Silicone hose & coolant odors

[Briankinley2004]

When I bought my boat last year the mechanical surveyor recommended I replace the failing wire reinforced hoses to the block heaters with silicone hose. I did that as well as changed coolant. Last winter I ran the block heaters quite a bit due to the weather and seemed like there was always a lingering coolant odor in the engine room. Never had any coolant loss but I spilled a bit with the coolant change, hose changes, etc. Well the odor disappeared except after running the engines for the day I seemed to notice a coolant odor in the ER. Again no coolant loss and the odor would go away. So after doing some paint stripping on the engines tonight I decided to turn the block heaters on to help dry things out as the humidity is 100% right now. After an hour or so the engine room begins to smell of coolant. I see no leaks and get curious. Using my nose I find that the odor is coming from the silicone hose. The newer hose that I installed is strongest however these hoses are also the longest ones. Some of the existing silicone hose also has a coolant smell when you sniff it. I guess I have found the source of the odor but is this normal? I was planning on replacing the water supply hoses to my heads with silicone but am having second thoughts now. I have put almost 200 hours on the boat since I changed the hoses.

[Cricket]

My guess is the smell is coming from the vent tube when the coolant gets hot and not leaching through the silicone hose. Maybe try adding a coolant capture tank if you don't have one already??? We've been using silicone hose for all kinds of applications without any smell issues.

[Briankinley2004]

I have expansion tanks. I "smell tested" and the odor is definitely strongest at the hoses however I noticed this AM that it wasn't there. I also noticed that the temps of the coolant was down to around 120 and was up at 150 last night. The hoses that smelled strongest were near the sending unit so I am wondering if the thermostat opened up and lowered the temp of the hose. Anyway I found it odd. Am also wondering if some coolant dripped out of the petcocks when I changed the system and got on the hoses emitting odor when it gets hot.

[racclarkson@gmail.com]

I have expansion tanks. I "smell tested" and the odor is definitely strongest at the hoses however I noticed this AM that it wasn't there. I also noticed that the temps of the coolant was down to around 120 and was up at 150 last night. The hoses that smelled strongest were near the sending unit so I am wondering if the thermostat opened up and lowered the temp of the hose. Anyway I found it odd. Am also wondering if some coolant dripped out of the petcocks when I changed the system and got on the hoses emitting odor when it gets hot.

Cricket is right. Heating by block heat or by running expands coolant and forces air out the overflow tube at the cap; expansion/recovery tanks inhale and exhale too. The silicone hoses are not transmitting the smell. As you've noticed, the smell is strongest when the metal is warmer. If it bothers you, spray some OdorGone around the area and see if it reoccurs. Your thermostats shouldn't be in play at any of the temps you mentioned.

150 seems awfully hot for block heat. Was that from mechanical or electric gauge? I would expect the temps to fall overnight in winter, but closer to the ambient range. What wattage heaters are you using? I'm using 1,000W Zero Starts on my 1271s. They'll give me about 120 in the summer and about 105-7 in winter (40-55 degrees ambient) from the mechanical gauges. My electric gauges are always off some. Shoot the motor around the sender with an IR temp gun.

[Briankinley2004]

The 150 was from the mechanical gauges. The port engine read this last night and the starboard was around 110. This am both of them were around 110 or so. Its about 70 outside. I turned them off so I could paint. Not sure of wattage but dont really use them down here. I ran last winter as I had the boat on the Northshore and it got in the teens. Ran to keep ER warm for freezing. Down here on the gulf it rarely gets below 32 and if it does normally doesn't stay. Very common to see water lines laying on top of the ground around here. Im wondering if the pressure switch on the port engine was stuck.

[racclarkson@gmail.com]

The 150 was from the mechanical gauges. The port engine read this last night and the starboard was around 110. This am both of them were around 110 or so. Its about 70 outside. I turned them off so I could paint. Not sure of wattage but dont really use them down here. I ran last winter as I had the boat on the Northshore and it got in the teens. Ran to keep ER warm for freezing. Down here on the gulf it rarely gets below 32 and if it does normally doesn't stay. Very common to see water lines laying on top of the ground around here. Im wondering if the pressure switch on the port engine was stuck.

110 is about right for that ambient. There's no way you're getting to 150 on block heat, and there's no way a Detroit is going to lose 40 degrees overnight with the heat on. Sounds like you've got sender/gauge issues. Again, an iR gun would be helpful.

[Briankinley2004]

I will check with the heat gun next time Im down. The higher reading was when it first came on. The sender for the mechanical gauge is right where the hose from the block heater goes to the water manifold so it is reading the output from the heater. Im thinking maybe since it was within the first hour or so it was just reading the initial water and once it all got circulated the temp of the water dropped. I dont think the engines were 140 for sure as they were not hot to the touch. The hose was almost too hot to hold but wasn't the next am