2004 Chevy Blazer V6 4.3 Engine 4x4 - 122,000 miles. Parked in home garage all the time. Owned since 2007 (15 year anniversary coming soon)

I dont know what has been up with my Blazer but it seems like it does not like being out when the temperature is 70 degrees or higher. I notice immediately that when it is warmer outside my Blazer seems to take a few more seconds to get from 0 to 40 mph or whatever the speed limit is. I live in Texas so I have to avoid driving my Blazer in the hot summer months when it is 90 to 100 degrees daily. I found this out the hard way due to overheating in 2016 and 2020.

The engine first overheated in summer 2016, but I never had any warnings. When I drove it for more than 30 mins on 80 degree and higher days is when the overheating happened. Replaced Radiator, Water Pump, and Thermostat, then the issue went away. However the previous overheating did cause a later transmission problem as water from radiator had gotten into the transmission, which I found out when the vehicle would not drive one day in December 2018.

December 2018 I had to do Transmission EPC and Transmission Manifold Pressure Switch due to this issue. After that everything was great again.

Then in June 2020 is was like summer of 2016 all over again. The overheating happened without me really knowing but I could tell the vehicle was driving much slower in the summer and sometimes was struggling slowly from red lights. Had to replace Radiator again, it was ruined. Maybe the 2016 Radiator was bad, not sure. But a former Blazer owner told me to replace Fan Clutch and said that might be reason engine kept overheating. After replacing Radiator and Fan Clutch I could still see that my Blazer did not like driving in warm weather.

August 2020, same exact transmission issue happened, water got in it due to previous 2020 overheatings. But this time I could tell the transmission was really bad. Had to rebuild the transmission and also replaced Coolant Temp Sensor. After that, everything seemed great for a few months.

Summer 2021 I noticed the same struggles of driving when it was hot outside so I gave my Blazer this summer off. Only driving it about 2 times a week on short distances (15-20 min trips and no highway).

Early November 2021, 65 degree day I had the Blazer on the highway and check engine light comes on. Said Transmission Slipping and recommended to replace Torque Converter Clutch (TCC) Solenoid. BTW this is barely 5k miles since the August 2020 transmission rebuild. It was under warranty so I took it back to transmission shop and just got it back yesterday (they had it for 2 weeks due to supply delays). I assumed they had to replace a few parts but they told me they rebuilt the entire transmission again, same thing they did in August 2020. It cost me nothing due to warranty.

Blazer is taking off so good at red lights right now. Not taking a little longer to get from 0mph to the speed limit. However it was 50 degrees today. I took it to a car wash yesterday when it was 75 degrees and noticed that today it drove better on stop and go traffic (red lights and stop signs) that it did at 75 degrees yesterday, although yesterday's driving was still good. But today at 50 degrees the Blazer took off from red lights like a Mustang.

I dont know what to do next. Someone told me to sell it now after this last transmission rebuild before the overheating happens again. I dont want to though, had my Blazer for 15 years and want to keep it. It looks so good, Black 4x4 with Black Tinted Windows. Low mileage (122k) for 2004. It is in great shape in and out, nice original paint job and perfect interior. When the tow truck guy took it to transmission shop last summer he was in shock that the inside of my Blazer had no tearing of the seats or anything.

I worry that even if I take it easy on my Blazer in the hot summers that the overheating will return. This ever happen to anyone else? Any suggestions? I want to keep my Blazer for many more years but worry about it's future.

 

When you say overheating do you mean that the temp gauge in the dash goes above normal? How high? At idle or while driving? Have you ever cross checked the temp reading with a scanner?

George

 

No, the dash never indicated any overheating. Issue was mostly at idle and then while taking off from red lights. Summer 2016 on one real hot day where I did a lot of shopping when I got back the engine seemed pretty hot. I could feel the intense heat and then all the sudden coolant is leaking out in my garage. Radiator went, so replaced that and Thermostat. Then same thing happened again week later so replaced Water Pump. Then it was ok.

