2000 Yukon Maintenance Question

[NotJLB]

We have a 2000 Yukon with 225,000 miles that we have had since new.

I have done the normal routine stuff . . . regular oil changes, tires rotating and balancing, new shocks.

But, I'm wondering about the coolant and the transmission fluid. Should they be changed?

You don't hear much about those any more.

TIA

 

[seven9st surfer]

Between the manufacturer and Chilton manuals, I put together my own maintenance spreadsheet. According the the manufacturer:

50,000 Miles (83 000 km)
Change automatic transmission fluid and filter if the
vehicle’s GVWR is over 8600 Ibs or if the vehicle is
mainly driven under one or more of these conditions:
- In heavy city traffic where the outside
temperature regularly reaches 90°F (32°C) or
higher.
- In hilly or mountainous terrain.
- When doing frequent trailer towing.
- Uses such as found in taxi, police or delivery
service.
If you do not use your vehicle under any of these
conditions, change the fluid and filter at 100,000 miles
( I 66 000 km).

As for the coolant:

150,000 Miles (240 000 km)
Drain, flush and refill cooling system (or every
60 months since last service, whichever occurs first).
See Engine Coolant on page 5-27 for what to use.
Inspect hoses. Clean radiator, condenser, pressure
cap and neck. Pressure test the cooling system
and pressure cap. An Emission Control Service.

So yeah, if you've never done those, you're probably well past due. But double check your manual's maintenance schedule.

 

[NotJLB]

Thanks. Make the one in the picture an XL, and I'll take it.

I just wondered if the risk of someone doing those things wrong was greater than the risk from not doing them.

So often you hear, "If it's not broke, don't fix it."

I wish all the hurricane victims the best.

 

[seven9st surfer]

Thanks. Make the one in the picture an XL, and I'll take it.

I just wondered if the risk of someone doing those things wrong was greater than the risk from not doing them.

So often you hear, "If it's not broke, don't fix it."

I wish all the hurricane victims the best.

As far as doing it wrong, the only thing I can think of is for the transmission fluid, make sure you get a change, not a flush. Especially with that long in between changes.

And while "if it ain't broke, don't fix it" is true, preventative maintenance is a different story. You're replacing worn-out fluids, not parts. Same reason you've been changing your oil and rotating your tires, so it wouldn't be broke in the near future.

And good luck getting your transmission pan plug out! Very common for those to be torqed down waaaaaay past spec. Mine might as well have been welded on, ended up just buying a new pan to make future changes easier.

 

[NotJLB]

Thanks.

We have as reliable of a local mechanic as can be, so I will put it in their hands.

We have a Florida place we need to go take care of and are purchasing a small camping trailer in case we need to sleep "outside" for awhile.

1200 mile tow

Towed an 18-foot trailer for a living for almost 20 years, so . . .

 

[MrBalll]

Liked stated be sure you mention to your mechanic you only want a transmission fluid change, not a flush.

 

[NotJLB]

OK. How about the radiator . . . a "flush" or just coolant change?

 

[Sasquatch]

If the transmission fluid has never been changed i would be cautious about changing it. I used to be a mechanic and when we serviced a transmission with little to no service history on more than one occasion the transmission failed shortly after the work was done and one couldn`t even back out of the garage. If the fluid is brown and smells burnt i wouldn`t touch it. With 225k on the clock i seriously doubt the fluid is even close to pink like its supposed to be.

 

[NotJLB]

That certainly makes what I ought to do uncertain.

I don't understand why putting good fluid in would cause a failure.

 

[Sasquatch]

I am by no means a transmission expert so i`ll just copy this explanation of what may happen.

Generally, if the transmission fluid has not been changed around 60,000 miles, varnish and sludge from oxidized fluid combine with particles from clutch and band wear and create a gummy--almost solid--goo that sticks to transmission parts.

When you change the fluid, the new ATF acts like a solvent to loosen this junk. Like sand, it can wear the friction materials off the bands and clutches causing slippage. Valves--and there are lots of them in the transmission--get stuck open or closed. This causes slow engagement or slippage. Once the buildup is removed, leaks that it prevented begin from seals and gaskets. Any oxidized fluid left behind makes the new fluid more prone to breakdown.

But fresh fluid will not provide more "bite" and cause accelerated wear. The amount of bite depends on the friction modifiers added to the fluid. ATF without friction modifiers allows less slippage in clutch and band engagement, causing harsh shifts.

Changing the transmission fluid on a high-mileage car is risky. Don't do it unless your transmission is running fine and the fluid is first-rate, because it can make transmission failure imminent.