: Questions about servicing my 99 Deville



chrissheets
10-08-06, 05:51 PM
I have a 1999 base Deville and I have a couple questions about servicing the cooling system and the tranny.

I just bought this car and it is my first Northstar. Is it true that my tranny has no replaceable filter? Is a flush all it needs?

The dealer wants $212 to flush my cooling system and they also replace the thermostat. Is this a fair price?

I am one who have always done my own service but with the fear of a blown head gasket I want it done right. Any thoughts?

Ranger
10-08-06, 05:58 PM
Just drain and refill the cooling system with a 50/50 mix of Dex-Cool and distilled water. Add the suppliment tabs to the radiator hose, not the syrge tank. No need to flush it.

There is a filter in the 4T80E trans but it is deep inside and only gets changed during a rebuild. There are two reusable screens in the pan. Click on the Technical Archives at the top left of this page and read up on trans flushing. :tisk:

chrissheets
10-08-06, 06:27 PM
Just drain and refill the cooling system with a 50/50 mix of Dex-Cool and distilled water. Add the suppliment tabs to the radiator hose, not the syrge tank. No need to flush it.

There is a filter in the 4T80E trans but it is deep inside and only gets changed during a rebuild. There are two reusable screens in the pan. Click on the Technical Archives at the top left of this page and read up on trans flushing. :tisk:

Thanks for the quick reply. I did an extensive search on these forums and read several posts on tranny service and I am getting mixed results. I really don't know what to beleive. Some say don't flush and some say flush. What I really want is enough people to post one way or another to get a concenus on what works best. I can appreciate everybody's opinion equaly.

My local Cadillac dealer says flush and wants $200 for it. Jiffy Lube wants $110. I have zero problems paying the $200 but I want to know what I am paying the extra money for. Does the dealer use better equipment? Different fluid? I feel I can find this out by seeing other people's experiances at different places. I cannot do this service myself because of my size. I cannot fit under my car even with jack stands.

As a forum moderator at another website catering to computers I can appreciate the need to do an extensive search before I post. Rest assured that was done. I just wish there were more posts/articles swaying me one way or another.

Ranger
10-08-06, 07:05 PM
Well, the dealer wants $200 for a flush, that is why they recommend it. The Technical Archives at the top of this page that I suggested you read was written by a well respected former poster who is a GM powertrain engineer. We pretty much take that as gospel.

chrissheets
10-08-06, 07:44 PM
Well, the dealer wants $200 for a flush, that is why they recommend it. The Technical Archives at the top of this page that I suggested you read was written by a well respected former poster who is a GM powertrain engineer. We pretty much take that as gospel.


Thanks for that information. It will help me decide.

zonie77
10-08-06, 08:00 PM
I am one who have always done my own service but with the fear of a blown head gasket I want it done right. Any thoughts?


My thought is if you want it done right do it yourself!:stirpot:

The recommended is not to flush. Drain and refill. That applies to trans and cooling system.

You still have to drop the pan on the trans. There is a plug to drain the "top" of the trans. There are posts with better instructions. The plug is 10mm and I believe it's hidden by the filter screen.

zonie77
10-08-06, 08:27 PM
In addition, even some flush eq mfg's don't recommend a flush if the mileage is over 100K.

GreenMachine
10-09-06, 12:23 PM
My Factor Service Manual states that you need to replace the gaskets of the pan after dropping the pan and draining the trannny, recommends replacing the screens.

Ranger
10-09-06, 04:48 PM
Unless they changed something, the gasket on my '97 was reusable and the screens can be flushed and reused although they where as clean as new. The only thing I replaced was the fluid.

chrissheets
10-09-06, 05:16 PM
Thanks for all the input guys. I am going to find a reputable pleace here in Denver and have them drop the pan. I have always done this myself but I am unable to do it right now. Anybody in Denver that has a good reputation?