OMC Options

[jhill51]

Got a '72 OMC outdrive and a Buick 225. Been struggling with overheating for 2 years. Finally determined it was the impeller late last summer, replaced impeller/housing and had some success but still not perfect. Now the problem is back again and it looks as though we've blown a head gasket or something else that is mixing oil and water. Couple of questions:

1) is there any options for replacing this hard to work on, hard to find parts for, OMC outdrive?
2) is it common that the impeller only lasts a few runs?
3) any bolt in options to replace that hard to find parts for 225?

Any help is appreciated.

 

[superbenk]

Re: OMC Options

Not really. The Stringer uses a completely different & much bigger transom hole than everything else. Also the transom on Stringer-based boats tend to be thinner because they were never intended to support the weight & thrust of the drive, so there's a lot of planning, design & work involved in converting a Stringer boat to something else.

The impeller should last at least 2-3 seasons (regular maint. regime suggests preventatively replacing it every 2-3 seasons). You're not running your boat without water circulating through the outdrive are you? Many stringers have an adapter on the trunnion cap to hook up a hose and run water through the drive while running (and thus through the impeller). If you don't have that you can find them on eBay sometimes. See this thread: http://forums.iboats.com/showthread.php?t=336474

If you're not running water through the drive everytime you run the engine, you're going to burn up and ruin the impeller in no time (within seconds usually).

 

[jhill51]

Re: OMC Options

No, this is a 35' houseboat so it is never out of the water. I was told last year to grease the impeller but I cannot find a zerk anywhere to do that. When we replaced the impeller and housing last year, the cooling problem got better but didn't stay that way for long. Seems like the first few times we could run the boat at 2000 RPMs and now it's back to barely above idle before it starts to overheat. Is it possible that I just need to grease the impeller again? If so, do you know where the zerk is to do that? I've been in the water hugging that outdrive several times and cannot find it. It's on a '71 OMC electric outdrive, "1971 OMC HUFR-20D 155 hp".

Appreciate any help.

 

[superbenk]

Re: OMC Options

There is no zerks for the impeller or greasing to be done to it. There is a zerks to grease the swivel bearing between the upper & lower gearcases. If that bearing is shot it could be allowing exhaust to enter the pickup under the impeller thus making it not suck water properly (ie, lose vacuum). The access hole for the zerks is very small, but it is directly above the cavitation plate in the very front of the drive. You'll need an extension to get in there all the way (about 3-5" in). Note that I have a hydro-mechanical drive, so the electric drive you have might be slightly different here.

You may also have a bad o-ring on the impeller shaft or bad o-ring and seal around the impeller housing causing exhaust to get sucked in reducing your vacuum. Is your thermostat & the engine water pump in good condition? How are your risers?

Last idea (for now) - you can pull the hose off the thermostat housing at the engine that leads back to the intermediate (that the raw water flows through) & start the engine to see what kind of pressure you get out of it (be prepared for it to pump A LOT of water!). If you have poor pressure out of that hose, you definitely have an impeller issue or a blockage. If you have good pressure, you have a problem elsewhere in the cooling system.

 

[jhill51]

Re: OMC Options

Ok, I'll try to find that zerk again. I'm not sure what kind of shape the risers are in but I have already replaced the waterpump and thermostat. I need to find that zerk as I'm thinking that keeping grease on the swivel bearing is what is causing my problem. I'll try to pull the hose off and test it...looks like I'm going to have to put head gaskets on it anyway. Someone has said that it could be a cracked block but I figured that would have caused it to stop running.

By front of drive, you mean the side that faces the transom, correct?

 

[superbenk]

Re: OMC Options

The hose comes from the housing between the engine & drive. Should be about a 1" diameter hose on the starboard side.

A cracked block could have the crack in the outside. You'd see water coming off the side of the engine & filling up your bilge.

 

[Bondo]

Re: OMC Options

Someone has said that it could be a cracked block but I figured that would have caused it to stop running.

Ayuh,... A blown headgasket makes it run rough,...
A cracked block fills the oil pan with water....

1) is there any options for replacing this hard to work on, hard to find parts for, OMC outdrive?

Ya glass the hole shut, 'n refit a Different driveline, Pulleys to Prop...