I've had the motor out to check installation after 18 years and sure enough the rear engine mounts are 80% 'devulcanised'.

is there a source of cheaper engine mounts than the genuine (win the lottery to afford them) Volvo engine mounts?

These people are great to deal with & a great Ozzie product:

polyflex.com.au

I recently purchased 4 mounts + a coupler.

Polyflex and Isoflex come immediately to mind - could be worth contacting them.

polyflex.com.au/marine-engine-mounts/search?filter_name=

isoflex.com.au/products/engine-mounts/?gclid=EAIaIQobChMI1eHe_9ai7wIVN51LBR3ahQ1kEAMYASAAEgInZ_D_BwE

Also Headland;

headlandengineering.com.au/our-products/randmarine/

You need the replacement mounts to be equivalent in stiffness, damping and load capacity to the originals so as to not muck up the support and vibration isolation dynamics of the whole assembly. Expect the forward mounts are also needing to be renewed?.

Select to expand quote

r13 said..
Polyflex and Isoflex come immediately to mind - could be worth contacting them.

polyflex.com.au/marine-engine-mounts/search?filter_name=

isoflex.com.au/products/engine-mounts/?gclid=EAIaIQobChMI1eHe_9ai7wIVN51LBR3ahQ1kEAMYASAAEgInZ_D_BwE

Also Headland;

headlandengineering.com.au/our-products/randmarine/

You need the replacement mounts to be equivalent in stiffness, damping and load capacity to the originals so as to not muck up the support and vibration isolation dynamics of the whole assembly. Expect the forward mounts are also needing to be renewed?.

I don't think so... they look more substantial and it's the back end that jumps around the most. The rear mounts haven't actually failed and maybe I'm exaggerating with "80%"...

I'll price it up though and decide!

Thanks for the advice; all. !

I agree with Lazz and R13 give Polyflex and Isoflex a call.

In 2019 i purchased the equivalent Bukh mounts from Isoflex for $245 vs $700+ from Bukh Aust

I would also recommend you replace all the mounts at the same time.

Ok if it's the rear end that jumps around the most assume you have checked all other possibilities for this result - ie as inferred above coupling damage, also alignment, unbalance somewhere in the drive train including coupling or prop, bent shaft, wear in any bearings, loose bolts, structural deterioration and weakness in bedplate structure and fastenings including holding the mounts, p bracket damage, loose shaft anodes, other. The industry standard for renewal of rotating machinery mechanical components (mounts, couplings, bearings, other) is 12 years. Boat engines don't get utilised as much as the typical rotating machine in a processing plant but at times they are under more adverse conditions.

I found the poly flex mounts recommended for my Yanmar are too soft and the yellow core material seemed to disintegrate in no time. I replaced the yellow cores with harder green cores which seem to be lasting better but vibration is worse.
The whole set up in my boat is wrong in the fact I have a soft mounted motor floating around on a rigid Shaft.
I should just make some solid mounts like these ones that I made for another boat.

by 'Jumping around' I just mean that the soft mounts seem to allow that when going in and out of gear and that this must put a strain on them. It runs true in gear. I've gone below and put a stick against shaft when in gear and it's not wobbling.
The mounts are 18 years old. When I originally installed the motor I reinstalled/glassed the p bracket in. 3 years ago I put a new shaft and cutlass bearing in and checked alignment.

I think the reason for the mounts starting to part is simply age but I will be checking alignment and whether the shaft is still true. I wrapped a line around the prop a few years back so I'll be checking that.

I really appreciate everyone's input here. When you're down under the cockpit pulling it all apart you feel like Robinson Crusoe.

I bought the genuine. $980 approx. They were on the shelf and saved time compared to measuring up and ordering after market ones and waiting.

you don't get a full engine mount though so I have a question:

Are any engine parts plated? Ie if they are I'll just go with a wire brush primer and Volvo paint

if not I'll take a grinder to them...