Paint discoloration lower unit
10-15-2002, 10:55 AM
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Paint discoloration lower unit
Been bothered all year by discoloration of the paint on my lower unit (Bravo 1) at the lower gear case. Have seen this heat induced discoloration at the top of many drives, hence, drive showers. But, this is the first time I've seen it at the bottom. Changed my gear oil, looked and smelled normal, not burnt. I suppose the discoloration is from excessive heat down there. Does this mean my bearings a going south or is it fairly normal for this like it is at the top? And.........if this is bad news (which I fear it is) how much does it normally cost to have a drive rebuilt, lets assume it just needs new bearings?
10-18-2002, 09:38 AM
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you haven't given much to go on about your paint discoloration issue.
What you call discoloration on the upper case of a Bravo drive is usually chalking due to the minerals in the water sticking on the paint as the water quickly evaporates off a hot drive. This is not paint discoloration since the underlying paint is still black and glossy. Bathroom cleaners (Lime away, CLR, etc) will aid in the removal of the mineral deposits.
Discoloration on the lower unit can fall into the same category of a build-up of some sort (minerals, scum, etc.) OR be something else.
Mercruiser factory paint is fairly tough and holds up well. Discoloration is not usually expected. If the drive has been repainted at any time (or touched up) then the replacement paint rarely holds up as well. Krylon or spray paint may look great for a while but will definitely fade or discolor if the boat is left in the water for any length of time. This may be what you are experiencing.
Urethane basecoat/clearcoat usually holds up well (from a spraygun with proper amounts of hardening agents added to the clear). One-part DuPont Centari also does a nice job.
I'm trying to hit on many issues since you really haven't given enough info for us to go on.
I wouldn't expect heat issues to be centered solely around the lower gearset. Easy to check, though, since abnormal gear or bearing wear would be the only possible cause of such. Pull the drain plug and look for sparkly metal particles in the lube... If there's not any, then I'm doubting the heat thing.
Hope this is helpful.
What you call discoloration on the upper case of a Bravo drive is usually chalking due to the minerals in the water sticking on the paint as the water quickly evaporates off a hot drive. This is not paint discoloration since the underlying paint is still black and glossy. Bathroom cleaners (Lime away, CLR, etc) will aid in the removal of the mineral deposits.
Discoloration on the lower unit can fall into the same category of a build-up of some sort (minerals, scum, etc.) OR be something else.
Mercruiser factory paint is fairly tough and holds up well. Discoloration is not usually expected. If the drive has been repainted at any time (or touched up) then the replacement paint rarely holds up as well. Krylon or spray paint may look great for a while but will definitely fade or discolor if the boat is left in the water for any length of time. This may be what you are experiencing.
Urethane basecoat/clearcoat usually holds up well (from a spraygun with proper amounts of hardening agents added to the clear). One-part DuPont Centari also does a nice job.
I'm trying to hit on many issues since you really haven't given enough info for us to go on.
I wouldn't expect heat issues to be centered solely around the lower gearset. Easy to check, though, since abnormal gear or bearing wear would be the only possible cause of such. Pull the drain plug and look for sparkly metal particles in the lube... If there's not any, then I'm doubting the heat thing.
Hope this is helpful.
10-18-2002, 11:53 AM
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Hopefully it is just chalking deposits from minerals in the water etc. If it is bad enough it will look like grey peeling paint. Almost as if the black is peeling and the primer is showing. However, it is really a mineral deposit.
CLR is my remover of choice. I soak a cloth in it and let it sit on the drive for a while.
Can you be more descriptive? What color? Can you peel it with your fingernail?
Do you have a picture?
Good Luck
CLR is my remover of choice. I soak a cloth in it and let it sit on the drive for a while.
Can you be more descriptive? What color? Can you peel it with your fingernail?
Do you have a picture?
Good Luck
10-24-2002, 10:51 AM
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Thanks for your replies guys, you've taught me some stuff here. I did think that the discoloration, even at the tops of drives was actually the paint discoloring. I did not know it was dried mineral depsoits causing the discoloration. This definitely makes me feel better about my condition because I have drained the oil, looked good, smelled normal and not very much stuff on my magnets. Drives have been repainted too. So........I think I'm probably OK. Thanks again.
