05 Z71 totaled due to engine coolant leak?

[mauger84]

Hey everyone. New here. I have an 05 Z71 w/ 155k miles. Took it in due to overheating and the mechanic said there is a coolant leak in the engine. I’ve been able to drive it still by just making sure the coolant is toped off but i just changed the oil and now it has a much worse leak, visible right below where the belts connect to the engine. I can see it spraying out. Basically it leaks out most of the fluid whenever i drive it.

Even though the interior is in really great shape, The car has substantial rust issues and so i’m thinking an engine swap isn’t in the cards. Now I’m asking myself what to do with it. Any suggestions would be much appreciated.

 

[OR VietVet]

Welcome to the forum.

Likely just a water pump. May be puking out of the water pump weep hole. Have it checked out correctly before giving up.

 

[adventurenali92]

Hey everyone. New here. I have an 05 Z71 w/ 155k miles. Took it in due to overheating and the mechanic said there is a coolant leak in the engine. I’ve been able to drive it still by just making sure the coolant is toped off but i just changed the oil and now it has a much worse leak, visible right below where the belts connect to the engine. I can see it spraying out. Basically it leaks out most of the fluid whenever i drive it.

Even though the interior is in really great shape, The car has substantial rust issues and so i’m thinking an engine swap isn’t in the cards. Now I’m asking myself what to do with it. Any suggestions would be much appreciated.

While a coolant leak can kill an engine if it’s gone into an extreme overheating scenario, I highly doubt your engine is toast at 155,000 miles. Especially if you’re filling it up with coolant after it’s leaked out, and still able to drive it. More than likely your engine is fine.

likely the water pump like @OR VietVet suggested above^ or possibly a crack at the bottom of the radiator could result in spewing coolant below the belts and pulleys. Or a third scenario that I just experienced my self with my 2006’s LQ4 6.0. There’s a small plastic, off kilter “T”shaped three holed connector that connects the coolant hoses that run up to the heater core, and this pieces connects said hoses to the water pump. GM made the connector out of plastic. Mine developed a crack and a couple of weeks ago the crack got big enough to spew coolant into a big puddle under skid plate. As you’re looking at the engine from the grille area this connector is just below the fan and pulleys on the passenger side of the engine block coming off the water pump.
I would recommend seeing another mechanic to figure out where the coolant is actually leaking out. Radiators, water pumps, and hoses age and crack, it’s just what happens as these trucks age.

 

[avalonandl]

LS water pumps are known to leak and fail. Isyour oil ok? No milkshake?

 

[Joseph Garcia]

Welcome to the Forum from NH.

Lots of knowledgeable folks here who freely share their knowledge, experiences, and perspectives. Knowledge is power.

I hope that you will become a participating member in the Forum's discussions.

Pics of the truck, please.

You are already receiving sage advice from the knowledgeable folks on this Forum.

If the coolant has not entered the oil system (milkshake), then focus on the exterior leak possibilities that folks have suggested above. If you are not comfortable doing the troubleshooting yourself, take it to a qualified mechanic at a local shop, and you should get a determination fairly quickly.

 

[MassHoe04]

I would agree with posts above. If the oil is not milky, then this may not be a certain death after all. Could be head gasket with external leak, water pump as noted... Might not be a major repair.

Absolute worst case scenario... Lots of great parts to part-out. Being a Z71, you have a lot of additional parts that are in high demand. Rear end, transfer case, snowflake wheels, fender flares, steps, trim interior, ROOF RACK (is highly desirable), etc.... If you have the ability to part-out yourself, you could probably make more than book value.

She may not be done just yet... Get the second opinion and see what the repair involves. You may be surprised to get it fixed for a few hundred $.

 

[RAMurphy]

Welcome to the forum. I agree with the multiple responses. These engines will run forever and at 155K miles I would spend a little money to determine the exact issue with the coolant leak. Water pump is a good starting point and then next the radiator. But first I would check the oil - if there is coolant in the oil then most likely a head gasket is your problem. I would not give up on her just yet.

 

[Excel]

needs maintenance,its a 20 year old truck,they are money pits but great for DIY types like myself
I am currently looking for one to build if you wanna sell it

 

[OR VietVet]

needs maintenance,its a 20 year old truck,they are money pits but great for DIY types like myself
I am currently looking for one to build if you wanna sell it

I have to take exception to the "money pit" statement. If it is taken care of, from day one, these NBS rigs are quite dependable. When you start customizing, the $'s can start adding up. I have spent a bunch on mine but all of it was by choice. The only thing I have had to do since I bought it over 2 years ago, is oxygen sensor and park brake work.

 

[willinnashville]

A few years back mine had a similar issue. Turned out to be a the plastic coolant pipe that goes from the water pump to the heater and expansion tank. I replaced it and the water pump while I was at it. If you're a DIY kinda person, these are the best vehicles out there right now

 

[Rocket Man]

Sounds to me like your water pump might be leaking which might or might not be the same issue as what the “mechanic “ found. I say that because he should have given you a little more information on exactly what kind of coolant leak he found- is it external or internal where it would be mixing with coolant and giving you milkshake oil. Another thing to note is although rare, sometimes the radiators fail and depending on options, you could have coolers for engine and transmission oil inside the radiator. If those coolers leak internal of the radiator, you can get trans fluid or motor oil mixing with engine coolant. It’s rare but it can happen. Have you checked your oil to see if coolant is mixing with it?

 

[OR VietVet]

One hit wonder? Results of testing? Do any testing?

