Mercury 150 black max smoking when started, normal?

[saltfisher]

Im thinking of buying a bass boat, and just looked at it. Its a 1988, and so is the motor. 1988 black max. Everything looked good, as the guy only used the motor and boat 1 time per year in canada. After that he fogged the engine and did all maintance. He did tell me when he runs the engine, it smokes alot for about 2-3 minutes untill the motor is warm. That scared me. Thats the only thing keeping me from buying the boat. He said it was normal, just embarassing at the dock. They really suposed to smoke that bad untill they are warm?

Thanks

 

[ddennis]

Re: Mercury 150 black max smoking when started, normal?

Either check yourself, or have someone check for you, the compression. should be above 100psi and each cyl shoudl be within 10% of the others. 2 strokes smoke. Its just a fact of life!

 

[WillyBWright]

Re: Mercury 150 black max smoking when started, normal?

Welcome to iboats.

I wouldn't worry about it. I would expect that from a motor that's had more fogging oil than 2-stroke oil go through it. It might go away as you use it and it might not. It might be clogged bleed valves which is a fairly easy and inexpensive condition to correct.

There is one aspect that concerns me however. The oil pump drive gears consist of a metal one driven by a plastic one. On motors that sit a lot with inadequate preparation, the metal one can rust up and take out the plastic one. It's been fogged and that's good news. But I'd still be inclined to remove the gear and inspect it before running it. Also a fairly easy and inexpensive operation.

 

[saltfisher]

Re: Mercury 150 black max smoking when started, normal?

Thanks guys. The motor looks great. There is barely no wear on the outside, and the inside looks clean, almost clean enough to eat off of it. I looked around where the carbs are and didnt see any signs of leakage there or anywhere. He said personally "the motor smokes quite a bit when you start it for a few minutes until warm" I have been hearing alot of people say not to worry about it. So if the compression tests out ok, this should be a good motor? Just say I need a new powerhead...... how much does a rebuilt one cost? I heard mercury still has rebuilt ones for sale and they are like 1/3 the price of a brand new one. The boat itself doesnt even look bad. needs some minor TLC like polsihing/buffing oxidation out, and minor stuff like that. $2500 i think is a good price. It also has a jackplate, trolling motor, seats, SS prop, and aluminum prop along with it.

 

[hkeiner]

Re: Mercury 150 black max smoking when started, normal?

Some smoke at startup is OK, but excessive smoke is not normal and can be remedied. If you have excessive smoke, in my experience there are two possible causes your might look in to:​

1) The float valve on one of your carbs is leaking. If a carb valve leaks, residual pressure in the fuel line may cause some fuel/oil mix to run into the engine after shut down. The fuel then evaporates leaving the oil behind. At the the next startup, the excess oil causes excessive smoke until it is burned off. Cleaning your carbs and replacing the valve and valve seat is a good routine maintenance thing to do anyway.​

2) There are two check valves that are part of the oil injection system that, if defective, can cause excessive smoke. The crankcase 2 PSI check valve feeds pressure to the remote oil tank. If this valve is defective, it can cause the air pressure in the remote oil tank to be too high or it may not release the air pressure after motor shutdown. If so, oil can then be slowly pushed into the fuel line after shutdown causing excessive smoke at the next startup. A second 2-PSI check valve, among other things, controls the flow of oil from the reserve oil tank under the cowl into fuel line under the cowl. If this valve is defective (less likely), it also can allow oil to slowly seep into the fuel line after motor shutdown. The next time the motor is started, too much oil is in the fuel mix causing smoke. Replacing these two valves is easy to do yourself and the parts are not expensive. I would replace them just to eliminate them as a possible cause. It worked for me when I had a similar problem. Read the following thread for more information on this. http://forums.iboats.com/showthread.php?t=182406​

Good luck and report back if you solve your problem​