VDO EGT M_O_U_S_E ??

Submitted: Saturday, Jan 27, 2007 at 19:03

ThreadID: 41676 Views:2783 Replies:6 FollowUps:5

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Ian from Thermoguard Instruments

Hi all,

The other day, a neighbour asked me to help get his VDO EGT gauge working. After checking the probe, I re-connected it and away it went (I think it was just wired back to front). We went for a test drive up some reasonable hills and all seemed OK but once it got beyond about 400 C, the gauge started 'flickering' up about 50 C higher than the 'average' reading, about once per second.

Now, while I've been flogging my digital gauges for several years now, I've never seen a VDO one 'in action' before. So, can anyone with a VDO pyro tell me whether this sort of behaviour is normal for them? I'd suspect that such a quality brand should be dead steady but what is your experience?

Is this one still a bit dodgy? (It's been installed in the car but not working for quite a long time - perhaps being wired backwards for a long time has damaged the analog meter movement? This is not a problem with digital indicators - a reverse-wired probe will display -10 or -11 C when the ambient temp is 20-odd C if wired backwards.)

Thanks for your help,
Ian

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Reply By: David from David and Justine Olsen's 4WD Tag-Along - Saturday, Jan 27, 2007 at 19:08

Reply By: warthog - Saturday, Jan 27, 2007 at 19:17

Reply By: Richard Kovac - Saturday, Jan 27, 2007 at 23:47

Reply By: Chaz - Sunday, Jan 28, 2007 at 02:14

Reply By: Ian from Thermoguard Instruments - Sunday, Jan 28, 2007 at 11:52

Reply By: Member - Brian (Gold Coast) - Monday, Jan 29, 2007 at 07:11

Monday, Jan 29, 2007 at 07:11

Ian... I have a VDO in my Patrol, it reads "smoothly" through the range up to 600 deg C.... I haven't had it past that!!!!

Cheers

Brian

AnswerID: 218293

Follow Up By: Member - Roachie (SA) - Monday, Jan 29, 2007 at 08:38

Monday, Jan 29, 2007 at 08:38

Brian,
I hope for your sake , that your thermo-couple probe is located in the manifold (above the turbo!!!!)................

FollowupID: 478700

Follow Up By: Member - Brian (Gold Coast) - Monday, Jan 29, 2007 at 09:06

Monday, Jan 29, 2007 at 09:06

Roachie,

Not sure but I think it's below the turbo, on the inlet to the unit. Why do you ask?

Cheers

Brian

FollowupID: 478702

Follow Up By: Member - Roachie (SA) - Monday, Jan 29, 2007 at 09:37

Monday, Jan 29, 2007 at 09:37

Brian,
Maybe I mis-interpreted your response, but when you said it read smoothly through the range up to 600oC, I assumed you meant that it has been up to 600oC? On reflection, maybe the gauge is simply calibrated up to that temp, but maybe you haven't had it up that high?
It is my understanding that a dump pipe maximum temp shouldn't be allowed to go much beyond 500oC. However, the manifold always registers a higher temp than the dump pipe and the "red-line" for the manifold temp is more like around 720oC.
On my old GU (2000 model 4.2TD), I had probe's above and below the turbo and the highest temps I ever registered were 615oC in the manifold and 450oC in the dump pipe.
If yours is in the dump pipe and you've seen temp up to 600oC, I would say she was running wayyyyy toooo hot (but then again I'm no expert and Ian from Thermoguard would be better placed to comment further on this matter).
Hope I haven't alarmed you unduly mate.
Cheers
Roachie

FollowupID: 478705

Follow Up By: Member - Brian (Gold Coast) - Monday, Jan 29, 2007 at 09:56

Monday, Jan 29, 2007 at 09:56

I'd have to have a look at it, SWMBO is out in it at the moment, but I will check which pipe the probe is in.... my understanding is that it's in the "inlet" to the turbo, is that not fed from the exhaust? And the more boost the higher the exhaust temp? And if that is allowed to continually heat up, lots can go wrong? That's my understanding, but am happy to be corrected.
My mechanic, and a few others, have told me that "rule-of-thumb" keep 500 degC as a maximum, but sometimes I have had it at 550-600 negotiating steep hills with the trailer on etc, but on the flat at 95-100kph, it hovers around 300 (not towing) and 350 towing. I watch the EGT like a hawk, and when it gets up around 500, drop back a gear and keep boost to around 7psi, this tends to dramatically reduce the EGT.
Like I said, I am happy to be corrected in any of this Bill.

Cheers

Brian

FollowupID: 478706