Temp rising when riding

[Bayliner1950]

Hey guys can someone help me out, I have a 1996 bayliner with a mercruiser 3.0. The first time I took it out the temp began to rise, we shut down the motor, and then was gonna let it cool before trying to make it back in to the landing, but when we re cranked it, it ran like a champ, now the temperature is rising when riding or skiing and going back down when you stop(motor is still running). I have replaced the water pump in the foot, also looked at the one on the motor and it looks good, any Ideas what it could be, when we took the foot off to replace the water pump, alot of carbon was in there, and we cleaned it all out, I was told possibly the riser, we also replaced the flap inside the exhaust, what exactly could be wrong with he riser, can it be cleaned and not replaced, any info would be greatly appreciated.

 

[Rocky_Road]

Re: Temp rising when riding

What "engine mounted" water pump, are you refering to? My 3.0L does not have a water pump at the engine...only a thermostat.

What temperatures are you seeing, on the water?

 

[Kovah55]

Re: Temp rising when riding

Circulating pump, mounted on the engine driven bye a belt. And if you have a 3.0 motor that is a merc or a omc you sure do have one.
Is that the original posters problem i don't think so. Take the long hose off the t-stat housing, with water going to the drive hold the hose straight up, start the motor, how high is the water shooting ? Good strong stream ? Only need to do this for 5-10 seconds, won't hurt anything. Good water stream, strong ? Then you may have a blockage down stream from the t-stat.
T-stat how old frozen closed? Replace. Run the boat still doing it, overheating?
Riser next remove and examine, all rusted closed? Flapper / shutter broke off and is blocking the exhaust?
You have a heat exchanger, such as a oil cooler, for power steering, may be plugged up, may have to be cleaned out. If equipped with a heat exchanger,check that before you pull the riser.

 

[Bayliner1950]

Re: Temp rising when riding

i just replace the thurmostat and all hoses and the flapper in the exaust, could it be clogged with carbon

 

[Rocky_Road]

Re: Temp rising when riding

Circulating pump, mounted on the engine driven bye a belt. And if you have a 3.0 motor that is a merc or a omc you sure do have one.

I have a 2005 3.0L, with raw water cooling...and there isn't anything (belt driven) in the parts breakdown, that circulates water, is belt driven, and is engine mounted.

This may be different for a 3.0 closed cooling setup...but the parts manual still doesn't show this engine mounted pump that you mentioned.

Please post a link to this circulating pump, so that I can locate it on my engine.

Thanks!

 

[Bayliner1950]

Re: Temp rising when riding

My boat has a 1995 motor in it so it could be different, is is the same as on a 1985 chevy s10 2.5L 4cyl.

 

[180shabah]

Re: Temp rising when riding

The circulating pump is number 7 in the diagram. This pic is from '98, but it is in the same location in both 1995 and 2005.

No this is not he same engine used in s10's etc. It is currently only used in marine and industrial applications. It has not been used in a passenger vehicle since the 1960's.

 

[Bayliner1950]

Re: Temp rising when riding

Well tell that to the tech from Mercury Marine who told me to get that part cause it was the same, he was right, they match up perfectly, go to autozone.com and do a parts search for a 1985 Chevy s10 blazer, 2.5L look at the water pump, they are exactly the same, but it still hasent solved my problems, thats all the tech would tell me short of bringing it in to the dealership, and Im not taking it to those crooks

 

[Kovah55]

Re: Temp rising when riding

It might fit a auto one look closer at the vanes they are not brass are they? And if used in saltwater will last maybe a year. If the vanes are made of brass use it.
Original poster you have a heat exchanger on it, and did you do the water test?
Rocky heres a pic for your engine mounted water pump.
http://www.wholesalemarine.com/mm5/merchant.mvc?Store_Code=1&Screen=seloc

 

[Rocky_Road]

Re: Temp rising when riding

It might fit a auto one look closer at the vanes they are not brass are they? And if used in saltwater will last maybe a year. If the vanes are made of brass use it.
Original poster you have a heat exchanger on it, and did you do the water test?
Rocky heres a pic for your engine mounted water pump.
http://www.wholesalemarine.com/mm5/merchant.mvc?Store_Code=1&Screen=seloc

Thanks, Kovah!

 

[Bayliner1950]

Re: Temp rising when riding

the veins are brass, and I have no intention of running it in salt water, I tested the boat when I bought it and used it about 5 times before I started having problems, I bout the auto piece because the only difference is the bottom of the vein plate is steel not aluminum, which to me is a stronger application, It measured exactly the same and bolted right on, what I am still wondering about is carbon build up, like I said, when we replaced the water pump in the outdrive there was quite a bit on large pieces of carbon, could that cause problems in the manifold and riser, also the parts numbers matched right up on the water pumps, exactly the same, and the auto one was only $35.00

 

[dbkerley]

Re: Temp rising when riding

Beat me up if I'm wrong. But, noone has answered the OP's question yet.

First the problem you are experiencing is caused by having too little water/coolant flow under load. For example, let's say that your system is only capable of flowing 60% of the specified amount of coolant. When idling and the engine is only demanding 40% from the cooling system it is more than adequate. However, when placed under a load and generating quite a bit more heat say an 80% demand that system is falling short and causing the overheat.

Long story short there is a restriction or weakness in the system. I would start with the intake screens and work forward until I found it. If there is no obvious restriction the fault may lie in impeller clearances or a weak pump.

The crooks at the stealership aren't. They are highly trained individuals working for a living just like everyone else. There are a lot of overhead costs that go into operating a business that you have to pay for just to have the privilege of walking in the door and being offended by the high prices.

If we charged admission fees, we could probably lower shop rates. No I don't work in the marine industry. I do have respect for those that are committed enough to weather the wild economic swings of a luxury seasonal industry.

 

[180shabah]

Re: Temp rising when riding

noone has answered the OP's question yet

'cause we still don't know if he as verified that all passages are clear of obstructions. With the problem he is describing, and having a new seawater pump, I would start at the other end and work backwards. Pull the exhaust manifold and elbow (as suggested above in post #3) Are the water passages in the elbow clear? Is there a lot of rust and scale?

Also, when you replaced the pump in the drive, were all of vanes on the impeller in tact? If not, did you track down all of the parts?

 

[Kovah55]

Re: Temp rising when riding

180 i was waiting for someone to back me up, don't want to happen to me what happened to the Chief. Got banned for a silly reason. And i ain't gonna get in no p---ing match when i know the op hasn't confirmed he has good water going to the t-stat.If good water going to the t-stat then it's down stream.
Got a heat exchanger? Clean it out! Got a riser clogged, or the mani, clogged got to find out where the blockage is period.

 

[Bayliner1950]

Re: Temp rising when riding

I got the problem figured out I think, I pulled the manafold and riser and there was ALOT of carbon build up, I am gonna see if I can clean it out, if not replace it, thanks to everyone who gave suggestions, p.s. the only reason I called the dealership crooks, is cause I had some hurt feelings toward them after they did some work on my bass boat, they charged me $500 to clean my carbs, and only replaced a $15 part, and it only took them 4hrs. I would just rather handle the work on this one myself, also the water pump was totaly intact, and still seemed in good shape, but I did replace it. Thanks to everyone.

 

[cooter2506]

Re: Temp rising when riding

My main concern is the carbon build up aftr the riser where the exhaust and water mix. Yes the manifold and riser need cleaned out and then the choke fixed or your fuel air adjusted to resolve that. But also clean out your exhaust pipe and outdrive from all the carbon. Just cleaning the manifold and riser may help but I dont think it will fix it totally. Also what do the water passages of the riser ad manifold look like?