Changed impeller, now engine overheats

[Madcityami]

Sorry for another engine overheat thread. I did read a bunch of threads but am in denial that they apply to me because most of them ended in corrosion related to running on salt water. I do not run on salt water, but I do run on a lake where the weeds look like they are from little shop of horrors. I’ll try to keep this to a few pointed questions.

Background: Last night, I changed the impellers and housings. Today, put the boat on the water, checked the oil and port engine temp warning went on after about 200 yards at no wake speed. I verified nothing coming out of pisser #1 so I shut it down and headed back to dock on the other engine. I had the boat pulled out of the water. There were some weeds wrapped around the impeller in my 400 yard journey, but pretty minor compared to what I've seen in the past without issues. I ran the engine on the hose...which in my mind would rule out any possibility of my impeller job somehow botching the cooling flow. It ran fine on the hose idle, but when I bumped up to 4k RPM, I got the overheat again pretty quick.

Question 1: Does this look like water is coming out of all the right places? The engine was running at idle and there was slight spitting from the pisser. It comes out of the top port after about 10 seconds.

Question 2: After about 10 seconds in, it appears the water out of the top port has either white smoke or steam. Should I be concerned?

Question 3: Is it possible (given the volume of water you see coming out in the video), that the hose did not provide sufficient water volume to keep the engine cool at higher RPMs? 4k didn't seem crazy to me, but I'm new to all of this. The pressure is not great from this hose to begin with.

Question 4: Does this theory seem plausible?:

1. Somehow, weeds covered the water intake from the start
2. 200 yards of no pisser time was long enough to get the temp warning
3. whatever was covering the intake came off when the boat was pulled from the water
4. My on-hose overheat was due to RPMs too high for water volume
5. I probably could have just put it back on the water and had a great anniversary-eve afternoon on the water

 

[Julian]

Sounds to me like a weed over heat and weak hose problem. Put her in the water and test again.

 

[buckbuck]

I would be careful running the engine above no wake while on the hose. It does not increase water pressure and only builds more engine heat. If you look at the amount of water coming out of the nozzle that is the indicator that your hose water is doing little to cool the engine and simply back flushing the pickup screen. I have found that clamping the cooling line between the Y fitting and jet forces all water to the engine and exhaust. You should be able to flush without an over temp while doing that.

 

[Madcityami]

Put it on the water this morning and all was good.

In summary: I believe the cooling intake was clogged, causing the port engine to overheat pretty quickly. Either pulling it out of the water or running on the hose flushed the obstruction. It still overheated on the hose because it was my first time using the hose and I didn't account for the reduced cooling/water volume of the hose when increasing RPM.

I do have one last follow up question...It seems pretty unlikely to me that something could clog the cooling water intake unless the water is seriously restricted from a pretty big clog in the pump intake on the bottom. It seems that even a partially obstructed pump at idle would push enough water past the cooling intake that it would be hard to "vacuum" anything up. Am I just wrong on that assumption or am I missing anything else? I only ask because if the cooling intake can indeed clog, the backup move would be pretty ineffective and pulling the boat out of the water seems to be the only option.

 

[WREKS]

@madyamaha I think you have noticed something. Your video shows your motor running at idle. It appears to me that you have sufficient cooling water and yet, your thermostat appears to be opening and closing, feeding and restricting water to the ''top port" hole that you reference. Once the engine reaches a certain temperature, the thermostat should open and stay open. Yours appears to open, close, build up heat (steam), then open again. to release it along with some water. I would try running it without the thermostat or exchanging thermostats to see if it makes any difference.

 

[Madcityami]

@madyamaha I think you have noticed something. Your video shows your motor running at idle. It appears to me that you have sufficient cooling water and yet, your thermostat appears to be opening and closing, feeding and restricting water to the ''top port" hole that you reference. Once the engine reaches a certain temperature, the thermostat should open and stay open. Yours appears to open, close, build up heat (steam), then open again. to release it along with some water. I would try running it without the thermostat or exchanging thermostats to see if it makes any difference.

Thanks @WREKS. Next time I get it on a rack, I’ll run the other side and see if it has the same behavior. Then I’ll try to reproduce on the port side again and swap the thermostat. Excuse my ignorance, but just confirming you are talking about part 29 on this diagram? From the diagram, I noticed a zerk on the thermostat cover. Does that need to be greased on a normal schedule? I just purchased the boat and I don’t know how well the previous owners kept on this.

 

[WREKS]

That's it. Regarding zerk fitting for intermediate shaft: Search forums! Careful! Over greasing can blow out seal.

 

[Madcityami]

I’ve watched the MR1 cooling video referenced on the forum a number of times. I’m not sure if it is because I don’t have the HO version, but should water be coming out of here?

 

[PortA]

Being new at this, as I just got a 08, 212X I've watched the ports on the transom as I'm flushing. What I don't see on mine is the steam, so your's is not getting enough water flow/pressure to maintain water flow after the thermostat is open. So to trouble shoot, I would take some vice grips and pinch off the hose to the pump. (Line prior to the "Y" fitting) Start motor and open flush hose and see if the water flow is better. When the thermostat opens the water will be warm/hot, without steam.
Let us know the results and if need be we can take you to the next step.

