Is it normal for one bank to run hotter than the other?

[Intoodeeep]

I have a 1988 175hp (I am running a 1979 235 powerhead, but everything else is the 1988 175) This is a new engine build. My starboard side bank is running warmer than the port side. The port side is about 158 and the starboard is about 170. The starboard side was running about 190 and I changed the thermostat and it is now running cooler but slightly warmer than the other side. I did pull the head and the plugs are in place and everything looks normal. I am dealing with a tachometer problem and I was thinking it was the regulator/rectifier, but I have ruled that out simply because I moved the grey tachometer wire to the yellow and grey wire and then tried the yellow wire and the tachometer was still reading wrong. So must be a bad tachometer. I only mentioned this because I know the regulator/rectifier can run hot sometimes.

So is this temp differential ok or am I missing something? It also has a brand new water pump. What is a normal operating temp range? My last motor never crept above 145.

 

[Bosunsmate]

Did you check the water deflectors when the heads were off?
Starboard bank always seems to be hotter on ones i have had, im not sure by how much
is that wot or idle temp?
regarding tach is your battery charging ok?

 

[Intoodeeep]

The deflectors are right where I put them when I built the engine. They didn't get push sideways or look out of the ordinary. The big reason why I pulled the head was I thought I had some water in the bottom spark plug. It may be coincidence, and I just may have gotten some water on the spark plug as I pulled the plug from the engine. The Thermostat housing was leaking from changing the t-stat. I ran the motor anyway for a few minutes because it only leaked a little. It is possible water got in that cylinder but after checking today and running the engine I found no evidence. So I will keep an eye on that for now. I am paranoid I think from the last motor going from a failed inner exhaust gasket and it cooked the piston in the same cylinder.

This was at idle. I have yet to take this engine out on the water yet, as I am troubleshooting the tachometer. Which I need so I can set the timing and start the break in procedure for the engine. My lower unit was also giving me a fit with shifting. It will go into gear with the engine running but will not go into gear all the way with the engine off. Even with spinning the prop. I think the shift cable I have has gotten stretched somehow. Its a new cable but who knows. I also just replaced the cuts in the control box as they were badly worn.

My fear is there is a packing peanut or something in the cooling area of the motor, that I may have missed somehow. God forbid that is the deal. :smash:

As for the tachometer, I am pretty sure it is charging. I was just thinking about that now and need to check in the morning when I get off work. The volt gauge on the dash does read 13-14 volts when the engine is running, but I just realized that don't mean squat for the battery. Don't know why I didn't think of it before. I did accidently (of course, because I wouldn't do it on purpose) reverse my battery cables. I didn't know until I realized the engine wasn't turning over because the starter was spinning backwards. :facepalm: A hand full of fuses later and the engine was running. I am hoping I didn't cook a brand new regulator/ rectifier, but it seems to be working. But that was me thinking that it worked because the volt gauge was reading 13-14.

 

[Intoodeeep]

Not sure if this matters or not, but the temp senders are located at the bottom cylinders. Thought this made since to me, since the upper cylinders are "monitored" by the temp sensors.

 

[emdsapmgr]

To test the shifting of the engine, take the shift cable off the lever at the cowling end. Shift he lever by hand through the F-N-R range. You should be able to shift it normally and correctly without the cable attached. Even when the engine is running on the garden hose. If everything is good, when doing it that way, then the problem is with the cable or it's adjustment at the cowling end. I'm still concerned about the high cyl head temps on the starboard head. The factory manual states that the cyl head temps should be 140 degrees +-15 degrees. It further states that if the cyl head temps exceed 160 degrees, that additional cooling system troubleshooting is called for. Keep in mind that the engine will signal an overheat at 203 degrees +- 6 degrees. The hot horn will silence when the head temp gets back down to 170, +- 15 degrees, which is still too hot, according to the factory. Have you pulled the cyl head cover off the starboard head to see what the water passages look like inside it? Do you have the tach on the correct setting?

