1990 175 xp overheating at idle

[Matt LeMunyon]

Hey everyone!
I have a 1990 175 xp (E175STLESE). When I woke the engine up this spring, I noticed the left cylinder bank thermostat housing was much hotter than the right when idling in our little test tank that we stick the lower unit in. I don’t have a temperature gun, but I could hold my hand on the right side no problem but couldn’t on the left. Today I just replaced both thermostats and pressure relief valves and fired it up, but now both sides are too hot to touch. I put everything back together exactly how I found it, so I don’t see how I could’ve done something wrong. I still have to change the water pump, but I’m confused since at least the right bank was still cool before. I’ll upload pictures tomorrow when I get a chance to take it all apart again but in the meantime does anyone have any tips or insight? Anything is appreciated

 

[racerone]

Is water at least 8" above the impeller in your test tub ??

 

[Matt LeMunyon]

Is water at least 8" above the impeller in your test tub ??

The water level in the tank is about 2 inches above the cavitation plate. I can’t fit a taller tub under the outboard because the engine mount and trim rams get in the way. I’ll post pictures of the whole setup as well

 

[racerone]

Go to your local ramp and test run.

 

[Matt LeMunyon]

Here are the pictures I promised of the test tub and the thermostat and pressure relief valve. Everything looks fine to me but I’m not an expert lol. The O-ring behind the pressure relief valve looks fine on both sides- no rips or cracks. I will try to get the boat to the ramp this weekend, and will pick up a temp gun some time this week

 

[racerone]

Look into issues with water diverters.----There are 3 on each side.----They guide water around for proper cooling.-----If 1 is out of position it can block water flow.

 

[Matt LeMunyon]

Sorry for the very late response but I finally grew a pair and decided to tackle the water diverters. None of them seemed out of position and they were all in their grooves in the block, but they looked original to the 30 year old motor and were all misshapen. The bottom 2 on each side were a breeze taking out and reinstalling. But the tops on each side have proved to be the most torturous experience of my young life. They both just break up into tiny chunks that are almost impossible to get to. It took me about half an hour just to get the top right all out and I’ve run out of steam getting the left one out. I’ll save that for tomorrow. The thunderstorms weren’t helping either.

There’s no real debris in the water passages either, but I’m doing my best to remove whatever I can. I’m going to remove the cooling jacket cover’s tomorrow as well to see if I can find any obstructions in there.

I’m hoping I’ll be able to get a newer 4 stroke at some point. I love 2 strokes but man these old motors just want you to hate them lol

 

[tphoyt]

Why not do the water pump while you at it.

 

[Matt LeMunyon]

Why not do the water pump while you at it.

I’ll be tackling that next, since it is due for a new impeller. I’ve just been dreading that because on mine the bolt to disconnect the shift shaft from the coupling is extremely difficult to see and reach with the vro pump in the way (I’m not sure if it’s the same for all years of the cross flow). But now that I’m getting more comfortable taking things apart I feel it shouldn’t be as bad as it was the first time.

 

[tphoyt]

It’s always easier after the first time around.
If you were only getting hot at idle it’s possible you’re not pumping enough water at idle.
If you’re lucky the impeller will still be intact and not broken up and causing a blockage.
How long has it been since the last change?

 

[Matt LeMunyon]

It’s always easier after the first time around.
If you were only getting hot at idle it’s possible you’re not pumping enough water at idle.
If you’re lucky the impeller will still be intact and not broken up and causing a blockage.
How long has it been since the last change?

It’s been almost 2 years but I only had it out on the water 4 times and ran it in the tub about 10 times since. It’s a project boat so i don’t have it out much. This hasn’t been a problem since I started it for the first time this season so it could very well be that and I’m just thinking to hard. I guess it’s good to do at least not knowing about the motor’s maintenance history.

 

[brodmann]

Yep. Whenever I pick up a used boat, I change plugs, water pump, lower unit oil, clean the carbs and drain all the gas out of the tank. You never know what type of maintenance has been done.

 

[Matt LeMunyon]

Yep. Whenever I pick up a used boat, I change plugs, water pump, lower unit oil, clean the carbs and drain all the gas out of the tank. You never know what type of maintenance has been done.

Trust me there was no maintenance done whatsoever. You should’ve seen this outboard when I first got the boat. It looked like the previous owner used it to dredge out his slip at marina. The cooling system was FULL of mud and sand. The only reason I bought the boat was because it seems kind of rare and worth restoring imo. Plus it only cost me $800 lol. So I’ve just been learning about and tackling different issues as I go along

 

[Matt LeMunyon]

Calling it quits for the weekend. Weather has been awful all day so I finished up with the diverters and put the heads back on with new gaskets. I’ll pick up a water pump kit this week and get that done first and see if that was the issue before I snap a few bolts trying to get the water jacket covers off. I’ll post an update afterwards. Thanks for the help so far everyone!

 

[Matt LeMunyon]

Just wanted to give an update. Spent about 3 hours trying to unbolt the shift rod so I could drop the lower unit. No combination of socket extensions worked. I removed the entire air box assembly. I tried to unbolt the vro and fuel pump to move it out of the way but the lines are so short it can’t be moved far enough to help. For the life of me I cannot understand how any engineer could’ve thought this was a good design, especially for something that needs to be removed for maintenance fairly often. I really want to avoid having to call a mechanic to remove a single bolt, but I’m just at a loss. Not a good start to the weekend