EGT Gauge Problems?

[Song Dog]

Under Product Reviews on TDR's home page, there's an article entitled "Westach Gauge Install". I have the same rotary switch set-up to monitor both pre-turbo and post-turbo EGTs on a single Westach Combo gauge.

It's worked great for over a year -- monitor pre-turbo temp when pulling loads (even though I'm unBOMBed), then switch to post-turbo for shut down.

About 2 weeks ago, pre-turbo temps got finicky. Sometimes it'll read OK, other times the needle won't budge under any circumstances. It might read low on the bottom half of the scale, but fine on the top half. It's progressively gotten worse.

All the while, post-turbo temps read normal. So, it's not the gauge, right? What's left? A disintegrating probe, poor connection, or bad rotary switch?

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2001, SLT 2500, reg cab, 4x4, 6 spd, HO, 4:10, LSD, Westach Combo Gauge, stock

 

[EMDDIESEL]

I dont deal with Westach much, but the problem you are describing sounds like it is most definatley a bad rotary switch contact or possibly a bad Thermocouple. You said it works fine on the post exhaust, so that rules out being a bad gauge.
What i would do is temporarily bypass the switch (And the post turbo Thermocouple wiring and hook the PRE turbo Thermocouple directly to the gauge and see if you still have trouble, if you do, its a bad Thermocouple (They do go bad, although it is pretty rare, but dont worry, they dont disetegrate, they just stop working internally). If the readings work fine, its a bad rotary switch.
I am betting its the switch, a bad switch contact can cause all sorts of erratic readings on gauges.

Good luck

 

[Alan Reagan]

When my thermocouple leads broke recently, this is exactly how it acted till I moved the wire going into the thermocouple. Mine is SPA and has a connector on top of the T/C. The wire had broken and was making intermittent contact. When I moved it, it broke all the way and left me stuck at the bottom. One way to test the T/C is measure the resistance at the leads with it cold. Then crank the engine up and watch for the resistance to drop. If it stays constant the T/C is bad.

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2001 HO 6 spd 2500, 4. 10 LSD, Towing Package, Electric Brakes, SPA EGT/Boost Gauges, Fog Lights, Real Backup Lights, Molded Running Boards, Lucerix X Mount Heated/Power Mirrors

 

[Michael Hughes]

Dong Dog
I would think the fastest way to check it, would be to use two jumper wires at the switch.

Do you have the wires coming out of the probes supported some how? If not, I would check for a broking wire near the probe.

Hope you get it figured out, and let us know what you found.

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1999 2500 ST LB 4X4 Metallic Red, 5-speed, 3. 54 gears, LSD, camper and tow package
Westach Boost/EGT (pre and post turbo) mounted on A pillar.

[This message has been edited by Michael Hughes (edited 05-15-2001). ]

 

[Song Dog]

"Dong Dog"? That was a slip, right? #ad


Sorry for the delay, I have an odd schedule. I just checked the thermocouple leads under the hood, all appears fine. I'll print this out since the other suggestions (all good) may have to wait until Monday. I'll let you know. Thanx.

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2001, SLT 2500, reg cab, 4x4, 6 spd, HO, 4:10, LSD, Westach Combo Gauge, stock

 

[OILBRNR]

Why don't you try switching the probes? They have a connector don't they? If the problem changes to post turbo, then the problem is the switch, otherwise the probe.

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'99 2500 4x4 • SB • QC • 3. 54 • LSD • AT • Leather • 16x8 M/T Alcoa Challengers • 285/75 BFG A/Ts • Mag-Hytec • Westach Guages • Line-X • Luverne Nerfs • Tommy Gate

Towing:
'99 28' Airstream Excella (~7000# dry)
'69 24' IMP Inca Twin Screw (~6000# wet)