stringer 800

[vicjunkie]

Re: stringer 800

yes, i can get the heat to rise on the muffs. I am actually thinking about going with through hull exhaust to stop all of these problems, what do you think.

 

[Howard Sterndrive]

Re: stringer 800

that's weird that it overheats on muffs - no load and the garden hose pushing. Generally a boat with a totally wiped out impeller will still run cool on the muffs.
Any chance the impeller vanes are flipped the wrong way?

I might pull the risers and see what's up with the exhaust manifolds. (but I can't see that being the issue - water is pouring out)
But it's a V8, so maybe something up with 1 side. Or a water shutter tore off and is somehow blocking the exhaust (I don't think that's even possible on a stringer, it would just fall out if it tore off)
Do you have a power steering cooler? Maybe blocked up with old rubber.

But again - we see water pouring out - so water is going in (lotsa flow) and pouring out (lotsa flow) and yet the water isn't picking up the heat from the engine - so maybe the water circulating pump on the engine is not working well. Could it be automotive with a rusted off tin impeller (marine have bronze). Or the whole engine block full of sand maybe? (I'm reaching with that)

Really need to verify this overheat with another temp indicator - even a K type thermocouple that comes with a $20 multimeter.....
Of course one's hand is pretty good - 190F scalds pretty instantly. I can almost keep my hand on a riser running on plane when things are working well. 145 is my threshold for pain.
A bit of milky oil in the upper after weeks of mooring is not unusual for these units.

 

[vicjunkie]

Re: stringer 800

remember it does the sam thing sitting still in the marina with no load, anything over 2500rpms. it takes longer to overheat when stationary, but ist still does. Impeller vanes are flipped the right way. new maifolds, and bead blasted the risers. new marine circulating pump.
so, here is may latest test. with the outdrive off, i pulled the hose off of the intermediate housing, and fed it with the water hose. temp starts creeping after a few mins at 2500rpms. Im thinking this isolates my problem not being in the unit, or do you think im not supplying it with enough water?, i pulled the drain cocks out of the side of the water jacket in the block, and theere is a ton of water pouring out of them.

 

[Howard Sterndrive]

Re: stringer 800

with no load, you don't need much water, but I always turn my garden hose on full before starting.

sounds like maybe the water is having some issue getting around the temp sender maybe - locall heating. All weird. It doesn't take much to keep an engine cool in neutral. I might pull the sender and drop it in a kettle and watch the resistance change on my mutimeter - theyre NTC, so ohms go down as temp goes up. don't use a lighter though - they don't survive that kind of heat

maybe some pics of the hoses, routing and tstat housing will get someone noticing something not right. Did it ever run cool for you?

manifolds put on in effort to cure overheat? correct riser gaskets for RWC? (there's 2 different styles)

 

[Boomyal]

Re: stringer 800

I am, as we speak, running my engine to heat up the oil, to change it. I DO NOT turn my 100psi hose up very far. In fact, it is just opened far enough that I can hear the water flowing. I DO NOT have near the water flowing out that vicJ does in his video. I DO have a heat exchanger for the engine but the log manifolds are raw water cooled. The water comes up from the hose feed or the impeller, through the heat exchanger and back out thru the manifolds. After running at 1200 rpm for the last 20 minutes, my engine temp is just below 180? (180? thermostat) and my log risors are just bouncing off 100?.

My IR gun shows expected temperatures at all the points.

 

[vicjunkie]

Re: stringer 800

ok,

I took my stat housing off, added some engine flush, and im gonna let it sit overnight. I replaced the manifolds because of improper winterization before i got her. they were cracked on the outer jacket, seeped a bit, so i decided to replace. The riser gaskets have all the right ports in them, i checked that. I put in another sending unit that I had off of an old manifold, gonna give her another try tomorrow. Yes it ran cool all last season, and even after i changed the upper for about 80 hrs of use. the overheating came on suddenly, in about 16 ft of water running around 3400rpms. temp got to prob around 220 or so. I have even thought of blown or leaking head gasket, but the motor purrs like a kitten, no water in oil, no rough running, easy to start, etc... i can touch my manifolds when running, but it is a rather fast touch, if you know what I mean, lol. I also ran the water hose to each of the water lines feeding the maifolds after i got through running her, and water pours from both sides, and cools them down fast.I know everyone keeps saying im sucking up exhaust gasses, but i held the feed line under water with the engine running, and there are no bubbles.

 

[Boomyal]

Re: stringer 800

Well, did you get your IR gun yet? Aim it at the thermostat housing or around the sending unit and budda bing, you get your answers. If you can put your hands on the manifold, that is the first clue that you are getting enough water up from the outdrive.

 

[vicjunkie]

Re: stringer 800

my ir gun should be here in the morning, ill let you guys know. what temp should my manifolds and risers be?

 

[nick_vw]

Re: stringer 800

A quick compression test will let you know if your head gasket is leaking or blown. I had a mercruiser 165 with a blown head gasket that ran quite well, but the hot combustion gasses eventually caused overheating, much like what you are describing. Could it be you got it too hot the first time it overheated?

 

[Boomyal]

Re: stringer 800

my ir gun should be here in the morning, ill let you guys know. what temp should my manifolds and risers be?

Maybe more important than your manifold temps, at least for starters, is the temp around your thermostat housing, on the intake around the temperature sender and on all the hoses leading to and from your water pump. That is where I would start, Your temperature gauge does not show the temperature of your manifolds.

 

[vicjunkie]

Re: stringer 800

so,

I didnt get my gun today, should have it tomorrow. I flushed my block out, changed my temp sending unit, installed a new v belt, pulley on the water pump, and checked compression ( 135-150 on all cylinders ) Started her up, and no overheating on the hose. I ran her at 2700 rpms for about 10 min, and never ran over 165 or so. Im gonna put the outdrive back on tomorrow, thought id go ahead and change the oil in the upper as long as i had it off, and hopefully ill get my gun tomorrow.

 

[vicjunkie]

Re: stringer 800

so, its fixed
dont really know what ifxed it, I flushed the block, installed a new v belt, new water pump pulley, temp sending unit, tore into the outdrive, checked the swivel bearing, and impeller. I ran on plane at 3600 rpms, 28mph for around 15 mins with no problems. Temp guage is still showing a little high, 190. I shot her with my ir gun, and showing 170ish. Im gonna get a new guage, and check my ground to the block. thanks for all of the suggestions, and happy boating to all.

 

[Boomyal]

Re: stringer 800

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