I was hoping to perform the DCT filter and fluid replacements myself. However, it appears a Scan Tool is required to perform a hydraulic system flush prior to changing the filter and a hydraulic system leak test after doing the filter change.

See posts #40 and #49 of this thread:

https://www.corvetteforum.com/forums...-new-c8-2.html

Are there any reasonably priced bi-directional scan tools out there that can do these procedures?

 

There isn't any tool that I know of that is capable of performing these procedures and being cheaper than the official gm mdi 2 diagnostic device. You are better off buying the official dealer tool and paying for the software on acdelco's website or getting it done at the dealership.

 

You can get a 3 day pass to the GDS2 software for $57.

https://www.acdelcotds.com/subscriptions

The problem is the cost of the hardware. As Mikeki7 said, the MDI2 is pretty expensive. The original MDI won't work with the C8.

I really, really, really wish GM would put together a VIN-locked DIY package that bundles access to the service manuals (eSI), programming (SPS) and diagnostics (GDS2). I'd be willing to pay a pretty good subscription fee for something like that.

 

I changed mine, you don't need to do anything other than change the filter and make sure its up to the fill hole, diagnostics is if there is debris in the trans due to a component failure.

 

Step 1 of the filter change procedure per the service manual (Doc ID 5384826) is to perform a hydraulic system flush procedure:



It isn't contingent on if debris is suspected in the system.

The full procedure can be found in post #9 of this link:
https://www.corvetteforum.com/forums...ct-filter.html

 

This is correct. This is exactly what GM is paying dealers to do at the 7,500 mile service. It's a very basic/easy DIY swap with plenty of YouTube videos demonstrating it.

 

I'll believe the procedure in the service manual over a YouTube video. The system flush only takes 8 minutes if you have the proper tool. According to @ChiTownVetteTech the system flush was added in the last few months. There was also a GM memo floating around (I don't know where it is now) that increased the labor reimbursement for the first filter change.

 

Let us know if the dealer does a simple filter swap or this flush procedure for you when you go in for your 7,500 mile freebie. The videos I've watched are from Chevy dealership service departments so I'm still not convinced the flush is required, or if GM will even reimburse dealerships for the procedure. Time will tell, I'm sure the proper procedure will get ironed out. For a filter that requires regular service intervals, I'd be shocked if it required specialized scan tools and diagnostic equipment (just my 2-cents).

 

I plan on asking the dealer if they do the flush procedure when they change the DCT filter before I bring it in. If they say no I'm going to ask why. If they don't have a good reason (like a superseding GM document or something) then I'll try a different dealer.
Don't get me wrong, I hope the procedure really isn't necessary. I'd really like to be able to do this myself. But I'm not going to risk future DCT problems or my warranty since the available documentation I've seen so far says it is required.

 

I hear ya! Hopefully the confusion is resolved before I'm due for the 2nd filter change.

 

Flush procedure reads:

​​​​​​This procedure is used to flush the transmission fluid through the filtration system before a repair is performed that may have been caused by debris in the fluid.

 

I have some experience in technical writing.

If I had made the statement "Perform the hydraulic system flush procedure"; and then made the statement within the flush procedure "Description This procedure is used to flush the transmission fluid through the filtration system before a repair is performed that may have been caused by debris in the fluid" with the intent of the second statement to relieve the technician from the requirement to do the flush if just performing a maintenance filter change I would have been torn a new one.

The first statement is a direction statement with supersedes a general description statement. Also, if there are any conditions on performing a procedure they should be stated in the initiating procedure. You don't want a tech to have to branch to another procedure only to find out it isn't necessary.

While I agree the procedure may not be necessary from a technical standpoint we just don't know at this time with the documentation available. The only documentation I've seen from GM states it is necessary.

Don't get me wrong, I was hoping to do DCT filter changes myself. However, unless I see a superseding document from GM, I'm going to bring my car to the dealer do DCT filter changes and make sure they follow the procedure.

 

you can do it any way you like, just remember, the right way is the GM way....

 

Still don't understand why you keep rehashing this in different posts and different forums. This is the 3rd post you have started over a simple filter change.

