Cooling issue with MeCruiser 3.0 with Alfa one drive 1997 vintage

Maximuss · Mar 17, 2013

Hi all, I'm having an issue with my boat I recently purchased. When I bought it the temperature gauge never worked. I changed it along with the sending unit. I also changed the thermostat. still I find the engine runs great and does not overheat that I can tell, however the gauge still reads at 100 and does not move from there. I lifted the engine cover and can put my hand on the thermostat housing and the hose and it is not hot to the touch. I also put my hand on the large hose going into the water pump and it seem like not much if any water is going into the engine. I ran it on the lake today for about 2 hours and had no issues what so ever. anyone have an idea what might be causing this?

Sorry I just realized I spelled Alpha one wrong.

Don S · Mar 17, 2013

Re: Cooling issue with MeCruiser 3.0 with Alfa one drive 1997 vintage

Get an IR temp gun, and check the temp of the engine right at the temp sender and see if it's running at 100? or less when warmed up.

If it actually is running that cold with a new thermostat, check the big hose on the circulation pump. Does it seem really stiff like a lot of pressure is built up?

Maximuss · Mar 17, 2013

Re: Cooling issue with MeCruiser 3.0 with Alfa one drive 1997 vintage

Don S said:
Get an IR temp gun, and check the temp of the engine right at the temp sender and see if it's running at 100? or less when warmed up.

If it actually is running that cold with a new thermostat, check the big hose on the circulation pump. Does it seem really stiff like a lot of pressure is built up?

No there is not a lot of pressure at the big hose, you do mean the water pump? or is it a circulation pump? I put my hand on it and it was easy to squeeze and was not too hot to touch?

I did this several times while out running the boat and everything seemed fine. I'm confused with this, is there some other pump to pick up water as well?

Don S · Mar 17, 2013

Re: Cooling issue with MeCruiser 3.0 with Alfa one drive 1997 vintage

You have two pumps for cooling. The raw water pump is in the outdrive and pumps water to the engine to cool the engine. The circulation pump is mounted on the front of the motor and belt driven. What would be called a water pump on a car.

I put my hand on it and it was easy to squeeze and was not too hot to touch?

Was that with the engine running above idle?

Maximuss · Mar 17, 2013

Re: Cooling issue with MeCruiser 3.0 with Alfa one drive 1997 vintage

Don S said:
You have two pumps for cooling. The raw water pump is in the outdrive and pumps water to the engine to cool the engine. The circulation pump is mounted on the front of the motor and belt driven. What would be called a water pump on a car.

Was that with the engine running above idle?

Yes, but I had ran the boat in the lake for about 2 hours and several times would set to idle then check the engine. Had it up to 40+ mph several times. my guess is the impeller let go due to age? But the engine never got hot, but seemed like it was lacking for more water in the cooling system to me.

Don S · Mar 17, 2013

Re: Cooling issue with MeCruiser 3.0 with Alfa one drive 1997 vintage

If your raw water pump was bad, you would have overheated, not over cooled.

Maximuss · Mar 17, 2013

Re: Cooling issue with MeCruiser 3.0 with Alfa one drive 1997 vintage

Don S said:
If your raw water pump was bad, you would have overheated, not over cooled.

True but I'm afraid that not enough water got up to the sender and the thermostat to begin with. I put a 140 stat in it, do you think the water was too cold that it kept the engine too cool? Sorry if these sound like dumb questions, I understand car engines and this is not much different. However, I do not know much about stern drives.

I thank you for your input and help with this matter as it has me stumped. I think the previous owner did very little and suspect the impeller in the Alpha one drive is probably in need of replacement it is a 1997 vintage and I'm sure it has never been changed.

Don S · Mar 17, 2013

Re: Cooling issue with MeCruiser 3.0 with Alfa one drive 1997 vintage

If it's the original, it's way over due to be changed, so nothing will be lost by replacing it. BUT, if the engine was overheating because of no water, you would have burned out the exhaust hoses and would never have been able to put your hand on the engine or manifold.
The engine wouldn't last long running it without cooling either.

