1HZ operating temp

Submitted: Monday, Mar 14, 2022 at 17:06
ThreadID: 143393 Views:9784 Replies:7 FollowUps:17
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I have a 1HZ -T that the original temp gauge reads at 1/4 most times, when towing up a very steep incline it reaches about 3/4. I also have an aftermarket gauge fitted at the top radiator hose outlet which I'm not sure if it is giving me an accurate reading. Normal driving sits around 80c-92c, when on highway & towing around 90c-95c. Towing up steep hills (Toowoomba Range) original gauge gets to about 3/4, aftermarket gauge gets to 120c+. It does return to 'normal' range as soon as I get back onto reasonably flat ground.
I have serviced every item on the cooling system ( radiator rodded & flushed, engine flushed, both hoses replaced, thermostat replaced, water pump replaced, viscous fan serviced & new fluid) The turbo runs at max 8psi & fuel delivery has been set by local diesel mechanic (no black smoke etc).
Now I'm thinking the aftermarket gauge may not be exactly accurate or if the position of the sender is what is causing the high temps. Any advice on the issue would be appreciated. Is the high temps from the position of the aftermarket gauges sender unit? Is there any way to check the accuracy of the gauge? Or am I just reading to much into it?
Cheers Tony
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Reply By: Member - John - Monday, Mar 14, 2022 at 18:02

Monday, Mar 14, 2022 at 18:02
Remove the sensor and put it in a kettle, when boiling it should show 100 degrees C.
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Follow Up By: Member - Tony w16 - Tuesday, Mar 15, 2022 at 08:09

Tuesday, Mar 15, 2022 at 08:09
Hmm, didn't even think about trying that. I'll give it a go. Sometimes the simplest things work best. Thanks for the idea.
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Reply By: Athol W1 - Monday, Mar 14, 2022 at 21:23

Monday, Mar 14, 2022 at 21:23
Tony
I would suggest that the aftermarket temp gauge is working as it should, especially as the original gauge appears to agree with it.

I would be REPLACING the TSVC, as I have found that servicing these units is not always successful, one thing that is critical is the quantity and quality of the silicon fluid that is used for the refill.

Also with the replacement thermostat was an original Toyota part used, or was it an aftermarket part. I have found that some aftermarket thermostats do not completely shut off the bypass system, I have even found thermostats used that did not have the bypass shutoff valve fitted.

As far as checking the accuracy of these gauges I use a temp gun purchased on Ebay for around the $50 to $100 mark, just point at the thermo housing and pull the trigger, the laser light tells what is being measured and the gauge gives the reading to a fraction of a degree. Also good for checking the temps of many other things like brakes and tyres.

Regards
Athol
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Follow Up By: Member - Tony w16 - Tuesday, Mar 15, 2022 at 08:20

Tuesday, Mar 15, 2022 at 08:20
With the TSVC, are you referring to the viscous hub? I should have mentioned that I did replace it with a new hub & then replaced the silicon fluid ( genuine Toyota) with amount specified by Toyota after no difference was made ( just trying to eliminate all causes of apparent hot running) Genuine Toyota thermostat was used. I am just starting to think I'm reading too much into the gauge as the original is within operating window, maybe the temp readout is accurate & that it reads a bit higher than what I'm used to in other vehicles due to the position of the sender (system outlet straight off the head)
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Follow Up By: Athol W1 - Tuesday, Mar 15, 2022 at 09:41

Tuesday, Mar 15, 2022 at 09:41
Tony

Yes the TSVC (Temperature Sensitive Viscous Coupling) is indeed the Viscous Hub.

The usual location for a factory fited temp sender is on the engine side of and close to the thermostat, there are a few exceptions to that where the original Ford Falcon had them fitted to the rear of the cylinder head. By fitting the sender to the top radiator hose you are missing out on readings as the engine is warming, and also getting false readings should the thermostat stick shut, but otherwise you will be getting true temp readings.

As you have apparently checked that everything is in good order then I ask if the vehicle was an original build with the Turbo engine, and also if the radiator is specifically for the Turbo engine. Whilst 120 deg temps when working hard for long climbs is not unheard of in the modern vehicles I, like you, would be getting a little nervous when seeing them and knowing that the top of the hill is yet to come.