1. Simple solution is just get DCT serviced at dealership to keep warranty. You will have a record of Factory service at dealer so warranty will be intact.
2. The DCT fluid is continuously filtered...that's what you are replacing when doing this procedure "the filter"
3. If pre flush is required that would point to DCT Isn't filtering fluid under normal driving that would be a class action lawsuit.
4. No car company can make it manditory to get any car serviced at dealership...any indy shop has the same software to perform this task if they work on GM vehicles.
5. I dont know much but what other car or manufacturer requires DCT preflush before filter change? plenty of European cars run DCT's and never heard of any requiring such a thing.
6.. When its my time i will be replacing filter myself and topping up fluid only. I'll let GM lawyers explain to my lawyer why a preflush is required, if the DCT fluid is being filtered during normal driving.

 

I keep posting because, so far, there hasn't been a definitive answer of why the pre-flush is there.

Let's look at some facts:
1) The service manual (at least the copy of the version posted) requires a pre-flush if it is interpreted using standard practices of technical writing.
2) @ChiTownVetteTech follows this procedure when he does a filter change. Some other people have reported that the flush was performed when they had their filter changed. Also, @ChiTownVetteTech stated that the flush was a recent addition to the procedure within the last few months. Coincidentally, there was a memo from GM about the same time that increased the labor rate reimbursement from 1.7 to 2.3 hours (see attachment).
3) The service interval for the filter is required more often than usual when compared to other transmissions. In fact, I haven't seen a situation before where a transmission filter change is required at twice the interval of a fluid change. This suggests that GM is very concerned about contamination in the DCT.
4) A flush procedure is commonly performed when operational issues are encountered.

There could be valid reasons why a pre-flush is directed per the procedures. I have some experience in filtration systems. Below are a couple of reasons I can think of but there are probably more:
1) There could be residual contamination in the system. Over time, this contamination could make it's way into the filter and impede its operation. Flushing this contamination into the filter before replacement may be required for the new filter to last until the next required interval. This could be especially true if the concern is silting where the individual particles are small enough to pass through the filter mesh holes but congeal on the filter.
2) Congealed particles trapped in a filter can break down over time and pass through the filter. These fine particles may cause problems with sensitive components. Flushing to remove as much of these as possible may be necessary to maintain proper operation between the required service intervals.

It's possible that the scan tool commands the transmission valves to perform operations not encountered during driving. It could sequence valves in such a manner that the passages have increased fluid velocity (perhaps even reverse flow) that could dislodge trapped contaminants and direct them to the filter. There may even be a specific service valve in the transmission that is only operated during servicing (this isn't uncommon in industry). It would be interesting to find out what the flush procedure actually does.

Its also possible that the flush procedure is intended to remove residual contamination from manufacturing and self-generated contamination during break-in. If that is the case, the flush at the first service would be the most important one.

As I see it, there are several potential reasons for the flush in the DCT filter change procedure:
1) It is a mistake to have it in the procedure.
2) It was always intended to be in the procedure but mistakenly left out and subsequently added.
3) There is another area in the service manual that gives relief on performing the flush but we haven't seen it.
4 It is only intended for the first service but the manual errantly requires it at every service.
5) Some initial problems with the DCT were traced to contamination issues and GM determined that the flush should be done at every filter service.

I'm just trying to get to the bottom of this.

By the way, I never said that independent shops couldn't do the procedure as long as they had the correct tools.

 

I'm on the boat that only changes the transmission filter for the first service. The memo mentions engine oil and filter, whereas it doesn't specify transmission fluid only the filter. Same with all the other documents that specify what is included in the free first service visit, that mention engine oil, filter and only transmission filter. Except for the service manual that is probably worded confusingly which I would say the flush is to be done if a repair was performed or the service intervals for the fluid. Also the added labor hours don't come close to the actual amount of time it takes to perform a transmission flush with the proper procedure using the GM diagnostic tool.

 

The documents that define what is done at the first service is meant for general direction. The procedures in the service manual provide the details.
The actual duration of the flush procedure is only 8 minutes. The added labor hours is sufficient to hook up the scan tool and perform the procedure. Remember, no fluid is replaced (other than the small amount fluid lost during the filter change).

 

A flush to me means draining the entire transmission of its fluid. Initiating the cleaning procedure in the gds program before the filter change should be done but I don't think its a make or break. Particles will work their way to the filter regardless. I think the main point of contention is the replacement of all the fluid during the filter change which I may have been confused about when you say the word flush.

 

I understand (and agree that flush usually means fluid replacement) but GM calls the procedure a hydraulic system flush so I used that term for consistency. What is interesting is I saw a version of the procedure with the same document number that called it a cleaning procedure.

 

Scan tool received. Just need to find some time to tinker with it.