Installing a Pyrometer: where to place on exhaust manifold?

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Installing a Pyrometer: where to place on exhaust manifold?

Post by NTSOG » 10 Jan 2022, 6:44 am

G'day,

I am going to install a pyrometer on my farm 'off-road' vehicle, i.e. my Fendt Farmer 280P air cooled tractor, so as to get a more accurate reading of engine temperature under load in hotter months. It's an older [1996] tractor and I'm not certain that the simple temperature gauge on the instrument panel is accurate as the tractor was not treated well by previous owners. The tractor has a Deutz F4L 913 engine of 4 litre capacity and, as tested, still puts out its rated 79 HP at the PTO. I've attached basic digital temperature gauges to the outside of the cylinders and know that the No. 4 cylinder runs hottest probably because it's furthest from the cooling fan. The question is where do I place the pyrometer? I've read an article recommending placing a pyrometer sensor as close to the exhaust exit of the No. 6 cylinder on a Cummins diesel because it is furthest from the cooling pump and thus runs hottest. Certainly the factory temperature probe on my engine is on the No. 4 cylinder. Access to the manifold is easy so I can put the sensor anywhere on it. [I thoroughly cleaned the cooling fins using a pressure washer and a .17 brass bore brush when I acquired the tractor and clean the cylinder fins/cooling system daily in summer, especially when hay cutting and raking. The oil cooler/system is fully functional and I have also installed a small blower fan behind the heat exchanger of the very complex hydraulic system which has 12 remotes.]

It seems logical to install the sensor close to the hottest, i.e. No. 4 cylinder exhaust, but I'm not a trained diesel mechanic. I have learned that maximum recommended exhaust temperature is 650C while maximum cylinder head temperature is 230C.

Any advice would be appreciated as I am learning as I go and this tractor is far more sophisticated than my old MF 35,

Jim
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Re: Installing a Pyrometer: where to place on exhaust manifo

Post by straightshooter » 10 Jan 2022, 7:55 am

If you have doubts about cooling efficiency the the safest response is to replace the water pump, preferably with a high volume water pump if available.
The usual understanding of the function of a water pump is that it simply circulates coolant. What is little understood is that the pump must also maintain sufficient water pressure within the cylinder head flow path to prevent the generation of steam pockets which can be the cause of cracking.
A standard water pump can be more than adequate when new but the ravages of wear and corrosion can dramatically reduce it's efficiency.
Replacement is cheap insurance.

EDIT: What a dumbarse. I should have read the first line of your post more carefully!!!!
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Re: Installing a Pyrometer: where to place on exhaust manifo

Post by cz515 » 10 Jan 2022, 8:06 am

Bizarre 4L air cooled diesel tractor.

Sorry most of my info is around petrol engines. But interesting topic
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Re: Installing a Pyrometer: where to place on exhaust manifo

Post by Gamerancher » 10 Jan 2022, 8:26 am

Air cooled engines don't have a water pump.
The #4 cylinder gets all of the hot air from the rest of the engine blown past it by the cooling fan shroud on that Deutz engine. Makes sense that the temperature sensor is placed there. A pyrometer measures exhaust gas temperature which is a result of the fuel/air ratio in the cylinders and displayed via a gauge . More common on turbocharged diesel truck engines but are also used on air-cooled aircraft engines, usually called EGT in that application. ( Yes, they are used in many other applications but let's stick to the point ) While one will allow you to monitor the temperature, not having any way to adjust the air/fuel ratio, there isn't much you will be able to do about it. Keeping the air-cooling system clean as you do and perhaps running the engine at higher revs is the best available way for you to keep the engine temp where it should be.
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Re: Installing a Pyrometer: where to place on exhaust manifo

Post by No1_49er » 10 Jan 2022, 8:51 am

^^^^^^^^^^^^ What he said.
Unless you have the ability to fiddle with the A/F mixture, EGT should be stable. The CHT will be hottest on the cylinder farthest from the cool air supply.
Aircraft engines, which for the most part, are air cooled, but there is the possibility to adjust the A/F mixture i.e. to "lean it out" or whatever, depending on what part of the flight envelope you're in.
But the Fendt/Deutz? Unless there's a fuel management problem, I don't think you're going to have a problem.
Just as we've got a forum here, for the most part firearm related, is there a Fendt/Deutz users forum that might have info for you. And, I believe a lot (all of) John Deere are also air cooled (or used to be). Perhaps you will find something there too?
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Re: Installing a Pyrometer: where to place on exhaust manifo

