Evinrude 25 hp, too hot to handle.

[glennkil]

Can I please have some assistance with this problem? I've checked through the forums but am still not sure where to go.<br /><br />Engine is a 1972 Evinrude 25HP Model 26203R. Whilst out yesterday and running at a cruise for 15 minutes (certainly not WOT) the engine stopped dead. Suspect that power had decreased over the previous 5 minutes. There was a moderate headwind and we were heading against a very slow outgoing tide but nothing major in the way of resistance.<br /><br />I suspect overheating as the WD-40 I religiously spray the engine with after each trip was boiling off like crazy and the vapour leaking out the cowling. Tried to pull the rope over as soon as it stopped to ensure it hadn’t seized and despite not starting it still turned over OK.<br /><br />Let things cool down and thankfully the engine started up fine and I continued on my way for another 20 minutes at a much reduced pace. Headed up river and swam for a couple of hours which was good as it was a stinking hot day at about 40 degrees Celsius (104 Fahrenheit).<br /><br />Against better judgement I headed back up to a cruise speed on the way home and things appeared to be OK although I think we may have lost a little power a few times and nudged the throttle up just a tiny bit to keep a constant speed. The wind was now at our back and the tide slack.<br /><br />Pulled the cowl off the next morning and noticed that a silver aluminium plug (has numbers on it) on the right hand side of the engine powerhead (looking from back) had become dislodged. This plug is a marker of some kind and just goes into a blank hole but I suspect it fell out due to the different expansion rate between it and the main casing.<br /><br />I replaced the water pump in this engine straight after I bought it before running it and it seemed to be OK up to now although I have never ran it at cruise (75 % throttle) for any longer than 10 minutes.<br /><br />When I bought it this engine it had never been run in salt water and all the internals including the metal water pump housing looked like new. I pulled the thermostat this morning and tested it in boiling water and it opened fine. Once again the housing and cover look like new. I also note a small rubber restrictor in a small hole to the rear of the large hole for the thermostat that covers a very small water passage?<br /><br />What could be causing this overheating problem? The fuel was fresh and mixed at exactly 50:1 with quality oil.<br /><br />This engine doesn’t have a pee hole as such but blows a fair bit of spray and exhaust out of the relief hole high on the leg. <br /><br />I really want to resolve this issue and don’t want to turn the motor into scrap by toasting it. Unfortunately this engine doesn’t even have a buzzer let alone a temp guage.<br /><br />Some help on this matter would be greatly appreciated.<br /><br />Cheers<br /><br />Glenn

 

[rodbolt]

Re: Evinrude 25 hp, too hot to handle.

i cant recall any rubber restrictors visible inside the t-stat housing. odds are its a piece of impeller. you should get a solid stream of water out of the idle relief port not just a mist. my advice is to remove the head, check it for warpage and inspect the cooling passages and cyl walls then go inspect the pump and housing.<br /> the reason why it shut off was it got so hot it lost compression or stuck the piston skirt to the wall. thats what is refered to as the automatic shut off. I hear it weekly. it actually has none. but that motor will warp a head rapidly and thats what the loss of power was trying to tell you.

 

[glennkil]

Re: Evinrude 25 hp, too hot to handle.

Rodbolt,<br /><br />It is certainly a restrictor in the water passage, its round and has a hole in the middle about the size of a pen tip. I'm keen to inspect the cylinder walls but how can I tell if a piston was scuffed up from the top? Wouldn't I be better off doing a compression check before pulling it apart? I really don't think that there is crud in the cooling passages as the entire thing looks new on the inside. Are there any other causes of overheating? Ignition timing? Carbon build up?

 

[Walker]

Re: Evinrude 25 hp, too hot to handle.

A couple of questions. Did you replace the impellor or the entire waterpump? Is you possible you picked up some debris on the intake screens while running?

 

[R.Johnson]

Re: Evinrude 25 hp, too hot to handle.

On that engine, there is a thermostat, a thermostat rubber seal ring, and a thermostat housing gasket. As rodbolt pointed out, there is no retrictor. I don't know what you found, but! take it out. You do know the engine is overheating, as the WD-40 is boiling off the surface, and the engine squeaked to a stop.

 

[glennkil]

Re: Evinrude 25 hp, too hot to handle.

