Engine Overheat Merc 228

[wahlejim]

1986 mercruiser 228 Serial Number 6271653

SEI 106 outrdrive

Intermittent overheat. New impeller during winterization last fall. Prior to the seasons launch, ran on muffs for about 2 minutes at idle before launching for the season. RPMs never over 1000. Boat is stored in the water during the season.

Symptoms: Looked down while pulling a tuber and gauge was over 210. Slowed down immediately, held at 210 for about a minute then lowered back to 160. Runs at 160 as long as I keep it under 3200 RPMs. anything over that, the temprature climbs.

What I have planned: New engine mounted water pump. Last time I started it, there was some squealing for about 20 seconds from the water pump. Can a stock gm water pump be used for this? If so, anybody know a part number?

I will also be replacing the thermostat, and it is my understanding that the 160 deg is the correct one for this engine.

Exhaust shutters will also be replaced. Does anyone have the part numbers for this?

I am hoping to do all of the work without pulling the boat. the boat is a 1980 sea ray that has been restored and I have plenty of access to the engine bay by removing my quick latch seats and dog house.

Is there anything I am overlooking in this? Any other suggestions on what to check here?

 

[wahlejim]

I think the admiral offended the boating gods on this one. We were out on the 4th and she made a comment about how well the boat was running this year so far. I cringed, spun around 3 times and knocked on as much wood as I could find.

 

[nola mike]

1986 mercruiser 228 Serial Number 6271653



Symptoms: Looked down while pulling a tuber and gauge was over 210. Slowed down immediately, held at 210 for about a minute then lowered back to 160. Runs at 160 as long as I keep it under 3200 RPMs. anything over that, the temprature climbs.

What I have planned: New engine mounted water pump. Last time I started it, there was some squealing for about 20 seconds from the water pump. Can a stock gm water pump be used for this? If so, anybody know a part number?


Is there anything I am overlooking in this? Any other suggestions on what to check here?

Having the exact symptoms on mine. I'm running close to 160 on the gauge at sustained 33-3400 rpms (never runs that high). Below that it's 140's. My impeller is 2 years old but hadn't been run more than a few hours(replaced the gear housing, which has been sitting since then, didn't recheck or change impeller...doh!).

Interesting that you mention the squealing. Mine has done that a few times as well. Figured it was the belt, tightened, I'll pay more attention to see if it still does that.

My first thought is going to be to double check my temps. I have a mechanical rad cap and IR gun that I'll check next time out. Upper normal is 200' from what I've read.

Second thought for me is that I've only cleaned the HX once in the 10 years I've had it (bad 470 owner!). It seems to me that a cooling system inefficiency would be more likely to have higher temps than inability to supply raw water, but that's just a WAG. It would be interesting to know acceptable HX inlet/outlet temps.

 

[Bondo]

New engine mounted water pump. Last time I started it, there was some squealing for about 20 seconds from the water pump.

Ayuh,..... It's Far more likely the belt is squealin', at 1st start because the battery is demandin' to be recharged from the use of the starter,.....

'n there's a pretty good chance the water level is right at the top of the y-pipe, or higher,.....
Changin' the shutters may, or may not happen at the dock,.... don't wanta sink yer boat,.....

1 way to check the impeller is to test the water flow, from the in-comin' water hose at the t-stat housin',....

 

[wahlejim]

Thanks Bondo,

I don't know why I didn't think of testing the impeller that way. real easy and simple. I can get the boat out of the water on the lift so I think the shutters can be done without a trip to the launch. Don't want to do the impeller in the water for obvious reasons.

 

[wahlejim]

Well, life happened and I finally got around to the boat this weekend. Pulled the incoming water hose to the tstat housing, water flow was there, but weak. Water was also coming back out of the housing, so my engine water pump is functioning. The squeal was non-existent this time around, which is strange because the boat has been sitting for 3 weeks.

Thermostat looked a little worse for wear so I will be changing that out. Realized I needed to suck it up and get the boat out of the water. Took the thermostat out and ran on the water a bit, temperature was climbing and I went back to idle at about 160-165 and it dropped again. It shouldn't have gotten that hot that quick without a thermostat in there. Pulled the boat. New thermostat ordered, outdrive water pump kit ordered. I have an exhaust boot and not a bellow so I put my scope up there. Shutters are surprisingly still in tact and look good. I was planning on doing the water pump kit during winterization, the plan is now accelerated to this week. Just stinks I lost a month of boating, but such is the life of a boater in Wisconsin.