 

[Intoodeeep]

Water passages looked good as well as the water deflectors. If I remember correctly the hole in the head gasket is kind of small to me for the cooling passages that lead to the head cover. Should I enlarge it some or am I better off pulling the head again and try and trace the passages to see if they are clear? I am at a loss of where to go next.
The tach is on the correct setting. I have swapped the temp sender wires for the temp gauges to see if one is reading off from the other and it reads the same when switched.

 

[metriccrescentwrench]

I'd suggest getting an IR temperature gun and check several areas on each bank as there are likely to be variations depending on where you measure. I'm getting a Rude 140 ready to run on my current project boat and the factory manual explicitly says that head temperatures will be hotter toward the middle of the head.

On my '93 Rude 175 I have my temp. senders near the top of each head and both sides always run within 5 degrees or so of each other except when running on the hose, in which case one side only gets to about 125 at idle while the other is at 140.

 

[emdsapmgr]

Agree. When you get into temp problems like this, it's best to be checking temps with a laser temp gun. Senders and gauges have an "allowable" factory tolerance.

 

[Intoodeeep]

I checked it with a heat gun. It was 150 at the hottest spot which is at the sensor. The rest of the head was 140-143. The port side head was 138-140. So its a hot spot. I pulled the head today to replace the head gasket as I had reused this one temporarily. I found a black line on the crush ring to the lower cylinder. Not far from the hot spot. Is this a blown gasket? I didn't notice it the first time I pulled the head but it could have been there. Actually It might have been as there was a spot I had to really clean with a rag. There is an indentation on the ring of the head as well. I can feel it. I sanded the area a little, but I am afraid to do much more as it could cause the gasket to not seat properly. How far can I go with this? Should I take it to a machine shop and have them take a little of to level it? Can I even do that and stay within tolerances?

 

[Intoodeeep]

No Title

 

[emdsapmgr]

Difficult to comment with no pictures.

 

[Intoodeeep]

I had it machined and it worked well. The hot spot was still there though. Not sure why and at this point I will now never know. I spent three years rebuilding the boat from the bottom up and even customized many areas with paint and fiber glassing. Spent the last six months building the second engine after the first one blew. I had an incident on the water Saturday. It ran well for the first few hours of service. I had a small fuel leak on one of the carb fuel lines. I cleaned it up and laid the rag on the side of the motor. I had my girlfriend start it so I could see where it was coming from. I couldn't see it, so I repositioned myself and stuck the screwdriver over by the rag. We were anchored and on the water when this happened. I was getting ready to set the timing, so that's when I discovered the fuel leakage which was fine before. When I stuck the screwdriver over by the rag, I must of hit the solenoid because it sparked and set the rag on fire. I yanked it away from the engine only for it to land in the well of the boat. I scrambled for it as my girlfriend did and in the process she tripped over and landed on the spare 2 1/2 gallon gas can knocking it can over, the cap to blow off I assume, and causing fuel to poor into the back of the boat. This caused the fire to erupt. I got it with the extinguisher in the back but it was under the floor already. When I opened the maintenance access hatch for the in hull fuel cell, a fire ball blew out. At this time there was no ability to save it. I think the fuel cell ruptured quick or the fuel line or lines. In less than two minutes from the start of the actual fire, the boat was completely engulfed. It was a great experience building the boat. I learned a lot. It was an accident/ (stupid mistake on my part) and other than a few singed hairs we are ok. The only pictures are from Virginia game and inland fisheries, who had to tow the boat in while it was still on fire. The fire department used 10 plus extinguishers with no luck. It did have a full twenty gallon gas tank. It was WRIC.com news website. You can google boat fire and you will see the short article and pictures. Thanks for everyone's help with the mechanical knowledge.

 

[emdsapmgr]

I looked at the pictures on the WRIC website. It's difficult to comprehend your accident and I am very sorry for your loss. Guess the good thing out of this is that you both are ok. You've been a good contributor to the website. Hope to see you back here again when you begin working on your next boat. Good luck.