What temps do you consider "dangerous" on a 1fz-fe (1 Viewer)

[mudgudgeon]

I also don't necessarily agree that the cooling system is at max capacity the moment the thermostat is fully open.

It's more that Toyota figured you need full coolant flow beyond that point.

With a pressurised radiator cap, and coolant to toyota specs, coolant has more capacity than 203⁰f.
If 203⁰ was the limits of the cooling system, Toyota would have installed a thermostat that was fully open at 190⁰, or something somewhat before it was at its limit

 

[jonheld]

No disrespect intended, but I don't entirely agree with your analysis of the cooling system capacity: the coolant and the load aren't the whole equation. Airflow is also a major factor. 203* at a standstill is very different from 203* moving. Also, the thermostat is fully open at 203, but is your clutch fan pushing maximum air at that point? Sure, if nothing else changes, then theoretically the temps would continue to climb. To my mind, the odds are on some other factor changing before you're in truly dangerous territory, or as you said, you can change a variable or two yourself (slow down, etc). What I'm trying to get a handle on is what is considered truly dangerous. If you are saying you aren't at all comfortable pushing it past 203, then fair enough.

All your statements regarding variables are 100% correct. My statements were regarding a highway drive scenario. Relatively constant speed, constant ambient, constant load. Sometimes I forget to mention things that are rolling around in my head. I apologize for that.

As far as "comfort" I prefer not to push the old girl too hard regardless of the situation. I like to wheel the rocks and I like difficult, technical trails. I'm usually very conservative on the throttle, and I have no issues pulling cable when needed. 4.88s and the new low range gears make it very controlled and I don't enjoy breaking parts as I have to drive her home. On my last trip out to Moab, she peaked around 210F, but that was in the heat of the day on Pritchett as I was towing another truck through some obstacles.
On long highway drives in the heat of summer I just keep the speed below 70, especially when towing my M416 with the AC on. Pulling hills I tend to kill the AC until I crest. That reduces the heat load and prevents me from getting passed by fully loaded dump trucks After driving a 3FE for 25 years, I have no issues with relaxing in the right lane.

In short, I keep an eyeball on the temp in summer and I don't like to go beyond the 203F mark.

 

[BTLSHP]

A a quick data point I just got home from a 50 mile drive to town and back and with the Toyocom OB1 plugged in my range was between 195-203F, mostly around 199F, 203F going up a long hill at highway speed. Outside temp in the low 90's, AC on. Seems about right for the conditions.

That is about what I saw on my Toyocom OB1 in around 2 hrs of stop and go driving around DC in 94f temps last week. 203 came after shutting off engine to park.

 

[PeterTheBeater]

I’ve got a 97 with aluminum rad(eBay), blue clutch with temp adjustment and 15k fluid, OEM thermostat, and an electric cooling fan for the AC. All the rubber stripping is more or less still there.

I can run as cool as 181 to as hot as 218. Sitting in Starbucks drive thru in Mojave I’ve hit 218. Anything over 210 and I start getting concerned. Most of the time, pulling up grades I’m around 195.

Ime armored with 35” and stock gears. Really nothing else I can do besides trying another radiator or ditching the fan clutch.

 

[Saito]

Water boils at 212° at sea level. For every pound of pressure you put on it, the boiling temperature raises 3°. All of the pressure gets vented to the overflow once it exceeds the cap spring pressure. Betcha it’ll hit 250° before that happens. I’d say making sure the system holds pressure is one of the most important and most overlooked things in the cooling system. Tons of hoses on these 80s. Tons of potential leaks.

 

[Marvelicious]

Water boils at 212° at sea level. For every pound of pressure you put on it, the boiling temperature raises 3°. All of the pressure gets vented to the overflow once it exceeds the cap spring pressure. Betcha it’ll hit 250° before that happens. I’d say making sure the system holds pressure is one of the most important and most overlooked things in the cooling system. Tons of hoses on these 80s. Tons of potential leaks.

