'72 merc 1150 temperature monitoring?

[monk-monk]

all right group i got another one for ya!! what's my options for monitoring the temp of this motor. ideally, dashboard mounted instrument or w/ in eyeshot

 

[emckelvy]

Re: '72 merc 1150 temperature monitoring?

Frankly, you'd be better off with a water pressure gage. By the time a temp gage goes off, the motor will be fried!

You may or may not have a fitting on cyl block cover over the spark plugs, if you do that's a good place to tap in with a 1/8"-NPT fitting for the gage.

Otherwise you'd have to figure out where to put a fitting, either in the cover or drilling the top of the block. If you end up needing instructions on where to drill at the top, I can hook you up with a friend of mine who's done that very nicely to his Tower of Power.

If you must install a temp gage, probably the quickest indication of temp on this motor would be on the exhaust manifold cover. There are any number of temp gages with a contact-type of sensor that you could mount on the cover.

In an overheat situation, the cover's going to get hotter a lot faster than the block, so that would at least give you some extra time to shut 'er down before going into Meltdown Mode.

Or, you could go with a water temp gage, they make those too.

If you search this site you may find something, or check out these search results:

http://www.boatfix.com/catalog/11.pdf

http://www.boatfix.com/bykeywordnew2.asp?textfield=temperature&texttype=2&submit=Search

HTH and let us know how you set it up...........ed

 

[monk-monk]

Re: '72 merc 1150 temperature monitoring?

you guy's are off the hook!! amazing results from this site!! if you,ve followed my threads on this 1150 it's all about to come together this weekend. i'll keep y'all updated

 

[monk-monk]

Re: '72 merc 1150 temperature monitoring?

chief, tell me more about this exhaust manifold contact type sensor you spoke about. went to those web addresses but, only sales no real info... PLEASE TELL ME MORE!!

 

[emckelvy]

Re: '72 merc 1150 temperature monitoring?

Well, I'd think that this cylinder head temperature monitoring kit would probably be what you're looking for, you'd have to write the mfr to see what the specs are on the sender. I went to the description on Faria's website and they don't say how the sender mounts.

http://www.boatrepairs.net/mall/index.cgi?cart_id=248549107&session_id=348402744&view_id=133010

 

[monk-monk]

Re: '72 merc 1150 temperature monitoring?

chief i gotta say how much i appreciate this post. you've taken your time to not only answer my thread but, then go and do research for MY NEEDS! All i can say is thanks very much!!

 

[Silvertip]

Re: '72 merc 1150 temperature monitoring?

There are basically two types of senders. The contact type is a thermocouple which measures the temperature of the metal it is in contact with. It generates a small voltage that can be read as temperature by the gauge. The other type of sender is a thermister or in techno speak, a temperature sensistive resistor. As such its resistance changes as its temperature changes. This type of sender screws into the water jacket and measures water temperature. The rub with this type of sender however, is you need one that is calibrated for outboards as they operate much cooler than a car for example. It should be capable of measuring 60 - 200 degrees or so. Most senders are calibrated in the 100 - 240 range. A gauge calibrated 120 - 240 for example would hardly ever come off the peg. So -- the best combination is a water pressure gauge in combination with the warning horn AND a temp gauge. The water pressure gauge should be put in and a new impeller installed. Then note the idle and wide open throttle pressure readings. Any deviation from those readings in the future indicates the impeller is due for another change. The gauge is no guarantee you won't overheat. Stuck thermostats, clogged water passages, etc can still cause overheating even though the WP gauge is reading normal.

 

[monk-monk]

Re: '72 merc 1150 temperature monitoring?

silvertip, i'm going to ask you and others in this forum a question but, first thanks for the input. as i've stated in earlier threads.. this boat sat covered in a barn in kentucky for nearly 20 yrs. i was not the first to get it. another man got it and tried to run it but didn't have much luck due to the burned wiring harness. What is the importance of this water pump impellor change and would you even attempt a run w/ out changing it. it peed good when the man started it

 

[emckelvy]

Re: '72 merc 1150 temperature monitoring?

The fact that it had decent flow when started is definitely a good sign; however, if you think that it's likely the impeller is the one that's been in the motor for 20 years (and how much older it is who knows), I woudn't run it on a boat until it's changed.