Post by Gamerancher » 10 Jan 2022, 8:57 am

You're wrong about John Deere, liquid cooled.
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Re: Installing a Pyrometer: where to place on exhaust manifo

Post by NTSOG » 10 Jan 2022, 9:48 am

G'day,

Thankyou all for your replies. I have searched specialist tractor sites, mostly US, where there used to be many air-cooled tractors such as Belarus, Deutz-Fahr and so on. I believe quite a lot of air-cooled tractors were imported into Australia in the 1990s - mine was one of 8 imported for use in vineyards which is why it has such a complex hydraulic system with 12 remotes. They are still being used in Europe, etc. and in other colder climates and are valued because they are very tough, easy to maintain and repair. [My neighbour across the road actually has an old Deutz-Fahr with the same engine, but he doesn't cut hay or cultivate.] I have got some useful information from tractor sites - more than I got from the local Fendt dealership whose mechanics were not able to advise me about max CHT. Neither have I received any advice from Fendt in Germany and the user's manual is pretty basic in fractured English/German. Trucking sites have been useful in learning the use of pyrometers and how air-fuel mix can be adjusted in more sophisticated engines.

The engines runs very well, starts easily even on freezing mornings and, when load is reduced, the cylinder temperature can be seen dropping quickly on both the factory gauge in the instrument panel and on the digital gauges I have attached to the cylinders. My only concern has been to avoid over-heating on hot summer days when running under load. Picking the best transmission [high, medium or low] range and gear for a particular job is critical, but my need is for an accurate temperature gauge that I know gives me a safe, immediate temperature reading so I can back off if needed before damage is done.

I've ordered an ISSPRO pyrometer and will install it as close as I can to No. 4 exhaust outlet. The device is quite expensive, but better than a cooked engine.

I figured there would be some blokes on this site with expertise in relation to engine management.

Straightshooter if you're a 'dumbarse', then you're a member of an illustrious club of which I am also a member - according to my wife.

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Re: Installing a Pyrometer: where to place on exhaust manifo

Post by Gamerancher » 10 Jan 2022, 10:15 am

Same tractors used air cooled engines as well as Lamborghini, whether their own or Deutz I'm not sure. Like all engines, heavy work on very hot days can lead to overheating. It 'ain't limited to air cooled, I've operated trucks that would overheat on hot days, Cat, Detroit and Cummins engines, in a variety of truck brands. Pulling road trains at harvest time, keeping the radiator clean is a must, the amount of crap that gets sucked into them from the paddocks is a big problem.
When the work load exceeds the cooling capacity, anything will overheat. :thumbsdown:
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Re: Installing a Pyrometer: where to place on exhaust manifo

Post by NTSOG » 10 Jan 2022, 10:58 am

Gamerancher: "... the amount of crap that gets sucked into them from the paddocks is a big problem."

That's for sure. It always amazes me how much rubbish and dust I find inside the enclosed cooling shroud and around the oil cooler and cylinders after a day of hay-cutting, raking and even carting round bales on the front end loader.

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Re: Installing a Pyrometer: where to place on exhaust manifo

Post by Gamerancher » 10 Jan 2022, 11:12 am

Yep, I'm hearing ya. The chaff created is light and easily sucked in by the fan, whether air or liquid cooled. My JD6620 constantly needs the radiator blowing out when haymaking/carting. Dust from ploughing/sowing/spraying... it never ends, just part of preventative maintenance.
My old' man used to drive a Deutz truck with a V8 engine, reckons he only had trouble with overheating on the hottest days hauling up the biggest hills. I can remember going in it as a kid, the heat in the cab was incredible, no air-con in those days.
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Re: Installing a Pyrometer: where to place on exhaust manifo