Most modern vehicle manufacturers deliberatly calibrate their factory fitted 'gauges' so that they do not change from the 'normal' operating temps untill they consider the temp to be abnormal, as they do not want the owners to be complaining under warranty about the fluctuating engine operating temps. In at least one such case the temp 'gauge' does not change between 75 deg and 115 deg when monitored via a Scangauge diagnostic tool.

Do you have a means of measuring the Exhaust Gas Temp (Pyrometer), and is that fitted before or after the turbo?

Regards
Athol
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Follow Up By: Member - Tony w16 - Tuesday, Mar 15, 2022 at 18:58

Tuesday, Mar 15, 2022 at 18:58
No,the 1HZ is a naturally aspirated engine, the turbo fitted is aftermarket. It has a top mount intercooler. I asked the radiator specialists when they were cleaning it out if they thought the radiator was suitable for turbo charged engine, & they said it was fine for it.
I have a EGT gauge fitted, the sender in the dump pipe post turbo. Max temp it reaches is around 300°c. We have in the past checked temps in other places ( pre turbo ect) & they were all within an acceptable temp range.
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Follow Up By: Athol W1 - Tuesday, Mar 15, 2022 at 19:38

Tuesday, Mar 15, 2022 at 19:38
Tony
I would be making further enquiries in relation to the radiator size, and in particular if there is a replacement core available with an extra row of tubes, as the fitment of a turbo does increase the heat load generated by the engine.

Whilst the original radiator in good condition may be suffficient during normal operation it is that extra heat load of towing and climbing a long hill when combined with the added heat load generated by the ability to burn more fuel (as that is what a turbo effectively does, more air means more fuel can be burnt = more heat load) can mean that the radiator is no longer suitable for the job at hand.

Regards
Athol
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Follow Up By: 2517. - Wednesday, Mar 16, 2022 at 13:36

Wednesday, Mar 16, 2022 at 13:36
I traveled with a mate who had a similar vehicle and same problems ,fitted a duel core radiator in Darwin solved the problem. Common problem with after market turbo so the radiator man said in Darwin.
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Follow Up By: Member - Tony w16 - Wednesday, Mar 16, 2022 at 14:55

Wednesday, Mar 16, 2022 at 14:55
Hmm, I might look into the radiator a bit further, It's the only thing left that hasn't been replaced. I'll try another radiator specialist & see what they say. Thanks for the info!
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Follow Up By: Member - FSH00 - Wednesday, Mar 16, 2022 at 23:26

Wednesday, Mar 16, 2022 at 23:26
Please let us know when you find the fix as I may be looking at the same issue in the future.
Pete.
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Follow Up By: That Troopy Bloke - Sunday, Mar 20, 2022 at 20:58

Sunday, Mar 20, 2022 at 20:58
You haven't mentioned what model the 1HZ is in. If it is a 75 series or early 78/79, there is an upgrade to a HDJ radiator that will fix all your issuesCMS I have this in my 75 and can vouch for this kit, my old bus runs cool as a cucumber now.

If a 80 or 100 series, I dunno, maybe a fan upgradeQikazz

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Follow Up By: Member - Tony w16 - Monday, Mar 21, 2022 at 08:01

Monday, Mar 21, 2022 at 08:01
That Troopy Bloke, it's in a 80 series.
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Follow Up By: Bob Y. - Qld - Tuesday, Mar 22, 2022 at 06:48

Tuesday, Mar 22, 2022 at 06:48
I’m intrigued that your EGT’s max out at 300° but coolant goes through the roof during steep climbs?
My V8 LC ute EGT sits between 300-320° on level going in most conditions, but recently, towing up new Toowoomba Range, EGTs slowly climbed up to 450° in 4th gear, until I backed off a bit & went back to 3rd. Like you, temps rapidly drop once at the top of the climb.

