Logo

My first scare on a BF150 with 294 hours

twin 150

Contributing Member
I am not sure, but I think my thermostat was stuck closed at start up. With about 45 seconds I noticed that there was no peeing! So I quickly climbed my ladder and ran into the cabin and shut that starboard engine off. Then I went back out to the motor and felt the aft right rear of the block and it was pretty darn warm. I wondered if my impeller was toast of did my thermostat stick closed? Anyway, 20 min later I tried it again and once the motor was started, I saw it peeing almost immediately. I am concerned.....

I have a 75 gal horse trough water container I slide under my motors and the water input screens are some 5" BELOW the water line.... Ambiant air temp was 45 degrees and it was fairly cold outside.


If it was stuck, doesn't it seem crazy that they wouldn't stick open like some cars if it fails----or maybe that is a special order one, but is that strange?

I'm going to order 4 thermostats (2 for each motor) and just redo them both.

Thoughts?
 
Last edited:
I'm not the 150 pro (that's hondadude and he's under the weather at the moment...get well soon Mike!) but I wouldn't think that the pee stream would be affected by the thermostat(s) as most outboards are designed with the tell tale as a bypass circuit. It could be that the tell tale passage was temporarily plugged or the water pump didn't prime up properly. Never hurts to change out the T-stats though if they've been in there for a while.
 
T-stats on an outboard seldom sick in the closed position, as you surmised. Jimmy is likely correct that there was likely an obstruction in the telltale circuit. When you have those t-stats out, back flush the system using a water hose with a rag tied around the end to get a good seal at the T-stat opening. Also, use a piece of heavy monofiliment to clear the telltale hose. The mono from a yard string cleaner works very well. BTW, I think the operating temp for the 150 is around 160 - 170 degrees F, so that will feel pretty hot to the hand.
 
Thanks guys.

The veracity of the water stream was so strong the second time it seems weird that there was a blockage. But listen, these kinds of things are definitely not my cup of tea.

Am I being too over-the-top for the thermostat replacements?

Motors are 2008 and they have 294 hours. Almost all of which has been since May 2010 - OCT 2011.
 
Time is just as much an enemy here as is operation cycles. Heading out towards 4 years on that set of stats, I would say you are behind the curve, not in front of it. Especially if you do your boating in salt water. But, if you are a diligent flusher, you might want to take a peek at the easiest one to get at and make a new strategy based on what you see. Always something to keep in mind though is this statistic:
Approximately 70% of all engine failure (on highway and off) begins in the cooling system. Thermostats are cheap insurance.
 
Ditto to all the above. Remember that there are two different thermostats on each motor. The one for the head is a cooling thermostat than the one for the block. Be sure to order the correct ones and then put them in the correct locations.

Mike
 
Anyone with a list of what I should replace?.....(I have two BF150s, One is a 2007 and the other is a 2008 CR)

A. Thermostats 2/motor
B. VST's 1/motor

???
 
Thermostat does not affect telltail. Manual says to replace water pump impeller at 200 hours. I have a little over 300 hours on my BF150-A4s and I am ordering impellers right now. Figured I would do the thermostats too.

Does anyone know where the thermostts are located on the blowout drawing. I am looking for them on boats.net and can not find the part numbers to order. Great prices on OEM parts there btw.
 
I have a couple more quick ones.
1. There are two configs shown. Looks like the parts are the same except the o-rings. Do you know which one is BF150A4?
2. Would you replace all the o-rings including the ones on the fittings that connect to the hoses? I think you had another thread about that.

Sorry, I am not really this helpless, but my service manual is with the boat in FL and I am in Chicago. Really appreciate the help!
 
Back
Top