Engine mounts

[mireland]

After good advice previously on the forum I have decided to try and change my engine mounts. The engine is a Bukh 36 and I think I have discovered that I can buy the same ones as sold by Bukh from a firm called Robush online. The Bukh people are great but I just cannot manage the £180 for 4 mounts when Robush charge £11 + VAT each! Bukh however do sell them complete with shims and Robush do not. Does anyone know where I would get some appropriate shims? Could I reuse the old shims, assuming they are not rusted to hell and that the new mounts are identical to the originals, or is that cloud cuckoo land. Apologies for this lamentable display of ignorance but your advice much welcome.

 

[Mistroma]

Robush BUKH Mounts

I bought mounts for my BUKH DV20 some years ago from Robush. They were identical to the mounts on the engine, same design and part no. stamped on the metal. I had the boat for 23 years so and am pretty certain that the mount were original BUKH fittings.

So I was very happy to use thes in place of the "Original BUKH spares". Only differences were:
1) They were bare metal so I painted them red (what else)
2) They came without shims (I had some spare on the boat, probably from original set)
3) They came without locking tabs (I reused existing ones)
3) They came without bolts (CLeaned & re-used existing)

I checked recently for someone else with a DV20 and seem to remember BUKH set was around £180 for 4. I wouldn't hesitate to buy a set from Robush and wouldn't even consider "wasting" money on the originals.

Robush were very pleasant to deal with and I think that my mounts were more usually found on a small diesel generator at a building site.

Just check the numbers stamped on your existing mounts and if Robush can supply them they should be exactly the same part.

Let's you see how much the markup is on marine stuff vs. builder's kit.


PS Shims are just used for fine alignment. If you replace all 4 then you could assume that the heights will be close to where they once were if you re-fit the old shims (in exactly the same place). However, you should really check alignment in the water so might need more shims. Don't know where you'd get them but you could just cut a slot in a penny washer if you need a thick shim. Nothing particularly special about shims except the thickness.

I seem to remember that my alignment was spot on using the original shims. So the Robush mounts must have been identical to the originals when new.

 

[TNT]

Shimming

Re your shim question, you will be able to buy washers of varying thichnesses from most DIY stores that will do the job, the hole (slots are better as you can slide them in and out without having to loosen everything off again) diameter can be slightly larger as long as most of the weight is supported by the main width of the washer, for thinner ones go to the local fabrication shop and they will churn you quite a few off on a guillotine for pennies, or if you get a decent set of tin snips cut your own out, it does not matter if they are not pretty as long as they are functional.
Take your time with the allignment, check the two flanges at 90 degrees and rotate them regularly. Its worth the extra messing round to get it right

Most B+Q's or similar will have tin snips and some carry sheet steel, dont use alluminium or copper, it compresses and the copper will work harden making it brittle.

have fun.

 

[mireland]

Thanks very much to you both for your informative replies. I feel much much confident about it now.

 

[VicMallows]

I bought mounts for my BUKH DV20 some years ago from Robush.

That's very useful information. I have a BUKH 20 in a Sadler29. I am wondering if the mounts vary significantly according to application? I seem to recall that my front mounts are different from the rear.

Were ROBUSH able to identify the required mounts by engine/application .... or do they require the identification numbers off the old ones .... impossible until you remove them.

Vic

 

[Mistroma]

It was a while ago but I remember reading the part nos. off the top of the mounts. I don't remember any difference between flywheel and gearbox end wrt part no.

I suppose that's possible depending on position, angle etc. putting a heavier load on one pair.

I bought "RAB2 Mounts M12 55SH 10-00179-01" according to my invoice. I still have their paper based catalogue and it has lots of info on various types, grades etc. There are graphs showing:

1) Load (kg) vs. Natural frequency (Hz)
2) Load (kg) vs. Static deflection
3) Interfering freq. vs. Degree of isolation

You could probably ignore try to work out load on each mount etc. However, I doubt they'd be likely to be so different you'd need 2 types of mount.

According to cat. RAB gives optimum stiffness & horiz. stability (due to shear & compression characteristics). Especially effective on small 1,2 & 3 cyl. diesels.

