Re: [OMC-Boats] overheating

From: Don Mandelas <dmandelas@...>
Date: Fri, 15 Aug 2008 18:19:22 -0700

As I read this Saga it reminds me of the time when I changed the water temperature warning light to a temperature gauge.
When I first installed the guage I wasn't exactly sure how to do it.
So, On my first attempt I replaced the sending unit inside the thermostate housing for one that works with my tempeature guage, and then, I just installed the guage in place of the light (using the original two boat wires.). Silly me.
When I turn the key to the on position the temperature guage pegged on the high side.
Then after reading the instructions that came with the temperature gauge I realised I needed to install a third wire to the gauge. After I added the third wire my guage worked fine.
I'm sure this isn't whats causing you overheating problem, but thought I would pass it along in case anyone attempts to do the same thing.
> Date: Fri, 15 Aug 2008 09:28:28 -0600> From: lee.k.shuster@...> To: omc-boats@...> Subject: Re: [OMC-Boats] overheating> > Jeff,> > I wonder if the "instrumentation issue" or electrical wiring / grounding> "mystery" is as simple as realizing that you have a temperature sender> incompatibility? I trust you (or your mechanic) do realize the original> OMC boats all used a simple "idiot" light (at least from the factory)?> The original temp sensor for the light is a simple "switch" that allows> the "HOT" light to come on at a pre-determined temp. A "temp" gauge> sensor on the other hand changes resistance, typically the Teleflex or> Stewart Warner type temp sensors are commonly found on American boats.> > Anyways, thanks for the update and keep after it, you'll get there! Tell> your mechanic Buicks aren't really much different from Chevies....> > Lee > > -----Original Message-----> From: omc-boats-bounces@...> [mailto:omc-boats-bounces@...] On Behalf Of JEFF DOOD> Sent: Friday, August 15, 2008 12:13 AM> To: Evinrude & Johnson Boats of the 1960's and 70's> Subject: Re: [OMC-Boats] overheating> > > On Aug 14, 2008, at 2:00 PM, Lee Shuster wrote:> > > Sorry, for not following this saga more closely, but is in the same > > boat that had the confusion over (even/odd-fire) distributors? How did> > > that get resolved?> > same boat. finally got the original distributer on there after lots > of trial and error. that helped but didn't completely resolve. > ended up being a carb thing that was causing the mid throttle > backfiring (not sure why). then after backfiring went away, lasted > for a few minutes, then engine developed internal noises - like > "rebuild" type noises. that's the way my luck seems to work. so > fortunately had a spare engine. swapped, a bit more carb stuff, and > viola - no more backfiring or engine noise. actually had it in the > water at full throttle for a total of about 5 minutes since then. > Now is this overheating issue. Well, apparantly not actual > overheating - just the appearance of overheating.> >> >> > Not that it should really matter, But what's the source of this > > current Buick V6? 231 (odd or even fire?) or 225 (odd fore)? As > > someone else pointed out, something as simple as the wrong manifold > > gaskets can lead to problems.> > buick odd fire (as best as i can tell). it came from another boat - > bought used from a guy last summer.> >> >> > Again, I go back to someone else's suggestion: Get a decent> > (hopefully)> > color flow diagram of the entire cooling system. Then start breaking > > the system down into it's individual parts. The original OMC manuals > > as well as the third-party SELOC & Clymer's are must have for you and > > your mechanic. A good understanding of the "theory of OMC cooling" is > > essential and can hopefully reduce the "chasing one's tale" approach > > to troubleshooting. This is part of what I meant in an earlier post > > about checking something as simple as the proper connections for the > > four hose mounting locations for each cylinder bank's > > manifold-to-thermostat hose routing. Direction of flow matters, kinda > > like + or - in electricity.> > Also what spec T-Stat are you running? Remember this is another area > > cars and boats differ. OMC spec'd at 140 def F 'stat. Cars are > > typically higher.> >> > What is meant by " So he checked for blockage etc - one part of one > > manifold was running> > very hot, while the others were fine. swapped out that manifold.> > Now engine is running at normal temps (albeit, on the hose),......> >> > Not sure if this mean manifold is fine to the touch? Or what method or> > > metric if instruments are suspect? How about some actual data points, > > in degrees F?> > he's checking everything with some sort of super duper scope which reads> the temp in F. and i guess he can check specific parts of the engine> with it, hence being able to pin point that 1/2 one manifold was> overheating.> >> >> > I understand what you are saying about gauges/instrument sensors, but > > remember that is only one point of reference.> > You or your mechanic should be checking flow rates @... various points in> > > the entire cooling system. Has anyone pulled the ends off the > > manifolds and checked for any restrictions or blockages? Swapping > > parts, especially used ones, when they are KNOWN to be good could lead> > > one to draw the wrong or inconclusive results.> >> > Don't get too frustrated, sounds like you are making progress. Still > > some quality boating time this year yet to go.