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#1
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engine monitor wiring harness install
How are your engine monitor probe leads and wiring harnesses secured? Adel
clamps on the rocker box covers? Tie wrapped to your ignition leads? Tie wrapped to the intake tubes? Adel clamps to the lower case/sump bolts? I'm interested to hear about your installations. What you like and dislike about the install location of the wiring harnesses and any problems resulting from heat and or ignition or alternator interference. Do you have service loops to allow you to swap probes or do you disconnect/reconnect probes when you have a problem? Thanks as always, Jim |
#2
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engine monitor wiring harness install
On Tue, 10 Oct 2006 10:49:15 -0500, "Jim Burns"
wrote: How are your engine monitor probe leads and wiring harnesses secured? Adel clamps on the rocker box covers? Tie wrapped to your ignition leads? Tie wrapped to the intake tubes? Adel clamps to the lower case/sump bolts? I'm interested to hear about your installations. What you like and dislike about the install location of the wiring harnesses and any problems resulting from heat and or ignition or alternator interference. Do you have service loops to allow you to swap probes or do you disconnect/reconnect probes when you have a problem? sig snip This might get a little long, apologies in advance. Tie-wraps really aren't the thing to use forward of the firewall. Limited usage on wire bundles is OK, but waxed lacing cord works much better in the long run. A tie-wrap WILL eat into engine mounts, intake tubes, baffles, engine cases etc. etc. over time. The life of the tie-wrap is pretty much directly related to temp, if they are away from exhaust/cylinders, they hold up OK on wiring, but waxed cord lasts the life of the engine+. Adel clamps and Koroseal lacing are the best way to go for securing everything else. It takes a little practice to get the hang of tying off Koroseal-stretch it too tight, it will break, too loose and things move around. Koro seal withstands engine oil/petroleum products quite well, and can stand most under-cowl temps, but too close to an exhaust stack will cook it. Depending on the engine type (I'm assuming we are talking AzTruck, with intake and exhaust both on the same side of the cylinder), wire runs need to be adapted to what you've got with regard to intake/exhaust configuration, position of CHT wells on the cylinders, baffle/cowling configuration etc. Bottom line is keep the wires secure and as far away from the e-stacks as possible/practical I would personally stay the heck away from spark plug gasket-type CHT probes if possible. Regular spark plug maintenance takes it toll on them. You need to look your exhaust over and plot a course for EGT probe positions. They need to be the same distance from the head, but often can be rotated around the stack to a good spot to get to your wiring, allow access for other maintenance, etc. Often, cylinder head-located wiring runs are possible both outboard (in relation to the crankshaft) and inboard of the rocker box. There are typically bosses/threaded holes that might be used for baffle attachment. Using an Adel on the outboard side is pretty straightforward. Using them on the inboard side requires sourcing fully threaded coarse thread bolts to extend beyond the "back" side of the boss, using a lock washer and plain nut to secure the clamp. Again, proximity to the e-stacks is an issue. Rocker box screws are a last resort, they work in a pinch, but IMHO not too well. Have used regular Adels on intake pipes, but on an Aztec they might be pretty close to the e-stacks. I useta have a pile of clamps (might be Piper, might be Lycoming, sorry, been too long) that had a relief to clear a primer line, the ones for injector lines have a bigger relief. They work extremely well for securing wiring to the intake pipes. As you indicated, sump bolts.studs work well as an attach point to run Adels/wires along the lower "inside" of a Lycoming. Just be careful to replace any lock washers removed with new, maybe throw a thin washer in here and there, and re- tighten any engine fasteners removed carefully. BTW, if your stash of Adels have -3 holes in them and you need to put a -4 bolt/stud through it clamp that sucker in a vise and run a Uni-bit through it and don't worry about. BTDT again, and again, and again, never had a problem. Have never personally experienced any electrical interference issues (call it EMI/whatever) with analyzers and alternator wiring, but that doesn't mean that it couldn't happen. If I was doing the work myself, I'd probably dummy up the runs along the alternator wiring with some tie-wraps and do a ground run with the analyzer powered up and watch the numbers. I'd probably tentatively shoot for EGT on the outside bottom of the cylinder heads and CHT along the sump and out the intakes, but you're a lot closer to an Aztec engine installation than I am. I'm not big on service loops or doubled-up wiring forward of a firewall (unless it's darn close to the firewall, and not much else), it's more crap in the way to get chafed/cooked/cut/boogered up during service. I wouldn't screw around with probe swapping either-probes