I think the OEM cap holds 13psi... 244*F I believe. It's not quite 3*/psi exactly, but pretty close.

All your statements regarding variables are 100% correct. My statements were regarding a highway drive scenario. Relatively constant speed, constant ambient, constant load. Sometimes I forget to mention things that are rolling around in my head. I apologize for that.

As far as "comfort" I prefer not to push the old girl too hard regardless of the situation. I like to wheel the rocks and I like difficult, technical trails. I'm usually very conservative on the throttle, and I have no issues pulling cable when needed. 4.88s and the new low range gears make it very controlled and I don't enjoy breaking parts as I have to drive her home. On my last trip out to Moab, she peaked around 210F, but that was in the heat of the day on Pritchett as I was towing another truck through some obstacles.
On long highway drives in the heat of summer I just keep the speed below 70, especially when towing my M416 with the AC on. Pulling hills I tend to kill the AC until I crest. That reduces the heat load and prevents me from getting passed by fully loaded dump trucks After driving a 3FE for 25 years, I have no issues with relaxing in the right lane.

In short, I keep an eyeball on the temp in summer and I don't like to go beyond the 203F mark.

LOL, I'm frequently guilty of having half the conversation in my own head. Totally understand.

I'm definitely willing to push things higher than many on here. I became a believer in the "Italian tune-up" when I bought and old diesel Mercedes that had been running waste vegetable oil (not converted to biodiesel). The biggest trouble with that is that it can have incomplete combustion that tends to gum up the rings. I had a ton of blowby when I bought it, but the harder I ran it (on actual diesel) the better it got. So I don't hammer on my old 80 all the time, but I do occasionally give 'er the heavy foot and see how she sounds passing people on long hills in second.

Full disclosure: my 80 isn't a candidate for "collector status", it's not something I depend upon daily, and I do this stuff close to home. I'd rather find the weak point when I'm on the highway within 20 miles of my house than somewhere far less convenient.

 

[SNLC]

Change your coolant in spring to 30/70 vs 70/30 for winter. Water dissipates heat best.

I used to do this when I would take my 6,000lbs 2003 supercharged Tacoma to Panama. Living in Wyoming I always ran 70/30 in the winter, obviously don’t need that in Panama. My first trip down the TPS in the throttle body got cooked from heat sink. I put a TB spacer on it and would go to 30/70, never had another problem with it.

My 80 has a new engine with 18,000 miles on it now. Stock blue hub currently. When it is 110* out and I got to sit idling in traffic it will creep to 210ish. Pulling a grade on the highway at 70+mph in the same heat will send it to maybe 205. Otherwise no issues. I got a new blue hub on the bench and some 20k fluid so I am upgrading.

Keep in mind, asphalt is about 140* when it is 100* ambient. Even hotter, I have seen nearly 150*. I check it once in awhile with a laser thermometer because I walk my dog and I don’t want his little paws cooked.

Cheers

 

[mudgudgeon]

I think the OEM cap holds 13psi... 244*F I believe. It's not quite 3*/psi exactly, but pretty close.

Coolant also raises boiling point, so theres more blue sky above that.


Not that I'd suggest pushing it to that point

 

[Marvelicious]

Coolant also raises boiling point, so theres more blue sky above that.


Not that I'd suggest pushing it to that point

Ah, good point.

 

[jpoole]

I answered 220 as that is when the AC cutoff kicks in which seems like where Toyota decided to get serious about the 1FZ engine temps.

Reality is though that in the rare event that the 1FZ in my 80 goes over 200 I'm paying attention and taking steps to keep it from going any higher. Over 200 is a pretty rare event on the humid, low elevation East Coast, even when towing but it has seemed easier the few times I've towed the camper further West and pushed the 1FZ harder against elevation and larger hills. I assume that a big part of the difference is that the drier air doesn't remove heat from the radiator as effectively but elevation, etc. are also very relevant.

