Lower Unit bolts

[Kirk Gibson]

OK Im on my second change of the water pump assemblies on my 2008 & 2010 F150s.
The first go around a three years ago (I am primarily salt usage) I used a white sweet smelling compound on the lower unit bolts and water pump housing bolts like the book said.
Well today I started on the port engine and when I went to take out the bolt for the anode at the rear it became very hard and I knew it was screwing up the threads in the anode. (but it needs replacing anyway) so after I got it out I am now working on the pump etc.
My question is since I run primarily in salt wouldn't be just as well to use a light coating of grease on the lower unit bolts? I think "red & tacky" grease might work just as well and make it easier next time. Lithium based.

[fairdeal]

I used a white sweet smelling compound on the lower unit bolts and water pump housing bolts like the book said.

was that Loctite 572? never used/smelled it

on bolts that I don't plan to ever remove - but might need to -
I use white PTFE pipe thread compound - Permatex, Ace etc

on the LU bolts, Mercury 2-4-C grease - because I bought a big tube years ago.
I think any good water-resistant grease would be fine - for my use.

But I wouldn't go three years witout removing the LU....

[pstephens46]

I take my F150 lower unit off every year to grease splines and the shaft bushing. I always use a small amount of marine grease on the bolt threads. Even though the manual doesn't specify it. Is lithium marine grease or is it waterproof?

If you are in Roanoke, VA, where is the boat?

[TownsendsFJR1300]

Just did my F150 WP in Feb.

Per RB, for salt water use, do not use any loctite on them (for the housing)- (Loctite 572 IS recommended in the manual).

I assembled mine dry, thread holes cleaned, new bolts(kit).

I don't wait generally for more than two years (and that's with flushing-even thru the small black rubber plug atop the LU)

There's no torque spec's, just good and snug.. They came out W/O an issue

The MT that did it before, didn't appear to have used anything either.

The LU itself, I put just a touch of the Yamaha waterproof grease (also used on the splines/bushing)..
The manual again calls for Loctite on the LU bolts...


Perhaps if used religiously in fresh water and changed yearly, you might need the Loctite..





.

[Kirk Gibson]

Thanks

Yes, I think it was the locktite I used before. (although I can't find any in my shop...maybe I used it all last time) The bolts came out ok except for the anode bolt which I really don't know if the locktite caused that or not. Doesn't matter because I will be putting on a new anode anyway. I have a tube of 2-4-C also (from my other past boats/sterndrives) and I will just go that way on the LU bolts. I generally tow this boat to NC a couple times a year and spend a couple of weeks each time and then a time or two a year at a local lake. But most of it's time is in salt.
Last time I changed the water pumps the old ones looked like new and today I only pulled the port LU so far and pulled the pump.
Looks like when I put it in, but no need to take chances. I rinse these babys like crazy every time I come back in so that helps I know.
Thanks for the input guys.
Kirk

[TownsendsFJR1300]

Just a side note.

Make sure you pull the wear plate and inspect to see if the drive-shaft SEAL SPRING is still there.

They don't last much more than 5 years (the tiny spring goes away). Mine was gone about 3 years ago and I had that MT replace those seals (I'll do them myself next time). I didn't have any water intrusion but definitely at least peek at them.

It's been discussed that when doing a pressure test on the LU (for leaks), if just the spring was missing, simply replace the spring (from a new seal) and re-test.

[Kirk Gibson]

Thanks

Yeah, always replace the wear plate with the wp job and inspect under it.
Seal nice and clean and tight.
Thanks for the reminder.

[Kirk Gibson]

Double checked

After reading your reply I decided I was going to actually put eyes on the spring. I went back out to the garage and pulled the seal cover and spring looks real nice and clean all the way around. I think if that spring goes one could replace it with a spring out of a new seal ...just to save some work. But now I have the piece of mind that the spring is there. Will do that from now on instead of just thinking it is good because it is clean etc. The cover came up easy, I guess it's held down only by the wear plate correct?
Thanks for the great tip.
At 62 now and not a day goes by I don't learn something.
Always willing to learn.

[JerEazy1]

Fwiw - I'll try and find the article - but don't use loctite on LU bolts or really any bolts under the waterline because it has some metal particulates in it that actually could speed corrosion on the threads and bolts. Instead us Marine Gasket Sealer on them. It's made for marine use, will maintain a water-tight seal and help avoid corrosion.

[pstephens46]

I'm going to skip the sealers. Little grease and a torque wrench.
Lower unit bolts come off with a 3/8"drive, no problem.
Guess you could replace lock washers at some point if you are concerned with things coming loose.

[99yam40]

Fwiw - I'll try and find the article - but don't use loctite on LU bolts or really any bolts under the waterline because it has some metal particulates in it that actually could speed corrosion on the threads and bolts. Instead us Marine Gasket Sealer on them. It's made for marine use, will maintain a water-tight seal and help avoid corrosion.

never seen loctite with metal in it.
maybe you are thinking of neverseze

[JerEazy1]

never seen loctite with metal in it.
maybe you are thinking of neverseze

maybe that is it - my mistake.

Regardless, the OMC shop manual says to use Gasket Sealer and although I don't have a Yamaha Manual, I would guess they would say to use Yamabond 4 ( https://www.amazon.com/Yamalube-Yama.../dp/B00545V1ZE )

But it's all the same thing.

The point would be that it's not to hold the threads as it's more to keep the water from penetrating. Grease would work, but that just tweaks me a bit because grease makes things slippery. Things that are slippery have a the possibility of slipping. Gasket sealer is tacky (like loctite) and never fully "dries" (like grease). So to me it's the best of both worlds.

[99yam40]

many years ago I would use high temp silicone gasket maker on lower unit bolt threads to keep the water and corrosion out.
it did that for me but was a pain to clean up the holes after taking apart again.
I am sure grease works well and easy to clean up.
Never heard of the bolts backing out, but could happen I guess

[TownsendsFJR1300]

Good idea ^^ using the Yamabond.

For a threaded bolt, MOST of it is squeezed out
and it's pretty easy to clean up when pulled apart...


Keeps water out, doesn't lock the threads and easy to work with...

Those bolts torqued down, are NOT going anywhere...

I use it on the oil drain plug on my motorcycle.

[JerEazy1]

many years ago I would use high temp silicone gasket maker on lower unit bolt threads to keep the water and corrosion out.
it did that for me but was a pain to clean up the holes after taking apart again.
I am sure grease works well and easy to clean up.
Never heard of the bolts backing out, but could happen I guess

Never heard of them backing out either - and there's obviously plenty of bolts holding it on. But I don't want to be the first guy either haha

speaking of which - and not to hijack or change the subject - what is the torque spec on the lower unit bolts?