From what i can see there are three water passages under the thermostat cover. The hole that the tstat sits in, a main large hole to the right and a very small one immediately to the rear of the tstat hole. This small one has the restrictor<br /><br />By the way, if this engine still starts and runs fine with the same power level what are the chances of damage?

 

[glennkil]

Re: Evinrude 25 hp, too hot to handle.

 

[byacey]

Re: Evinrude 25 hp, too hot to handle.

Check also to make sure your fuel system is clear and free of dirt, including the carb main jet and float bowl. Running too lean could cause it to run hot also. I guess the first step is to verify that your cooling system isn't restricted by any extra parts that shouldn't be there.

 

[British Seagull]

Re: Evinrude 25 hp, too hot to handle.

G'day concerning the thermostat i have the same motor from 1967 and the only places i found any blockages when it ran hot where in the water passages and they were salt. as for the thermostat i wouldnt worry about it take it out all together the water doesn't get cold enough and they heat up quick anyway its an old motor so its cooling system is likely to be bad anyway

 

[Pony]

Re: Evinrude 25 hp, too hot to handle.

I would think running without a t-stat is not the best solution. If you search this forum long enough you will see that johnnyrudes are meant to run at a certain temp......the t-stat serves a purpose.<br /><br />Simply not using one because the cooling system may be bad since its an older motor makes very little sense. If the cooling system REALLY is bad.......it needs to be fixed properly.

 

[glennkil]

Re: Evinrude 25 hp, too hot to handle.

Hi,<br />Checked with the local dealer. They advise the the little restrictor was a modification to allow the engine to warm up quicker. He thinks that I could have picked up a plastic bag and to check the impeller again in case I fried it but I don't think so. I assembled the water pump without sealer on the plate or housing cover, is this OK?. I actually bought a head gasket at the dealer but think I would be better doing a comp test before pulling the head. Comments??<br />Even the dealer recommended pulling the thermostat if I didn't do any trolling. <br />What now guys?? I am at least an hour away from the nearest ramp to test anything and I don't want to put my wife and child in the boat and have it row it back because it has toasted itself. Aside from the $$$$$ it is a major pain.<br />How common is it for an outboard to get hot, stop and still be fully serviceable again?<br />By the way there seems to be some confusion regarding the output of the hole on the leg. It isn't a pee hole but a combined exhaust relief and "spray" hole. (Please correct me if I'm wrong). I get a spray of hot water out of it at idle and a fair flow going along. I replaced just the impeller not the housing which despite being over 30 years old did not have a scratch, nich or even a pit in the housing. Ditto the thermostat housing or any part on the engine. This engine never saw salt water and hasn't seen much use. To kill it by cooking the guts out of it would be criminal. Please help.

 

[MCM]

Re: Evinrude 25 hp, too hot to handle.

Hi Glen, no sealer I'm aware of needed for the water pump. A compression test would be a prudent thing to do after an overheat such as yours. Running without a thermostat is not reccommended as OMC motors don't like running too cool any more than they do hot. It can cause carbon buildup in the cylinders among other problems.<br /><br />It's possible for a motor to get that hot and not suffer any permanent dammage and a comp. test would help in that regard.<br /><br />Post back any findings as to comp #'s etc.

 

[mikeyzx2]

Re: Evinrude 25 hp, too hot to handle.

I think prior to '78 or '79 they didn't have pissers. for example my '77 V4 doesn't, the water spits out the two holes near top of leg. those are just relief ports when idling, as well as indicator that there's water flow. <br /><br />Anytime a motor overheats there's a 50/50 chance that something's gotten hurt, like the pistons or cylinders walls typically. <br /><br />There's a recent post concerning running without thermostats, you need to read it. They're there for a reason.....

 

[itstippy]

Re: Evinrude 25 hp, too hot to handle.

You might be fine. Get a trash barrel and fill it with water to run the motor in so you can test it without driving an hour to the ramp. Make sure the water comes up high enough to submerge the water pump. It may take ten or fifteen seconds of running for a good spray of water to start coming out of the exhaust relief holes. It should quickly get nice and warm, like dishwater. Let it run for a half hour or so to make sure all's well. Don't take it over high idle. It'll warm up to operating temp in five minutes and will overheat in ten or fifteen if it's gonna overheat at all. You should be able to touch the top of the head without burning you finger.<br />I will bet you that there are more of those 22CI OMC's that have overheated to the point they stop running due to weeds/muck/plastic bags than there are owners who will admit it happened. They are tougher than most.

