Easiest way to change engine mounts

[a64pilot]

Nothing is rotted. Mounts look like they are original and that makes them 29 yrs old, they deserve retirement is all.
My lag bolts, have machine threads, 3/8 I believe. I'm sure there is a threaded insert in the solid glass stringers, so far bolts have come loose easily with no hint of corrosion.
I'm going to try the soccer ball idea.


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[daletournier]

Some mention supporting engine under oil pan....isn't there a concern of bending the pan? I'm doing my 3gm30f sometime this year , so I'm interested.

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[JPA Cate]

The beauty of using the basketball idea is that it will evenly spread the load over the area of the bottom of the pan.

[daletournier]

Originally Posted by daletournier

Some mention supporting engine under oil pan....isn't there a concern of bending the pan? I'm doing my 3gm30f sometime this year , so I'm interested.

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Ummm. ....still not convinced. I've never changed engine mounts on a boat, but I was a motor mechanic in my 20 's. You could be right but it makes me a little nervous. I'd like to support the engine from the top if possible , mine being a mid mount engine makes using the boom difficult. Anyway , good discussion.

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[a64pilot]

My only concern is for the thickness and of course the strength of the pan under the engine, this pan of course exists only to catch spills, and there is no reason for it to very robust, so I'll try to keep an eye on it for deflection and listen for cracking of course.
Normally I wouldn't lift from the engine pan either as they are usually just stamped thin sheet, but as you say the ball ought to do a good job of spreading the load.
I don't see what this won't work, did I just jinx it?


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[a64pilot]

I'm going to guess a 4-JHE ought to weigh 500 lbs, maybe a little more? Just a guess though.
Now I'm no good at math so check me, but if you assume a flattened Soccer ball will cover a half a square ft, that still 72 square inches.
500 divided by 72 is 6.9. If so then ignoring the stiffness of the ball, then just a tiny bit shy of 7 PSI should support the engine, that of course means 7 PSI on the oil pan too.
Even if the ball is only 50 square inches, it's still only 10 PSI.


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[Tayana42]

a64pilot, if you have a basketball available it is a bit large than a soccer ball. Circumference of about 30 inches compared to 26.5 inches.


S/V B'Shert

[Nicholson58]

Originally Posted by a64pilot

I assume pry the engine up one side at a time with a 2x4?
Lifting would be difficult without removing the top portion of the enclosure.
Jacking, well maybe with a porta power, which I don't have.
4JHE in an IP38, any tricks I need to be aware of? things to be careful of?

rent a port-a-power or get one from Harbor Freight. There are also wedge blocks that consist of two wedges and a connecting bolt that draws them together, making it a small jack. Can you rig a 4 x 4 over the companion way and use a block & tackle?

[Paul L]

a64
Are you aware that the mounts on the 4jh differ for the left side versus the right?

[unclemack]

Might a fender fit better than a ball and be tougher if you're doing it that way?
Portapower's v-shaped ram is called a spreader ram, only ever used them as a last resort because they slip when the angle changes.

I've managed before by just tilting even much bigger engines sideways by pulling/pushing on the upper block - not the rocker cover or head - replacing two mounts one side then doing the other side.

Never worked on your engine but going from photos it looks like removing the four bolts that fix each mounting bracket to the block might be easiest.
One bracket at a time, should only need to lift that corner half an inch or so.

[Paul L]

Easystow inflatable fenders (Easystow Fenders) are good to have onboard and they show pic of engine being rasied with one:

[Sandero]

I couldn't get a mechanic to replace mine on a MD17D so I did it myself... Your engine is likely not the same but here is what I did. Hoisting the engine is not necessary.

1. You change one mount at a time... hopefully with ones that use the same mounting holes and bolts. You have to unbolt the coupling to the shaft first. TAKE PHOTOS AND MEASUREMENTS. LOTS. You'll have to remove stuff to get at the mounts...

