Toyota Tundra Forums banner
1 - 20 of 32 Posts

·
Premium Member
Joined
·
1,362 Posts
Discussion Starter · #1 ·
I changed the timing belt, tensioners, water pump, t-stat, hoses, serpentine, etc about two weeks ago. Used all factory Toyota parts and completely drained the radiator and block and went back with 50/50 distilled water and Toyota Red coolant.

I have a scan gauge and always watch my engine temp. If I remember correctly, it pretty much stayed right at 184 F consistently. Once I got it back on the road I noticed it was running between 184 F and 190 F with fairly mild outdoor temperatures (60 F - 85 F). Of course, the factory gauge is pointing to the middle of the range as it's always done, so if I didn't have this damn scan gauge installed I'd never know any different :rolleyes:.......

I first thought maybe the new t-stat was bad, so I replaced it with another new Toyota t-stat. It did make it run closer to the 184 F - 186 F mark more often, but it's still getting up to 190 F at times.

I then thought that maybe I had messed up the coolant mixture, so I completely drained the radiator and block and refilled again with the 50/50 mix of distilled water and red coolant......still with the same results.

Since nothing else changed, I'm either imagining that it always ran at 184 F without fluctuation, or it has almost got to be that the new water pump is not as efficient. I did notice that the water pump's impellers looked a little different, but didn't pay it much attention at the time.

So.......any ideas of what's going on??????
 

·
Registered
Joined
·
170 Posts
I changed the timing belt, tensioners, water pump, t-stat, hoses, serpentine, etc about two weeks ago. Used all factory Toyota parts and completely drained the radiator and block and went back with 50/50 distilled water and Toyota Red coolant.

I have a scan gauge and always watch my engine temp. If I remember correctly, it pretty much stayed right at 184 F consistently. Once I got it back on the road I noticed it was running between 184 F and 190 F with fairly mild outdoor temperatures (60 F - 85 F). Of course, the factory gauge is pointing to the middle of the range as it's always done, so if I didn't have this damn scan gauge installed I'd never know any different :rolleyes:.......

I first thought maybe the new t-stat was bad, so I replaced it with another new Toyota t-stat. It did make it run closer to the 184 F - 186 F mark more often, but it's still getting up to 190 F at times.

I then thought that maybe I had messed up the coolant mixture, so I completely drained the radiator and block and refilled again with the 50/50 mix of distilled water and red coolant......still with the same results.

Since nothing else changed, I'm either imagining that it always ran at 184 F without fluctuation, or it has almost got to be that the new water pump is not as efficient. I did notice that the water pump's impellers looked a little different, but didn't pay it much attention at the time.

So.......any ideas of what's going on??????

Sorry I can't help you out, but I am due for the same service soon. How much did it run you for all the parts? Also, is it neccessary to change the water pump when changing the timing belt? I never understood why everyone changes both.

I hope it all works out for you though.
 

·
Registered
Joined
·
113 Posts
I have run my SG2 for over a couple years now (I am at 50K) and monitor the engine temp closely. I live in California where the weather doesn't vary too much... I want to say it stays at 186 for much of my driving, but extended hill climbing through mountains it can get to 190 and hit 192 on a hot day. I haven't changed my belt or WP yet and don't plan to for another 50K. Just wanted to put it out there that i think this is normal temp fluctuations. Sounds like your radiator is def well flushed and I don't think you have any problems with possible overheating.

Also the coolant I bought from the dealer was already pre-mixed 50/50 so I didn't add any water... maybe that is where the extra couple degrees came from.
 

·
Registered
Joined
·
560 Posts
Don't get insulted, but let's look at the basics:
1. t-stat should be marked 82 degrees C
2. if suspended in a pot of water on a stove with a really good thermometer, you should see the t-stat open between 80-84 degrees C
3. "travel" of t-stat between 95 degrees C and 40 degrees C is 10mm
4. jiggle valve should be at 12 o'clock when installed
 

·
Registered
Joined
·
246 Posts
Sorry I can't help you out, but I am due for the same service soon. How much did it run you for all the parts? Also, is it neccessary to change the water pump when changing the timing belt? I never understood why everyone changes both.

I hope it all works out for you though.

The reason most people change the water pump at the same time is, you have to remove the belt to change the water pump.
Pumps usually dont go 200k miles and so DO you want to spend the time or money to do the job 2x or just 1?

I believe when we bought the tbelt parts for the boss's tundra it was around 5-600.00 from the dealership.
 

·
Registered
Joined
·
1,332 Posts
I have a V6 so not exactly a V8 but I have had a scangauge for 4 years I would say and my Tundra has always run at 191 on the gauge. This is exactly in the center of the temp gauge on the dash.
 

·
Registered
Joined
·
1,863 Posts
If I'm right, I think water can run a little bit cooler than the actual coolant will. So, it is possible that you had slightly more water than coolant in your system prior to changing it. A 50/50 mix is good, but not always necessary. I think often times you can get away with more water and less coolant, depending on the weather where you live.

I just did my timing belt service as well as the water pump (and I'm glad I did; the weep hole for the water pump had been leaking a bit). I don't have a scanguage but I've had no issues so far. When I refilled the radiator I poured 1 gallon of strait Toyota Red coolant. I then put about 1.5 gallons of DI water in. Now I didn't drain the block, so there may have been some of my old mix in there.