are too cheap and labor (and the potential to screw up a "good" probe trying to find a "bad" one. Keep new or proven serviceable spares (one of each type installed), then once you install it, you can leave it-worst case, you just swapped a probe out of your stock from a serviceable one from your engine. Running CHT's & EGT's (and Tanis heaters, for that matter) is just like re-plumbing or re-wiring a standard engine install. It's kind of a Zen deal. Once you seen what works and what doesn't work, you just get a feel for it. Just don't get ticked if your master wiring plan gets change by somebody that walks up and says "Um, wouldn't it make sense to run those wires on the inside of that thingie there". For the most part wires need to be SECURE from the firewall to the point they transition to the engine (with a sort of "loop" or extra material to allow the engine to shake) and then secure until they get to the probe. The bottom side of the cylinder will get awfully crowded with intake, exhaust, spark plug, CHT probes, EGT probes, not too mention the lovely little rod that ties the baffles together, just keep it as "clean" and simple as possible. Hope at least a little of this helps; TC |
#3
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engine monitor wiring harness install
No need to apologize TC, you're a wealth of info!
No spark plug gasket type CHT's, I've got the bayonet type. Yes we're talking about the Aztruck. The cleanest route actually looks like it may be tucked up along the sump/case joint and lying above the intake tubes. This places the wires a good distance from all exhaust pipes but makes accessing the wires and installing the Adel clamps a contortionists worst nightmare... maybe with the bottom cowl off. EGT probes look like they will be best installed with tips pointing forward , probe lead extending aft at a slight outward angle allowing to drill the holes without dropping the exhaust. This would leave plenty of room for the covered lead to then turn inward and upward towards the case for securing. Once I get back to the engine mounts, it's a piece of cake. There are some notes about not running the leads against the alternator run, but the info is very limited. Thanks for your time, it's very much appreciated. Jim |
#4
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engine monitor wiring harness install
On Tue, 10 Oct 2006 21:39:30 -0500, "Jim Burns"
wrote: No need to apologize TC, you're a wealth of info! No spark plug gasket type CHT's, I've got the bayonet type. Yes we're talking about the Aztruck. The cleanest route actually looks like it may be tucked up along the sump/case joint and lying above the intake tubes. This places the wires a good distance from all exhaust pipes but makes accessing the wires and installing the Adel clamps a contortionists worst nightmare... maybe with the bottom cowl off. EGT probes look like they will be best installed with tips pointing forward , probe lead extending aft at a slight outward angle allowing to drill the holes without dropping the exhaust. This would leave plenty of room for the covered lead to then turn inward and upward towards the case for securing. Once I get back to the engine mounts, it's a piece of cake. There are some notes about not running the leads against the alternator run, but the info is very limited. Thanks for your time, it's very much appreciated. Heh, didn't take much time to type, I need the mental exercise anyhow. With regard to your "lower" wire runs-will be a good time to take another look at your rocker drain hose/clamps. FWIW whenever I allegedly hung a "new" engine I typically threw away the factory drain hoses and clamps and used chunks of MIL6000 hose and nicer quality clamps. It eliminated a lot of goofing around with them later. I would suggest keeping the EGT clamps anti-seized up, and leave them attached to the harness (disconnecting the clamps from the stack) when dropping the exhaust. Not sure what your practice is, we dropped the exhaust every 100 hours to renew gaskets/hardware, kroil on all the ball joints, anti-seize on the slip joints, ensure that the front crossover was still intact & not ready to escape through the nose bowl. After you've dropped the bottom cowls a hundred or so times, you get where you don't think twice about it... Been out of the PA-anything game for awhile, but am always willing to help out with questions from owners/pilots that give a ****. Regards; TC |
#5
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engine monitor wiring harness install
How are your engine monitor probe leads and wiring harnesses secured? Adel
clamps on the rocker box covers? Tie wrapped to your ignition leads? Tie wrapped to the intake tubes? Adel clamps to the lower case/sump bolts? Ours is a mix of both types, where appropriate. And, just like TC says, the zip ties have grown brittle and broken in the areas that get extremely hot. I've replaced about half of them, and the analyzer has only been in the plane four years. I may have to buy some of that waxed lace stuff. -- Jay Honeck Iowa City, IA Pathfinder N56993 www.AlexisParkInn.com "Your Aviation Destination" |
#6
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engine monitor wiring harness install
I know what you mean about the drain hoses and clamps.