Post by bladeracer » 10 Jan 2022, 11:18 am

NTSOG wrote:G'day,

Thankyou all for your replies. I have searched specialist tractor sites, mostly US, where there used to be many air-cooled tractors such as Belarus, Deutz-Fahr and so on. I believe quite a lot of air-cooled tractors were imported into Australia in the 1990s - mine was one of 8 imported for use in vineyards which is why it has such a complex hydraulic system with 12 remotes. They are still being used in Europe, etc. and in other colder climates and are valued because they are very tough, easy to maintain and repair. [My neighbour across the road actually has an old Deutz-Fahr with the same engine, but he doesn't cut hay or cultivate.] I have got some useful information from tractor sites - more than I got from the local Fendt dealership whose mechanics were not able to advise me about max CHT. Neither have I received any advice from Fendt in Germany and the user's manual is pretty basic in fractured English/German. Trucking sites have been useful in learning the use of pyrometers and how air-fuel mix can be adjusted in more sophisticated engines.

The engines runs very well, starts easily even on freezing mornings and, when load is reduced, the cylinder temperature can be seen dropping quickly on both the factory gauge in the instrument panel and on the digital gauges I have attached to the cylinders. My only concern has been to avoid over-heating on hot summer days when running under load. Picking the best transmission [high, medium or low] range and gear for a particular job is critical, but my need is for an accurate temperature gauge that I know gives me a safe, immediate temperature reading so I can back off if needed before damage is done.

I've ordered an ISSPRO pyrometer and will install it as close as I can to No. 4 exhaust outlet. The device is quite expensive, but better than a cooked engine.

I figured there would be some blokes on this site with expertise in relation to engine management.

Straightshooter if you're a 'dumbarse', then you're a member of an illustrious club of which I am also a member - according to my wife.

Jim


I've had nothing to do with diesels, but I built a contraption to give me temps on all four pipes coming out of the head on my race bikes for tuning, in real time on the dash (I also ran an air/fuel gauge on the dash but ended my racing before I did any real work monitoring individual A/F ratios on each cylinder - the day I crashed was the day for testing the setup that let me flick the gauge between A/F ratios on each cylinder). Not interested in actual temperature though, just tuning all four cylinders to be the same. Getting an actual temperature is _very_ dependent on how close you are to the point you want to measure. On the header pipe the temp 200mm down the pipe can be 100C less than at the head. If you have a "do not exceed" spec, and you know precisely where they want that temp, then that's where you need to measure it to be relevant. Mounting it elsewhere will give you different readings. Any scale buildup inside the engine can also affect the reading you get. How you tune a diesel to alter the temperature is not something I've looked at, but I would assume richening the air/fuel ratio?

Does it have an oil cooler? That also sucks heat out of the head and cylinder by reducing oil temp before sending it back into the engine. I ran temp gauges on a race bike for a while to monitor temp of the oil coming out of the engine compared to where it goes back into the engine. I don't recall the difference but it was significant (one of the fittings developed a leak so I removed it and never bothered fitting it again).

We run premium diesel in the Landcruiser and tractor, but whether that has any effect on running temperature I have no idea.
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Re: Installing a Pyrometer: where to place on exhaust manifo

Post by NTSOG » 10 Jan 2022, 1:31 pm

G'day bladeracer,

The tractor does have an oil cooler inside the cooling shroud on the right side of the engine. It seems to be doing its job as is the hydraulic oil heat exchanger boosted by the motor-cycle blower fan I installed behind it. The maximum specified exhaust temperature is 650C according to a bloke on a US tractor site who actually has the installation manual for this engine. [Also 230C on No. 1cyl. Head temp., 140C oil in pan.] He didn't specify the exact location on the exhaust manifold, but I will install the sensor as close as I can to the No.4 cylinder exhaust outlet - I understand that there is a significant drop in temperature further away from the cylinder. If you look at the attached photo of the manifold on the left side of the engine, I aim to fit the sensor just at or before the curve of the manifold at No. 4 cylinder before the vertical mounting bolt. I'm not going to disassemble any of the complex hydraulic piping to get improved access - better for a mug amateur mechanic to leave old seals and joints alone!