A $20 part at best (and a lot cheaper at this site or www.boatfix.com) and definitely not worth messing up a powerhead that, if good, is worth well over $1000 by itself!

With all the info at this site, it shouldn't be too scary to drop the lower unit and do that impeller replacement yourself. Likely you'll be shocked at the condition of the rubber impeller after sitting for so long. Lucky that the blades haven't yet busted off and plugged up the water passages, an even worse fate!! :$

 

[monk-monk]

Re: '72 merc 1150 temperature monitoring?

ok fellow iboaters, i'm listening to you!! It'll be changed before it is launched. i hope this powerhead is as good inside as it looks outside...honestly, as the saying goes.. it's so clean you could just about eat off it

 

[Caddy_Kid]

Re: '72 merc 1150 temperature monitoring?

I have a new Faria cylinder head temp gauge (http://www.boatersland.com/far-13009.html) because it runs from 60-220 degrees. My '65 inline has no fancy thermostats, etc so it really never gets much above 100 degrees. At least this way I can tell the needle moved! All the water temp gauges start at 100 degrees plus.

The sender unit on this one (as with probably all of this type of temp sensor) is a small round plug with a wire hook up pressed into a short (inch long or so) piece of metal with a big hole in the end oposite the sender. To mount the sender, they want you to remove a head bolt and put the sender over the bolt and re-tighten it. In my case, I have no head, just a water jacket, so I epoxied it to the side of the top cylinder water jacket. Had to run a ground wire to it (which you wouldnt have to do if it were attached to the bolt), but no problem.

In my case, it would probably drain the water jacket and overheat long before the temp sensor told me, since there is nothing to stop the water from draining if the water pump let go. But, the boat had a temp sensor from the factory, and I have a new water pump and look at the "pee" stream often, so we'll hope. I also couldnt get the plug out of the top of the motor for running a pressure gauge!

 

[monk-monk]

Re: '72 merc 1150 temperature monitoring?

thanx for the info caddy, absorbing what you've said... it sounds to me like a temp gauge isn't going to give me any cushion as a car temp gauge would. keep a fresh water pump and skip the gauge??

 

[Silvertip]

Re: '72 merc 1150 temperature monitoring?

Keep a fresh water pump AND make sure the over-temp warning horn is working.

 

[monk-monk]

Re: '72 merc 1150 temperature monitoring?

silvertip, what about this horn...where's it located...does this '72 1150 have a horn?? thanks for your time!

 

[emckelvy]

Re: '72 merc 1150 temperature monitoring?

Hain't no horn on a standard control box/wiring harness for your '72 1150 but you can certainly rig up something aftermarket.

Just be sure that any accessories you power up are tapped directly off the battery and not the Merc harness. There was a good discussion on this in a recent post if I recall.

 

[gregtobin]

Re: '72 merc 1150 temperature monitoring?

Gents-
I'm a new boat owner and trying to read up as much as possible on the Merc 1150 (mine's a '75).
I'd like to do some simple preventive maint and like the idea of changing the water pump and installing some kind of temp monitoring system. I'll go ahead with the Faria cylinder head temp guage as that looks easy and not expensive.
Can you give me a rundown on replacing the water pump? And, is the impeller you talk about inside the water pump or is it separate?
What's are the best repair books for this motor?

Thanks very much
Greg
Frederick, MD

 

[monk-monk]

Re: '72 merc 1150 temperature monitoring?

greg, I just installed a new water pump in my '72 1150. It really isn't that difficult. In my situation, the impeller was actually in pretty good shape...but, the seal and o-ring in the lower pump housing was shot...this was my first water pump change and again, it wasn't difficult. Be careful to make certain what type of fastener holds the zinc trim tab on...mine was a twelve point aircraft bolt where i've heard of allen head bolts also. There's also a 9/16th's bolt hidden under this trim tab. Most importantly, once you get in there ...change as many parts as your budget can afford...don't disassemble it and leave in an old $10.00 part. P.S. Call iboats for assistance in locating your parts....I support those who support me!!

 

[monk-monk]

Re: '72 merc 1150 temperature monitoring?

and yes Greg, the impeller is inside the upper pump housing...that is why i say change it all while you have it apart...upper and lower housings, impeller, and all associated gaskets...call iboats, they will help you!!