Heating up on the highway

[mtbtim]

I am going to go another direction with that and say that the new thermostat spring is used on other Toyo thermostats, thus saving Toyo some $$$ in material costs if the spring used in the old T stat was unique or slated just for the 5vz.

I'll buy that theory as well.

 

[4Runner4TW]

Are you observing these temperatures with your A/C on? This will definitely warm up the ambient air prior to it reaching your radiator.

I noticed that mine gets warm on the highway, but only when the A/C is running. My truck usually runs 186-188°F in normal stop and go traffic but the temperature will increase by ~5°F with the A/C. When I'm on the highway the temperature will creep up to 198-202°F (at 2400 RPM) but immediately return to normal temps when off the highway. I noticed this yesterday and was considering doing a search about it, so it's convenient that I can just tag along on this thread. My temperatures haven't gotten high enough to raise any concern though...

I'm running a new radiator, new thermostat, new water pump, fresh coolant, etc.

Yes AC on. Looks like you’re having the exact same issue.

 

[4Runner4TW]

So it wasn't a Toyota thermostat installed? As Charlie stated,.start there first.

The one the shop installed was not. So I replaced it with a Toyo one. I’m pretty sure I went 6 o clock. I remember going with what ever Toyota recommended. I’m going to order a new radiator tonight. At this point I’ve put 130,000 miles on it and who knows how many the previous owner did.


Today just drove to work. 14 miles: 7 highway 7 City. It’s 100 out. AC on. It got to 202 at the top of a climb. Once I hit the city it dropped to 188. Sat and idled in the parking lot the temp went from 186-190.

 

[4Runner4TW]

Just ordered the Denso radiator and Toyota cap. I'll get them installed this weekend and see how that fares.

If those don't solve the issue I'm thinking the water pump the shop installed may be crap?

 

[aontkos]

The one the shop installed was not. So I replaced it with a Toyo one. I’m pretty sure I went 6 o clock. I remember going with what ever Toyota recommended. I’m going to order a new radiator tonight. At this point I’ve put 130,000 miles on it and who knows how many the previous owner did.


Today just drove to work. 14 miles: 7 highway 7 City. It’s 100 out. AC on. It got to 202 at the top of a climb. Once I hit the city it dropped to 188. Sat and idled in the parking lot the temp went from 186-190.

I think the temperatures that you and I are seeing are perfectly acceptable. Everyone drives in different environmental conditions and totally different driving habits. I wouldn't get worked up about it.

Scan this and rest easy.

 

[LittleCaesar]

The one the shop installed was not. So I replaced it with a Toyo one. I’m pretty sure I went 6 o clock. I remember going with what ever Toyota recommended. I’m going to order a new radiator tonight. At this point I’ve put 130,000 miles on it and who knows how many the previous owner did.


Today just drove to work. 14 miles: 7 highway 7 City. It’s 100 out. AC on. It got to 202 at the top of a climb. Once I hit the city it dropped to 188. Sat and idled in the parking lot the temp went from 186-190.

How clogged are the radiator fins? Ever pulled off the grille and hosed down the condenser and the radiator before? I will be curious to see what the old one looks like.

Ever have this problem before changing out the TB and all, even when you were hauling that trailer years ago to the PNW?

OEM or at least Aisin pump?

 

[4Runner4TW]

How clogged are the radiator fins? Ever pulled off the grille and hosed down the condenser and the radiator before? I will be curious to see what the old one looks like.

Ever have this problem before changing out the TB and all, even when you were hauling that trailer years ago to the PNW?

OEM or at least Aisin pump?

I hosed out the front a few weeks ago anticipating a hot summer here. It was quite bad. I do use this truck off road a lot and because I have AC and he doesn't he always going in front because of the dust out here.

Its only overheated once and that was due to a bad radiator cap. That was two years ago now. I have no Scangauge data before the TB job was done.

Asked a mechanic friend of mine and he thinks it could be a flow issue as well.

 

[LittleCaesar]

Good luck then. I hope it will be a radiator or the cap, but my gut tells me it is the water pump or the tensioner, where the impeller just isn't moving quickly enough at high speeds.

At least though the coolant temps aren't crazy high.

Keep the thread alive.

 

[DaMonkey]

Just ordered the Denso radiator and Toyota cap. I'll get them installed this weekend and see how that fares.

