1980 Chrysler Sea King 15 Overheating/Waterpump Concerns

[Samu_el]

Hello everyone. I have been fixing up my 1980 Sea King 15 Hp. It had a blown head gasket and bad condenser. I installed a new impeller and sanded/cleaned the pump housing and followed Chrysleroutboarddude’s waterpump video. video. I am concerned about cooling at high speeds. I got it running on both cylinders last week and I noticed that the waterpump works the best at idle and low speeds, but when when on plane, it gives out intermittent flows of water. I don’t have a temperature reader but I pour a bit of water on the head and it starts steaming and hissing even near the spark plugs when I’ve been at high speeds for a couple of minutes. When I go back to idle, the flow is constant and it seems that it is cooling head back down. I just pour water on the head to check the temp. The head of the motor had some dark discoloration when I first got it. This is my first outboard I’ve worked on and used myself so I don’t know much. When I shut off the motor, it seems to start back up fine when I think it is overheating. I attached a video of me at idle and getting up on plane. Since the video I lowered the trim on the motor. Is water hissing on the cylinders head normal at speed? My dad and uncle overheated and broke the motor almost 3 decades ago and I want to avoid doing the same after fixing it up. Thanks

 

[Samu_el]

Apologies, I didn't realize that my video isn't an mp4.

 

[jerryjerry05]

If the head gets so hot the water steams??? then somethings too hot??
The video shows the motor pumping out the back holes on the mid section.
Get a heat gun, Harbor Freight usually under 25$
I don't think they put a thermostat in the smaller motors.

 

[Samu_el]

Yeah I believe I've heard that somewhere, where if you pur water on the head then it shouldn't sizzle and evaporate? Yeah there are no thermostats on these motors until around 1984ish and mine's a 1980. I'll go out and buy a heat gun maybe from Harbor Freght if its good. (I went to buy a compression tester over there for $29.99 and found it was garbage after buying it.) And what temperatures should I pay attention to or range? Is the head and the block the same temperature? I never seen a video of one of these motors pumping water at speed so I am cautious. Thank you!

 

[jerryjerry05]

No thermostat: you should be able to touch the head without burning yourself.
The area around the plug and the plug will get hot enough to burn, be careful.
Might be the cooling passages are blocked? the heat gun will help show that.
The pic shows a thermo from a 40 that had the passages almost 75% blocked, it still ran and got a little hot, that's what the owner said.

 

[Samu_el]

I am suspecting that I might have an exhaust leak into my cowling since when I put my cowling on the motor sputters a bit. Could this be related to my water flow problem at higher speed? I will try to take a better video of my motor at the water since I didn’t know about the overheating problem then. I want to buy a decent Temperature gun eventually. I think my problem was similar to the one demonstrated in this video

. Should exhaust come out of the two holes at the back as I think mine’s was?

 

[jerryjerry05]

Looks like it runs good.
I'd get the heat gun before there's any damage??
It has water/exhaust coming from the back: Normal
What did the old impeller look like when you removed it?
Missing any vanes/blades?

 

[Samu_el]

The old impeller looked fine it wasn't missing any fins, just old and covered in calcium. I wasn't able to get a good heat gun yet, but I took my boat out today to demonstrate my problems. I poured water on it and showed the steam so I have no doubt that is is overheating. I decided to take the engine off of the outboard to inspect the pickup tube and insides. I plan on eventually getting a new rubber mounting seal and the bottom gasket. What should I be looking for in terms of the overheating problem? The impeller seems to work strong. But when I get on plane, the waterflow starts to weaken. I uploaded a video demonstrating what is going on:

Apoligies for getting back late, school has kept me busy. Thanks!

 

[jerryjerry05]

The pic of the mid section, it shows where the water tube comes up from the lower unit, is/was there a grommet or anything where the tube meets the top into the powerhead?
There should be some kind of seal to stop the water from shooting out the edges? where the tube meets the head.
When the two parts are put together you can't see how much room is between the two parts? Part #49 is the seal, rubber it should be at the top where the water tube meets the top. If not there? Might make it overheat.

 

[Samu_el]

I am almost certain that the motor has never been opened up or pulled until I got to it except maybe the impeller? I’m sure I saw it there. I will remove it and inspect for any imperfections. When I looked at the water tube from the bottom, it looked like there was a bit of a straight crack at the grommet. I’m not sure if it supposed to be that way to install or if it’s actually broken. I’ll have to find out how to get to it since it was not attached to tue powerhead. I’ll update from here. Thanks!

 

[Samu_el]

I was able to pull the water tube out today. The top piece looks like it has a crack as I suspected, but I’m not sure it it’s supposed to be like that. Could this be my problem?

 

[jerryjerry05]

The plastic grommet if it's not sealing against the motor could cause the problem??
That crack isn't big enough to worry about.
I'd get a heat gun and take the temp on different parts of the head.
You have a good pump and it shows that it's pumping real good out the back, then I'd look at the cooling passages around the pistons(pull the head)

 

[Samu_el]

I took some pictures of the head though they’re not the best, I didn’t see anything substantial in the head. I’m thinking that I might remove the exhaust plate on the side and look through there?

 

[jerryjerry05]

You break the gaskets seal?
That gasket could be a problem.

 

[Nordin]

That head gasket is fried.
Top cylinder metal gasket is broken.

 

[Samu_el]

The head pictures were taken when I got the motor. I since then took the head to a shop and reinstalled a gasket twice afterwards.

 

[Samu_el]

I took apart the exhaust housing and didn’t see much. I shot a water hose through the engine prior and soaked the jackets in vinegar overnight. It seems fine. I’m not sure what else could cause this problem. The bottom gasket at the bottom of the motor looked fine. The waterpump seems strong. I’m really puzzled as to what could be the problem. I’ve looked through just about everything. I wish I could get a hold of the man behind the YouTube channel Chrysleroutboarddude.

 

[Samu_el]

Hello everyone. It’s been a month. I found that the passages and the pickup tube all seemed to be fine. I replaced the driveshaft seal on the impeller housing. I added a new wear plate. Still no luck. I’ve found the motor pumps good water in neutral and reverse but for some reason giving throttle in forward gear greatly reduces the flow of water at the back. I took temperatures with a gun and at full throttle in forward, the head near the spark plugs topped out around 221 degrees! I found out doing some research that this problem is also common among Gamefisher/Force and all others that she’s the same design. I took a video of the motor idling:

 

[jerryjerry05]

What's the temp on the sides of the cylinders?

The plug area is gonna be hotter than the rest.
Doesn't look like there's a cooling passage there??

 

[Samu_el]

I think it was 170+? I know that the other surfaces on the head away from the spark plugs were still over 200. It definitely doesn’t want to push much water out at half throttle and above, but reverse and neutral are completely fine. Something with being in the forward gear is messing with the water flow I guess. I didn’t get to take a good video because it was dark.