engine overheated

[Uncle Dave]

Re: engine overheated

DT<br /><br />I would bet my grandma's sows ear purse that the exhaust elbow or manifold is clogged with rust. Fairly easy to take off and replace.<br />All the cooling water and exhaust gasses has to squeeeze thru those small passages .<br /><br />Uncle Dave

 

[dallas T]

Re: engine overheated

Well,the last few posts seem to be on to something.<br /><br />I pulled the 3/4" hose (from transom to thermostat housing) and checked for flow again (still good).<br /><br />Next, I pulled the hose that goes from the thermostat housing to the exhaust and hooked up a garden hose. After a minute or 2 I checked the exhause at the prop and cool (hose water) was exiting.<br /><br />Ran the boat at idle and still good. Took it for a little ride and it was better but still not totally fixed. So we may be onto some thing here. Time to pull off the elbo etc. for inspection.<br /><br />Thanks again for all the help!

 

[dallas T]

Re: engine overheated

Updates:<br /><br />I pulled the exhaust elbo and it had a lot of rust in the water passages. Tried to push water through and it appears that approx 1/2 is clogged. Is this something I should try to clean out or should I just replace? The exhaust manufold seemed clear.<br /><br />Also, I took a look at the flapper and it was gone! I looked around for flapper debris and could not find any. Everthing appears to be clear from the flapper down through the outdrive. Should I be concerned about the missing flapper or just get a new one?<br /><br />I guess it is just a coincidence that when Bob ran it aground and clogged the intake screen, the elbo finally clogged up??? <br /><br />Thanks again,

 

[rbezdon]

Re: engine overheated

Seems like the crud you picked up just finished the clug up job. I would pull off the drive and look for the flapper. It is likely stuck beyond the y pipe and in the bellows of L/U somewhere. On the manifold and risers, get new. The cost is not so cheap but a new engine is more. The large flked off rust clogging the passages is the walls of the things and that means they have thinned. If you clean them and one of the walls rust through quickly, it could let water into the exhaust and that would be the beginning of the end. I know you could clean them and pressure test but think if the walls are 1/2 or less as thick as new how long before they rust through??

 

[dallas T]

Re: engine overheated

Good points.<br /><br />I ordered the elbo from basicpower.com along with some misc. gaskets and a thermostat (local shop does not stock elbo and basic power was much cheaper).<br /><br />Hopefully it will arrive before the weekend!<br /><br />Thanks,

 

[dallas T]

Re: engine overheated

Update:<br /><br />The elbo came in on Friday! After installing the elbo and some misc. gaskets, fired up the boat and she was running cool. Took it out for a ride and the temp. barly got above 100 degrees (still no thermostat). So, I think this one is finally solved. Will install the thermostat tonight.<br /><br />In summary, this is what I think happened.<br />1) the boat ran aground and sucked in sand/muck clogging the raw water instake screen.<br />2) the boat overheated due to lack of flow.<br />3) either from the excess heat or some sand or just plain bad timing, the elbo clogged up with rust<br /><br />Thanks for all of the help!

 

[dallas T]

Re: engine overheated

More problems...<br /><br />Boat ran great on Saturday & Sunday, then on Monday Bob noticed some milky oil coming out of the breather.<br /><br />Did some searching on this sight and think it could be one of the following:<br />head gasket<br />cracked head<br />cracked block<br />exhaust manifold<br /><br />Not sure where to start the diagnostic journey. I will see if I can borrow a compression tester. Any thoughts?<br /><br />Thanks,<br /><br />Thanks

 

[Haut Medoc]

Re: engine overheated

When you pulled the risers/manifolds apart did the mating surfaces look good? I would pull the risers off and look for evidence of water leaking between them. Check the plugs/cylinders for water. Is the oil on the stick milky?. If you had a cracked head /block your oil level would rise rather quickly I think, has it?.......JK

 

[dallas T]

Re: engine overheated

I replaced the elbo because it was all rusted / clogged up. The elbo to manifold surfaces looked fine. It took a bit of work to scrape off all the old gasket material from the manifold but when I was done it was smooth and clean.<br /><br />The oil on the stick is milky as well as the oil that came out of the breather.<br /><br />Oil level has not risen significantly.<br /><br />So, here is what I plan to do:<br />1) tow the boat to the ramp, pull it out of the water and get it on muffs.<br />2) pull the plugs and check for water (is it safe to crank the motor with some water in the oil or do I need to change the oil first?)<br />3) run a compression test<br />4) remove the recently installed elbo and inspect surfaces<br /><br />I assume compression test would rule out head gasket and other major motor issues.<br /><br />I assume if I find water after removing the plugs, it is a manifold issue.<br /><br />Are these two assumptions correct?<br /><br />Thanks,

 

[dallas T]

Re: engine overheated

Update:<br /><br />Pulled the boat out of the water and did the following:<br /><br />Pulled the plugs and checked for water (no water)<br />Ran a compression test(all cylinders looked good, so I assume good head gasket)<br />Pulled off the recently installed exhaust elbo (looked good)<br />Pulled off the exhaust manifold (looks bad, rusty and probably leaking through the water jacket)<br /><br />Ordered new gaskets and exhaust manifold, does it sound like I am on the right track?<br /><br />Thanks

 

[Haut Medoc]

Re: engine overheated

If the manifold was crusty, then by all means replace it. Was it crusty inside the exhaust passage or the water passage? If you show no sign of water on the plugs or in the cylinders, then I doubt that it is a bad maifold. Did you crank the engine with the plugs out? (Ground coil first) Any water at all? The water is getting in somewhere.A compreession test does not necessarily mean that you can rule out a head gasket. A leak down test would tell you more.Replace the manifold and post back, you are starting in the right place.....JK

 

[dallas T]

Re: engine overheated

It was crusty in the water passage and no water came out of the cylinders when I cranked the engine with the plugs out...<br /><br />Most of the exhaust passages had the normal exhaust soot but 2 small areas were clean (like they had been washed with cooling water) so I assume that is the source of the problem/leak.<br /><br />The new manifold is due for delivery on Monday...

 

[dallas T]

Re: engine overheated

Update:<br /><br />Installed the new manifold, verified the oil was water free. All seemed goo so in the water she went. Temp was normal, oil was water free after running for several minutes. A few laps around the lake and still no problems. I think we have the problem solved...<br /><br />Thanks all for the help!