02 DTS shakes around 60mph to 75mph

DonRSD · #1 (**permalink**) 08-11-09, 12:03 PM

hey, LOOOOOONG time lurker, finally decided to join.
i put 2 & 2 together and used my company email to register....lol

anyway. i have a 2002 Deville DTS w/54k miles on it.

around 60 mph the car shakes. nothing TOO bad, but i notice it.
is this a tire problem, motor mount, suspension etc?
im no 'car guy' so i wouldnt even know where to start.

i have a GM warranty so i can get it fixed, but i dont want the dealer telling me its the tires and when i drive away the shake is still there.

any help would be appreciated

DevilleDeeman · #2 (**permalink**) 08-11-09, 04:10 PM

Sounds like front motor mount to me...tires would shimmy at many different speeds. Check for play in the engine. When in gear with the hood open give it some gas with the other foot on the brake. If it moves considerably it's probably the motor mount.

DonRSD · #3 (**permalink**) 08-11-09, 05:16 PM

Quote:

Originally Posted by DevilleDeeman

Sounds like front motor mount to me...tires would shimmy at many different speeds. Check for play in the engine. When in gear with the hood open give it some gas with the other foot on the brake. If it moves considerably it's probably the motor mount.

well i just had my tires balanced/rotated thru the caddy dealer as its free.

the steering wheel doesnt move at all, just seems like there is a rattle/shake feeling in the cabin.
nothing to make me crash, but i notice it

i will bring it in to the caddy dealer again to check the motor mounts.

and is my temperature guage supposed to 'move' past halfway (12 oclock) to the next line(1 oclock) then come back to the middle (12 oclock) while in driving on the highway?

**Ranger** · #4 (**permalink**) 08-11-09, 05:38 PM

Be sure that they did a "road force balance". These things are terribly sensitive and finicky. I have had to go as far as replacing tires at 24K on an '02 SLS.

JimD · #5 (**permalink**) 08-11-09, 05:38 PM

Quote:

Originally Posted by DonRSD

....and is my temperature guage supposed to 'move' past halfway (12 oclock) to the next line(1 oclock) then come back to the middle (12 oclock) while in driving on the highway?

At vehicle speeds at ar or above approximately 35-40 MPH, I would not expect to see the coolant temperature guage to move at all. Period.

John Wicz · #6 (**permalink**) 08-11-09, 07:17 PM

My 2 cents say that it may depend on the ambient temperature and just how often it fluctuates (should not be very often).

John Wicz · #7 (**permalink**) 08-11-09, 07:41 PM

Quote:

Originally Posted by Ranger

Be sure that they did a "road force balance". These things are terribly sensitive and finicky. I have had to go as far as replacing tires at 24K on an '02 SLS.

I second what Ranger said about road-force-balancing, out of curiosity what brand and model are the tires?

**Playdrv4me** · #8 (**permalink**) 08-11-09, 07:56 PM

Have your coolant tested for exhaust gases. The needle should not move with air flowing over the radiator and I've never had one move while cruising above 40mph as Jim stated.

If you find that your combustion gas test comes up positive, USE that warranty and have them do the head-work.

DonRSD · #9 (**permalink**) 08-11-09, 09:12 PM

hey guys thanks for all the replies. you are all a blessing in disguise.

i have one more issue.........
when i start my car it is very rough for about 10 seconds then smooths out.
this only happens when the engine is cold. so if i drove to walmart, then went into the store for 30 minutes and fire up the caddy there will be no rough idling at startup
the dealer had my car for a WEEK and couldnt diagnose the problem.

i can bring the car back in for repairs for free this week so i need a response as to what to tell them to look for

-rough idling when the engine is 'cold'
-temperature gauge moves even when doing 60 mph but nothing too excessive
-car has slight vibration when doing 65-70mph

MisterBlue · #10 (**permalink**) 08-12-09, 12:13 AM

Both the rough idle for 10 seconds and the temp guage moving past 12 0'clock sound like head gasket symptoms. I've had 3 fairly new Caddys, and the temp guage goes to 12 o'clock and then never moves, doesn't make any difference if it 15 degrees on the interstate or 95 degrees in bumper to bumper traffic. The vibration sounds like a tire problem - out of balance or out of round tire on the rear (or else you'd feel it in the steering wheel).

codewize · #11 (**permalink**) 08-12-09, 09:57 AM

It's not a motor mount. You're suffering from the same thing as every other 00 - 05 Deville.

As Ranger said you need to make sure they did a Road Force balance on the car. These cars are so sensitive about the front end it's crazy.

The smallest bit of wear in any front end component will cause that. So much so that there is a TSB telling dealers to clean the back sides of the wheels when customers complain of a shake

I've found that if you really want to keep it away you'll need to balance your tires about every 5000 miles, keep the rims clean as hell, make sure there is absolute 0 play in tie-rods, ball joints, steering components etc. Then and only then will the shake be gone.

regarding tires I've also noticed that a commonly over inflated tire can contribute to that factor. The stated PSI is only 28 - 30 # not 32 or 35 like everyone puts in tires.

Good luck

brendanw · #12 (**permalink**) 08-12-09, 10:56 AM

Is the term "road force balance" specific to a Cadillac qualified service center, or that a fairly generic term, i.e. is that better done by a Cadillac dealership than a reliable mechanic?

I notice the same vibration around 65 MPH and have yet to figure out. It seems like it's something suspension related. I am planning on replacing the rims and tires in the near future and was going to wait until then to do antying about it

**Ranger** · #13 (**permalink**) 08-12-09, 11:33 AM

No, it is not Cadillac specific.
http://www.gsp9700.com/

DonRSD · #14 (**permalink**) 08-12-09, 12:53 PM

well the caddy dealer told me 'the shake is going to happen, its how the car is made' referring to when i START THE CAR

and when im on the highway the temp guage rises to 1 oclock then comes back to the middle (12 oclock)

im going to call them AGAIN and hear them scramble for an answer

**Playdrv4me** · #15 (**permalink**) 08-12-09, 01:20 PM

Bullshit, rough idle at startup is a classic symptom of pulling headbolts because coolant is beginning to seep into the combustion process (this is usually, but not always also accompanied by a P0300 DTC).

Forget about the road vibration for now, that can be addressed at a nominal cost later on. If you really only have a week left to have them address anything, have the combustion gas testing done (radiator shops can do this or you can buy the kit at a Napa auto parts store for about 50 bucks and have a local mechanic do it) and bring the results to them. I find that for some odd reasons dealerships tend to weasle out of repairs when corporate is paying for things so it will be hit or miss to ask them to do the test themselves.

You don't want to pay for this job out of your own pocket...