 

[Joe Reeves]

Re: Evinrude 25 hp, too hot to handle.

Either the water pump has failed, was not installed or sealed properly, the thermostat jammed, or the water passageway is restricted with salt corrosion (or some foreign material) at some point, or a combination of any of the above.<br /><br />To have a engine overheat to the point you describe.... boiling the WD40 you spray on the engine, coupled with having it get to the point where it locks up solid, there are no short cuts especially when you mention having a wife and child which will also be in the boat.<br /><br />Note.... There are no water deflectors in that engine's crankcase (block) water passageways. I assume that's what you're speaking of when you mention a "restrictor"? If so, educate your mechanic as the water deflectors which are used in other engine are designed to divert the water in a definite flow direction to avoid a stalemate which would lead to overheating in those (not yours) specific engines.<br /><br />I believe that there may be some sort of restrictor in the thermostat area though. Seems to me that I came across a update bulletin about that.<br /><br />It could very well be that you picked up a plastic bag which would cause the problem you encountered, however that doesn't matter at the moment as the moment you raise the engine, the bag drops off, leaving you in ya ya land. Bottom line is that everything must now be checked.<br /><br />I strongly suggest you do not play with the engine but rather do the job properly, and in my opinion that would be:<br /><br />Drop the lower unit and dismantle the water pump for inspection, then regardless of what you see, install a new "complete" water pump kit, sealing any gasket that might exist with what is known as simply "gasket sealer" (Small can that has a brush attached to its screw off cap). And on the metal to metal or plastic to metal surfaces, use a sticky sealant named "Marprox Sealer 1000" or "Boat Armor Sealer 1000", available at any reliable automotive type store, or what used to be known as "OMC Adhesive" (I don't know what Bombardier calls it now) which would be available at your local marine dealership.<br /><br />While the lower unit is off, remove the cylinder head and scrape out, clean out the water passageways as good as posssible, then use pressurized air to blow up the water tube and into those water passageways checking for any other possible restrictions.<br /><br />Install a new thermostat and head gasket. Torque the head bolts to 96 to 120 inch pounds in the following sequence.<br /><br />9..10<br /><br />5...6<br /><br />1...2<br /><br />4...3<br /><br />8...7<br /><br />The following should be of interest to you.<br /><br />(Gasket Sealers)<br />(Usually available at any reliable automotive parts type store)<br />(J. Reeves)<br /><br />Do Not use any type of sealer on outboard carburetor or intake manifold gaskets as this would cause blockage of various fuel/air passageways. Also, there are new type gaskets, including head gaskets, which are used through out the engines that are coated with a substance that gives a shinny appearance to them. These gaskets are coated with a self sealer and are to be installed as is.... no sealers! Older style head and fuel related gaskets that are not coated with this substance are to be simply coated with oil.... nothing else.<br /> <br />All other gaskets (hopefully I've not overlooked anything above) should be coated with Gasket Sealer (the type that comes in a can that has a small brush in its screw off cap). This also pertains to some water pump installations that use a gasket between the plate and the lower unit housing.<br /> <br />Marprox Sealer 1000 or OMC Adhesive or Boat Armor Sealer 1000 (same substance) should be used on any metal to metal or metal to plastic surface (such as impeller hsg to plate) to eliminate air leaks. It should also be used on the Spaghetti tubing that is used on many powerhead crankcase halves, lower unit skegs, etc. I have found that this substance works quite well on various "O" Rings such as what are found on lower unit carrier and upper driveshaft bearing housings (Note that this substance is obviously not to be used on all "O" Rings).<br /> <br />DO NOT use any sealer on the large "O" Rings that are used on the upper and lower crankcase heads (The housing/heads that slide over the top and bottom of the crankshaft). On those "O" Rings, use only a coating of grease.<br /> <br />The exception of surface to surface contacts pertains to the later model matching crankcase (block) halves (which does not incorporate spaghetti tubing) which call for "Gel-Seal", or any other surface that calls for Gel-Seal. This substance seals in the absense of air, and if called for, must be used. One other form of Gel Seal that can be substituted is "Loctite #518". Nothing else that I know of will do!<br /><br />I advise against using silicone or permatex on a outboard engine. It simply will not function properly. The exception to this (as per OMC's recommendation), is to use the black Permatex (heavily) on the gasket 306242 which seperates the inner exhaust tube from the exhaust housing on the 1959 35hp and 1960 to 1970 40hp OMC outboards.