 

[WREKS]

@madyamaha[/USER] Your engines do not use that port.

Take care if you start pinching off intake water lines. That raises the water pressure going through the head and manifold gaskets. That can be a good thing but, if the pressure is too high, water/steam may breach the head and/or exhaust manifold gaskets and go into the cylinders and/or lubrication system. I would not exceed the system pressure which according to a study by @buckbuck is around 25PSI.

 

[PortA]

WREKS, as said I'm new with these engines. But what I see from the video is that there's water/steam and then no water/steam. per you observation, you state the thermostat is opening /closing. I can't see the thermostat operating in this manner after it reaches operating temperature and opens up. There's no cold water hitting the thermostat it to close it. So what we might be seeing is very little water flowing through the engine. The engine is boiling over.
As to over pressuring I see you have water pressure around 40-60 psi. Using the the Yamaha flush hose with a 3/16" opening I can't see a volume to over pressure the cooling system that has 1/2" supply hose that's tee's off to the oil cooler, then the 1/2" goes into a 3 line header, 2 lines feed to the exhaust manifold and 1 feeds the engine block. From the engine block there's a outlet that feeds the 4 exhaust ports. From the engine block is the thermostat. (If I have all this correct) I can't see that much more pressure increase by cutting off the pump supply hose. (Don't see that much water flowing from the jet, in the video)
Back to the problem: After re-reading the problem I see Madyamaha states " It ran fine on the hose idle, but when I bumped up to 4k RPM, I got the overheat again pretty quick."
1. I would retest on hose at Idle, if you get no alarm, take back to the lake and test it.
2. If you have steam, check thermostat and/or which thermostats. If you still get steam, restrict back flow from jet pump, so there's more flow to engine. If over-pressuring is a concern and you don't want to pinch the hose, remove the water inlet cover on the side of the pump, leave screen in and put cover back on with 2 bolts. (see picture) this way you can take a rag and restrict flow to build pressure to engine. You should get hot water flowing from thermostat without steam.
If you still have issues, let us know.

 

[WREKS]

At idle, it takes very little cooling water to cool the MR-1 engine. If it is overheating there is probably an internal blockage. Overheat problems start and compound by boating in shallow water. Sometimes a blockage can be flushed out. I just do not think it is wise to over pressurize the cooling system.

 

[Madcityami]

Thanks for the suggestions. I have had it back out on the water with no issues. At this point, I want to try to reproduce and compare the other side to see if it is an intermittently failing/sticking thermostat. I have a cheap hose pressure gauge so I can see what the marina hose is really putting out. I’ll report back results good or bad to give the thread closure. Again, thanks for the guidance @WREKS @PortA @Julian

 

[PortA]

Madyamaha, pressure will be inserting. A easy hookup point would be the flush hose connection, adapt the flush hose connection to our test gauge. You can get a reading from both engines, to compare.

 

[drewkaree]

Question 4: Does this theory seem plausible?:

1. Somehow, weeds covered the water intake from the start
2. 200 yards of no pisser time was long enough to get the temp warning
3. whatever was covering the intake came off when the boat was pulled from the water

I drop in at the launch right at my place on the lake. Number 1 can, indeed, happen. It happend to me a few weekends ago. 200 yards was longer than it took me to get a temp warning. Look at a few of my pics somewhere around here for the distance you can see with your own eyes - from my pier to the opening leading out to the lake is all it took. Luckily for me, it's only a few feet deep there to allow me to get out, and I DID have to get out. I hadn't realized it, but at the end of our launch, there was so much crap/weeds built up, I launched straight into it and essentially forced it to cover my intake from the get-go. When I went to the cleanouts, I was pulling weeds off of there for a EASILY a good 5 minutes, and it only got the crap off the impeller shafts, not anything that was covering the intake grates. I ended up hopping off the boat, and the pile of shit that I pulled off the starboard intakes, I'm shocked at. We've started weed removal on our little section of the creek, and especially at the end of the launch area. Normally, the neighborhood does some weed abatement, but I think the DNR has been slow to issue permits to companies this year with all that's going on. With nowhere near the amount of boaters on the water this year due to all the restrictions, there's a definite and noticeable uptick in the amount of weeds around us. I'm guessing if you're near Madison, it's been the same for you.

 

[Madcityami]

@drewkaree Yes, I'm on Mendota most of the time. Seems like I've been pulling weeds out of the clean outs on every outing since mid-July. Not sure about you, but I've noticed my port side seems to attract more weeds than starboard. I know the pitch is different, but I didn't think it was that much.

This is my first year boating, but there does not seem to be a shortage of boaters by me. I think there are a lot of "pandemic, first-time boaters" like myself. I can tell by the panic'd look on their face pulling into the slips. Up until recently, I had that look

 

[drewkaree]

I've been driving through your area for work. I'm not a regular to boating there, but to my eyes, it looks like it's light on the water. Maybe not, but more traffic should result in less weeds.

For me, there's no preference for the weeds as to which side they like to clog up, and I can also tell you that with experience, you'll be able to see trouble spots better. I would often be in areas where I thought I'd be fine, only to clog up.

I'm thankful for the cleanout ports though, because it's only been once that I felt like I had to jump in.