Gamerancher: "... the heat in the cab was incredible." After a couple of hours of work the old girl does get pretty hot. I don't have an air conditioner in the cab, but simply open all windows and prop the doors open - and sweat - a lot

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Deutz 4.0l engine F4L 913 left side
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Re: Installing a Pyrometer: where to place on exhaust manifo

Post by bladeracer » 10 Jan 2022, 2:51 pm

NTSOG wrote:G'day bladeracer,

The tractor does have an oil cooler inside the cooling shroud on the right side of the engine. It seems to be doing its job as is the hydraulic oil heat exchanger boosted by the motor-cycle blower fan I installed behind it. The maximum specified exhaust temperature is 650C according to a bloke on a US tractor site who actually has the installation manual for this engine. [Also 230C on No. 1cyl. Head temp., 140C oil in pan.] He didn't specify the exact location on the exhaust manifold, but I will install the sensor as close as I can to the No.4 cylinder exhaust outlet - I understand that there is a significant drop in temperature further away from the cylinder. If you look at the attached photo of the manifold on the left side of the engine, I aim to fit the sensor just at or before the curve of the manifold at No. 4 cylinder before the vertical mounting bolt. I'm not going to disassemble any of the complex hydraulic piping to get improved access - better for a mug amateur mechanic to leave old seals and joints alone!

Gamerancher: "... the heat in the cab was incredible." After a couple of hours of work the old girl does get pretty hot. I don't have an air conditioner in the cab, but simply open all windows and prop the doors open - and sweat - a lot

Jim


How does the manual say to measure the temp there? If that's where they measure it there should be a boss or something for mounting. CHT is usually done aftermarket with a sensor washer on the spark plug or glow plug. But if they have a sensor port or boss built in you'd likely get different readings from mounting the sensor elsewhere. I would log the temperatures over time and under different conditions and determine your own "do not exceed" requirements from that.
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Re: Installing a Pyrometer: where to place on exhaust manifo

Post by NTSOG » 10 Jan 2022, 4:58 pm

G'day,

As you suggested there is a cylindrical shaped 'boss' under the manifold closely adjacent No.4 cylinder and protruding downwards and slightly rearwards: it is clearly visible in the attached photo. As can be seen the boss is very close to the cylinder but also the cabin bulkhead. Accessing it would require considerable disassembly of adjacent piping and removal of the manifold itself which is beyond me. While I have access to AGCO's Fendt parts book and the user manual, nothing is discussed about temperatures. As I said a US bloke gave me the temperatures as he has an installation manual for the F4L 913 engine. Where I will have to install the pyrometer sensor is about 3+" out from the cylinder. Each cylinder is tapped [14mm dia.] and about 59 mm deep [right side] for insertion of a bi-metal temperature probe which feeds to the analog gauge on the dashboard, though only one is installed - on No.4.

I think you're correct: the factory specification of 650C maximum EGT can only be a [very high] guide for me as the pyrometer I will install will be 3+" away from the cylinder and temperatures drop as gases pass along the exhaust tube. As you say I will have to "log the temperatures over time and under different conditions and determine [my] own "do not exceed" requirements from that."

Many thinks for your interest and advice,

Jim
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Re: Installing a Pyrometer: where to place on exhaust manifo

Post by GQshayne » 10 Jan 2022, 7:55 pm

I can see what you are trying to do. But keep in mind that you are using a sensor to monitor combustion temp, not overall engine temp. Yes the two are connected, but your cylinder temp will be mostly effected by your air/fuel ratio. This temp can also change by hundreds of degrees in a matter of seconds on some engines. Does not mean your engine will be overheating.

Your EGT gauge will mostly tell you when the engine is operating under more throttle, or load. It will also indicate a fuel system that needs attention, as often this causes poor A/F.
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Re: Installing a Pyrometer: where to place on exhaust manifo

Post by NTSOG » 11 Jan 2022, 12:25 pm

Thanks for your input GQshayne. It's clear that I cannot play with air-fuel ratios especially on such a simple engine designed decades ago. I understand that the temperature at the exhaust can change very quickly - certainly much quicker than the variation I see on the analog gauge on the instrument panel and also the two digital gauges attached to the outside of cylinders 1 and 3 which are a bit quicker to show changes than the factory gauge. Hopefully by testing under load on both hot and cold days I can get some numbers that allow me to operate with greater confidence, especially on hot days than I can at the moment. Presently when hay cutting, cultivating and slashing in spring-summer I spend the whole time watching the factory temperature gauge always wondering if it's accurate. In winter there's no problem for obvious reasons.

