Replace engine mounts

[esarratt]

I have an old MD7a; it has the original engine mounts.

I am removing the engine to do some work on it.

Should I replace the engine mounts while I have it out?

The boat is an 81'.

[kayakerChuck]

YES!!

[esarratt]

1) Nigel Calder he notes "some engines have adjustable feet which greatly simplifies things" (pg 240, Marine Diesel Engines).

I don't think I have adjustable engine feet (mounts). Can I install these?

2) Again he notes, "Almost all engines today are mounted with flexible feet and couplings." (pg 238)

Any problem with me installing flexible feet?

Flexible couplings for the shaft?

[esarratt]

It seems like Nigel Calder or Don Casey recommended some type of really nice engine mount.



Anyone know what I am referring to? They said they were the ones to get.

[deblen]

You already have rubber mounted adjustable engine mounts.
The threaded stud sticking out of the top of each mount allows you to raise/lower each corner(4) of the engine vertically.
I doubt if the mounts have slotted mounting holes where they bolt to the boat.
When you remove the engine,I suggest you un-bolt the mounts from hull,so that they will come with engine. Mark the fiberglass bed around each mount first.
https://marinehowto.com/replacing-motor-mounts/


Plug your ears!


Cheers/Len

https://www.youtube.com/watch?v=vtiKvR3wc7s

[deblen]

You already have rubber mounted adjustable engine mounts.
The threaded stud sticking out of the top of each mount allows you to raise/lower each corner(4) of the engine vertically.
I doubt if the mounts have slotted mounting holes where they bolt to the boat.
When you remove the engine,I suggest you un-bolt the mounts from hull,so that they will come with engine. Mark the fiberglass bed around each mount first.
https://marinehowto.com/replacing-motor-mounts/
Cheers/Len

[esarratt]

Originally Posted by deblen

I doubt if the mounts have slotted mounting holes where they bolt to the boat.

If the mount doesn't have a slot, couldn't I just take it to a machine shop and have them slot one of the holes?

[grantmc]

Simple answer yes replace.
The rubber degrades over time and those mounts have done a some heavy lifting. And a new set of mounts is only a couple of hundred dollars
https://ab-marineservice.com/en/prod...vo-penta-md7a/

I recall wondering the same of my own mounts when I replaced an engine 15 years back. With the engine out the mounts looked so so, but then I unbolted one from its bearer it virtually fell to pieces, so rusty and munted.

Also a good chance to check the bearers, give the entire engine bay a good clean and perhaps paint too where appropriate.

[deblen]

Originally Posted by esarratt

If the mount doesn't have a slot, couldn't I just take it to a machine shop and have them slot one of the holes?

Personally,I wouldn't change holes in new mounts.
New mounts may have slots for their rear bolts,to allow for some side to side adjusting.
I would be leery of having any slotting fore and aft.The full thrust of the prop pushing the boat forward/backwards is transmitted thru those 4 mounts to the hull.

When you re-install the engine,the first step,before permanently bolting the mounts to the hull,is to align the engine coupling to shaft coupling side to side and fore/aft. Then,plug old holes,if un-usable,and drill new.
After bolting to hull, fine tune the up/down with the vertically adjustable mount studs.Make sure the mount brackets are sitting down tightly on all 4 lower nuts & lock/double nut, so the lower nuts can never move.Then tighten the upper nuts.

Re-mounting an engine,after mount change is quite technical & requires patience/perfection to do correctly.
Cheers/Len

[skipperpete]

The replacement cores are €50 each and the complete assemblies are about €150-170 each, I’d wait until the engine is out and you can dismantle the mounts to decide if the base plates are still in serviceable condition, if so just wire brush em, hit em with a bit of rust converter and a coat of paint , screw on the new cores and you’re good to go.

[esarratt]

Originally Posted by grantmc

Simple answer yes replace.
With the engine out the mounts looked so so, but then I unbolted one from its bearer it virtually fell to pieces, so rusty and munted.

I looked at them closely this weekend. The front mounts are in pretty good shape, but the rear ones (toward the propeller) are badly rusted.

[Knotical]

Check out PYI, I replaced mine with theirs and they are much better than the OEMs I had.