1976 Mercuiser 233 Raw Water Cooling - Help with diagnostic procedures

[Lancer76]

This summer, I purchased an almost wonderful 1976 Chris Craft Lancer 23'. The boat is equipped with the original Mercruiser 233 (Ford 351W) with a MR-1 outdrive and was run in fresh water. Prior to my purchase, the boat was covered, but not run for about 2-3 years. When I got the boat, I went through the ignition and changed the points, condenser, plugs and wires and adjusted dwell. I also changed the stern drive impeller(all but the lower portion of the impeller housing), lower unit oil, and engine oil. The impeller I swapped out had disintegrated. With that done, the engine ran wonderfully on the hose. Temp never went above 150 F.

I launched and found that with higher RPMs the engine temp went to greater than 180 degrees. It would cool at lower RPMs. I could putt putt around all day without overheating, but could not go above 1.5K- 2K RPM without rising temps.

Since then, I have replaced the entire lower unit pump (complete housing), searched for and found more old impeller, replaced engine circulation pump (old one was weeping), drive belt, T-stat, and starboard riser. I also took off and cleaned port riser.

I only swapped out the starboard riser because the temps on the starboard riser were the highest, so I thought their might be a fatal restriction. I used an infrared thermometer for engine temps. I have run water through the engine and cooling hoses with a garden hose, and I don't think there is a restriction, or at least I don't get back pressure.

Took back to the lake and same thing. No better. I did take of the raw water supply hose off at the engine while on the water at idle and I thought the flow from the lower unit seemed meager, but I didn't measure it.

I am wondering about water supply from the sterndrive to the engine. I took off the outdrive today and disconnected the hose at the engine and ran the hose down it. The flow from the engine side of the hose to the sterndrive is impeded somewhere and I get back pressure. Is that normal? Should I explore removal of the bell housing to check for lost impeller pieces. FWIW, the PO said he never had this issue. There is no oil cooler on this boat.

How should I proceed to get this thing cooling correctly? I feel like I am not doing this in the most logical fashion.

Thanks.

 

[Scott Danforth]

the raw water flow should be about 15 gpm at 1000 RPM.

there should be a power steering cooler between the transom assembly and the thermostat housing. this is the first point of things clogging.

 

[Bondo]

The flow from the engine side of the hose to the sterndrive is impeded somewhere and I get back pressure. Is that normal? Should I explore removal of the bell housing to check for lost impeller pieces. FWIW, the PO said he never had this issue. There is no oil cooler on this boat.

Ayuh,..... Welcome Aboard,..... The flow should be free, both ways on that line,.... ya had the drive off, Right,..??

When ya pulled the raw water supply hose in the lake, it should bubble straight up 'bout 5 inches at idle,...

It could be jambed up impeller bits, or the fittings at either end, or the transom hose itself,...
Might be a good time to do a full bellows job,...

 

[Lancer76]

Thinking the same thing, Bondo. I will replace bellows.

Regarding the bellows and gimbal bearing, upon removing the sterndrive and looking into the gimbal bearing bellows, I see a small amount of water on the bottom of the bellows - maybe a 1/4 cup. The bearing is well greased and spins nicely. The fore-aft play is about a 16th inch at most. Does the presence of water argue toward changing the bearing or is it's feel.more important. The bellows don't appear torn so wondering if the water is from accumulated condensate.

 

[Scott Danforth]

Thinking the same thing, Bondo. I will replace bellows.

Regarding the bellows and gimbal bearing, upon removing the sterndrive and looking into the gimbal bearing bellows, I see a small amount of water on the bottom of the bellows - maybe a 1/4 cup. The bearing is well greased and spins nicely. The fore-aft play is about a 16th inch at most. Does the presence of water argue toward changing the bearing or is it's feel.more important. The bellows don't appear torn so wondering if the water is from accumulated condensate.

there should be no water in the bellows by the u-joints. a single drop is too much water. that means you have a compromised bellows somewhere.. the bellows is to keep water away from the bearing and u-joint shaft

the presence of water suggests you need to consider replacing the bearing, and probably replace the input shaft seal on the drive as well. also get a bellows kit.