Load rating seems wide at 10-130 kg with max static deflection only 3.5mm.
Type Max. Load (kg)
RAB-0 130
RAB-2 105
RAB-3 70

So if your mounts look the same then they'll probably be RA, RAEM or RAB
RA & RAEM seem to be for much larger loads 2.1T & 3.4T
So that means you are probably looking at RAB-2 (which is what I bought).

I think the BUKH was around 220 kgs (from memory). I guess that makes RAB-0 look a bit overkill.

 

[Mistroma]

UPDATE: I looked at my records again and found I'd bought 2 lots (2 and then 4) and now remember keeping 2 from last order as spares. I had problems with fuel leak on one side and ordered extra mounts in case the problem returned and softened the mounts again.

Unfortunately, I only have detailed records for last purchase (I had the boat for over 23 years).

I had a quick look around on Web and DV20 mounts can be bought as sets.
£120 http://www.boatpartsandspares.co.uk/bukh-engine-mounts-1865-p.asp

Look closely at expanded picture and you can see that it is a set of 2 RAB-2 mounts and 2 RAB-0 mounts

OR £205.08 http://www.tnorrismarine.co.uk/spares.php

The sets come with shims, lock tabs & bolts but I'd prefer to pay Robush £66.82 for 2 x RAB-0 & 2 x RAB-2. Bolts, lock tabs & shims don't come to £140 and are pretty easy to get (probably just reuse old ones).

Suggest that you still try to read part nos. from your mounts to be very safe just in case you have a very non-standard set-up.

 

[VicMallows]

Mistroma,

Many thanks for your detailed reply. Printed out and stuck in the workshop manual so I can find it when needed!

Vic

 

[RobBrown]

Info?

Just came across this post via the current Bukh DV20 thread. Very useful info for me as it happens as I am looking to put my recon Bukh 20DV back into my boat next week and am taking the opportunity of putting in new engine mounts. I also bought a set from boatpartsandspares. I hadn't realised they were 2 different pairs until I read this thread and having checked, confirmed I have the RAB 0 & RAB 2 sets. But I have already taken the old mounts off and don't know which goes where!! On basis of the info that the RAB 0 takes a max 130kg load and RAB 2 105kg, I would guess that the RAB 0 pair should be @ the heavier end, so I would infer the flywheel end. Anyone know for sure?

 

[VicMallows]

Just checked the original BUKH instruction sheet for my (BUKH20) mounts:

" two mounts are silver colour, two are gold. The silver mounts go at the front (flywheel) end "

Not very helpful if the new mounts are not similarly coloured

If you have not done so already, I suggest a PM to MISTROMA. Having recently done the job I'm sure he will remember which ones go where.

Do please post the eventual answer for the RAB0/RAB2 mounts here.

Vic

 

[RobBrown]

Thanks Vic. Unfortunately, as per the photo in the boatparts link, all 4 are the same chrome colour! Just the type nos on the top distinguish them. As you suggest, I will try Mistroma by PM.

 

[RobBrown]

From the Horse's mouth

Mistroma was unable to give definitive info, so I phoned Al Pearson at Bukh UK today. He says the set is not really intended for the Bukh 20, but for the Bukh 36, a much heavier engine. They now supply four identical RAB 2s for the DV20, tho 20 years ago, they were supplied in different coloured pairs with slightly different load ratings. The RAB 0 s were definitely overspecced, but would be OK. He said bette rto put them at the flywheel end, as the heavier.

 

[VicMallows]

Thanks for posting the update. All noted for when/if needed.

Vic

 

[Mistroma]

Glad you did get an answer. As I said in pm, it was over 5 years since I changed the last 2 mounts and couldn't remember which ones had gone where.

I also remembered seeing a comment a few years ago to the effect that Bukh sold shims, tabs and bolts as as sep. kit for around £18. That isn't too expensive for 4 bolts, lock tabs and shims and makes the mounting kit price look even more ludicrous.

4 x mounts with bolts, shims etc. £171.50 + VAT

OR
Bolts shims etc. £18
4 x mounts £55.68 +VAT

Hmmm difficult choice (NOT). Though I haven't checked price & availability of the bolts & shims.