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Reply By: Gbc.. - Tuesday, Mar 15, 2022 at 09:53

Tuesday, Mar 15, 2022 at 09:53
I had toyotas for years, then changed to an isuzu powered holden. Bugger me if the temp guage didn't actually go up and down a bit as I went up hills, towed, drove in soft sand etc. and scared the bejeesus out of me until I got used to a guage that gives useful information. The toyota temp guages hardly ever move, not because they aren't getting hot but because the graduations are so far apart (probably on purpose) that the cap needs to be ready to get blown off before the guage gets to red. I'd guess you are seeing the same thing first hand - nothing 'wrong' with either guage, just they move according to different graduations.
AnswerID: 639831

Reply By: mountainman - Saturday, Mar 19, 2022 at 14:04

Saturday, Mar 19, 2022 at 14:04
PWR do ally radiators that could be your best bet
AnswerID: 639871

Reply By: Member - DOZER - Sunday, Mar 20, 2022 at 12:20

Sunday, Mar 20, 2022 at 12:20
Does your turbo run a new exhaust manifold, or an adaptor? Restriction pre turbo will cause a hot motor under load, there is a brand renowned for adapting the exhaust to suit a small turbo that causes overheating, your motor is a heat pump, keeping it cool is hard if the heat cant get out from inside
AnswerID: 639883

Follow Up By: Member - Tony w16 - Monday, Mar 21, 2022 at 08:06

Monday, Mar 21, 2022 at 08:06
It has a turbo specific manifold fitted, no adapter. It didn't always run hot, it used to run at quite acceptable temps. It's just got me stumped now that I've checked/double checked/replaced the whole cooling system it won't return to the temps it used to run at.
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Follow Up By: Member - FSH00 - Monday, Mar 21, 2022 at 20:54

Monday, Mar 21, 2022 at 20:54
DOZZER what would you say are a good brand of turbo kit for the 1HZ 80s or what is not.

Thanks,
Pete.
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Reply By: Member - Tony w16 - Tuesday, Mar 22, 2022 at 17:39

Tuesday, Mar 22, 2022 at 17:39
Ok, it would seem like we have solved the issue. It appears it was a combination of two things. The new aftermarket viscous hub was faulty ( it would work to a point but wasn't locking up as it should) and the aftermarket temp gauge has a bit of a fault. After looking at everything a lot closer & then borrowing & fitting another identical gauge we discovered my gauge was reading approx 10-15% high! So the temps are all within reason & I now have a fully reconditioned cooling system...
AnswerID: 639909

Follow Up By: Member - John - Wednesday, Mar 23, 2022 at 06:56

Wednesday, Mar 23, 2022 at 06:56
Tony, thanks for posting the outcome.
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Follow Up By: Member - Tony w16 - Wednesday, Mar 23, 2022 at 07:45

Wednesday, Mar 23, 2022 at 07:45
John, it was after trying your idea that I looked a bit closer at the gauge, I had a small pot of water on the boil in the engine bay on a gas cooker with a thermometer & the sender unit side by side, gauge was reading 120c+ & thermometer was just over 100c. Thanks for the heads up on such a simple idea!
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Reply By: Member - FSH00 - Wednesday, Mar 23, 2022 at 09:56

Wednesday, Mar 23, 2022 at 09:56
G/Day Tony, just wondering if you could let me know some info about your after market turbo setup & how it has performed for you e.g. supplier,kit,inclusions,parameters set & running. May be looking at doing the same in the future.

Thanks,
Pete.
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Follow Up By: Member - Tony w16 - Wednesday, Mar 23, 2022 at 14:39

Wednesday, Mar 23, 2022 at 14:39
Hi Pete, I purchased the car with the turbo already fitted, all I can tell you is it's a CT26 & HPD top mount intercooler running about 8-10 lb boost. Not enough to hurt the engine but just enough to make it tow etc a bit better. I have talked with a diesel/turbo specialist & he said it's no use trying to run much more boost in these engines. I find it's easier & you get better information if you talk to independant mechanics rather than large franchise operations who are willing to take as much money as possible when it comes to setting things like this up
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Follow Up By: Rob K (VIC) - Monday, Apr 11, 2022 at 17:29

Monday, Apr 11, 2022 at 17:29
FSH00, if you live in Melbourne try AXT Turbo in Dandenong. They did my 1HZ in a LC100 many years ago and I had no problems with the installation. Just have to watch the EGT temperatures when going up hills and back off a gear if needed.
Cheers
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