> > > thanks - yeah, it seems to be narrowing down. talked to him several > times throughout today. at end of the day, it appeared to be down > to just a wiring issue somehow. (again, just on the hose). The > temp of engine is now uniform and normal after swapping out > manifold. Rigging up a gauge straight off battery is confirming > that. his scope is confirming that. But when it's connected into > the dash stuff the needle moves right over to 240. Even without the > engine running. Definitely some elec wierdness, however not as > simple as you might expect. There's two guys on it, and neither can > trace down why it's doing that. different gauges are doing the same > thing, so not a gauge problem. He's already considered grounding > issues and that wasn't it. 3 different sending units show same > thing. So he's stuck. Will call him tomorrow morn. I am > actually feeling pretty good about things right now though. A simple > wiring thing at this point. However, I can't water test without a > perfectly functioning gauge. So although it seems minor, until it's > resolved i am still stuck out of water. But atleast it's not > overheating - atleast on the hose. The one big thing i have > learned through all this so far is that testing on the hose is pretty > worthless. Testing in the water is really essential. I've also > learned that my mechanic is swearing to never work on another buick> engine again.> > wish i had the time to learn to do most of this myself. i am hating > having to rely on a mechanic who hates my engine! But i understand his> frustration. There have been a lot of weird issues with this whole> thing.> > jeff> > > > > >> >> > Lee> >> > -----Original Message-----> > From: omc-boats-bounces@...> > [mailto:omc-boats-bounces@...] On Behalf Of JEFF DOOD> > Sent: Thursday, August 14, 2008 1:39 PM> > To: Evinrude & Johnson Boats of the 1960's and 70's> > Subject: Re: [OMC-Boats] overheating> >> > well.......frustratingly close to getting the problem solved. but> > still not there. it's very weird. here's whats going on - my> > mechanic has had it for a couple days. it was overheating on the> > hose for him also (good thing, so not just happening underway). So> > he checked for blockage etc - one part of one manifold was running> > very hot, while the others were fine. swapped out that manifold.> > Now engine is running at normal temps (albeit, on the hose), but> > every gauge he hooks up to it says it's overheating. He swapped out> > all the sending units to different ones from another engine (not new,> > but different). Still, even trying different gauges, it says it's> > overheating. He is confirming the actual engine temps with a special> > heat sensor thing he uses - same as fire dept eqpt, say he trusts it> > more than any gauge. Could be the engine IS actually overheating and> > his eqpt is bad - but i don't think so - it sounds legit. maybe> > other mechanics use this too when they can't trust any gauge.> > nonetheless, assuming that's not the prob - then it would seem like> > the sending units. but again, he swapped those out too.> > possibility of 2-3 bad sending units in a row, but that seems like a> > stretch. any idea?> >> > if it were a crack, or blockage, or bad thermostat, or hoses, etc -> > the engine would be running hot - which it supposedly isn't. yet> > trying different gauges and sending units didn't make any> > difference. Any other parts of the chain we're forgetting about > > here?> >> > the weekend is coming and i'm so close to having this thing usable > > again its driving me nuts!!!> >> > jeff> >> >> >> >> > On Aug 11, 2008, at 11:57 AM, Ethan Brodsky wrote:> >> >> On Mon, 11 Aug 2008, JEFF DOOD wrote:> >>> i am getting very close to being able to use my boat finally, won't> > >>> go into all the recent past history but it's been a journey. long> >>> story short, i have a different engine in it now. another buick> >>> v-6. runs, starts, sounds good, doesn't backfire and lose all > >>> power> >>> at mid throttle, etc. only one problem. when on the hose, it's> >>> operating at normal temps. when under load, the temp gauge is > >>> just> >>> races right up to the overheat range. thought i might be the > >>> gauge,> >>> no such luck. on 2nd test, same thing. idling at dock it temp> >>> gauge barely moves. but after about 10 seconds at full throttle it> >>> starts moving up and within about 30 it's almost pegged. putting> >>> on> >>> a new sending unit next, seeing if that does anything. if it's> >>> got> >>> blockage somewhere, then wouldn't it heat up while on the hose at> >>> the mechanic's shop also? it's getting water through there.> >>> pretty> >>> sure mechanic replaced impeller at last go around. and there> >>> doesn't seem to be any obvious leaks or cracks anywhere in the> >>> manifolds. any ideas?> >>> >> My first thought would be to check the thermostat? Is it working.> >> Is it> >> the right one? Engines in cars usually ship with thermostats that > >> open around 180-200F, while marine engines are usually supposed to > >> run> >> >> around 140-180F. If you've got an automotive thermostat in there, > >> the> >> >> gauge will show it as overheating all the time, and it'll be running > >> a> >> >> lot hotter than it should. If it's sticking shut, that would also > >> cause overheating.> >>> >> If that's not it, I'd ensure that all the cooling passages are open > >> by> >> >> testing them one at a time. Look at a drawing of the coolant > >> ciculation patterns (in the service manual) and hook up a garden hose> > >> (engine> >> off) to> >> each of the inlets and make water comes out the corresponding outlet.> >> Check both passages in each exhaust header and the engine block > >> passages.> >> Also try opening the two drain cocks on each side of the engine and > >> see if you have water pouring out.> >>> >> Ethan> >>> >> --> >> Ethan Brodsky > >> _______________________________________________> >> OMC-Boats mailing list> >> OMC-Boats@...> >>> >> > _______________________________________________> > OMC-Boats mailing list> > OMC-Boats@...> >> > _______________________________________________> > OMC-Boats mailing list> >> >> > _______________________________________________> OMC-Boats mailing list>>> _______________________________________________> OMC-Boats mailing list> OMC-Boats@...>
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Received on Friday, 15 August 2008

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