[Solved] 2000 Yukon XL high operating temp

ryanguy426

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But is it still overheating? I thought I read that its running 230deg even when filled with coolant. Make sure you dont have any air trapped in the coolant system!
Will report back on that tomorrow. Normally overheats in town and in drive thrus in the middle of the day (90°+ out) Night driving and mornings are fine, holds 189° - 195° when it's cooler out (80° outside at dark is always fine).

I've followed the coolant fill procedure I found online. Filling, revving up and down to 3k rpm with the cap on loosely, adding coolant as it needs it. It always seems like I'll get small bubbles out when I squeeze the top hose no matter how much I squeeze and fill. Hopefully that changes with the hose not dripping anymore. The drip was definitely evaporating off which is why I never found it. I appreciate all the help up to this point
 

alpha_omega

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But is it still overheating? I thought I read that its running 230deg even when filled with coolant. Make sure you dont have any air trapped in the coolant system!

I think the thermostat and the drip repair will be a 95% fix but I would still get a clear air flow for that radiator. IMO.
These guys are absolutely correct. You need to bleed the air out of the system or all your hard work is for nothing. Also, get that old thermostat checked and make note that it’s good practice to change out the radiator cap and/or overflow cap whenever you do a water pump swap or coolant flush. The seals get hot, stretch out, warped or dry rot. Good thing is the caps are cheaper than a tow and less stressful too. No need to run hot and risk damage to the engine.
Now you know that just because you don’t see a leak doesn’t mean that you don’t have a leak. Same goes for your other fluids, since they can end up down the back of the engine block, or on top of the tranny, t-case, torque converter, before burning off.


Have you checked the tranny fluid to see if it is also the right color AND consistency? When was the last time your tranny fluid was changed?

*one more thing I just thought of. Are you running the correct coolant (DexCool) for your vehicle with the proper 50/50 ratio using Distilled Water with it and not tap water?
 

ryanguy426

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These guys are absolutely correct. You need to bleed the air out of the system or all your hard work is for nothing. Also, get that old thermostat checked and make note that it’s good practice to change out the radiator cap and/or overflow cap whenever you do a water pump swap or coolant flush. The seals get hot, stretch out, warped or dry rot. Good thing is the caps are cheaper than a tow and less stressful too. No need to run hot and risk damage to the engine.
Now you know that just because you don’t see a leak doesn’t mean that you don’t have a leak. Same goes for your other fluids, since they can end up down the back of the engine block, or on top of the tranny, t-case, torque converter, before burning off.


Have you checked the tranny fluid to see if it is also the right color AND consistency? When was the last time your tranny fluid was changed?

*one more thing I just thought of. Are you running the correct coolant (DexCool) for your vehicle with the proper 50/50 ratio using Distilled Water with it and not tap water?
Trans fluid is fine yes, it looks great. Rebuilt trans within the year according to the person I bought it off, fluid is used but nowhere ready to be changed based on what I've seen.

Yes, it's running Dexcool with distilled water. Flushed everything out real good before replacing the pump to make sure it had fresh clean Dex and distilled in it. I'll get the thermostat done again asap. I also have one of those tools with a bulb on it, you suck up the antifreeze and it tells you if it's the right mix. It looks good.

I stated above what I did to try and get air out. Is that the correct procedure? I see a lot of forum posts from around 2007/2008 with dead links that supposedly linked to a "burping procedure" but haven't found anything online about that, except for revving up to 3,000 RPM on and off for 30 seconds each time in between, and filling coolant as necessary. I've also done the method of squeezing the top radiator hose to get bubbles out, and add antifreeze as needed.
 

alpha_omega

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Squeezing the top hose works, but all of the other “tips and tricks” like putting the vehicle on ramps so the air flows uphill or adding extra fluid to the overflow so it can draw down to the radiator or out the overflow hose as needed are nothing more than bad practice.
The reason that squeezing the hose works is because it’s helping to “burp” the system. The only way to properly and fully burp the system is with a Venturi vacuum/pressure system designed for this. You can rent them at your local auto parts store or look them up online (Airlift is the brand I know and trust using).

Other guys may have different views on their tool brand of choice, but I’m a stickler for professional quality tools. My Pa never learned me to do things half-assed. Instead he taught me to do the job right the first time, otherwise you have to undo and redo, so you’re then doing it at least three times if you cut corners. So when it comes to quality tools and quality parts “Buy once, cry once”. OEM parts may cost more than the auto parts brand, but there is a reason for that.
 

ryanguy426

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Here's a video I took just now been working on it for about an hour. I replaced the thermostat with a new 187°. Heat is strong, scan tool confirms operating temperature and it hasn't gone over 210° yet. Seem to be adding coolant little by little. Squeezing the hose about every 5 minutes yeilds some bubbles.

Will report back tomorrow on what temps I see in town when I drive it tomorrow.
 
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ryanguy426

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Looks like the thermostat was it! Sitting idle in a parking lot at 210°, only hit max of 214° in the same drive thru I've overheated in previously! AC on and everything!

Thank you everyone. I feel a lot better about driving this up and down i95 in the next coming days! Only issue it has at this point is starting like crap, but I'll just deal with it until I get back
 

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When you get a couple more drives in and it seems great still, please edit your post Title and type in solved at the end. Others find them easier that way and can help them.
 

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