2. The engine is connected to the mounts by heavy brackets which are bolted to the sides of the engine. To change a mount.. wedge some wood under the engine where you are going to remove the mount. You have to unbolt the bracket from the engine.. then remove the large adjustment nuts on the top of the mount and lift the bracket off leaving the mount bolted to the stringer... the engine is resting on 3 mounts. The pan is lighter gauge metal but but can support the weight. Blocking should be reasonably large to spread the load.

3. Install the new mount to the stringer (after cleaning / prep etc.). The ht adjustment is done by raising the bottom nut which the bracket rests on... then tightening with the lock washers and top nut or nuts. With the new mount installed to the stringer... drop the bracket onto the bolt... adjust the nuts so the bolts of / for the bracket to the engine align. Insert all bolts and torque them down to the engine. You'll want a hefty wrench with perhaps a pipe extension for added leverage to torque them.

3. raise the lower nut on the mount until it comes up to the bracket. This is a rough position. Do not tighten the top nut.

4. Now repeat this for the remaining 3 mounts.

5. Assuming that your engine has moved somewhat for various reasons... you next have align the engine coupling. Rotate the prop side of the coupling to align the bolt holes. You should be able to get one to align...at least. If the don't you have to raise the bottom nuts on the mounts. Once you get it reasonably aligned you can install the remaining 3 bolts.

6. Alignment is done with a feeler gauge inserted between the coupling plates. You raise or lower the mounts to get the plates parallel... same gap with feller gauge at each bolt. You might need to lever the engine up with a crow bar hand turning the lower nut if turning the lower nuts takes too long with a wrench. Usually you can't turn the nuts very much because of little clearance. The alignment takes time and is important. If it's not well aligned you will have vibration and probably leaking from the dripless shaft seal... which requires alignment and proper pressure at the bellows.

This project takes some time... but is low tech and all you need are some bits of wood to shim/hold the engine... a large wrecking bar to lever the engine. the correct wrenches and a pipe extension to get more torque, feeler gauges, a camera and patience.

For some mounts you can assemble the mount without having to remove the bracket by sliding the mount in place and inserts the alignment bolt thru the bracket through the nuts below. Note that this bolt has a square top to tighten it in place.

If I could do this on a mooring... you can!

[Sandero]

You may have to "twist" the engine to get the couple plates to perfectly align. The mounts will have at least one slotted hole so it can be rotated.

The alignment can be tricky especially if you have removed all the mounts and have the engine suspended or resting on a soccer ball.

The method I described above essentially gets the engine back where it was... BECAUSE YOU NEVER ACTUALLY MOVE IT VERY MUCH. This saves you lots of headaches and alignment problems.

When changing one mount at a time... the remain 3 can EASILY support the engine... but as mounts are "soft" it WILL drop a bit hence the blocking/shims. Also couple alignment is a much simpler process since the engine is basically in the same place... with only new mounts.

I can't say the system I used will work for every motor installation. It worked for mine and I don't see why others would not be similar enough for this system to work.

If you don't HAVE TO suspend the motor.... or support it on soccer balls... then the method described is the way to go... actually easy peasy just takes time and the right tools.

[a64pilot]

Originally Posted by Paul L

a64
Are you aware that the mounts on the 4jh differ for the left side versus the right?

Yes, I have 200's I believe for the starter side (left), Port. and 150's for the other side.
I don't know why they are different though, perhaps it's just the weight of the starter?

Thanks.

[a64pilot]

Sandero thanks, but a reason for doing this is I have a driveline vibration. Last haul out I paid for the shaft to be removed and checked for pitting and straightness and new Cutlass bearing and of course engine alignment. Above 2300 for any length of time and she gets into a self excited vibration, that very quickly has you reduce throttle.
Vibration remains unchanged, I have either a bent shaft, or an engine alignment issue. Same vibe with two different props. I do not believe they checked and adjusted engine alignment, of course I'd rather it be alignment. Here is hoping.
I'll measure the threads showing on the old mounts with my Caliper and set the new bottom nuts to that measurement, that ought to get me close. Except for access maybe, it doesn't sound like alignment is that hard to adjust.

I want to try the soccer ball / fender as well, it sounds like a good trick to have available.