I'm Running Hot! Help!

[Restless22]

I just bought a 1988 Wellcraft Aruba with the 350 Merccruiser I/O and Alpha 1 out drive. We love out first boat.

BUT, yesterday with a full load of passengers it ran in the 170-180 range. I thought this was ok, and on a seller demo the previous day, he told me to keep it either in the middle of the temp gauge or slightly higher and to not let the buzzer sound. I never let it get over 190 on yesterday's trip, so I never hit the buzzer.

The impeller and bellows are pretty new, and the belts and hoses look fine, and there is no steam, etc. The engine is a 350 Magnum, with a carb and uses raw water cooling.

My heart is sinking today!

What am I up against? What is this going to cost me???

 

[Eric 3.7LX Alpha 1]

Re: I'm Running Hot! Help!

I just bought a 1988 Wellcraft Aruba with the 350 Merccruiser I/O and Alpha 1 out drive. We love out first boat.

BUT, yesterday with a full load of passengers it ran in the 170-180 range. I thought this was ok, and on a seller demo the previous day, he told me to keep it either in the middle of the temp gauge or slightly higher and to not let the buzzer sound. I never let it get over 190 on yesterday's trip, so I never hit the buzzer.

The impeller and bellows are pretty new, and the belts and hoses look fine, and there is no steam, etc. The engine is a 350 Magnum, with a carb and uses raw water cooling.

My heart is sinking today!

What am I up against? What is this going to cost me???

Just curious how do you know that? Did the seller have a log record for the boat for any parts that were changed? and the date they were changed, or receipts for their purchase?

Could be a brand new impeller, but if it's started without water on muffs it's toast in a quick time.

 

[Restless22]

Re: I'm Running Hot! Help!

The seller supposedly had this done at the on-site marine shop. I'm going to ask the shop for the records today.

 

[Restless22]

Re: I'm Running Hot! Help!

Also, it runs above 160-170 when running hard, not when idling, at wake speed or when cruising. It only heat up when running hard. That's why I thought it may be working too hard. I feel like a total fool.

 

[Scott Danforth]

Re: I'm Running Hot! Help!

get an IR thermometer and measure the block. the gauge may be off. you will need to verify this.

Also, where are you boating. My boat with a 160 thermostat would run about 160 in Wisconsin, and about 180 on the golf (40 degree water vs 90 degree water)

 

[tpenfield]

Re: I'm Running Hot! Help!

Start with the thermostat making sure it is the right one for the engine, etc and work your way up the cost curve from there.

170-180 sounds a bit hot for a 350 engine, but check what it should be a la maintenance manual.

 

[Restless22]

Re: I'm Running Hot! Help!

I'm in NE Alabama, on the Tennessee River

 

[JoLin]

Re: I'm Running Hot! Help!

Start with the thermostat making sure it is the right one for the engine, etc and work your way up the cost curve from there.

170-180 sounds a bit hot for a 350 engine, but check what it should be a la maintenance manual.

Restless also mentioned that he 'never let it get above 190', so IMO something's definitely going on. He also mentioned in another thread that the PO had warned him not to let the temp get to 220, or the alarm would go off. Why say that unless it happened to him? That raised a red flag for me.

 

[QC]

Re: I'm Running Hot! Help!

Yes ^^^^ and both alarm and gauge would have to be bad, and bad the same increment

To the OP. Congratulations on your first boat. Don't get down, we'll help you figure it out here. This kind of stuff is part of the deal. Every time you fix, modify, add, or improve something you will know your boat better.

 

[Restless22]

Re: I'm Running Hot! Help!

Service records indicate a new impeller on 6/2011. Also, new prop on 6/10, electrical repair on 6/10, and spark plugs on 6/11.

I placed a call to the local on site shop for an evaluation to see if repair is needed.

 

[Scott Danforth]

Re: I'm Running Hot! Help!

did you confirm the gauge and alarm to real life?

did they change just the impeller, or the complete pump and housing? that is the first place I suggest looking.

