New head gasket, now truck overheats

Just in case some one comes along with a similar issue and views this thread.

Turns out the headgaskets were installed backwards. See the above thread titled "1996 unused for four years" (post #137 in this thread) for pictures of the old head gasket incorrectly installed compared to the correct oem headgasket.

The left and right sides are nearly identical, except for one nickel sized port on the left head that is absent on the right. Mine were installed with the port blocked due to the right head gasket being placed on the left head.

 

I'm glad you decided to do this yourself, doing mechanic work isn't hard at all, the hardest part is getting up the courage to try to do it yourself.

ps- I wouldn't blame the other guy, you can see how easy it is to make such a mistake if you are not aware that they are "side specific" gaskets because "in general" its not uncommon for head gaskets to be made with extra holes so that you can use them on either side

 

So I was asked to check in here and read up on the fun. I didn't read every page because to be honest it looked like a lot of back and forth about the thermostat position as well as the right coolant to use. So here is my take:

Yes, believe it or not the direction of the jiggle valve for the 3.4 does make a difference. I had heard this time and time again and was not going to drink the kool aid, so i decided to take a Tacoma 3.4 that I had in my shop and do an experiment. To try and keep it as controlled as possible the first thing I did was allow the engine to warm up to operating temperature and check it. Temperature was a reasonably steady temperature of 180ºF. Right where I expected it. The job was to replace the coolant pump because it had just started developing a leak, so off I went, replacing the water pump, and inspecting the thermostat. After the water pump was replaced I removed and inspected the thermostat and found that it was clean, and in good condition. I also noted that the jiggle valve was located in the 6 o-clock position.

I mixed up a 5 gallon container of coolant and reinstalled the thermostat, but I put the jiggle valve in the 12 o-clock position. I refilled the system with my air-removal kit and started up the engine. I waited for it to warm up and noted that while it did eventually get to 180ºF, it took a lot longer to do so than expected. Thinking perhaps this was just due to having a new coolant pump I wanted to retest this, so since it was getting close to closing time I left the truck to sit overnight.

Next morning I opened up shop and started the truck. (It was the middle of summer, so ambient temp was 85º) Interestingly enough I noticed that after a few minutes the check engine light came on, and the coolant temp was 170ºF. I waited and before too long the engine finally did reach the 180ºF mark. Checking the code the truck had a P0125, insufficient temperature for closed loop operation. So I went ahead and had one of my techs remove the thermostat and reposition the jiggle valve to the correct position. We then refilled the system using the same coolant that was in the 5 gallon container and to try and keep the test as close to even as possible waited until after lunch to restart the truck. Coolant temp at start up was I believe 86 or 87ºF. Engine warmed up, no check engine light, and it reached 180ºF a bit more than 10 minutes faster than the morning startup.

Now WHY it does this, I can't explain. But it happened.

 

I made the same mistake on a 5.0 Mustang(head gasket upside down...I was drunk) also, so I was leaning in that direction when reading this.
that or the clogged radiator. Usually a burp condition is taken care of in 10 minutes of trying...but yes, I've seen many Toyo's that need to be burped.

 

Well the head gasket job is done, and the engine no longer overheats. If you been following my other thread you saw they were installed backwards (left on right right on left). See the referenced thread for pics and details.

https://www.tacomaworld.com/threads/1996-unused-for-4-years.398268/

 

I'm glad everything worked out ok happy driving!!!