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Author Topic:   c.2004 Yamaha 90 Power Head Repair

Soho posted 07-14-2014 08:27 PM ET (US)
Faced with classic symptoms of clogged water jacket overheating, I managed to get all the bolts out of my 10-year-old [i.e., c.2004] Yamaha 90 head and remove the head cover and the head. Lots of gunk in both. The jackets around the cylinders look not too bad. So far, so good. Will test thermostat; it is nearly new and was first thing I tested when this overheating started happening. Will replace and also service water pump as normal to complete the fix.
Would there be any harm in soaking the head covers and head in vinegar to help remove the crud before brushing and power-washing them clean?
There is one odd bolt on left side of the head, does not hold it onto the block and just appears to have some water passages to it, but nothing else: what is this? Is it a place for a diagnostic sensor to be inserted? It would get water flow past it.
Are there zincs in there I should replace?
What should I use for gasket sealant? What is recommended by everyone when putting it all back together again?
Thanks in advance for your input. I hope this has it nailed.--Ron
RevengeFamily posted 07-15-2014 07:06 AM ET (US)
Ron--the vinegar may be helpful at loosening some of the contaminants from the heads. Even though it is a mild acid, it will attack the aluminum. I don't imagine that it will do any damage, but acid is acid.
As far as the "odd" bolt, I believe you are correct, that may be where internal zinc should be located.
For gasket sealant, I have used "Permatex." Not sure of the name or number on the container, but it is a black substance with a brush built into the lid.
Prior to inserting the bolts, I give the threads a touch of wheel bearing grease. This will keep them from becoming stuck in the future. Best of luck--Norm
Soho posted 07-15-2014 10:18 PM ET (US)
Thanks Norm. I did provide a vinegar bath for the pieces, just a few hours really, then ammonia rinse to neutralize the acid, power washed them, compressed air dry and then WD-40. Bit of overkill but I must admit it did a pretty good job as most of the crude is gone from them. Just some finishing up cleaning to do while cleaning the mating surfaces. I figured the vinegar is mild enough to not do any real damage.over a few hours. Mechanic confirmed no need to use any sealant on the head gaskets, so I will follow that. First time I have done this operation so keeping fingers crossed the head reconstruction goes well. The crud was not so much in the actual water jackets around the cylinders, but rather in the head piece and the cover to some degree.
On the bolts, yes, I always clean them up, and their respective locations, and grease before reassembly.
Thanks for the input
Ron
RevengeFamily posted 07-20-2014 07:19 AM ET (US)
Ron,
Doesn't sound like over kill to me... let us know how she runs when when you get her back together...
And then theirs the story of my Yamaha...
Took my Boston Whaler Revenge 22WT for a trip to the lake yesterday... she has twin 1999 Yamaha F100's... get her wet, start the engines to warm a bit and check telltales... I have water flow so all appears right and ready...
We were maybe 300 yards away from the launch ramp and I get an overheat alarm... shut the motor down and idle back to the ramp on her sister...
Pop the cowling, check the thermostat... it's wide open... rinse it in the cool lake water and discover it's actually stuck in the open position... Start the motor without the thermostat cover on. seemed to take longer to fill the block with water than I expected... so I load her back on the trailer and head to a quiet shade covered corner of the parking lot. Pull the lower unit and discover the impeller has deteriorated quite a bit... I have a spare pump assembly as well as a new thermostat on board. It took me an hour and a half to put it all together with the new parts and relaunch... Then spent the rest of the day cruising, fishing and swimming with the family...
Love my Yamahas!!!
Norm

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Author	Topic: c.2004 Yamaha 90 Power Head Repair
Soho	posted 07-14-2014 08:27 PM ET (US) Faced with classic symptoms of clogged water jacket overheating, I managed to get all the bolts out of my 10-year-old [i.e., c.2004] Yamaha 90 head and remove the head cover and the head. Lots of gunk in both. The jackets around the cylinders look not too bad. So far, so good. Will test thermostat; it is nearly new and was first thing I tested when this overheating started happening. Will replace and also service water pump as normal to complete the fix. Would there be any harm in soaking the head covers and head in vinegar to help remove the crud before brushing and power-washing them clean? There is one odd bolt on left side of the head, does not hold it onto the block and just appears to have some water passages to it, but nothing else: what is this? Is it a place for a diagnostic sensor to be inserted? It would get water flow past it. Are there zincs in there I should replace? What should I use for gasket sealant? What is recommended by everyone when putting it all back together again? Thanks in advance for your input. I hope this has it nailed.--Ron
RevengeFamily	posted 07-15-2014 07:06 AM ET (US) Ron--the vinegar may be helpful at loosening some of the contaminants from the heads. Even though it is a mild acid, it will attack the aluminum. I don't imagine that it will do any damage, but acid is acid. As far as the "odd" bolt, I believe you are correct, that may be where internal zinc should be located. For gasket sealant, I have used "Permatex." Not sure of the name or number on the container, but it is a black substance with a brush built into the lid. Prior to inserting the bolts, I give the threads a touch of wheel bearing grease. This will keep them from becoming stuck in the future. Best of luck--Norm
Soho	posted 07-15-2014 10:18 PM ET (US) Thanks Norm. I did provide a vinegar bath for the pieces, just a few hours really, then ammonia rinse to neutralize the acid, power washed them, compressed air dry and then WD-40. Bit of overkill but I must admit it did a pretty good job as most of the crude is gone from them. Just some finishing up cleaning to do while cleaning the mating surfaces. I figured the vinegar is mild enough to not do any real damage.over a few hours. Mechanic confirmed no need to use any sealant on the head gaskets, so I will follow that. First time I have done this operation so keeping fingers crossed the head reconstruction goes well. The crud was not so much in the actual water jackets around the cylinders, but rather in the head piece and the cover to some degree. On the bolts, yes, I always clean them up, and their respective locations, and grease before reassembly. Thanks for the input Ron
RevengeFamily	posted 07-20-2014 07:19 AM ET (US) Ron, Doesn't sound like over kill to me... let us know how she runs when when you get her back together... And then theirs the story of my Yamaha... Took my Boston Whaler Revenge 22WT for a trip to the lake yesterday... she has twin 1999 Yamaha F100's... get her wet, start the engines to warm a bit and check telltales... I have water flow so all appears right and ready... We were maybe 300 yards away from the launch ramp and I get an overheat alarm... shut the motor down and idle back to the ramp on her sister... Pop the cowling, check the thermostat... it's wide open... rinse it in the cool lake water and discover it's actually stuck in the open position... Start the motor without the thermostat cover on. seemed to take longer to fill the block with water than I expected... so I load her back on the trailer and head to a quiet shade covered corner of the parking lot. Pull the lower unit and discover the impeller has deteriorated quite a bit... I have a spare pump assembly as well as a new thermostat on board. It took me an hour and a half to put it all together with the new parts and relaunch... Then spent the rest of the day cruising, fishing and swimming with the family... Love my Yamahas!!! Norm