I would follow the plumbing, removing the hoses and backflushing where you can. start at the drive and work your way to the exhaust.

you may have debris. the Alpha pump can generate about 18GPM at about 20 psi. with that low of pressure and flow, it can be easy to plug something.

if you have an oil cooler in the line from the drive, take a look. sometimes things get stuck in there. from there, look at the plumbing to the thermostat housing. inspect everything inside and out. then move on to the plumbing to the manifolds and risers.

Mercruiser uses thermostats from 140F thru 195F depending on configuration, ect. generally raw water cooling is 140 or 160 degree. and 180 and higher are used with closed cooling. however since they look alike, it is possible it could be the wrong thermostat is installed.

using steady and methodical troubleshooting, along the way you will discover the issue.

 

[Don S]

Re: I'm Running Hot! Help!

Service records indicate a new impeller on 6/2011. Also, new prop on 6/10, electrical repair on 6/10, and spark plugs on 6/11.

All it takes is a plastic bag in the water to damage an impeller.
You also mentioned you have a new prop. What is your WOT rpm with this prop? If you are over propped, that in itself could cause an overheat.

 

[Restless22]

Re: I'm Running Hot! Help!

I'm not sure if they changed the whole shebang or not. I will check. I guess it's a wait and see for me now. It may a couple of weeks until the shop can see it.

I am just totally depressed today, and I don't look forward to telling my family.

ETA: I don't know if I mentioned this, but the temp needle stays right in the middle at idle or wake speed, so I guess that's normal?

At moderate speed it bumps just a bit higher.

At WOT is where it shoots up. By simply slowing down, it drops.

So it cools fine when slow, but not when fast. I assume this means that the impeller is working fine at slow speeds?

 

[Scott Danforth]

Re: I'm Running Hot! Help!

That just means that you have enough flow to cover the heat generated at lower speeds. you could have a partial blockage somewhere.

these are all things that you can do yourself. you dont need to wait for a shop. we can walk you thru it. start by reading the stickies at the top of the sub-forum

 

[Scott Danforth]

Re: I'm Running Hot! Help!

Don has a good point.

with the new prop, what is your WOT RPM?

 

[Restless22]

Re: I'm Running Hot! Help!

I don't know

 

[Don S]

Re: I'm Running Hot! Help!

You need to do some checking. Since the alarm and gauge use different senders/switches and they are both saying the same thing, I would have to assume you are actually overheating.
You need to remove the drive, check the pump impeller, housing, and water pocket cover for signs of overheating warping, bubbling etc. which can and do cause problems at higher rpms.

The thermostat could not be opening fully, not un common on raw water cooled engines.

Remove the exhaust elbows and check for blockages. in the water passages.

he told me to keep it either in the middle of the temp gauge or slightly higher and to not let the buzzer sound.

The fact that the seller told you this tells me he knew there was a problem, and led you to believe it was normal, but it is not normal.

 

[JoLin]

Re: I'm Running Hot! Help!

I am just totally depressed today, and I don't look forward to telling my family.

Try not to take it too hard. This is just your first taste of boat ownership. It's potentially a simple problem, and it sounds like the rest of the boat is doing fine. If that's true, you're running ahead of the curve. Trust me.

You got a bunch of good advice here, and as someboady mentioned, I'd work my way 'up the cost curve.' If you flush everything out, check that you have the right t-stat, and record your WOT rpm as Don suggested, you might just find your issue right there. If you don't, then it's on to the shop for troubleshooting.

I feel bad that I was the bearer of bad news in your other thread, but it's a lot better than letting you negligently destroy your engine. Buck up- this will be resolved, and you'll spend the rest of the summer just enjoying the boat with no worries.

 

[Restless22]

Re: I'm Running Hot! Help!

Where is the sticky for doing the checks before the shop does? Can this be done in the slip? My boat lives on the hydro lift.

 

[achris]

Re: I'm Running Hot! Help!

Also, it runs above 160-170 when running hard, not when idling, at wake speed or when cruising. It only heat up when running hard. That's why I thought it may be working too hard. I feel like a total fool.

Water pocket cover....