 

[oilbrnr]

Approaching 210* I start to take notice.

I'll hit 210* this time of year (summer 100+) on a hard run up to Flagstaff from Phoenix (6,800 lbs). Yesterday I think it was 105ish and kinda humid due to monsoon season here, lots of stop and go in Phoenix/Tempe/Scottsdale traffic. 187-195* all day long.

I can't remember, has there been much discussion of the difference in IAT of Dorkel'd vs. stock intake fender intakes? Is there much/any radiator/engine compartment hot air feedback loop in stock form? Just curious in general is all. I know that my Scanguage IAT will show about 9* warmer than actual (well from my Gentex GM rear view mirror with temp/compass) outside temps with a Safari installed. No clue what it was prior to install as I didn't have the SG.

 

[REKCUT]

Mine runs pretty much at 197 year round once it warm up . Doesn't differ from summer to winter just takes longer to get there in winter. Will occasionally get in the low 200 range on long slow tail climbs when the rpm range is under 2k. drop a gear and get it back above 2k and it drops back down. No turbo.

226.

I also take notes of anything coming from this source

 

[Cruisers and Co]

I feel like we've moved away from what's dangerous to what people are comfortable with.... 210 is not dangerous, 220 isn't dangerous, 226 is AC cut off and obviously where the Toyota Engineers thought load needed to be taken off of the cooling system. In my mind 230+ (numbers chosen in the pool) is dangerous as that's to get past what Toyota wants it to be at. 226 you should be actively trying to get heat out of the system.

Now like I said before most of the time you should never be seeing more than 210 with a healthy system and if you are there is likely something going on with the coolant system and should be investigated.

I can't remember, has there been much discussion of the difference in IAT of Dorkel'd vs. stock intake fender intakes? Is there much/any radiator/engine compartment hot air feedback loop in stock form? Just curious in general is all. I know that my Scanguage IAT will show about 9* warmer than actual (well from my Gentex GM rear view mirror with temp/compass) outside temps with a Safari installed. No clue what it was prior to install as I didn't have the SG.

IAT's can play a huge roll in coolant temp. Gen 1 of the turbo, before I figured out how I wanted to incorporate the stock airbox, pulled air from inside the engine bay through a crappy cone filter. There was a certain point were IAT's would hit a point that you could watch the Coolant temps started to climb and would not stop. When on the move not an issue, stopped at a light temps would just continue to rise on a hot day. Airbox pulling from a fender or snorkel not an issue. I wish I had a record of intake air temps but they'd get past 160 and I do recall seeing up to 180's which makes sense with the air coming through the radiator (220+) being sucked right back in.

 

[BTLSHP]

Ok, I am trying to get our Maryland area '94 ready for life in Denver. I have just put in a Toyobd I and have been watching my temps with interest. I assume Denver brings less cooling due to drier less dense air. The car is generally running in the 195-199 range now.

I have a new water pump and every hose in the system is new. I am looking at the radiator right now which is an 8 year old replacement by Toyota with shredded foam. I have the 1.25 x 1.25 inch stuff that appears to be a consensus recommendation and have fit pieces under the radiator at the support and inside between the rubber mounting isolators. As I see it there is a tight fit with little gap between the shroud and the radiator that I could firm up with no more than a band type paper clip.

Along the top of the radiator I have something like a 1/8th inch gap between the front support and the radiator. Is that something I am trying to fill? What else? I am starting the fan clutch fluid today.

Thanks,

 

[jpoole]

I feel like we've moved away from what's dangerous to what people are comfortable with...

