2.4 ltr running hot?

[gregg canavan]

I just got back from the lake...2nd time out this year, boat ran great...62mph at 5000 rpm. Here's the question...I run a 28' offshore V-hull with tripple mercs. My temp gauges are perhaps screwed up. 2 of my motors are running cool, but the 3rd is running hotter than the others. It has 14lbs water pressure at 5000, but the tell tale stream isnt as strong as the other 2. also the temp of the water coming out of it is hotter. I checked the temp of the hot water coming out of my faucet in the sink with a laser temp gun and that was 140 , it was so hot you couldnt keep your hand in it, but the boat temp wasnt THAT hot, so I'd guess it was less than that. I dont run thermostats, so rule that out and the water pressure is up to 14 lbs...what do you think?

[Boat Racer]

My bet is the impeller, those things need a couple runs, on them, to soften up.....
One thing, have you made any changes over winter, to kill time LOL? I don't know which engine it is, middle, or outside, but if you made NO changes, I bet on the impeller!
You need to run washers, where the thermostats would go, that water has to be slowed down to cool the heads!
Hope this helps..

[gregg canavan]

well I should have told you, the lower unit is a fresh rebuild with a new lower housing,impeller, and upper housing. the motor has all the thermostats cut out so they are only the shell and gasket, eliminating the spring and pellet. What I want to know is how hot is too hot, and how long does it take at 4500/5000 rpm to cook a motor?

[gregg canavan]

more thoughts...I ran this motor HARD today, I just dont know if the guages are accurate. Remember, I do have 14 psi of water pressure and a decent stream of water at the tell tale tube. by the way, its the starboard motor, a 20" right hand nose cone low water pick up unit

[Boat Racer]

MY VOTE IS STILL THE IMPELLER... A new one takes a while... I have started running mine two years, before I replace it(unless a drastic change in temp. occurs)YOU STILL NEED SOMETHING IN THOSE HEADS TO SLOW THE WATER DOWN...
I can find out what size washers are in mine and post it for you if you'd like!!!
As for how hot is too hot, I'd say head temp. of 180 deg. would cause me to back off the throttle...
What about fuel, you aren't leaning it out, is it a carb. or EFI?

[gregg canavan]

ok...I DO have restricters in the heads where the t stats go...instead of using washers I removed the moving parts of the t stats(you know, the spring and the copper pellet as well as the 2 little arms that hold them all together) so the t stat is now a washer with a gasket, no parts to open or close.All 3 motors have new water pumps and this is the only one that runs hot. The other two are mercury impellers, but this one is an aftermarket impeller...still its brand new...I just ran a compression test, 120 psi in all 6 cylinders, even. These are carb motors, no oil injection, I premix all my fuel 40/50:1 merc oil non synthetic all motors run the same fuel, through 2 holley electric fuel pumps at 5 psi to mechanical pumps on the motors. I never run lean, all motors jetted right #2&5 cylinders 82 mains 1346 80 mains. how wet or dry should a piston top look throgh the spark plug hole with a little light...?I need to know whats up here before I have a problem...youre help and thoughts are appreciated.

[Boat Racer]

Plum each head seperately, the right head will run hotter than the left( water travels up higher).. I really don't believe you have a problem..... I think the impeller needs some time on it, mine was the SAME way, until i got some hours on it...
If you feel you do, you can buy a complete water impeller kit( will have gaskets, the plastic tube( which could be cracked),& a couple other things in it and replace it all....
Piston tops on mine, look dry.
[ May 11, 2003, 03:00 PM: Message edited by: Boat Racer ]

