omc stringer 175 overheating at idle

[whitesig]

1976 omc stringer 302 V8 175hp overheats at idle.<br /><br />I have checked previous posts and done the following. I replaced the complete assembly for the water pump in the upper unit of the outdrive. I took off the lower unit and looked for any problems. Everything looked ok.<br /><br />If I am under way the temperature drops to normal. If I stop at idle the temperature climbs to above 200.<br /><br />The problem seemed to have started when I replaced the lower unit. It appears to be an older version then the one I took off. However, I did get stuck on a sand bar during the same time period.<br /><br />I took off the hose from the back of the engine that runs to the thermostate housing. At idle hardly any water comes out. If I increase the RPMs a very small stream of water comes out.<br /><br />I would appreciate any help troubleshooting this problem.

 

[KaGee]

Re: omc stringer 175 overheating at idle

At idle you should be able to fill up a 2 gallon bucket fairly quickly.<br /><br />Did you replace the impeller housing when you changed the impeller??

 

[whitesig]

Re: omc stringer 175 overheating at idle

I replaced the housing, impeller. Bought a complete kit.

 

[KaGee]

Re: omc stringer 175 overheating at idle

It's possible that you have a bad impeller, but I would take off the side caps and inspect for debris blocking the water from getting up through the drive. Did you replace the O rings and gaskets on the pivots?? You also might remove the pivot caps and run water backwards from the hose at the thermo housing to make sure the passages in the intermediate are clear.<br /><br />There have been cases where the impeller shaft spun on a new part. Unlikely, but possible.

 

[whitesig]

Re: omc stringer 175 overheating at idle

When I ran water back down through the hose I noticed that quite a bit of water leaked from the side caps. I took the side caps off and the o rings where flattened out. In fact the smaller o rings were missing on both sides. <br /><br />Could water leaking from behind the side caps cause not enough water to make it to the engine.

 

[KaGee]

Re: omc stringer 175 overheating at idle

Yes.

 

[whitesig]

Re: omc stringer 175 overheating at idle

I replaced the orings and gaskets on the side plates. I've also flushed back from where the hose connects to the thermo housing. I just put on a new impeller and impeller housing.<br /><br /><br />I still notice when I take the hose off at the thermo housing at idle no water comes out. However, if I increased the throttle just a little the water started to flow pretty good.<br /><br />Any ideas

 

[KaGee]

Re: omc stringer 175 overheating at idle

Did you by chance take off the 2 oblong plates on each side of the upper unit to see if they were clogged up? I forgot about those till I looked at my unit today. <br /><br />Is this just doing it while on muffs??<br />Have you tried launching it to see what happens in the water?<br /><br />The system is pretty straight forward, I'm scratching my head on this one.

 

[whywhyzed]

Re: omc stringer 175 overheating at idle

I believe it was the guy who goes by "rodbolt" that once posted about a new stringer impeller that was bad- the rubber part was slipping on it's hub

 

[whitesig]

Re: omc stringer 175 overheating at idle

When I have a hose connected in the driveway it does not overheat. It only overheats in the water. I haven't taken the two oblong plates off but I will this week. Thanks.

 

[whitesig]

Re: omc stringer 175 overheating at idle

I took the two plates off and they were not clogged.

 

[KaGee]

Re: omc stringer 175 overheating at idle

Sure sounds like you have a blockage there. Have you ever taken the upper shroud off from the lower? That is the only thing left... a blockage in the lower, not allowing enough water to reach the pump.

 

[Boomyal]

Re: omc stringer 175 overheating at idle

Kagee, I have lots of thoughts but no specific hands on knowledge, here, beyond this. As you have said, the impeller should fill the hose to the t-stat housing, at an idle. <br /><br />It's no mystery that the motor might not overheat on the hose. It's not so much relying on the impeller to get water up to the t-stat housing.<br /><br />Water should not be leaking out of the end caps under any scenario.<br /><br />Before I die, I am going to take one of these things apart and learn it from end to end. I know a lot about the peripherals but have not personally disassembled one.

 

[KaGee]

Re: omc stringer 175 overheating at idle

"The problem seemed to have started when I replaced the lower unit. It appears to be an older version then the one I took off. However, I did get stuck on a sand bar during the same time period."

Gary, don't know what to tell you. There is something centered around that lower unit. As to what, I just don't know.

 

[KaGee]

Re: omc stringer 175 overheating at idle

Something else did come to mind... <br /><br />I'm sure you have inspected the exhaust rudder screens for blockage... corrosion, paint or otherwise... what shape was the swivel bearing in?? <br /><br />Oh, and you do have a manual don't you? My Seloc shows great pictures of the breakdown. Your lower unit is way different from mine.