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Re: Installing a Pyrometer: where to place on exhaust manifo

Post by GQshayne » 11 Jan 2022, 7:57 pm

Not sure that an EGT reading will vary a lot depending on ambient conditions. Your engine temp will vary a lot though. Hence the issue of using the EGT to monitor engine temp.

I think the EGT will be useful to monitor your fuel system operation. Poor fuel metering or a blocked airfilter will soon have the EGTs up, letting you know you have an issue. On such an old engine the injector pump may not be in the best order. Richer AFR in a diesel is hotter, leaner is cooler. I know nothing of your injector pump, but would expect it to have a basic fuel metering adjustment such as a mixture screw.

The other comment I would make is about your nominated max temp of 650c. That sounds quite high to me. My 4wd engine runs forged pistons, and are very high quality as they need to be. 650-700c would be close to max temp if taken in the manifold, however that really would only be acceptable for a number of seconds. On a stationary engine that had a constant load, or a tractor which can operate on a set throttle/load, then I would have thought that it would need to be lower than that.

I am speculating, and am adding my thoughts for your consideration. It is difficult to compare engines that are so different.
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Re: Installing a Pyrometer: where to place on exhaust manifo

Post by bladeracer » 11 Jan 2022, 8:19 pm

Your forged pistons are probably aluminium, the tractor is likely cast iron or steel pistons?
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Re: Installing a Pyrometer: where to place on exhaust manifo

Post by NTSOG » 12 Jan 2022, 5:59 am

G'day,

Getting any detailed information from the Deutz and also Fendt companies about the F4L 913 engine has been very difficult and others report the same issue. I was fortunate that the bloke in the USA had the installation manual and was able to tell me the temperature parameters, e.g. max. 650C for exhaust gas temperature. What I do know is that replacement pistons offered by various sources are all cast iron. Regardless I will continue to be conservative in running it under load in summer and record temperature at the exhaust and also the cylinder temperatures for specific operations in relation to ambient conditions. It'll be an interesting exercise.

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Re: Installing a Pyrometer: where to place on exhaust manifo

Post by GQshayne » 12 Jan 2022, 7:41 pm

bladeracer wrote:Your forged pistons are probably aluminium, the tractor is likely cast iron or steel pistons?


Mine are definately ally. The tractor I assumed would not be. Hence my comment about constant load being a factor. It is difficult to make a comparison. I am just trying to add what I know about such things to give a bit more to consider.

It will be an interesting exercise.
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Re: Installing a Pyrometer: where to place on exhaust manifo

Post by cz515 » 13 Jan 2022, 7:26 am

Hmm,

I do wonder why don't you just tear it down and check it. Saying that I don't get how the previous lever would have been unkind. I mean I can understand if it was water cooled, or not changing the oil wearing the bearing etc.

But as it is if it was air cooled it was made to run and run in hot and cold weather. I would just run it until it died... which might not happen for a long while.

If an engine overheats, it's usually the head gasket that cooks itself first (not sure if this has a head gasket). I can't imagine using a tractor that you can't use after 30 minutes or baby it all the time.... something I would get rid off (or get fixed)
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Re: Installing a Pyrometer: where to place on exhaust manifo

Post by No1_49er » 13 Jan 2022, 8:20 am

I wonder if anybody ever drove a VW or Porsche (air-cooled variety) across the Sahara?
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Re: Installing a Pyrometer: where to place on exhaust manifo

Post by cz515 » 13 Jan 2022, 2:53 pm

Plenty mate, the 911 came air cooled and had a tradition soaked in rally and racing
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Re: Installing a Pyrometer: where to place on exhaust manifo

Post by NTSOG » 14 Jan 2022, 9:45 am

G'day cz15,

I certainly don't baby the tractor, but want to make sure I don't wreck it by 'cooking' it due to a suspect temperature gauge, so I'm careful, but still use it for all the heavy jobs on my property. I don't have the skills or money to repair or replace a wrecked tractor, especially a Fendt.

