Removing Tilt Tube, 1985 Johnson 90-HP

[Kolbert]

I have purchased a new tilt tube, and I am now trying to replace the original tilt tube on my 1985 Johnson 90-HP outboard engine on my 17-footer. This narrative will describe my efforts.

The nut on the Port end has sheared off as shown in Fig. 1. below. The tube was steel, not stainless, and had rust on both the Port and Starboard ends.

I put the engine on a hoist from the ceiling to take some of the pressure off the pivot. I sprayed some PB-Blaster on both ends to free up what I could. I was able to get the Starboard side to rotate some. After working it to the point that it was turning well, I had to try and move it out of the slot. I used a wedge to get some space and it moved out a little, but then the bolt and exposed tube sheared off.

Fig. 1. Tilt-tube end with nut sheared off.

TiltTubeNut_.jpg (72 KiB) Viewed 14947 times

Next, I carefully used some heat on both ends to work in some more PB Blaster. Had a 1-inch solid rod and tried to drive out the tube from either end--but nothing [moved].

Fig. 2. The reluctant tilt-tube.

TiltTube_.jpg (75.42 KiB) Viewed 14946 times

My plans for the next approach to removing the old tilt-tube:

1. drill out the tilt tube, at the risk drilling off-center or enlarging the hole so there would be play in the bracket;
2. use a cut-off wheel on the center of the tube to cut it in half, then use a sledge to drive it from the center out;
3. use a SawzAll tool between the outer and inner bracket (the one with the grease nipple) to separate the engine bracket from the outer bracket, and then beat out the inner part of the tube; for the outer part it could be then either driven out, drilled out, or picked-out the rusted remainder of the tube.

Suggest better ideas for removing the original tilt tube.

[jimh]

You will need to be careful when trying to drive out the tilt tube. When you do succeed, the engine will need to be in a stabilized position so it does not suddenly shift position.

Your situation reminds me of an old joke:

Q: How many therapists does it take to change a lightbulb?

A: It only takes one, but the light bulb has to really want to change.

The analogy to the tilt tube is that you can get the tube out of the engine bracket casting, but you have to really want to get it out.

It might be easier to work on removal of the stuck tilt-tube if you removed the engine from the transom. With the engine not sitting on a fiberglass boat, you could use a torch and apply heat to the tilt tube and the casting. I would be very afraid to use a torch to heat the engine tilt tube area while on the fiberglass boat, as the heat from the torch could easily damage the hull. If you do want to work on the tilt tube while the engine is still on the boat, you need to get some thermal blankets that are used in welding to protect the hull from the heat of the torch. Even then, the heat needs to be used prudently so you don't melt the hull or even worse start a fire.

Also, I think your idea of cutting off most of the tilt tube in the middle between the two end bores may make removal easier, as you can work on one side at a time, independently. Using a solid steel round of a diameter just smaller than the bore of the cast housing, you should be able to drive out the stuck tilt tube, after using a lot of penetrant fluid and heat.

[fno]

My bit of advice is to hold off on the destructive methods you suggested and to obtain and apply liberal amounts of a product called Kroil. It was developed for aircraft repair originally but has been adopted by many other applications. PB Blaster has itss merits for many things but Kroil is the real deal and in regular use by our military mechanics. It's available on Amazon and also McMaster-Carr has it. Not cheap but well worth it when you save valuable components.

One word of advice, regardless of the penetrating oil choice, use direct or indirect tapping (not striking) with a hammer in safe place to help the penetrating oil penetrate. It does not penetrate by itself and time is a virtue. Leave it on there overnight if you can, whacking it a few times and then a few times more in the morning after. I have removed or unstuck everything from a 4-32 screw to 1-1/2-inch-diameter Allen cap screws rusted in place for ten years.

As for your suggested methods, forget #1. You will just hurt yourself and mess up the motor. #2 might work if there is clearance between the brackets. #3 is a non starter as well. There are very few things that I took a Sawzall to that were usable afterwards.

One last piece of advice is to seek out a friend or business with a suitable press to do the pushing. A good hydraulic or mechanical press makes hammers, cut off wheels and Sawzalls look like Neanderthal tools in my book.

Reach out via private message if you want further advice.

[Jefecinco]

Consider using a brass drift pin to drive out the tilt tube pin. It transmits force very well without damaging any harder metal parts it may come into contact with.

As fno wrote, a hydraulic press is a marvelous device when properly used.

[msteinkampf]

I am following this discussion with interest because one of the swivel tube nuts is seized on my 1991 Mercury 90 HP outboard, and I see a similar project in my future.

I would not discard the option of drilling out the swivel tube just yet. Your tube probably has an outside diameter of one inch, an inside diameter of 3/4 of an inch (or less), and a length of about 12 inches. If you can drill out the tube with a drill bit slightly larger than the inner diameter of the tube, you can significantly decrease the holding power of the corrosion and allow the tube to be driven out with your one-inch punch. The tube itself will guide your drill bit and minimize the risk of damage to the bracket. In your case, starting with a bit just larger than the diameter of the steering rod and moving up in increments to a bit just smaller than the outer diameter of the swivel tube might allow a one-inch punch to move the tube. I have successfully used this technique in the past with metal sleeves. Of course, you do want the motor supported during this process, and varying the amount of upward force on the unit may reveal a "sweet spot" that allows the tube to move more easily.

M

[Kolbert]

Thanks msteinkampf [for the suggestion of using a drill to increase the ID of the tilt tube to weaken its adhesion to the engine tilt bracket]. Your method of [increasing the inside diameter in steps] looks logical.

I was looking for larger drills up to 1-inch diameter, but and most were the extra long length. Long drills would not give enough space for a cordless drill motor and the long drill. I will have to look at some other purchase options for the drills.

During my initial attempt, I had the motor supported by a come-along cable attached to the ceiling. I used the same setup when I fully removed the engine to drill new bottom holes and move the engine up 2. Using the skeg support and front trailer adjust jack might give better control over the force being exerted on the tube. Would still have the ceiling cable as a backup.

[msteinkampf]

Varying the amount of support using the trailer jack is a good idea. You can look at the engine swivel tube to see when you are fully supporting the weight of the engine, but not pulling up on the bracket. See my post here for details:

Installing an Atlas Micro Jacker Hydraulic Jack Plate on a MONTAUK 17
https://continuouswave.com/forum/viewtopic.php?f=6&t=7564&p=45599#p44088

M

[jimh]

ASIDE to msteinkampf; many thanks--again--for your extraordinarily comprehensive article on the details of your 90-HP engine mounting change.