Running hot

[RichRab]

I have a 2002 Merc alpha 1 gen 2 5.0 sea water cooled engine not multi port draining system. Where we boat low tide is difficult so we have hit mud a few times over the years. The boat runs fine but when going at higher rpm (not completley opened up) the temp goes up to around 200 deg. At idle or as soon as you slow down the temp drops to about 170. The boat was kept in the water and the first thing I tried was therm. (I do not remember any flow restrictors of any kind in the housing) Second pulled the boat and water pump in outdrive. Third tried flushing/ backwashing everything I could find including the power steering cooler. Beginning of this year man. risers elbows. Still the same. The Barr manifolds came wit 2 sets of gaskets foe the 3 inch risers. I put the ones that were orig in with the full f;ow big 4 holes and had the same prob. I called Barr and was told the reccomend the ons with 2 big and 2 small holes to restrict water flow and carry more heat off. I put them in (4) and no diff. I think the gauge is accurate because if it gets too hot he buzzer comes on and it consistently reads the same results. I am looking at the Merc book that came with the boat and it after the steering cooler it shows a check valve and then a cool fuel box. ( I wish I looked closer with the man. off). I don't remember seeing them and did not specificully look for them. I am thinking one of them might be a prob. Also have heard but never saw the water pump shaft on the motor breaking. What do you think? Thank You RR

 

[Don S]

Re: Running hot

Have a read of this Merc service bulletin.
http://www.boatfix.com/merc/Bullet/95/95_13.pdf

 

[RichRab]

Re: Running hot

Thank you for the quick response. Except for the clear hose and the alignment pins in step 4 I did all this. I am working on the oil leak from the easy oil change problem that I posted and hoping to reach it by taking the manifold off so I will not be able to put the boat in the water yet for this test. but thank you again. Will advise RR

 

[RichRab]

Re: Running hot

I bought the clear hose but I ordered a new easy drain hose and the boat is just sitting in the driveway without oil (post is "oil in the bilge'' under merc outdrives) which is another issue. I am changing the oil drain hose and gasket in hopes it is not the oil pan rotted out. The old gasket is cracked almost all of the around. I hate to not accomplish anything while waiting for the parts I ordered but do you think it is worth changing the water pump in the drive. The one in there is about 18 mos. old with maybe 10 hrs. on it but I am wondering if the overheat problem before I changed the manifolds could have damaged something. The pump has never been run dry. I put a garden hose in both directions and cannot find any restrictions.

 

[RichRab]

Re: Running hot

UPDATE__The mech said my temp gauge is off 25 deg. The next thing is I will change the sending unit. He said it is not uncommon for the gauges to give innac. readings.

 

[Bondo]

Re: Running hot

but do you think it is worth changing the water pump in the drive. The one in there is about 18 mos. old with maybe 10 hrs. on it

Yes... Along with a Full system Flushing...

 

[RichRab]

Re: Running hot

Everything was flushed with the motor in and out. The plastic tube that runs through the transom was checked and good. The motor is back in with the new oil pan and the mech. test drove and said the reading at the therm. housing is 160 and the gauge is reading higher. I changed the temp. sending unit and at 3200 rpm the gauge is about 190- The reading with a gun that reads temp. at the therm housing is about 170--Sounded good but I shot the elbows and the whole top of the port side is about 100 deg. the front of the star. side about 100 but the back of it where it exhausts is about 200. I was not prepared to work on this and did not have tools or the clear plastic hose with me.

 

[RichRab]

Re: Running hot

With the boat in the driveway I put the outdrive in a big tub filled with water covering the lower unit. I waited for the temp to get to 180 on dash gauge and put the clear hose from therm. housing to port side ( I could not find the service bulliten that I printed out saying starboard side). There was no water flow at about 1800 rpm. The hose was in the tub to insure enough water. I did not want to go higher while sitting on trlr. I loosened the clamp on the hose going to circ. pump and there is pressure there at housing. Both hoses going to spacers on exhaust hardly have any water and no pressure. I remember a spacer on therm. in housing. Do you think that might be damaged from prev. overheat? I had a diagram of water flow but cannot find it, if there is a diagram that would be helpful. Thank You, RR

 

[RichRab]

Re: Running hot

Replaced the pump in the outdrive. Put the boat in the water last month and temp. still climbing. I put the clear hose on and there was very little water in it. I pulled the boat home, put the drive in a big tub and removed the hose coming through the transom and there was no water flow. I got a garden hose and forced water back into drive and then tried it and had water flow. When I removed the tub there was mud in the bottom that had to be inside my hoses. Ran it up to 5000 rpm and I can hold my hand on risers. All looks good. Thanks to those who gave their advice.

 

[RichRab]

Re: Running hot

Just a note- I like doing all work myself so I know what was done. The oil pan rotted out last year and the motor had to be pulled, so I paid a mechanic. I told him of overheat problem and repeatedly asked that everything be flushed and checked when the motor was out and everything is easier to get to. He told me did. I don't think so.