 

[BarryvG]

Hey everyone. New here. I have an 05 Z71 w/ 155k miles. Took it in due to overheating and the mechanic said there is a coolant leak in the engine. I’ve been able to drive it still by just making sure the coolant is toped off but i just changed the oil and now it has a much worse leak, visible right below where the belts connect to the engine. I can see it spraying out. Basically it leaks out most of the fluid whenever i drive it.

Even though the interior is in really great shape, The car has substantial rust issues and so i’m thinking an engine swap isn’t in the cards. Now I’m asking myself what to do with it. Any suggestions would be much appreciated.

Had an '01 Z71 I loved, but it was getting on in years back in 2018. Had a coolant leak the mechanics couldn't source, but it kept going down. Finally I was looking at a Tahoe message board & the topic came up. Literally the next day I was back on the phone with the mechanic, as it was in the shop to find out WTF was going on, and I think he read the same post. At least in MY case it turns out that there were a grouping of 5.3L Z71s/Tahoes that year that came in with poorly cast "heads" & ONE of mine had cracked. They suggested replacing both heads, which was expensive ($2K? at the time & some other stuff), but I had them do it. It was not broadcast to the public, because it was not considered a safety recall issue. And it was NOT covered, even though it was a defective head. I can't say if there were "bulletins" going forward for later models like yours, but I only had about 85,000 miles on it at the time, as I only put about 6K miles/yr on her. There was also a sound that wasn't normal, but who knows.

 

[Fless]

Had an '01 Z71 I loved, but it was getting on in years back in 2018. Had a coolant leak the mechanics couldn't source, but it kept going down. Finally I was looking at a Tahoe message board & the topic came up. Literally the next day I was back on the phone with the mechanic, as it was in the shop to find out WTF was going on, and I think he read the same post. At least in MY case it turns out that there were a grouping of 5.3L Z71s/Tahoes that year that came in with poorly cast "heads" & ONE of mine had cracked. They suggested replacing both heads, which was expensive ($2K? at the time & some other stuff), but I had them do it. It was not broadcast to the public, because it was not considered a safety recall issue. And it was NOT covered, even though it was a defective head. I can't say if there were "bulletins" going forward for later models like yours, but I only had about 85,000 miles on it at the time, as I only put about 6K miles/yr on her. There was also a sound that wasn't normal, but who knows.

Likely were Castech 706 heads.

 

[Rocket Man]

And it’s another newbie that comes here, asks for help or recommendations, and after we all offer advice he doesn’t come back and follow up. I’m left wondering the details on what’s wrong with that engine.

 

[mauger84]

Sorry for the delayed response, been on vacay with the family since i posted. BLOWN AWAY by the friendly suggestions.

While a coolant leak can kill an engine if it’s gone into an extreme overheating scenario, I highly doubt your engine is toast at 155,000 miles. Especially if you’re filling it up with coolant after it’s leaked out, and still able to drive it. More than likely your engine is fine.

likely the water pump like @OR VietVet suggested above^ or possibly a crack at the bottom of the radiator could result in spewing coolant below the belts and pulleys. Or a third scenario that I just experienced my self with my 2006’s LQ4 6.0. There’s a small plastic, off kilter “T”shaped three holed connector that connects the coolant hoses that run up to the heater core, and this pieces connects said hoses to the water pump. GM made the connector out of plastic. Mine developed a crack and a couple of weeks ago the crack got big enough to spew coolant into a big puddle under skid plate. As you’re looking at the engine from the grille area this connector is just below the fan and pulleys on the passenger side of the engine block coming off the water pump.
I would recommend seeing another mechanic to figure out where the coolant is actually leaking out. Radiators, water pumps, and hoses age and crack, it’s just what happens as these trucks age.

Thanks for the thoughts. I just check the T”shaped three holed connector and it seems sound but is wet, so this could be one of the spots leaking... i suspect there are multiples. I am going to take it to a better mechanic this week.

 

[adventurenali92]

Sorry for the delayed response, been on vacay with the family since i posted. BLOWN AWAY by the friendly suggestions.

Thanks for the thoughts. I just check the T”shaped three holed connector and it seems sound but is wet, so this could be one of the spots leaking... i suspect there are multiples. I am going to take it to a better mechanic this week.

Gotcha! Good luck and hopefully it works out for the better!

 

[Rocket Man]

I spoke too soon, glad to hear back from you. A better mechanic is a sound plan. Be sure to ask questions about exactly what’s leaking. If he determines it to be an internal engine leak I would mention the Castech 706 head issue. If it has them and they’re leaking, it doesn’t mean the end for the engine- just depends on what you’re willing to spend to fix it. These motors can easily go 300-400,000 miles or more.

 

[OR VietVet]

Doubt if could be heads if it is "spraying out". But hell, I am wrong about something at least once a day.

 

[mauger84]

Hey everyone, sorry for the delay, I've been away on vacay with the fam since I posted and haven't had time to respond. BLOWN AWAY by the helpful feedback.
- I checked the oil and it's not milky... looks good.
- I don't think the engine is gone, it still runs very strong.
- I do plan to take it to a better mechanic this week to have another look.

Before I left for vacay, I ran some K-Seal coolant leak repair and some Bar's Leaks through the system and thought most of that bled out after running the engine for 15 min. But days later my wife drove it and told me she didn't have any issues. I just refilled the coolant with water (added about 1.5 gallons) and ran it for 15 min and believe the leak has largely been resolved (at least for now).

I'll report back here as I get more info. Either way, I think I'm interested in selling it. Carmax told me they'd buy before all these issues for $2k. Would be happy to hear what you all think it's worth.

Thanks again.