OMC overheat at higher rpm! I don't get it! Everything replaced!!

[pipercherokee]

Ok, I am looking for some help. I know there are posts all over the place about overheat problems and I know all the regular things to check and am at my witts end. I have a 1986 Sea Ray 250DA Weekender. 5.7 OMC Stringer. Yes it's a stringer. 800 Series outdrive with all the typical nuances that come with it. But, this spring I put a newly remaned motor in with all new exhaust manifolds and risers, new marine engine water pump, new water pump in the outdrive which I took apart last evening to make sure it still looks good. Looks just like when I put it in, still brand new. Engine and water pumps maybe have an hour on it. Engine runs impeccably. Starts right up. Timing is set correctly. Stays at 180 degrees if I am just putting around on the lake, but start putting some rpms to it and it slowly rises in temperature. It did this on the garden hose and in the lake. No, difference. I think it would go clear above 220 degrees if I let it. There was one thing I did notice last night prior to me removing the outdrive to check the water pump, I had the hose off that feeds the thermostat housing so I could check the water flow rate while my wife started the engine. Outdrive is setting in a large tub of water with garden hose feeding the tub at full rate. First time she starts it, nothing. No water. I tell her to shut it off and try again. This time, tons of water. Fills a 2 gallon bucket in 20 seconds flat. The only thing that is original in my new setup is the intermediate,(transmission, I will call it),

Thank you for any help anyone can provide.

 

[pipercherokee]

Something else I want to mention. My power steering worked fine prior to this fiasco. Now it makes noise. It still assists in steering but is rather noisy now as I turn the wheel. Not sitting still, but only while turning. Not sure if pump is bad or if it the 2 problems could be intertwined. When I reinstalled my outdrive, I did not have the steering quite centered. It turned sharper to the left than to the right. Hope to get this more centered prior to reinstalling it. Just wanted to mention it as it appears these are my last problems I need to get ironed out.

 

[Scott Danforth]

it sounds like your running out of water somewhere

2 gallons in 20 seconds is possibly a bit low, however if you were at idle, that may be correct (i dont remember the specific pump curve). you should be getting close to 5 gallons in about 16 seconds at 2000 RPM.

when you replaced your pump, what did the old impeller look like? if there were any blades or pieces missing, did you find them?

your power steering oil cooler is between your raw water pump and the motor. have you pulled the power steering cooler to inspect it? you may have a clogged cooler. if you have a breach, you would fill your power steering up with water. you may want to check.

also, its a good idea to use an IR thermometer to verify your gauge reading to reality. the gauges on boats are notoriously inaccurate.

 

[southkogs]

I think I would check a few things in this order: proper operating temp target should be (I think) 160 degrees, then make sure your swivel bearing is greased (zerk on the front of the outdrive hidden behind the plastic screw lookin' thing) - sometimes your exhaust can leak over giving you temp problems. After that, check your stat and see if it's working properly.

If it is, I'd put the 800 unit on muffs and feed water up into it, or take it to the lake. It's tough to get the entire drive submerged in a tub and a Stringer needs to be underwater. The muffs will feed the impeller a little better, but dunkin' it in the lake would give you the best test.

You may have tried all that already by your post, but I thought I would double check.

Welcome aboard ... I'm assuming Piper Cherokee as in the airplane?

 

[pipercherokee]

Cool, thanks for some replies. Yes Piper Cherokee as in the airplane. This outdrive I have put on the boat is a different one than what was on it before I changed to the new remaned engine, but you both have made some good points I want to check into. I kind of feel the power steering issue is related so will check into the cooler on it. I really am starting to think a blockage in that area. Thermostat is working in a pan of hot water anyway. 160 degree thermostat. I wondered if not being able to completely submerge the drive as it would be in the lake was why I didn't get water at first. I just figured as long as it was submerged above the location where your muffs would be, that it would work as it does at the lake. IR thermometer sounds like a good thing also. I'll get back with you. Thanks again for your insights.

 

[bruceb58]

I wondered if not being able to completely submerge the drive as it would be in the lake was why I didn't get water at first. I just figured as long as it was submerged above the location where your muffs would be, that it would work as it does at the lake.

Nope, it doesn't work that way. Needs to be submerged to a level above the raw water pump or it won't prime. When you are underway, the pump will be above water level bit then you have the force of the water into the pickup that provides water pressure.

So, just to be clear, it is overheating when your boat is in the water?

Make sure you do what Southkogs said in his post about the swivel bearing.