 

[glennkil]

Re: Evinrude 25 hp, too hot to handle.

Itstippy,<br /><br />Keen to run it in a barrel but the engine didn't overheat until it was under moderate load. I don't think that a fast idle would reproduce the issue but I'm keen to hear response if you think otherwise.<br /><br />Joe,<br /><br />Thanks for the detailed reply. I really appreciate your time. My plan is as follows.<br />1. Compression test.. If no good.. out the door!<br /><br />2. If still ok and I suspect it is due to the fact it still starts, idles well and makes good power. Pull the leg and check the water pump. I did not use any sealant on the housing to plate as I was advised. The vanes were installed facing the correct way and I dont think there is a right way or down up for the impeller face to the plate. New O rings were used on the spacer tube that the main drive shaft from the power head runs through.<br /><br />3. Pull the head and check the bores. Clean out the water passages. Is this also an appropriate time to clean carbon from the piston heads? If so how without causing damage? <br /><br />4.Reinstall with a new head gasket (the one I bought has shiny sealant on the face BUT the dealer said to STILL use sealant. Who's right??<br /><br />5. Try it out!!<br /><br />I know 99% that this issue is not caused by corrosion. I'll post some photos of the internals that will indicate the total lack of salt or deposits in the engine. It is clinical with zero pitting of any surfaces exposed to water. Could the headgasket have previously been installed incorrectly blocking a passage?<br /><br />I have a maintenance manual on CD but it is none too specific about much at all. It does mention removal of the exhaust cover plate to check for warpage after getting hot.. Agree?? <br /><br />This problem intrigues me as I ran it for short bursts over xmas at cruise speed for no longer than 10 minutes but did heaps of low speed runs with zero signs of problems. But the first time I run it for 20 mins at cruise under moderate headwind and load it burns up.

 

[itstippy]

Re: Evinrude 25 hp, too hot to handle.

Is there a chance that there was cavitation going on and the intake was sucking up air at higher speeds? Maybe at slower speeds all is well but when you give her some juice the situation changes and air bubbles get into the cooling system. What kind of boat is this on? Does it plane out or is it a displacement hull? Take a good look at your setup.<br /><br />You are right, it sounds like running it in a barrel won't necessarily prove it won't overheat again under similar conditions. I was thinking plastic bag or some other obstruction. Also do whatever Joe Reeves says. If he says to stand on your head and whistle, do it. Really and no kidding.

 

[glennkil]

Re: Evinrude 25 hp, too hot to handle.

itstippy, the boat is a 3.37 metre aluminium runabout and the hull has quite a defined deep "V" at the front. Cavitation had crossed my mind but I came home at cruise speed (down wind, with tide) with no problems. The enfine is a long shaft and the prop is way, way below hull level. That said I have a bad feeling that if I had of turned around and headed back upstream that I would have been frying eggs again in a short time.

 

[Joe Reeves]

Re: Evinrude 25 hp, too hot to handle.

If the head gasket has the shinny sealer on it, DO NOT use any kind of sealer. Many of those gaskets state right on them "Do not use sealer".<br /><br />If you have the old type gasket, use nothing but oil on it.<br /><br />The cavitation plate should be approximately 3/4" below the keel (bottom of the boat), no more than 1". Any less than 1/2" or more than 1" is prone to problems.

 

[glennkil]

Re: Evinrude 25 hp, too hot to handle.

Joe, Do you ever sleep?? Must be awful late over there! Have visted your way for what have been the most fantastic 3 holidays I have ever had! Remember sitting on Jetty point watching a space shuttle launch and seeing a 4 foot mackeral take a bait fish right in front of me. Blew me away.<br />Thanks for your help..<br /><br />Actually gasket says "do not use sealer" but dealer said ignore it.. I'll take your side on this one!!