

 

Thanks, I will change it immediately, is there a certain brand of it or anything that meets the GM specs? Thanks!

 

After looking back over my records, I am mistaken, I haven't changed the differential fluid before. It was the transmission that I changed the fluid haha, it seems as lately I have begun to suffer from CRS....Cant Remember Stuff... I was wondering why I would ever make the mistake of putting transmission fluid in the differential ...anyways I will proceed to change the differential fluid to the one suggested by ipuig and see what happens, would you all recommend that I change the seals first before the fluid change to see or change the fluid and then see if it still leaks?

Thanks all!

 

If you are saying that you by accident (of course) put ATF into your deferential.....?
I would buy extra rear diff fluid 2 qts (w/out additive. Drain the ATF out & then refill with the diff fluid & then drain all of that fluid out. (contaminated)
Then proceed with your proper diff fluid/additive refill.
Do as was suggested with the figure 8's in a parking lot.
I would wait on the (metal axle seals ?) untill you have your diff fluid under controll.
Now if you were refering to the large O rings (rubber seals) that go on in between the differential & side covers, then of course, drain the ATF out & then change out the rubber O ring/rings & then proceed w/the fluid change out.
Good luck

 

Change the fluid and verify that the vent is working. A malfunctioning vent can cause the case pressure to build up causing the seals to leak.

 

No one has offered an explanation of your noise while turning a hard left, so here is what was causing mine when I installed new headers. The pipes are so close together that the forces in a hard left turn cause the pipes to "chatter", then quiet down after straightening the steering wheel. Even though this location is forward, it can appear to come from the dif area at speed. It was fixed by tack welding between them, making them rigid, thus acting as a unit. No more noise, except that of the big holes coming out the car's *** end!

 

Thanks for the response! I didn't actually change the differential fluid, I realized that I actually changed the transmission fluid with transmission fluid (the proper procedure) and in fact had not actually changed the differential fluid. (sorry for the confusion!) So the whole time, the car has not had any other differential fluid (to my knowledge) other than what came from the factory, so I will indeed check the vent to make sure it is properly working. Js there a way to determine that the vent is indeed working properly? Or is it mainly visual inspection? Thanks for the help!

 

FANTASTIC! Thanks for the reply, did you do that for both headers and put a tack in between each tube? Thanks for the input, appreciate it! Hopefully I can get all of the kinks worked out to let the pipes ring!!!

 

Yes, it is on both sides...we put 4 tack welds total, two on each side. They are not a long continuous bead, but just about the size of a pencil eraser and a few inches apart, right in the valley between the pipes where they are almost touching each other. As soon as I pulled out onto the road I knew that awful sound was gone for good. I looked for my pictures of it but couldn't find them for you. Next time my car is up in the air I'll post some shots for you.