 

[pipercherokee]

Yes, I have had it in the lake once since motor change and I have had it on muffs also. It overheated in the lake while up on plane. It cools off to right around 180 when I just putt around at idle or a little faster. Since we are talking about cooling, I also installed a new water heater with a heat exchanger. When you hook up a water heater this way, is there an in and out on the water heater, because it didn't show any. I just figured it didn't matter. Figured the water just makes a loop inside the water heater and comes right back out to the engine (exhaust manifolds). Is this correct. I tried to figure out the overheating problem with the water heater hooked up and bypassed. It did it both ways and always when I tried to keep the boat up on plane. Reason I ask about an in and out on the water heater is there was a leak coming from somewhere out the bottom of the water heater itself. So I thought either this brand new water heater is leaking (which is another problem that sucks) or maybe I was trying to force water into the out of the exchanger. I don't know, just some thoughts and really 2 different problems.

 

[Howard Sterndrive]

are you sure the impeller vanes were oriented the correct way? (contrary to popular belief, they will NOT right themselves)

Many years ago, one supplier had impellers where the center hubs liked to break free in the rubber- a long shot that one. Is the little impeller drive key in?

 

[pipercherokee]

Key is in place and I installed per Seloc manual, and TC Electronics video on youtube. Good point though. Didn't try and turn impeller real hard to see if it was slipping on the collar itself. Will check also.

 

[pipercherokee]

Another thing. The thermostat kit come with 2 cork type gaskets. Does one go in 1st, then the thermostat and then the other? It doesn't seem like it would stay where it's put very well. That is the way I had it installed and now after removing it again the 1st cork gasket I had installed 1st seems it won't really seat up well. It's kind of too small or something. It was all still in place when I took it apart to inspect it. I have seen pictures of some of these thermostat housings where the thermostat looks like it goes in and then a rubber o-ring, but mine has a really much wider gap in there than what an o-ring would fill. Should I put some sealant of some sort to help hold the thermostat in place?

 

[bruceb58]

This may be your issue. The thermostat is absolutely held up in place in the thermostat housing with an o-ring. If it isn't, it won't work properly. There is a groove in the housing that the o-ring goes into. Very possible that if your housing is old, that groove has corroded away. Not uncommon to have to replace this housing.

 

[MCJagger]

I am wanting to grease my swivel bearing as well, but I have no idea where the zerk is. I too have an 800 series stinger. does anybody have a picture, or an excellent description? and can this be done with the boat in the water? Sorry for the highjack.

 

[southkogs]

Grease Point is located here:



On the front of your drive, the "plug" should be a plastic (usually red) bolt lookin' thing.

 

[pipercherokee]

Hmmm. Thanks for the picture. That's a new one for me. Another question. Where can I get that exhaust gasket in the picture. The big round one in the top of picture. Mine is cracked. Would this cause much issue with overheating?

I have now taken off the power steering cooler and there was a blob of crap in it. Didn't seem to impede the water flow too much but it couldn't have helped anything. Ordered a new thermostat housing and thermostat with new o ring. Hopefully that helps also. Could exhaust be getting back into the impeller area somehow?

 

[southkogs]

I think the exhaust seal is still available from shop.evinrude.com.

Yes, exhaust can effect the function of the impeller. That's why greasing it and the seal are important.

 

[vinnie1234]

Another place not mentioned here is the ears on either side of the upper gearcase. If the 800 is like the 400 (my boat) the water gets onto the intermediate through there. It takes about 2 minutes to remove the ears and inspect the passage way. 4 bolts on either side. While you are at it you could stuff some grease into the bushings for the tilt too.

 

[jobofly]

What kind of Greece do you use for the zerk?

 

[southkogs]

What kind of Greece do you use for the zerk?

I use Ancient Greece. :laugh: Sorry. I couldn't resist.

Seriously, the local auto parts place here carries Coastal Marine Grease. So, that's what I stick in the gun.

 

[pipercherokee]

Ok, just an update. I have replaced my thermostat housing and thermostat with new. A lot better fit of thermostat with new o-ring. Re-installed water pump in outdrive properly. Cleaned out power steering cooler which had a blob of crap in it. Shot 20 squirts of Johnson/Evinrude Triple Guard Grease 775776 into swivel bearing and have now run it on the muffs for quite some time. Never got above 170 degrees. It already looks better than it did before. I will lake float it one evening this week to get it up on plane and see, but so far so good.

 

[southkogs]

Awesome! Good luck.