Lower unit bolts--thread locker vs. gasket sealant

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Ken O

New member
Time to replace the Honda BF90 impeller. Last time I just put Locktite blue on the bolts that attach the lower unit to the rest of the engine. So far I've only run the motor in fresh water, but there's salt water in the future. Several forums advocate some sort of gasket sealer on these bolts so they don't seize after sitting in salt water. The Honda manual specifies Locktite 271, which is the red stuff. Maybe the spec has changed, but I can't see using the permanent-need-a-torch-to-get-it-off stuff here.

My guess would be to go with Locktite blue again, but maybe there are better options. What has worked for people and what has not worked? Thanks!
 
Ken O,
I overhaul outboards for a hobby and have worked on every brand and size. I've got a least 10, that I am finishing up at this time.
After YEARS of failures and seeing corrosion from minor to major, my solution to ensuring that a fastener comes apart in the future is to use Tef-Gel on them. The stuff is expensive, but it really works and you only use small amounts. Tef-Gel forms a barrier, so that stainless to aluminum will not cause corrosion. Tef-Gel also prevent stainless steel fasteners from galling. With few exceptions, I use Tef-Gel on every fastener on outboards, trailers and most anything else that may see saltwater.
Additionally, larger surfaces, such as drive shafts, shift shafts, water pick up tube, prop shaft, etc, I coat with liberal amounts of Green Grease. Green Grease can be purchased at Napa or other auto stores. Green Grease is water proof and it is synthetic, so you can use it to coat your impeller before installing it, as well as use it to cover battery terminals, etc. Green Grease comes in a large grease gun size container, but it is very inexpensive.
 
Ken O":a5eaicub said:
Time to replace the Honda BF90 impeller. Last time I just put Locktite blue on the bolts that attach the lower unit to the rest of the engine. So far I've only run the motor in fresh water, but there's salt water in the future. Several forums advocate some sort of gasket sealer on these bolts so they don't seize after sitting in salt water. The Honda manual specifies Locktite 271, which is the red stuff. Maybe the spec has changed, but I can't see using the permanent-need-a-torch-to-get-it-off stuff here.

My guess would be to go with Locktite blue again, but maybe there are better options. What has worked for people and what has not worked? Thanks!
Click to expand...

IME, Locktite Red is not permanent. Might take a little more umph than Blue but not that much more. Maybe on small screws it is stronger, but nothing you can put a wrench on.
 
Thanks a bunch for the thoughts. I have both Tef Gel and waterproof marine grease. My Tohatsu 9.8 kicker manual specifies Tef Gel for certain inner parts. I've had the same little tube for several years, so the cost isn't an issue.
 
I've used red Locktite on my bikes for years so nothing would come apart. Which it did with blue Locktite. Never had a problem removing red coated screws; If you can get a wrench on them, they'll come out.

Boris
 
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