If those don't solve the issue I'm thinking the water pump the shop installed may be crap?

i think if the water pump was bad, you would be overheating in traffic.

sounds like you have a flow problem at high RPM. very good chance your radiator cap will fix it because a negative pressure differential from a bad cap can cause this.

i'd suggest before you put in a new radiator or new water pump, get the truck hot in the driveway, let the coolant get hot and expand. open the hood and throttle up. watch your lower radiator hose, pretty good chance you'll see it collapse like nostrils getting pulled in your nose when you sniffle super hard. if that's the case, it's either hose or cap. just an easy check before you throw too many parts where you don't need to.

 

[absalom]

My money is on radiator. The symptoms sound identical to a POS Suzuki Samurai that I had with overheating issues at speed. Replaced rad, fixed all issues 100%.

Be sure to only use genuine OEM Toyota LLC coolant, non-diluted.

 

[traildog]

For what it's worth, I too am in AZ and use to ride a motorcycle in the summer and the faster I would go the hotter my skin would get. Sometimes to the point where my hands would start to tingle from the heat. Think convection oven.

 

[JoshuaHufford]

First car I had as a teenager (72 Plymouth Valiant) would overheat at any highway speed but was fine in town. This was a no ac car with no fan clutch on the fan. A new radiator fixed the problem, it was very clogged up.

The faster you drive the more heat your engine produces, it doesn't matter how much air is moving over the radiator, if you can't get enough coolant flow through the radiator it won't be able to dissipate the heat. I'm thinking flow problem for sure.

BTW, I'm new here and new to 4Runners, just bought one 2 days ago. What is the jiggle valve????

 

[Saybo]

First car I had as a teenager (72 Plymouth Valiant) would overheat at any highway speed but was fine in town. This was a no ac car with no fan clutch on the fan. A new radiator fixed the problem, it was very clogged up.

The faster you drive the more heat your engine produces, it doesn't matter how much air is moving over the radiator, if you can't get enough coolant flow through the radiator it won't be able to dissipate the heat. I'm thinking flow problem for sure.

BTW, I'm new here and new to 4Runners, just bought one 2 days ago. What is the jiggle valve????

The jiggle valve is exactly what it sounds like. A little jiggly piece on the front of the thermostat. It allows air to escape the engine block and make it's way to the top of the radiator to be expelled.

 

[JoshuaHufford]

Thanks! So this is something all thermostats have correct?

 

[thegipper]

Thanks! So this is something all thermostats have correct?

No.

My 4runner was the first vehicle I've owned that had a jiggle valve on the Tstat.

 

[4Runner4TW]

No.

My 4runner was the first vehicle I've owned that had a jiggle valve on the Tstat.

Everyone agrees 6 O Clock is the correct position?

I remember when I installed mine I found posts for 6, 12, 10, and 2. I think I even remember someone saying Toyota recommended one way but the FSM said another.
A mechanic friend of mine said 12. Logic there is air bobbles raise. I am the one who installed the current thermastat, but I cant remember which way I went. I guess I'll find out soon.

But anyway 6 o clock is where I will make sure it is at.

 

[LittleCaesar]

At 6 all day long.

 

[4Runner4TW]

Quick Update!

Parts came in yesterday and I just got them all installed. Fresh new Toyota coolant and radiator cap.
I went with the Denso radiator on Amazon that everyone seems to like. Didn't come damaged which I guess is an issue.

Thermostat is at the 6 O'Clock position. Made sure to check that.

Burped the system, ran it with the heat on. According to the Scanguage with the heat on while burping it was around 184-188. Once fully burped I put the AC on high and continued to let it idle (now with the cap on). No leaks. It idled around 188-190. When it was at 190 a quick rev would drop it down to 188. Total time idling in the garage (vented) was about 30+ minutes.

Real test will come on my drive to work today. Its a mixture of 65 mph highway (which is where the issue was) and 35 mph city. Total time about 25-30 min. Excited to see if this helped.

I ran my shop vac with the carpet attachment on the AC condenser in both suction and blow modes. There was a lot of dust and bugs! As for the radiator it looked stock, but didn't seem in bad shape. Just dirty, but the inside seemed fine.

Will update tonight. Temp in my part of Arizona today will be around 95-98 degrees.

 

[4Runner4TW]

Just drove to work. It’s about 98-100 out. AC on high. One passenger. On the highway temp stayed around 191. At the 6% climb that’s about a mile long it got to 198. Came down and floated around 191-195 in traffic.
Not as good as I hoped, but it never hit the 202+ mark like it was. I’ll keep an eye on it over the next week.

 

[phattyduck]

At 6 all day long.

Just so everyone is clear - 6 o'clock for the 5vz. Almost every other engine it should be installed at the 12 o'clock position.

Sounds like the problems are fixed. <200 in demanding (~100*F, AC on, uphill at speed) conditions is good and right around 190*F the rest of the time is perfect.

-Charlie