Motor Getting Warm

[suprasam]

Ok, so I changed my thermostat....sealed everything up and did a test run in the driveway. Well the gauge is shot also I find out, but the motor seemed to be getting hot. So I thought maybe the thermostat was messing with the water flow, I took that back out and then closed everything up and tried again after it was cooled. Well again it crept up, water seemed to be flowing through the exhaust fine though. I thought OK maybe my impeller was shot, although I just replaced it last year. So I took the pump off and looked it over and all looked fine. Although the fins seemed bent, so I kept the pump off and ordered a new one. I know that isn't my issue though. Any thoughts on why it would be getting warm? From what I have been told, is that you should be able to touch pretty much any part of your motor at all times without it being way to hot. The portions that were hot were around the sending unit, and also the metal portion below the t-stat, and above pump. I will see if I can find a picture of where I am talking about and post. Any help would be appreciated.....hopefully the above made sense.

[csuggs]

Your motor should run around 160* most of the time. Using " touch" as your guide is hard to do. You would be better to get or borrow an infrared thermometer until you get your gauge working properly. Aim the thermometer at the place where the sending unit goes in the manifold, and at the neck of the manifold where the thermostat is located. I did that to see if the the t-stat was working and you could actually see the temp change as the t-stat opened and closed. By the way, the temp WILL go up when you shut down - this is normal.

[Jetlink]

What Clint said... I get home from a day on the water and open the engine compartment to be greated by a blast of air that is hotter than when I opened it at the marina just after taking the boat out of the water to remove the plug. Also, using the "touch/feel" method is probably not going to work as Clint said as well. As a reference, I have toasted my leg once or twice when running my boat on the trailer by accidentally pressing my leg up against the riser, yet my thermostat is working and on the hose I get up to about 140-150 degrees American on the temp gauge.

[docdrs]

If your engine is getting hot without a thermostat in it and your impeller is fine and you are getting lots of water flow then you might want to look at your water circulating pump as the culprit.

[suprasam]

9532Thanks for the help guys, I know using "hands" isn't a good choice at all.....so I will try to find the infared thermotator and see where we stand. Right now pump is a part until the new impeller comes in tomorrow.
Doug, if I am pushing out water through exhaust fairly easy, wouldn't that mean I am getting water through easy enough....meaning the circulating pump is working well? I will also look into that after I put a gauge, and impeller. Thanks for all the help and so quick!
Here is a picture of where its getting warm, this isn't my motor I borrowed from JETLINK, because his had the best profile.

[csuggs]

I believe what you're pointing to is where the water goes to the circulating pump after passing by the t-stat. When the t-stat is closed, that will be warmer, when open, there will be cool lake water flowing through.

[docdrs]

I believe what you're pointing to is where the water goes to the circulating pump after passing by the t-stat. When the t-stat is closed, that will be warmer, when open, there will be cool lake water flowing through.

I could be wrong but don't think so. The thermostat lets water out of the engine, when the water under the tstat is hot enough it will open allowing water to escape and out the exhaust. When this happens cool water coming from the lake to your arrow and to the circulating pump will flow into the circulating pump and into the engine. If your circulating pump is not working properly then no water willl flow out the thru the tstat and no cooler water will flow thru that hose/pipe that is getting warm. If water is not circulating via the pump and when the tstat is closed all the excess water bypasses the circ pump and flows out the exhaust. If you take your tstat housing off you will see how this all works.

[Jetlink]

Man, I am puzzled from where you are pointing at on that picture. That is just downstream from the raw water pump and therefore should be cool water running through there. I am planning on firing up the boat for the first time all season tomorrow so I will have to take a note of that temperature there. I think I know where my thermometer is still... Hopefully I will be able to contribute some more to this tomorrow.

[sydneyACE]

It's so hard to tell how hot it's really getting without a guage. I'm guessing that your motor isn't actually getting TOO hot. Without the guage in there, you always kinda think worst-case scenario. The parts can get pretty-hot (to the touch) even when the engine isn't TOO hot. My very un-scientific test is to lightly touch the risers. They are hot but I can keep my hand on them for about 2 seconds before it's painful.
As the others said, a laser themometer would be a better test. Keep in-mind an engine can run pretty hot before anything bad starts to happen. What does your car/truck run when sitting in traffic? It's not un-common to see water-temps in the 190-210 range on a V-8. (Obviously they have antifreeze in them and are pressurized, so the boiling point is higher than normal but...)

Most importantly, just get your guage fixed so you know for sure. :) That peace of mind is priceless. It takes some of the fun outa running-it when you are constantly worrying that the engine might be over-heating. I know because I ran mine all last season without a guage.

Anyway, good luck! Let us know what you find-out.

[csuggs]

I could be wrong but don't think so. The thermostat lets water out of the engine, when the water under the tstat is hot enough it will open allowing water to escape and out the exhaust. When this happens cool water coming from the lake to your arrow and to the circulating pump will flow into the circulating pump and into the engine. If your circulating pump is not working properly then no water willl flow out the thru the tstat and no cooler water will flow thru that hose/pipe that is getting warm. If water is not circulating via the pump and when the tstat is closed all the excess water bypasses the circ pump and flows out the exhaust. If you take your tstat housing off you will see how this all works.

