Replacing EGT Gauges

CO_Skymaster · #1 03-28-09, 10:03 PM

I currently have a digital EGT gauge in my Skymaster. It has a switch which allows me to switch between looking at the front engine and rear engine. After dealing with it for about 2 years, I've decided a digital reading isn't the best for me and would like to replace it with a dual analog gauge. I like it better for diagnositic and leaning. I was looking at two manufactures, Alcor and Westach. The Alcor is about 530 dollars while the Westach is about 150 dollars. Does anyone know if the Westach has lower quality. Is it only certified for experiements (couldn't find exact information on this, but I was going to call and ask). I see no reason to pay 400 dollar extra if it's for name only.

On a side note, I was curious about replacement alternators since I had trouble with them for awhile. I was interested in replacing my alternator system with a Plane-Power system. I decided to call them Friday and ask them. They said they have a current gear driven alternator for small block TCM engines, but are currently working on a replacement alternator for the TCM 0-300 series.

Karl

skymstr02 · #2 03-29-09, 08:51 AM

I had a Westach EGT in my AT-6G, and had numerous problems with the gauge and the probe. I never could count on it. This unit is not TSO'd.

The ALCOR unit is much more accurate and trouble free. This unit is TSO'd. This is also the original equipment provider for Cessna in the 60's and 70's.

You will probably spend as much to keep the Westach unit working over the life of the airplane, as you will spend to purchase an ALCOR unit.

EGT's are not required equipment, and unless you are operating under an FAA operating certificate, ie, 135, a TSO'd unit is not required to be installed.

The bottom line, if it were me, and my checkbook, and I didn't want the headache, I would go with the ALCOR system. Just be sure and do not shorten any of the extension leads from the probes to the gauge, the length is critical as part of the calibrated resistance in the readings.

The ALCOR system can be calibrated after installation. Remove the probes from the exhaust pipe, use a propane torch to heat the probe to a "cherry red", and using the adjustment screw on the back of the instrument, adjust the needle to 3/4 scale. This doesn't take long to heat the probe, and you need two guys to do this.

CO_Skymaster · #3 03-29-09, 11:38 AM

Thanks for the input. The current EGT is an EI and it would work for awhile, then stop. I had to take it back to the mechanic 3 times before it would work reliably. Sounds similar to the Westach gauge problems. Alcor EGT it is.

Thanks,

Karl

hharney · #4 03-29-09, 01:06 PM

I just purchased an Alcor Model 204-18B Item #45993 last October. My original (alcor thru Cessna OEM) was beginning to give me intermittent readings on the rear so I changed the probe and still didn't solve it so I swapped the rear lead for the front lead on the gauge and it still had funny stuff going on on the rear. New gauge and it's fixed. The new one is a little nicer than the original. Has the user setting needles for reference purposes where the old original from 1968 did not have these. I purchased it through Aircraft Spruce and it was $490.95. I wanted the JPI or EI digital stuff but didn't want to commit to the big bucks for that part of the system at that time. Maybe someday.

JeffAxel · #5 03-29-09, 07:41 PM

Karl,
On your alternators, be sure it is the alternator that is the problem. Could be the coupling. You have to know if you have the old or new style to check, but there should only be a little motion when you try to move the fan with the engine stopped. If that coupling is loose, it fouls up the whole system. The old style can leave parts in the engine too, so be sure and check it out. Of course, alternator diodes can go out too, but the Ford alternators in Skymasters aren't any more prone to this than other alternators. If both alternators are ok, the problem can be in the setup that balances the alternators. All the contacts in that setup have to be clean so the resistances are correct, otherwise it doesn't work well either. One solution is to change the voltage regulators to the setup used in the Cessna 310 which has a true parallel setup. Tom Carr at CPA has a copy of the 337 form for this conversion. He should be able to help you if you are a CPA member.

CO_Skymaster · #6 03-31-09, 08:34 PM

Thanks Jeff,

I was on a learning curve when I first purchased my Skymaster 2 years ago. I did learn a lot about the electrical system, thanks in part to this forum. I found the battery was weak and would not easily accpet a charge and the voltage regulators had some issue. After replacing the battery, voltage regulators, and cleaning all the contact. I was able to keep the front alternator on-line and determined the rear altenator was dead. I had the alternator replace during my last annual. Mine is really old and doesn't have a coupler. The system is stable now, but while all this was happening, I thought it would be great if I could just install a Plane-Power alternator system.

Karl