Even if it isn't 50/50 I'm not too worried about it freezing up. A 50/50 mix yields freezing protection up to something like -34 degrees Fahrenheit. Even if I have less than that, I will never see 10 degrees or so where I live.

So Jon, if you want your truck to run a bit cooler, just drain a little bit of your mix out and put strait DI water back in. It's worth a shot!

Oh, and here is an article I found. It relates to a plane engine but it's the same premise. Coolant Mix and Overheating
 

·
Premium Member
Joined
·
1,362 Posts
Discussion Starter · #10 ·
Don't get insulted, but let's look at the basics:
1. t-stat should be marked 82 degrees C
2. if suspended in a pot of water on a stove with a really good thermometer, you should see the t-stat open between 80-84 degrees C
3. "travel" of t-stat between 95 degrees C and 40 degrees C is 10mm
4. jiggle valve should be at 12 o'clock when installed
So what would happen if it wasn't at 12 o'clock? I'm pretty sure I put mine in at 6 o'clock :confused:.
 

·
Premium Member
Joined
·
1,362 Posts
Discussion Starter · #11 ·
I was thinking the same thing as far as the mix ratio goes, the coldest I've ever seen it get here in the last 31 yrs has been about -12 F, so I was thinking about running mine at -15 to -20 and calling it good.
 

·
Registered
Joined
·
560 Posts
So what would happen if it wasn't at 12 o'clock? I'm pretty sure I put mine in at 6 o'clock :confused:.
Donno. Might be that air prefers the high road.

But the Toyota repair manual says to do it that way. I wish I knew a cool way to paste the page right here. What I can do is paste it into a Word document and then attach that file to this post. (or something like that)
 

Attachments

·
Mech. Engr. / Mechanic
Joined
·
824 Posts
You have to remember that thermostats are a mechanical device. It's just a bulb filled with wax that expands when heated. Don't quote me, but I've read that there is a 5% tolerance for manufacturers. So.. an 180 degree thermostat will open anywhere from 175.5 to 184.5, which means that two new thermostats can give you a possible difference of up to 9 degrees when opening. I wouldn't sweat the reading you were getting. It's normal.
 

·
Premium Member
Joined
·
1,362 Posts
Discussion Starter · #15 ·
I honestly can't remember if I installed the jiggle pin at 6 o'clock or 12.....it was one or the other I know :rolleyes:. Suppose I'll pull it when I get home today and go ahead and throw it on the stove to see where it's opening while I'm at it.
 

·
Registered
Joined
·
232 Posts
I have been pondering your question. So, here is a WA theory:

The old timing belt was stretched just enough to retard the timing a tiny bit. The engine ran just a tad cooler.

The new belt brings the timing back to spec and the engine runs just a bit warmer.

This assumes that timing effects operating temperature somewhat.
 

·
Premium Member
Joined
·
1,362 Posts
Discussion Starter · #18 ·
I agree that it's still operating within reasonable range, but it just bugs the hell out of me that it's characteristics have changed after putting all new factory parts on it.

Another reason it bugs me is that it hasn't got up to our typical summer temps of 95 F+, so I'm crossing my fingers that it stays around that 190 F mark and not more like the low 200's.

I often spend hours in the woods at very low speeds and highway + RPM's, due to my t-case reduction, so I'm particularly sensitive to engine and trans temps and this truck has been the first I've owned that I never worry about overheating while off-road......makes me mad that now I'm worrying about it :(............

I also wondered about the timing deal, but figured surely it wasn't stretched that bad....dunno.

The coolant mixture ratio that someone touched on earlier could be a real possibility, since I doubt my original was dead on 50/50 like it is now. Also wondered about my factory t-stat opening up farther than spec or something. Also curious what effect worn out radiator cap would have, since it's the original. I just don't see something deciding to "break" during the 12 hr course of me replacing all the new parts - makes me suspect t-stat, water pump, mixture....and I've since replaced the net stat with another - I'll rule that one out today on the stove.

I'm thinking about replacing the small amount of coolant, that I'll have to drain to pull the stat out, with pure distilled water. The only thing that's making me second guess that is because the service tech told me that they seem to run cooler with a 50/50 mix......which goes against other things I've read.........I believe that water is more efficient heat transfer fluid than coolant and that a 50/50 mix is more likely just an easy thing to get right if you're a tech working on the clock :confused:.
 

·
Registered
Joined
·
1,863 Posts
I stopped going to Toyota dealerships around here because of the service techs.

My money is still on the mixture. 50/50 is nice and easy and works well, but it's also really easy to sell it that way too! I just think your mix could be brought down a little bit and that may make a difference.

And honestly, I have no idea which way I installed my thermostat.... :confused:
 

·
Premium Member
Joined
·
1,362 Posts
Discussion Starter · #20 ·
I stopped going to Toyota dealerships around here because of the service techs.

My money is still on the mixture. 50/50 is nice and easy and works well, but it's also really easy to sell it that way too! I just think your mix could be brought down a little bit and that may make a difference.

And honestly, I have no idea which way I installed my thermostat.... :confused:
I agree.......oh......and it looks like I'm not the only one pulling a t-stat today :D!
 
1 - 20 of 32 Posts
Top