Oshkosh1 · Mar 17, 2013

Re: Cooling issue with MeCruiser 3.0 with Alfa one drive 1997 vintage

I see you're in Canada...Must be in BC...I can't imagine there's too many lakes without "hard" water up nort der hey(sorry!).
How cold is the injection water?

If it's real cold...you're engine will also run "cold".

Maximuss · Mar 17, 2013

Re: Cooling issue with MeCruiser 3.0 with Alfa one drive 1997 vintage

It was real cold, it was hailing as we were getting ready to launch the boat. The cold weather may have been the factor but I'm not totally convinced.

Don S · Mar 17, 2013

Re: Cooling issue with MeCruiser 3.0 with Alfa one drive 1997 vintage

If it's real cold...you're engine will also run "cold".

Not with a good thermostat it won't. If you have a 140? thermostat, you might not get more than 140, but you won't run less than the thermostat rating. In warmer water, you would see 160 to 170 but never less than 140.

Maximuss · Mar 17, 2013

Re: Cooling issue with MeCruiser 3.0 with Alfa one drive 1997 vintage

Don S said:
Not with a good thermostat it won't. If you have a 140? thermostat, you might not get more than 140, but you won't run less than the thermostat rating. In warmer water, you would see 160 to 170 but never less than 140.

Hence back I mentioned touching the thermostat housing and hose coming from it and it was not hot to the touch I could keep my hand on it, I don't think you should be able to do this. It seemed to me like there was a air lock or not enough water flowing.

Oshkosh1 · Mar 18, 2013

Re: Cooling issue with MeCruiser 3.0 with Alfa one drive 1997 vintage

Yes...by "cold" I meant the T-Stat rating.

I know when I'm running my engine on muffs in spring w/50ish deg water it will only run around 140 or so. "hot to the touch" is more of a personal perspective. I regularly handle very hot BBQ briskets/shoulders etc so my asbestos hands don't even flinch when grabbing "hot" items usually.

Kinda like me watching kids run around on rocks with bare feet like it's nothing...I'm a tenderfoot nowdays!

Maximuss · Mar 18, 2013

Re: Cooling issue with MeCruiser 3.0 with Alfa one drive 1997 vintage

Well I think its off to the boat repair shop for me, let them figure it out. I have a few other small issues with the boat as well. I'll post what it was or not when it is back from the shop. Thank you all for your input in trying to help me figure this out.

Maximuss · Apr 28, 2013

Re: Cooling issue with MeCruiser 3.0 with Alfa one drive 1997 vintage

Update, took the boat into the shop. Bad ground suspected, changed all the gauges to update the boat had some electrical issues (ground being one of them) had the lower sea water pump changed, told it was not bad anyway. Engine water pump was starting to weep, changed that out as well. All in all it still does not get hot, gauge goes to about 100 and that is about it. guess it is a good thing, everything is set to go now for boating season. Guess with the cooler weather still the temperature will remain low. Thank you all for the input and advise. Happy boating all.

Don S · Apr 28, 2013

Re: Cooling issue with MeCruiser 3.0 with Alfa one drive 1997 vintage

You need to do as suggested in my first reply.

Get an IR temp gun, and check the temp of the engine right at the temp sender and see if it's running at 100? or less when warmed up.

Click to expand...

Don S · Apr 28, 2013

Re: Cooling issue with MeCruiser 3.0 with Alfa one drive 1997 vintage

If it actually is running that cold. Pull the thermostat housing and check the bypass hole and see if it's plugged up. If it is, that would be a cause of over cooling.

Bt Doctur · Apr 28, 2013

Re: Cooling issue with MeCruiser 3.0 with Alfa one drive 1997 vintage

or your installing the sender with a lot of teflon tape.

Cooling issue with MeCruiser 3.0 with Alfa one drive 1997 vintage

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