Exhaust temp gauge Nissan 3 ltr TD

Submitted: Thursday, Apr 07, 2005 at 11:27
ThreadID: 21849 Views:2153 Replies:4 FollowUps:2
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We went to have the transmission oil temp gauge fitted, but they discovered it already had one - with just light if it goes over - it hasn't so far - didn't know about this. They had also suggested (more expensive too!) fitting an exhaust temp gauge for the turbo. Had this done, but it is hard to find info. on what temperatures are safe. Has anyone else done this? Anyone know what temp range is safe?
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Reply By: Member - Geoff M (NSW) - Thursday, Apr 07, 2005 at 12:34

Thursday, Apr 07, 2005 at 12:34
Hello MotherHen,
Don't have an answer for you but with your indulgence I'll borrow some air time in your thread.
Who'd you talk to about transmission and exhaust gas temperature monitoring?

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AnswerID: 105540

Reply By: Ian from Thermoguard Instruments - Thursday, Apr 07, 2005 at 12:55

Thursday, Apr 07, 2005 at 12:55
Hi Motherhen,

The safe limits for Exhaust Gas Temperature (EGT) depend on whether the temperature sensor is installed before or after the turbo-charger.

If before (i.e. between the exhaust ports and the turbo), temps up to about 720 C should be OK for brief periods but I don't like to see more than 700 C for more than a few tens of seconds.

If the sensor is downstream of the turbo (e.g. on the exhaust pipe just below the turbo outlet flange), the maximum safe temp is quite a bit lower. As the exhaust gases expand through the exhaust turbine, they give up energy (to drive the compressor side) and emerge at a lower pressure and temperature. Unfortunately this temperature drop will vary from one engine design to another, so it's difficult to put an exact figure on it. Some sources quote figures of up to 200 C and I have actually measured temp drops of over 160 C on my Land Rover. So, the maximum you probably want to see downstream of the turbo is probably about 500 to 550 C.

I always recommend an upstream installation if at all possible, as it is the hotter upstream gases that are impinging on the turbine blade tips, the turbine housing and the wastegate valve & seat. These are the bits that usually suffer first from excessive EGT but in extreme cases, the piston crowns and exhaust valves can fail too - very expensive!

Please feel free to visit my site and download the EGT Information Sheet. It gives (I hope) a good description of the causes and effects of excessive EGT. Hope this helps.
AnswerID: 105546

Follow Up By: Ian from Thermoguard Instruments - Thursday, Apr 07, 2005 at 13:00

Thursday, Apr 07, 2005 at 13:00

By the way, may I ask what brand of EGT gauge you had fitted and what it cost? Please feel free to email me direct if you don't want to post this publically: ian_AT_thermoguard.com.au Thanks.
FollowupID: 362656

Follow Up By: Member - Roachie (SA) - Thursday, Apr 07, 2005 at 14:43

Thursday, Apr 07, 2005 at 14:43
Let me start by saying I have no financial interest in Thermoguard etc.

I have fitted one of Ian's Thermoguard EGT set-ups to my 2000 GU 4.2TD. I did most of the fitting myself except for drilling and tapping the hole in the exhaust manifold just above the turbo.

The gauge works really well and it is surprising to see how quickly the temp rises and falls under varying conditions.

I drive my truck reasonably hard, but the maximum temp I have "achieved" going up through the Adelaide Hills on a warmish day with 1200kg of camper trailer on the drawbar, was 585c. A similar temp was reached recently as I entered the Hume Hwy at the end of the Sturt Hwy, between Wagga Wagga and Gundagai, where there is a longish uphill pull. I had disconnected the plug in the bottom of my radiator which causes the air con to go off as soon as the coolant temp goes even a smidgin above normal. Coolant temp still goes up to about 3/4 on the standard Nissan gauge (but I have no idea what "actual" temp the coolant is at when the gauge is up like that).

There seems to be no corrolation between coolant and Exhaust Gas temps; sometimes the EGT will be highish and the coolant will be normal, other times the opposite applies.

Next step is to get a VDO coolant temp gauge I guess.


FollowupID: 362677

Reply By: hoffy - Thursday, Apr 07, 2005 at 14:37

Thursday, Apr 07, 2005 at 14:37
I have fitted an EGT on my 3l auto Patrol and the temps I am seeing are
Highway cruising @100k,s 400- 470
Highway cruising @ 110 k up to 520-535.
Town driving 350 - 380.
Naturally the terrain has a lot to do with temps as does headwind etc.

The highest I have recorded has been 565 pulling our van up a steep range, but this soon came down to the low 500s by easing off the power.
By the way I am reading the temps just down stream of the turbo.
Would be interested in your readings as a comparison.
Hope this helps
AnswerID: 105562

Reply By: awill4x4 - Thursday, Apr 07, 2005 at 22:26

Thursday, Apr 07, 2005 at 22:26
Motherhen, all the auto's come with a light warning about transmissions running too hot, the problem is that often by the time the light comes on the auto trans is so hot that damage has already been done. As an example. About 3 years ago our auto light came on climbing the hills on the Princes Hwy down past Orbost on our way to Merimbula. We stopped, let the auto cool down and topped up the trans just slightly. The light never came back on and we drove around Merimbula happily for a week and on our return to Melb the auto trans destroyed itself totally in Traralgon, no warning light, no nothing, resulting in a $4000+ auto trans rebuild.
What apparently happens is the factory lining can come apart from the torque convertor lock up band which then clogs up the oil cooler mounted in the radiator and the auto then cooks itself as the oil has nowhere to go.
If I had a proper gauge I could have monitored the normal auto trans temps, seen an increase in temps and had it fixed while on holiday and saved myself a lot of money in repairs. It still probably would have required a rebuild but at least I would have saved the planetary gear set which was totally destroyed in the blow up.
I now have a VDO gauge on the trans and can accurately monitor auto temps, particularly when under load towing or 4 wheel driving.
I also have a manual lock up switch for the torque convertor so I can tow in 3rd gear and lock up the torque convertor at any speed. Locking up the torque convertor is the key to running your auto trans at the lowest temps possible.
Regards Andrew.
AnswerID: 105680

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