Coolant/radiator blown

[farvour]

Hi all. New to these forums. I just got a 1999 Yukon SLT a couple of weeks ago. I was driving home today and when I pulled into my garage I noticed that there was coolant leaking from the front underneath the bumper (driver's side). Looks like the radiator or something popped... it has since stopped now that the engine cooled down. Any ideas? The place I got it from is offering a warranty to repair for a discounted rate so I do plan to drive it in as long as it does not overheat on the way there. It has 114,000 miles, and I do not think that the coolant was flushed...

I had a second thought regarding this though. There are 4 lines going to the radiator (which usually indicates that there is an internal transmission oil cooler?). I noticed when driving on the highway, some times the torque converter lock up is not 100%. It eventually always locks up but seems to take a little while some time. Would a going-bad/blown radiator have caused some heat issues for the transmission?

Thanks all!

 

[retorq]

No, it wouldn't have, With that many miles I would guess it's stock and will blow up soon. You can do a flush/fill with some additive to see if it will fix ...

 

[99Vortec]

Is the leaking fluid green or orange colored?

Orange colored coolant is factory dex-cool antifreeze.

On the drivers side of the radiator, there are metal lines for the engine oil cooler, on the passenger side they are for the transmission oil cooler.

On my '99 Yukon Denali, the brake pedal switch was malfunctioning. And causing shift interlock problems and some wierd transmission problems. (I noticed it one night when I got out to open and close a gate and the brake lights went on.) I believe that same switch has torque converter control on it. (Maybe someone can confirm?) Funny thing was that my cruise control was still functioning. I would have thought that the brake switch malfunctioning would have disengaged the cruise control.

Just a thought.

In any event, get that cooling system pressurized first!

gl

 

[rolfsent]

My 97' Yukon was having the same trans issues, a couple weeks after that started happening my trans totally took a dump and got rebuilt.

 

[ccapehartusarmyINF.(ret)]

you need to get the leak fixed because your cooling system is no longer pressurized
your cooling system is supposed to be pressureized to about 15 psi wich raises the coolants boiling point to 245 dagrees when you have a leak in the system you lose that pressure and your coolant will boil at 212 dagrees and you motor will overheat alot easier

 

[SunlitComet]

incorrect fluid levels in tranny can make problems too. ensure to check with engine running on level surface.

 

[farvour]

Hi all I wanted to update everyone that it did end up being the radiator sprung a leak. That's fixed now.

The transmission issue is/was unrelated to that which I anticipated. Similar to what 99Vortec stated, I have the strange problem on certain days where the lockup does not seem to want to occur. I know there is a brake switch that can go bad, but it never happens when it's dark for me to see it. What is interesting is that when the lockup doesn't happen, the cruise doesn't work either, which is what led me to believe it could be the switch as I was finding on the internet. If it's a mechanical problem, wouldn't that cause the PCM to set a code? I guess the question here is, does cruise control still work even if the TCC had a problem performing full lock-up because of a mechanical issue or a valve body problem? There are no PCM codes set, I even brought it to AutoZone to have them check when it it is happening and there are no codes/historical. Do you suspect this to be the switch? I try to kick/jiggle around the brake pedal on the highway when it starts happening, but it doesn't always make it work again. It likes to just randomly start working again, then then cruise control works again. Some days I can make it all the way to work and back without any problems... others, it's like it just doesn't want to lock up and I can't set cruise.

---------- Post added at 01:21 PM ---------- Previous post was at 01:16 PM ----------

incorrect fluid levels in tranny can make problems too. ensure to check with engine running on level surface.

I checked the fluid level with the truck running, warm, level surface and it looks good. It does seem a little high but I can't really tell on the dipstick where the cutoff is. Is it possible there is too much fluid? In line with my previous post, I do have a problem when I start the truck cold, it wants to do a 1-2 shift relatively quickly/brisk, and as it all warms up, it smooths out just fine...

related to the TCC lockup issue?

 

[SunlitComet]

it sounds like you definitely need a new brake switch but check its connector wiring for damage as well. you can overfill the tranny and cause issues. when you pull out the stick to read it and can't notice where it stops on the stick look on the backside of it and the break point between wet and dry should stand out better. a 1-2 kick cold is not that bad. but if it continues with a hot tranny then the issue needs to be addressed. should not be related.