Sterndrive trimed all the way up makes a grinding sound

"ok, 3.0 omc engine. Runs grea

"ok, 3.0 omc engine. Runs great, stern drive runs great when trimed all the way down in the water. Changed fluid clear as a bell, no metal in the fluid or anything like that. When i trim the sterndrive all the way up makes somewhat of a grinding sound, when i trimmed the stern drive back down it went away. It only does it when its trimmed all the way up or when its almost all the way up. Anybody had this problem before or know what it is."

"Is it still running when you

"Is it still running when you trim it all the way up??? You don't say what year or if it's a Cobra (I'm assuming it is) They should never be run trimmed all the way up it's too hard on the u-joints and the gimbal bearing, your probably hearing one of them when you do this. Do you have a working trim guage? This should show you the safe amount to trim up."

"Sorry, It is a 1989 Four Winn

"Sorry, It is a 1989 Four Winns 170. With a 3.0 omc , yes it is a cobra drive. There is no trim guage on the boat, i can not tell that there has ever been one on it. I dont understand why some boats have them and some do not. Kinda like hour meters, ive noticed some have and others do not. Let me ask you this, should i have the gimbal and the u joints checked out. Is there any harm in starting the motor with the sterndrive all the way up , but leaving it in neutral ? I guess what im saying is when i back down the ramp into the water the sterndrive is all the way up. I start the boat up , let it run for a couple minutes, shift into reverse and back out, as im backing out, that is when i start trimming the sterndrive down. I thinking now that trimming down before i put it in reverse is the best action. Do you think i have damaged the gimbal or the u joints ?"

"First of all let me ask you t

"First of all let me ask you this, is the lower unit in the water when you start it up? If it's not then you better think about having your water pump impeller replaced because you've probably toasted it. Anyway you never start the engine with the the drive trimmed all the way up, even though it's in neutral the drive shaft is always turning as soon as you start it (this turns the water pump in the drive unit). For the trim gauge OMC always included the trim sending unit on the drive but some boat manufactures did not include the gauge with the standard package. I recommend you don't raise it anymore than half way before you start it, all the way is only meant for trailering or beaching the boat and thats with the engine off. You may be OK if you stop raising it so high but in the fall you should take it in for service and have them replace the impeller and remove the drive and check the gimbal bearing and the u-joints."

"Thanks for the information bo

"Thanks for the information bob, about the drive, yes i always have the drive in the water or a hose hooked to it. Before i start it up.
Thanks Again for your help."

"Bob,

A somewhat related qu

"Bob,

A somewhat related question:

Is it true that on land with the flusher hoses connected, you should only run the motor in gear, rather than letting it run in neutral, because the impeller isn't turning and getting water in the engine in neutral?

I've always thought that I need to get it into gear pretty soon after starting to avoid damaging the engine."

"No Doug...that's not true

"No Doug...that's not true, in fact I would avoid running it in gear for safety reasons (unless you remove the prop first) As soon as the engine starts the drive shaft going into the sterndrive is turning, (water pump is on the end of this shaft), the only thing not turning is the prop shaft."

"[b]"I thinking now that t

""I thinking now that trimming down before i put it in reverse is the best action. Do you think i have damaged the gimbal or the u joints ?"

Trimming Down,.... Before you even Start the motor is What you Should be doing.......

All that Knocking you Hear,......
That's the U-joints trying to come Apart......

I'm Sure you've done Some Damage,......
How Much is the Question......."