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Re: Installing a Pyrometer: where to place on exhaust manifo

Post by cz515 » 14 Jan 2022, 10:07 am

Add an after market oil temp gauge/sensor.
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Re: Installing a Pyrometer: where to place on exhaust manifo

Post by NTSOG » 14 Jan 2022, 11:47 am

cz515: "Add an after market oil temp gauge/sensor."

That can be the next project, though the factory oil sensor appears to be operating.

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Re: Installing a Pyrometer: where to place on exhaust manifo

Post by NTSOG » 28 Jan 2022, 6:56 am

G'day,

The pyrometer is installed on the outside 'face' of the manifold just downstream from cylinder #4 [hottest cylinder] - not as close as I would like, but as close as I could install it. I have done moderate work with the tractor on two consecutive hot days: 34C and 36C. Running the tractor mid-afternoon in the heat the pyrometer indicated a steady maximum temperature of about 275C under load [Middle gear range, second gear, RPM 1100+/-] doing some light ploughing with a spring-tyne cultivator on a very rough paddock and, next day, slashing long grass with a 5 foot slasher [Low range, 2nd. gear, PTO 500-540 RPM]. Given the advice that the maximum EGT specified by Deutz is 650C, there's 'room' to operate the machine harder if needed. Cylinder temperatures during the work were: No. 1 - 74C and No. 3 - 90C approximately; both readings are well below the Deutz maximum of 230C [for No.1] quoted by Deutz. The factory analog gauge [reading cylinder No. 4] was in the green up about 45-50% of the range, so perhaps the gauge is still accurate after all. I was especially intrigued by how quickly the temperature reading changes on the pyrometer compared to the other two gauges.

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Re: Installing a Pyrometer: where to place on exhaust manifo

Post by Gamerancher » 28 Jan 2022, 7:51 am

The pyrometer measures exhaust gas temp, take your foot off the throttle and the temp will drop. To get to 650C would take a lot of doing in a non-turbo engine, there just isn't the fuel load. Truck engines will get up there under heavy load lugging up steep hills when you are down in the revs with your foot flat on the throttle. Drop down a gear and the temp will drop or get over the hill and lift your foot it will drop pretty fast. Most truck engines will run around 450C under normal load driving down the highway, the temp will plummet if you lift your foot going downhill, or when pulling up, a few down changes in the gearbox and idling in gets it down to shutdown temp which is around 200C. It always amuses me when blokes have a truck idling for ages to "cool down the turbo", it doesn't take much to get the temp down before you stop, idle/shutdown timers are for lazy bastards who can't figure it out or read a pyrometer.
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Re: Installing a Pyrometer: where to place on exhaust manifo

Post by NTSOG » 28 Jan 2022, 9:02 am

Gamerancher: "... idle/shutdown timers are for lazy bastards who can't figure it out or read a pyrometer."

And also wives who can't be bothered to learn the fundamentals of operating machines, i.e. 4 wheel drives they use to tow a heavy horse float. I had an after-market turbo installed on my 1996 Nissan Patrol GQ [4.2 D]. The turbo made a world of difference to the vehicle under load. I also had a turbo-timer installed because my wife cannot be bothered to learn how to operate machines in general. She just wants to get in, turn the key and off she goes and be blowed with maintenance or correct use. I could not trust that she would give the engine sufficient turbo cool-down time before shutting it off.


"... idling in gets it down to shutdown temp which is around 200C."

That's interesting. In the two days I've operated the tractor with the pyrometer I've noticed that the EG Temperature comes quickly down to 150C as I 'idle in' with no work load on the machine. The analog and digital temperature readings take longer to come down.

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Re: Installing a Pyrometer: where to place on exhaust manifo

Post by Gamerancher » 28 Jan 2022, 11:55 am

Gauges read different depending on where they are and what they are measuring. Your cylinder head one will read hotter than exhaust gas and one in a liquid cooled engine is reading coolant temp not head temperature.
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