I'm confused about how the thing works then. But here's how I understand it . . .
WHEN THE ENGINE'S COLD - TSTAT IS CLOSED and you have a "closed loop" of water circulating and re-circulating through the motor via the circulating pump. At the same time, the fresh water from the raw water pump is bypassing the engine block and going straight out the exhaust.
WHEN THE ENGINE IS HOT - TSTAT IS OPEN and you now have an "open circuit" of fresh water running through the engine block and out the exhaust.
Is my understanding correct?

[Jetlink]

That is how I believe it to work Clint. The t-stat opens to allow cool water to help cool the block otherwise the water is bypassing and going straight to the exhaust.

[cadunkle]

First, fix your gauge. Somewhere in the 130*-140* mark will burn you in short order and cause you to quickly (involuntarily) pull your hand back. Your motor will have either a 145* or 160* thermostat if raw water cooled, possibly 180* if closed circuit cooling with heat exchanger. Fix your gauge, because without it you have no idea if you have a problem or not.

Secondly, the part you're pointing to is the thermostat housing. This is where hot discharge water at thermostat temp is discharged. Typically it will mix with some fresh water then some will be recirculated and some discharged out the exhaust. You are picking the hottest part of the engine to complain about being hot, while not quantifying the temperature there. About the only way you could say for certain it's too hot is if it was burning the paint off the housing... Kind of like exhaust ports will typically do.

[suprasam]

LOL yah I think everyone now understands.........hmmm yes I am a rookie(no shame) when it comes to the mechanics of my motor. I appreciate the help, I do, I know the gauge needs to be bought and one is on order, along with a new impeller. The impeller will be in tomorrow (suppose to be) and if so I will go by and see if I can rent (autozone) a infared temp device. They usually rent out loaner tools, maybe this is something they have also. Either way, thanks and I will keep you posted to see if I was being a puss or maybe had to many beers while working on my boat in my garage and got over worried for no reason.
edit: My motor is fresh water cooled

[DAFF]

Think of your cooling system in three parts...

First is the intake where fresh water is sucked from the lake into the water separator (which helps keep the trans cool) through the impllar and brought to the top of the engine. Here is is greated by a variety of hoses which transfer the water to various area of the engine.

Second the water is pushed into the engine side. Here the water pump takes over moving the water throught out the engine and heads. This is where the Tstat works like a cork holding this water around the engine block to create the optium run temp. If the engine runs too cold then it will be less fuel efficient and run poorly and rich. Adding heat will optimise fuel burn and maintain a equilubrium of sorts. Keeping the T stat closed holds in the warming water, too hot then it open letting the heated water escape.

Thrid is the exhaust manifold side of things. Here is where the heated water from the engine is mixed with the flow from the impelar, excaping via the manifolds and exhaust and out the rear of the boat.

One thing to remember is the rate of flow from the garden hose is likely lower then the flow from the raw water impellar. This reduction of flow will reduce the effective cooling of the engine causing things to run on the hot side. Myself the impellar is good, time to fix the guage and launch the boat. By using some bumpers and tie off the boat run it for some time dock side in gear and watch the guages. After 15 min or so you will determine any issues.

Also double check all the hose clamps and hoses in the cooling system. Look for tightness and make sure they are all tightly in place.

[Salty87]

^good stuff

the pressure from the water hose can mask an impeller on its way out. good advice to run it at dock and wait a bit. your exhaust will get louder and sound different when you're cruising and lose waterflow. then you'll start smelling rubber and losing power. not good so be aware.

harbor freight has cheap infrareds. you don't need anything fancy.

if you're in a bind and need parts locally, nautique dealers and prob more now run PCM engines and usually have parts.

i didn't pay great attention...it's your first boat, have you had her out yet?

[suprasam]

Salty, no its not my first boat.....I would say around my 8th or so. I bought this one in September of last year and has been a good boat, just small issue with it now. Thx

[Jetlink]

Suprasam, I fired up my boat yesterday on the hose and the warmest I was able to get the temp gauge was around 140 or so, this also checked with the temp at the thermostat housing. I know I am running a 160 degree thermostat because on the water my temps are higher than on the hose. Hope that helps give you some insight.

[lbagby]

Re overheating at running speeds. I looked through the threads and didn't see anything about checking the screen. I happened to drive across lots of vegetation that had washed down the river after some storms. At idle and low speeds the temp was perfectly normal, but at cruising speeds the temp immediately went up. Several things can cause this, but knowing I might have sucked up some debris I pulled the raw water intake hose near the transmission (I'm not looking at the boat so can't say exactly). In any case there is a screen, not a filter, to catch just this sort of crud. I cleared it out, reattached the hose, and everything was fine.

86 comp original owner