Summer 2019, year before the transmission got rebuilt is when I really noticed a lot that the vehicle was struggling in stop and go traffic. But once I got going it was fine, it was just going from 0mph to the speed limit that seemed like a long climb/struggle. I replaced the Fan Clutch based on someone's suggestion in July 2020 when I noticed the same sluggish conditions as previous 2019 summer, but still needed a transmission rebuild in August 2020. It is possible that the transmission damage was done in 2019/2020 and me replacing the Fan Clutch was the true issue with the hot engine, but I really dont know.

Mass Airflow Sensor had to be replaced in 2019 and in 2020, but transmission shop just told me that they also saw Mass Airflow Sensor when they did the check engine light diagnostic. They said they dont deal with engine work. However the check engine light is now off after they rebuilt transmission this week. The light was on due to Transmission Slipping Code according to Auto Zone, which transmission shop confirmed. But they also mentioned possible Mass Airflow Sensor code. I dont get why Mass Airflow Sensor would keep going bad, I got it from a different place each time.

I have not cross checked the temp reading with a scanner, will need to try that. But the gauge was at lowest setting this morning since it was so cold and then it moved up a little when driving, still way in safe range.

43 degrees this morning so Blazer drove great. I still worry that its only cuz the recent transmission rebuild and that all the same issues will happen again.

 

If you never have a high temp indication on the dash gauge and no high temp indication on your scanner then you probably don’t have a coolant system problem but rather a problem related to a vehicle that gets to high normal operating temperature with the fuel system, ignition or mechanical system. A Marginal coil, ICM, fuel pump, etc. I think it’s time for some standard issue diagnostics. Let me know if I can help. Do you have any codes?

George

 

Also, a MAF code does not mean a bad MAF sensor necessarily. Again proper diagnosis is key.

George

 

you mean any check engine codes? No, none now since the transmission just got fixed.

Do you think I need to take it in a shop for the full engine diagnostic? The one you pay for that is better that the free one from AutoZone?

 

That depends on how involved you want to get in the diagnostics and repair of your truck. We can get you set up with good scanner capability and I can walk you through the process. You would learn a lot, potentially save a bunch of money and in some cases get it fixed right with less aggravation depending on the quality and honesty of the shop. If you have no tools and have no desire to learn with no patience for a logical diagnostics thought process and flow then by all means turn it over to your local mechanic, just know that few are gifted problem solvers for these type of issues. I live for this type of thing and have not hired a mechanic for 40 years across 2 dozen vehicles but that's me. I'll stick with you as long as you want if your game. I don't think your overheating, its time to find out why your truck runs crappy when its hot outside. Could be as simple as a bad coil, but there are many possibilities.

Could we hit a dead end with no joy? Its possible but plenty of guys come here after multiple trips to the mechanic with no joy and I have not hit a brick wall in quite a few years. Most of the guys here quit before we are finished because a wonky hard problem takes some work and patience.

Let me know if I can help.


George

 

George, thanks this sounds great. I would like to try to diagnose this myself since the shop was never able to pinpoint the issue. Right, it has to be something else not related to overheating/cooling system.

I have a my own tools, so should hopefully have what I need if I do the repair myself.

What do I need to buy for the scanner/diagnosing?

thanks

 

A proper scanning tool is essential to doing your work on anything complicated, otherwise you have to guess and throw **** against the wall with the parts cannon. These days there are many cost effective solutions. Les, one of our moderators is the resident expert and wrote this summary:

https://blazerforum.com/forum/2nd-ge...lazers-103424/

Bi-directional control is nice but optional in most situations. Live data, cmp retard, and graphing is essential. in my book. I am sure that Les would be glad to help you if you have questions. I use a high end Snapon which you don't need so my recent experience at a more reasonable price point is limited. Before that I bought an inexpensive used android tablet off ebay, the BAFX BT OBD port dongle off amazon and installed the two apps Les talks about. It was good stuff on the cheap. Lately people seem to like the ilink 400 as standalone tool. I have not tried this one myself but it sounds like it gets close to my Snapon for way less than stupid money, if you only work on the one vehicle. I work on about 6 of them.

Once you get up and scanning, lets get your truck fixed. My favorite problems are complicated and turned away by repair shops before you get here.

George