[gregg canavan]

hi...thanks for the input...I have found and fixed the problem today...check this out. I sent this lower unit to a marine mechanic over the winter to rebuild. I have used this guy before on other small jobs, he says he is certified and was the top mechanic at the local marine service dealer until he went out on his own. Now mind you I own an auto repair facility, have 2 full time employees and turn a wrench every day...I just dont want to be 15 miles out to Block Island when a lower unit blows up because I did something wrong...so I dont mind paying someone who claims to be a pro a couple hundred bucks in labor to do a job right so I dont have to worry. Well this guy put the WRONG water pump base in...The one he used was for an inline 6, not a V 6, and has a 5/16 HOLE in the side of the water pump base! It wasnt until I blew into the nose cone and heard the air rushing out that I knew where the loss of pressure was. Once I put in the correct water pump base and replaced the unit back on the motor was I assured the problem was fixed. Now I have all the water pressure AND volume to keep that motor cool. And the tell tale stream is twice as strong as yesterday and nice and cool to the touch. Thanks for all your input

[Boat Racer]

QUOTE BY BOAT RACER!!!
One thing, have you made any changes over winter, to kill time LOL?
AHHHH, now we're talkin'!!!!!! GOOD TO HEAR.
[ May 11, 2003, 07:27 PM: Message edited by: Boat Racer ]

[gregg canavan]

if this motor ran warm, almost to the H on the gauge, but not overheated, do you think any harm was done to it? I mean can these motors run a little hot for a couple of minutes or do they get damaged easily? Remember, I still had 14 lbs water pressure, the tell tale water was hot to the touch but not scalding hot, and my compression is even at 120 psi all 6 cylinders. I ran the motor yesterday after replacing the water pump base and it ran perfectly, but I still havent put it back in the lake. Next weekend I plan to head out to the ocean with it? what is your feeling on this. Remember, it never overheated...it only ran to the high side of the guage for a couple of laps around the lake, and the lake is not very big. Tell me what you thinkn. Gregg

[snappertapper]

i would think it is just fine.

[gregg canavan]

hey guys...thanks for your opinions...as always its great to talk with other go fasters about boats...its finally spring and I've been waiting for this since last October, when I had that last 80 degree day on the ocean. I'll probably take 1/2 day off on thursday and get out there...See ya
Gregg

[Boat Racer]

Greg, just got in, been out of town since Monday... I agree, it should be, OK.
Just keep it a little rich, you won't be disappointed.

[gregg canavan]

hey guys...thanks for the input...I went out to the lake wednesday...ran perfect all afternoon. temps on all 3 nice and cool, water pressure at 15psi at 5500 rpm 69 mph...not bad for a 6000 lb boat. Sunday I'm going to the ocean, out of providence RI to point judith.Should be lots of open ocean out there. Hey, what do you think of changing head gaskets? do you think they should be changed periodically or only touch them when there is a problem? this boat is run in fresh and salt water. all 3 motors have less than 175 hrs on them and they all run perfect. should they be left alone and avoid opening them up? Thanks, Gregg

[Boat Racer]

What we do and what the big time racers do...
I change mine every couple years, my father hasn't change his in 5+ years.. He still has great running motor, I believe that as long as you're not running nitrous, then you are OK, on going every so many years.....
The big time racers..
I was told, by a guy that builds & races Mercs, to change'em every year.... But that would be 3 sets, every year, that would get $$$$$$$$... I recomend that you torque'em down, ever so often(and check your plugs)....
JUST MY .02 CENTS WORTH!
[ May 17, 2003, 04:28 AM: Message edited by: Boat Racer ]

[Shadow Crazy]

When the temp reaches 180*+ it is too hot. Running a restrictor plate instead of a stat may cause higher temp when at low speeds. I have to throttle up for a few seconds to cool it down.
Run it for a bit then pull the plugs and look for the dreaded "milky" gack on your plugs. If you did any heat damage it will show up just like that. If you were able to put your hand in the water coming out of the motor,, you didnt cook anything. One thing you might want to do while you have the plugs out, look at the top of your pistons and make sure they are shiny (no carbon buildup). If they are black, get some head gaskets and a wire brush & clean em up. The plugs arc off the top of the pistons. Food For Thought.