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Fitting Thermoguard EGT Gauge


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Just finished fitting the Thermoguard EGT gauge in preparation for a bit of twiddling - I wanted to fit one and watch it for a couple of months before I do anything :)

The 300Tdis sold here don't have EGR so no problems in putting the thermocouple there:

egt-2.jpg

I opted for the supplied pre-drilled blanking plate to avoid messing up the old one so I could keep that in case I ever want to remove it. I also straightened the thermocouple and re-bent it again as per instructions from White90 but I thought I had F'ed it up so I don't think I'd do that again - even being very very careful and using a block of wood with the exact sized hole drilled in it, it still kinked the thermocouple slightly and damaged the crimping at the end where the lead goes in - it is a very strong thing and needs a lot of force to bend it. My advice would be to try and get a straight one supplied in the first place as it does need to go further in than is possible with the standard shape and I had a job to get it to go into the fitting because of the fact it wasn't perfectly straight.

Run the thermocouple lead up the air intake hose, bit of an "S" to allow movement between engine and bulkhead, and in through the existing grommets:

egt-3.jpg

I decided that the best place for the display unit was under the middle of the dash, not much room for anything else there due to the gear lever, and it would be easily visible and out of the way:

egt-1.jpg

The thermocouple lead goes in through the bulkhead to behind the speedo binnacle, along under the trim to the left of the speedo binnacle, and out underneath the facia beneath the radio (hidden underneath the EGT display) then into the back of the display unit. Power lead goes down into the fusebox, the ground picks up on a spare earth and the positive side goes into the feed to the radio which is on a 5 amp fuse.

Having been out for a test drive the max I could get was 603*C with some heavy right foot up a long hill in 5th, normal driving was in the range 300-400*C and up to about 550*C pulling up a hill "normally" so I reckon there's a bit of scope for amending the settings in due course ;) - I'll watch it for a while yet though, I am curious to see what it does off road with no airflow through the intercooler, and also when towing. Interesting also to see that you can get quite high EGT off boost, if you labour the engine along in 5th at about 25mph with full throttle you can get up to about 450 without developing much power at all :o

Cold idle gave about 100*C and hot idle after the test drive about 170*C.

Should be a useful bit of kit I hope and will remove the element of doubt when I later get around to making some adjustments and fitting a bigger intercooler. The advice is that temperatures over 720*C are likely to damage something so I'll be staying well clear of that.

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If we're producing a tech-archive type thread then I'll add that I just fitted the probe for my EGT gauge and found problems undoing the two allen-head bolts on the exhaust manifold to take off the EGT valve. I finally got them undone by applying a torque while Mr TroddenMasses 'shocked' the manifold (where the bolts are screwed in) with a hammer and a long pin punch.

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Mine didn't have the allen head bolts it had normal flange screws (they took quite a bit to undo though) so I wonder if this was a common problem and LR changed them? Lots of copper grease went on them when they went back in but not sure how long even copper grease will last at 500 odd degrees :huh:

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I've wired up my EGT gauge and I'm pleased to report the results are very similar to Stephen's at tickover and lugging around. I've already tweaked the boost on my Tdi without any problems so I was interested to see a peak temperature of 735°C up a long hill - the difficulty is finding a long enough hill to peak the EGT without running into anything!

I'll be staying below 700°C now I've got the gauge (it drops quite quickly with even slightly less throttle). I've heard of melted turbines and cracked exhaust manifolds but - what actually fails? Is it the exhaust turbine, the inlet impeller, or something else entirely?

Overall though, apart from the slight hassle of straightening and re-bending the thermocouple it was very simple to fit and I'd recommend Ian's setup to anyone.

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John

Any temp near or above 700 will result in a cracked manifold not a melted turbine..

a mate cracked 3 before he fitted the EGT from Ian.

did you re form yours as I did?

I suggest turning the fuel down a bit and keeping those temps down.

egr1_24851997.jpg

egr2_24851995.jpg

egr4_24851999.jpg

if this is going to the tech archive I'll add my pics

Now using this mounting:

IMG_1439.JPG

washers now removed :)

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The problem I had is that my thermocouple was a lot shorter than Tony's and I kinked it where the bit crimps on to the outer end as there wasn't much to swing on when trying to straighten it. Mine sticks into the manifold about the same amount as Tony's but with the crimped on bit right tight against the compression fitting.

seems to work all right though - max temp so far still 603*C normally doesn't get over 500*C in normal driving

High EGT can melt pistons, valves, crack manifold or fry the turbo, or a combination of the above. Not sure what happens first in practice and I don't want to find out :)

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BogBuster probably kinked the thermocouple because it was bent using a hole in a wooden block. You need to bend them around something which has a large radius.

As BogBuster said, pistons etc fail if the egt are too high.

Temps can get too close to the melting point of aluminium pistons. That is why Cummins use steel piston crowns in some of their engines that can exceed 30psi boost pressure.

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BogBuster probably kinked the thermocouple because it was bent using a hole in a wooden block. You need to bend them around something which has a large radius.

Bending it after fitting into the plate using the wooden block was no problem and worked fine, it was straightening the original bend that was formed in the thermocouple as it was supplied, that caused the problem. You need to do this to be able to push the thermocouple right into the fitting which allows the tip to stick right out in the exhaust gas flow. I don't think you would be able to use the method you suggest for straightening it.

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  • 4 weeks later...

I fitted my EGT gauge back in 2001 and seem to have been the first on the forum. I wanted to get the thermocouple closer to the exhaust valve than the EGR plate, so fitted it to the manifold:

P1010030Small.jpg

Here is the 'gauge' itself. P1010025Small.jpg

It is actually a furnace control computer which has an output with a settable temperature. This is used for an alarm. I currently have mine set to go off at 725c. When I first fitted the meter I found I could easily exceed 750c so eased off on the tweak of my injector a bit. Now I can get to 725c on a long uphill at 1.05bar, especially with a trailer. As someone said earlier, you only have to lift off very slightly for the temp to go back under 700c.

Mine idles when warm at 150c. When stopping the engine, I wait for the temp to drop below 200c (an arbitrary number). Often it is already lower, but when pulling off a motorway to refuel I find the temp takes ages to come down. I then sometimes refuel with the engine running.

ps I also have the alarm buzzer connected to the alternator warning light, the oil pressure warning light and to a float switch in the coolant overflow tank.

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  • 1 year later...
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