Our left engine is nearing TBO and the drain hoses have been a recent pita. Since we did the lower cowl mod STC, it's only a 5 minute/1 man project to drop the lower cowl and they've been off and on quite often. In fact, it made replacing the alternator and quick drain valve a simple project rather than a royal pain. Thanks for the tip on the MIL6000. I'll pick up a length of it so I can replace some of those drain hoses that have become hard and brittle. Jim |
#7
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engine monitor wiring harness install
Ahead of the firewall, when I do use zip ties, I use the high temp 205
degree C Mil spec tie wraps. They aren't cheap but seem to last quite a bit longer than the generic Menards nylon. Jim "Jay Honeck" wrote in message oups.com... How are your engine monitor probe leads and wiring harnesses secured? Adel clamps on the rocker box covers? Tie wrapped to your ignition leads? Tie wrapped to the intake tubes? Adel clamps to the lower case/sump bolts? Ours is a mix of both types, where appropriate. And, just like TC says, the zip ties have grown brittle and broken in the areas that get extremely hot. I've replaced about half of them, and the analyzer has only been in the plane four years. I may have to buy some of that waxed lace stuff. -- Jay Honeck Iowa City, IA Pathfinder N56993 www.AlexisParkInn.com "Your Aviation Destination" |
#8
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engine monitor wiring harness install
Hi - Regarding Jim Burns' engine monitor installation, it's probably too late to take the following advice into consideration, but just in case: When installing the CHT / EGT probe wiring, consider trimming and routing the individual cylinder probes' wires to central harness connection points near the middle cylinder on each side. The idea is that this would allow diagnosis of weird engine monitor indications by swapping harness/probe connections between cylinders rather than something more speculative and intrusive like replacing individual probes. This is a good thing if one's engine monitor starts giving spooky, then worrysome, then eventually absurd indications. It goes doubly if the monitor does something like that on both engines, ugh! Such a sensor connection swap has allowed us to contra-indicate actual engine mechanical problems during a still-ongoing episode. - FChE |
#9
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engine monitor wiring harness install
Great idea Frank, but yep, probably too late... kinda.
I installed service loops in the nacelles to allow me to pull the slack forward and essentially allow me to do as you suggest. As far as routing, I routed everything inside of the intake tubes, using Adel clamps to secure the alternator and/or starter cable to the sump bolts, then the CHT/EGT leads are double adelled to the cable. This made for a very compact and neat install. I disposed of a whole bushel basket full of old brittle cable ties that had been installed over the years. My A&P inspected everything yesterday and gave me a smile and a big thumbs up. The left engine oil galley plug came out relatively easy. I built a little "dam" out of rope caulk so it would hold a pool of Kroil in the plug. I kept it saturated for 3-4 days before trying to remove it. Then when the time came, I heated the case with a propane torch, tapped in a hex head socket, first tightened, then reheated, and finally turned it out. No stripping, no EZouts. Next step is to install the indicator. I've already moved the FF indicator and the #2 altimeter to allow me to install the indicator in an appropriate hole. Hopefully I'll have it finished by the end of the week. Thanks for your ongoing suggestions Frank! Jim "Frank Ch. Eigler" wrote in message ... |
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