BTW, pulling the drive is an annual event, replacing the bellows is an every 2-3 year event (check your service manual).

 

[Lancer76]

Ok. Will replace all bellows, check all water passages and change out the bearing. That'll at least make me feel good and allow me to get to know this set up better.

Thanks for all the info!

 

[Lancer76]

Took out the gimbal bearing today with a NAPA rental tool, which was an easy job. Once that was off, I unsecured the shift cable and pulled the bell housing. Removed bellows and water hose. Inside the water hose I found three good size chunks of old impeller. That makes me feel good. I still have to check internal (boat side) water hose and the water tube in the upper outdrive, but this is a good sign. Thanks for the encouragement. While I'm in there, I am also going to replace the trim limiting switches. I do have a new shift cable and associated components and u-joints, but I am not going to replace those because the existing ones are looking brand new.

 

[achris]

Unless the gimbal housing has been changed to a later sytle, those trim limit and gauge sender switches are no longer available.

Also, while you have the drive off, check the water pocket cover. You may not find it leaking, but while it's off, it's a 5 minute check. If it is leaking, the sympton is overheating at higher revs, cooling down as you pull the revs back. So....

Also, bellows are not a 2-3 year event. A maintained system, without any external influences (like someone jabbing a screwdriver into them), should have the bellows lasting well past 10 years. On a Volvo, yes, bellows need to be done at the 2-3 year interval, but the Merc system is quite different.

Chris.....

 

[Lancer76]

Thanks Chris,
I did put the clear tubing in line to the circulator pump and did not see a stream of bubbles. Also the plastic hose fitting on the bottom of the upper end of the outdrive (assuming this is what is referred to as the water pocket) is not melted or visually deformed. I think that that part is ok. At this point I am trying to remove that darn upper bolt on the thru transom grommet associated with the trim sensor wires. That is a poor design. Actually the wires are poorly designed as they rot out. Any help with that upper bolt would be appreciated.

 

[achris]

... Any help with that upper bolt would be appreciated.

Specially bent spanner. I'll get you a photo...

Stick a screwdriver through the other end and turn. Works a treat.

 

[Lancer76]

Awesome. Made the spanner by putting 7/16 offset wrench in vice, heated with MAP gas torch and bent the wrench handle. Bolt is out! A Huge thank you!

Now my question is what is the general consensus about putting that bolt back in? I've seen posts where folks leave it out and only use the bottom bolt. Also saw posts where an Allen head bolt is used instead of the stock hex head bolt. If I do put something back in, I'm wondering if it can be shorter than the stock bolt. Anyway, what's best?
Thanks again for your input!

 

[achris]

If that grommet falls out, your boat sinks. Use one bolt, use 2 bolts. Your choice.

 

[Lancer76]

Gotcha. Two it is.

 

[Lancer76]

I put the new wires in and bolted it up. Two bolts. Took no time at all. Installed lower bolt first. Gimbal bearing changed, new water hose and new bellows. A full day. Getting there.

 

[Lancer76]

Well, put it all back together and took her out to the lake. No overheating! The impeller pieces in the water hose was the problem. Bonus gimbal gear and bellows.
THANKS EVERYONE.

 

[CamaroMan]

have a 74 searay 23ft with same motor - have u got some pics? was about to offer some ideas but see ur all sorted! one thing i highly recommend is replacing the timing chain - 10 bucks at autozone! gets the timing dead on.. i thought mine was good till i put the new one on!

 

[Lancer76]

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Photo of boat and engine (233 Merc; Ford 351 W). I haven't had an issue with the timing and seems to run fine. What prompted the new timing chain?

 

[CamaroMan]

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wow- what a beauty, i really like the color.. I was having some issues with a bad water pump seal and had some front bits off.. i guess boats are in drive mode all the time so timing slack might play less of a role maybe. I just noticed a distinct growl coming form the motor after the change - anyway yeah the fords run great imo! I get almost 3 miles / gallon on the sea with mine..