 

[LittleShip]

This company are very helpful and will speak to you via phone to give advice.....

http://www.randdmarine.co.uk/downloads/RandD_Engine.pdf

Tom

 

[mireland]

Just checked the original BUKH instruction sheet for my (BUKH20) mounts:

" two mounts are silver colour, two are gold. The silver mounts go at the front (flywheel) end "

Not very helpful if the new mounts are not similarly coloured

If you have not done so already, I suggest a PM to MISTROMA. Having recently done the job I'm sure he will remember which ones go where.

Do please post the eventual answer for the RAB0/RAB2 mounts here.

Vic

Job now done. Bought mounts from Robush.uk.

RAB 0 go at front end - designed for the extra weight there (130Kg)
RAB 2 go at the rear end - less weight (105Kg)

It was a real fiddle faddle with a car jack and blocks of wood and bent double in a confined space and although I did one at a time it was not easy realigning the engine to centre the prop shaft in the stern tube. Good result though I think. Will report again when on the water and engine running!

Thanks to all for advice and encouragement.

 

[LittleShip]

Check your alignment once you are floating.......... It shouldnt be done when out of the water.

Tom

 

[VicMallows]

RAB-2 Price Update

For the benefit of anyone coming across this thread in the future, I have just (June 2012) bought 4 RAB-2 mounts from ROBUSH

Current price is £18.68 each +VAT. Bottom line cost with VAT and carriage for four £104.06, and arrived next day.

Their 'online shop' does not appear to be maintained or functional, but very efficient service over the phone. (01473738569).

 

[Heckler]

That's very useful information. I have a BUKH 20 in a Sadler29. I am wondering if the mounts vary significantly according to application? I seem to recall that my front mounts are different from the rear.

Were ROBUSH able to identify the required mounts by engine/application .... or do they require the identification numbers off the old ones .... impossible until you remove them.

Vic

I bought my MD22 ones off robush, the important thing is to check the hardness numbers, for example the vp ones had 45 stamped on them, this is the shore hardness number. For info the d55 vp engine uses the same ones. Robush wont know which of their products are used for what application, but all you have to do is browse their website, choose the shape etc and then use the scale drawings to check the bolt hole dimensions etc. Then use the shore hardness number off your old one to match it up
Stu

 

[brianday]

Replacing Bukh 20 engine mounts - updated info

Lots of useful info in this thread - I am re-installing a Bukh 20 in my Rival 34 and wanted to replace the engine mounts since they looked worn out

I have double checked most of the above info and come up with the following conclusions

several firms offer the official Bukh mounts including bolts,shims and washers

www.tnorrismarine.co.uk £171.50 plus VAT plus PP
www.twmarine.co.uk £153.26 plus VAT plus PP = £183.90 plus £12
www.frenchmarine.com £153.26 plus VAT plus PP

a special offer was available from
http://www.boatpartsandspares.co.uk for £120 but they are out of stock with no forecast of any change

as several have said you can get just the mounts from Robush - they are UK agents for www.trelleborg.com/en/ who are the manufacturers in sweden

www.robush.co.uk are very helpful and can supply the RAB- 2 mounts
a quick chat with becky becky@robush.co.uk got a special offer of £78.44 for 4 mounts and VAT and standard post included (£5)
this is about £20 below their list - they are happy to accept other orders at this price

I think it possible to get the Bukh shim kit for around £20 - awaiting quote

there are several other suppliers of anti vib mounts that may be cheaper where you have full design control

www.randdmarine.com
www.avindustrialproducts.co.uk

the latter advertise on ebay and have similar mounts for £13.99 and £4.99
the Bukh mounts are very low at just 30mm, randd mounts are 42mm or more

some mounts use height adjusters - these look easy to use but are designed for stationary use as holding the engine up in the air by 20mm or so could experience huge stresses when a boat is pounding through waves while supporting a 220Kg engine

the av sell 12mm height adjusters for £3.99
Robush do Height adjusters for £6.15 plus VAT

many thanks for all the leads
Brian