This does seem to be true but I'll say that "comfortable" in part reflects fear of HG failure and the long aluminum head on the iron block with their different expansion rates. There are a lot of factors that may contribute to HG failure and beyond truly overheating I don't think there's much/any proof that running temps over 200 F contributes to HG wear. Even so, since the 80 so commonly stays at or just under 200 I've grown comfortable with that temp range and will take steps to cool the 1FZ down, as possible, in the rare event that it climbs above 200. Keeping the temps at a more moderate level at least makes me feel like I'm stressing the HG less by moving the head/block less. I'm not going to take dramatic steps to drop temps until closer to 220 but I'll slow down a bit, drop down a gear or turn off the AC when the rig crests 200 and temps will drop right back down. This is typically on a hill so once at the top normal driving resumes.

 

[Marvelicious]

I feel like we've moved away from what's dangerous to what people are comfortable with.... 210 is not dangerous, 220 isn't dangerous, 226 is AC cut off and obviously where the Toyota Engineers thought load needed to be taken off of the cooling system. In my mind 230+ (numbers chosen in the pool) is dangerous as that's to get past what Toyota wants it to be at. 226 you should be actively trying to get heat out of the system.

Yeah, you're getting what I was going for. I will say, I think this has been a pretty good thread overall and there's a lot of good discussion here. Rather than discuss someone's specific problem, we're getting into the meat of whether they have a problem or if they're just overreacting because it's a hot day and they aren't used to seeing temps over 200. I suspect that this is the main reason for the big "dead spot" in Toyota's temp gauge: they didn't want a line up of panicked customers at the dealer service department every time there was a heat wave!

This does seem to be true but I'll say that "comfortable" in part reflects fear of HG failure and the long aluminum head on the iron block with their different expansion rates. There are a lot of factors that may contribute to HG failure and beyond truly overheating I don't think there's much/any proof that running temps over 200 F contributes to HG wear. Even so, since the 80 so commonly stays at or just under 200 I've grown comfortable with that temp range and will take steps to cool the 1FZ down, as possible, in the rare event that it climbs above 200. Keeping the temps at a more moderate level at least makes me feel like I'm stressing the HG less by moving the head/block less. I'm not going to take dramatic steps to drop temps until closer to 220 but I'll slow down a bit, drop down a gear or turn off the AC when the rig crests 200 and temps will drop right back down. This is typically on a hill so once at the top normal driving resumes.

There's probably plenty of value in the discussion of what's "comfortable" also. It's a big, long engine and there's probably some validity in keeping an eye on it. I know people have theorized over the EGR system playing a part in HG failures and I'm sure it plays a part in this as well, though I'd need a lot better equipment than I have to do more than theorize.



Something I was kicking around and mentioned in one of the other threads is a set of those hood risers. I wouldn't want to run them on a day to day basis, but as something to help get a rig off the trail, or just to keep rolling on the road trip with the AC on, they shouldn't take more than a couple of minutes to install/remove if you do it right. Did anyone ever get around to testing them to see how they work in practice? If they work like I think they should, it would pull more heat out of the engine compartment, but without a wind tunnel, I can't be sure they wouldn't actually pull air in at the back instead of through the radiator.

 

[mudgudgeon]

I suspect that this is the main reason for the big "dead spot" in Toyota's temp gauge: they didn't want a line up of panicked customers at the dealer service department every time there was a heat wave!

Toyota foresaw MudOCD!

 

[mudgudgeon]

I know people have theorized over the EGR system playing a part in HG failures and I'm sure it plays a part in this as well

No EGR on Aussie 80s AFAIK. They still have HG failures

 

[peacesells63]

I have had mine past ac cutoff several times prior to going through the cooling system. Still on original head gasket. After going through the enitre cooling system, I rarely see over 204. I dont really worry until the ac cuts off. The coolant temp drops as fast as the interior temp rises once the ac is off, so it has never been a problem.

 

[Cruisers and Co]

I think most head gasket failures were the result of a change in materials during the 90's. Since replacing head gaskets I haven't seen reports of users having issues like there were with the originals and IIRC there are 3 or 4 revisions (@OGBeno maybe you know the exact revision count?)