Brad Christy

Guys,

OK... So there's been no forward progress since the last post, and I'm getting impatient....

First off, I ordered the gauge not knowing about the whole matching impedance thing in regard to the sender, so I didn't order the sender from Gaffrig at the time, ordering one from Amazon, instead. It would be nice if their website gave some advisory on this matter. Sometimes the upsell is valid and valuable. Of course they will not divulge the ideal impedance range of the sender, as that would obviously cost them a $24 sale . Since then, as per advice from here on OSO, I've ordered the matching sender from Gaffrig, but the one I've been told to get, the 1/8"NPT variety, is out of stock and a shipment of them seems to be on the slow boat from China. The boat is usable at this point, with the gauge panel finished, rigged and installed, and the signal wire for the gauge ran, but I'm waiting until the sender is in hand to do an oil change and the modifications to the remote filter mount for the sender. It's not really a major hitch should weather cooperate, but I'm stuck, and it's pissing me off. I really want this project behind me. So...

Is there any reason I can't use the 1/4"NPT fitting? They apparently have them in stock. Mirage sent me some pics of his modifications for the 1/8" unit, and there seems to be enough room for the larger sender. I would just do it, but I don't want to get into it and find it's a no-go for reasons. Advice?

Thanks. Brad.

Wally

iTrader: (1)

If you have the room for the 1/4" then go for it. I had a 1/2" pipe plug on a port i had to use an adapter to use the 1/8" sending unit....but if i had a 1/4" sending unit it would have been the same thing.
As far as the sending unit goes....if they wont tell you the value then you can figure it out with a rheostat. wire up the gauge to a battery and use the rheostat as the sending unit and wire it to ground....you can turn the knob on the rheostat and get the gauge to swing....dial it in to low temp and take a reading with a volt meter set to resistance.....then dial it into the high reading and same thing measure the output resistance....from there its smooth sailing finding a sender that works.
Another way is to get some resistors in different values and wire then inline to ground...the resistor acting like the sending unit. From reading online it seems like the value would be like 330 ohms for the low temp and around 30 ohms for the high temp...

Brad Christy

Wally,

Where the Hell did you find that info? Not that I'm doubting you, I just can't find anything. When you say "low temp" and "high temp", you mean peg to peg on the gauge, right?

It looks like there's plenty of room, by the pics that Mirage sent me, but I'd have to commit to the work to find out for sure. He told me to use the 1/8" sender, and I don't want to assume it was just what he decided to use, then get into it, find I can't use the 1/4", and then either have the boat out of service until the 1/8" sender arrives or have to put it all back together, then having to pull it all back apart again, wasting precious boating time.

I've got a guy coming to the shop tomorrow with a rheostat to determine the impedance range of the gauge. Then it will be time to decide whether to continue the waiting game with Gaffrig.

Thanks. Brad.

boatnt

iTrader: (1)

I have not read the whole thread, so,this is the sending unit I installed on mine works fine

Brad Christy

Guys,

Sender is finally in, so I'm prepping for the final step on this: the oil change and simultaneous filter mount mods and install of sender. I've changed the oil in the past, but it's always been a matter of pulling the oil through the dipstick tube. The problem is it always seems to yield less than the prescribed 9qts it's supposed to have and takes less than 9tqs to reestablish "full" when I fill it back up, so my impression is that I'm not getting it all out. Since I'm "upgrading" to the AmsOil, I'd like to change that fact. I've located the drain tube that is factory from Merc on the side of the oil pan. Apparently, the tether was lost as some point, and it's no longer attached to the drain plug, but the plug and clamp is still there. NBD on the tether. But I've noticed a small amount of oil in the bilge (spots, not puddles). I also noticed, upon locating the drain tube, that the right angle fitting it's attached to the oil pan by swivels semi-freely. The machine builder in me thinks this should probably be a banjo fitting that locks into place once orientation is established, and I can't think of a real reason it should need to swivel. But I also can't seem to determine if there is a bolt head there that would tighten it down either. I'm thinking this might be the source of the oil in the bilge. Is this swivel normal, or do I have an issue? Or is it just a matter of spinning it around until it tightens up? I did spin it around one revolution, but nothing changed.

Thanks. Brad.

Ryanw10

When you suck the oil out of the dipstick, do you let the motor get up to temp first?

Brad Christy

Ryan,

Yes. Always done that. Cars, boats, whatever.

Thanks. Brad.

Wally

iTrader: (1)

Brad sorry i didnt see your reply back on the 17th asking where i found the info....i actually went through this when i had my stinger and got the wrong sending unit...turns out that VDO uses the same reading but they use the in the opposite way...so my gauge was reading high psi when it was low and high temps when it was low as well...had to call autometer tech support and they told me their sweeps...but this go round i didnt remember so i did a quick google search for temp sending unit resistance measurements...

As far as the swivel on the drain tube...if memory serves me right as ive had only one of those setups in a boat about 30yrs ago....its like an airline swivel...it moves but you cant tighten them up...if it gets loose and seeps then you have to replace it.....I could be wrong on this but thats what i remember the one was that i had.....take you cell phone and video up in there and see if you can see it better that way to make a call on it.

Brad Christy

Wally,

All good on the sender info. The sitch has worked itself out from Gaffrig. I've got the sender THEY say I need for THEIR gauge, so....

Near as I can tell the oil in the bilge is not coming from the swivel fitting. I still can't see why it would need to swivel. A banjo fitting would be more appropriate and wouldn't ever wear to the point of seeping. To the oil in the bilge, though, it may have been the plug in the drain tube. It would seem that when the tether was lost, so was the plug, and whoever "fixed" it just used a bolt . Threads don't make for a very good seal inside a rubber hose with a hose clamp. I'll be making a new stainless plug before tucking the tube back through the drain plug hole and adding the new oil. I know a guy for that sort of thing.

I do have a couple other spots that may at least be contributing to the oil in the bilge, so I'll have to keep an eye out for that and make sure it's not getting worse. I may have to drop it off to Hilltop Marine and let their spider monkey crawl down there and figure it out.

Thanks. Brad.

Brad Christy

Guys,

Oil change is done. Filter mount modifications are done. No leaks. The drain tube out the drain plug hole is the shiznay, FWIW. I was able to let it drain the entire time I worked on the filter mount, removal, mods, reinstall.... Took a full 9qts to establish "full", after short run to populate the filter and warm it up. Pretty satisfied there....

Wiring is done, but I'm getting nothing from the gauge except backlight with nav light switch (I got that part right, at least ). I'm thinking I've got the ignition 12v and the signal lead swapped on the back of the gage. Probably got them backwards, looking at the diagram and not reversing it in my head while looking at the front of the gage. But now I can't find the wiring diagram. I'm usually pretty good for not throwing this sort of thing away until at least the project is complete and verified, but it's nowhere to be found; probably got swept up in a cleaning session after getting the dash back together. I've verified continuity where I'm supposed to have it and none where I'm not, solid grounds and ignition 12v at the gauge. I've tried getting ahold of Gaffrig, hoping to either discuss or have them email a diagram, but they seem too busy to answer the phone, and their email tech support is outlasting my patience. Assuming applying 12v to the signal output post of the gauge hasn't already damaged it, is it safe to swap them and see if it comes to life? Or will it damage the gauge if I had it right the first time and there's just something else going on? I can't fire it up again without taking it back out of the shop and hosing it up, but we're planning on taking the boat out on Thursday, and I'd like to have it back together, even if not proven out by then. I'm guessing I will at least see the needle jump with ignition ON if I get it right.

Thanks. Brad.