Is it powerfull enought to remove Bukh flywheel

[Poignard]

If, last time the flywheel was fitted, a thread lock compound was used on the bolt threads, is there any reason to think any more force will be needed to undo them than if they were fitted yesterday?

 

[Charlie Boy]

Threadlock comes in different grades
Low purple
Med blue
High red

Hope I’m not teaching anyone how to suck eggs

 

[Poignard]

Threadlock comes in different grades
Low purple
Med blue
High red

Hope I’m not teaching anyone how to suck eggs

Not at all.

There is no reason for the flywheel bolts to have been fitted using an uneccessarily strong grade of threadlock. When I took the flywheel off my BUKH engine for the first time in its life after 15 years. The bolts unscrewed without needing anything other than a hand tool. When reassembling I used Loctite Blue - medium grade.

Here, by the way, is an extract from my copy of the BUKH Workshop manual:

 

[Bilgediver]

the flywheel should have been torqued on; 4-4.5kgm (28.9-32.5 ft.lbf) and thread lock used. Those figures are lifted from the manual.
It may be that a serious thread lock has been used in which case you may need to heat the head of the bolt gently before undoing.
You can purchase a hex key fitting for a torque wrench, looks just like a normal socket fitting but with a hex key tip

Failure to follow these instructions on reassembly may result in the flywheel coming free when running. This happened on a boat at our marina but fortunately the flywheel came to rest sitting on the engine bearers.

 

[Charlie Boy]

Failure to follow these instructions on reassembly may result in the flywheel coming free when running. This happened on a boat at our marina but fortunately the flywheel came to rest sitting on the engine bearers.

It’s a serious lump to have whizzing around the saloon.
Years ago, when I was about to remove mine for the first time I rang Bukh UK (when Al and Norm were there, so proper advice). Al nearly fell of his chair laughing at the idea that I might drop it on my toes.

 

[Charlie Boy]

Not at all.

There is no reason for the flywheel bolts to have been fitted using an uneccessarily strong grade of threadlock. When I took the flywheel off my BUKH engine for the first time in its life after 15 years. The bolts unscrewed without needing anything other than a hand tool. When reassembling I used Loctite Blue - medium grade.

Here, by the way, is an extract from my copy of the BUKH Workshop manual:

View attachment 206332

My mental hypothesis was that maybe someone else had used a stronger grade

 

[Rhylsailer99]

My mental hypothesis was that maybe someone else had used a stronger grade

I think I will be using loctite 262 or 263

 

[Poignard]

My mental hypothesis was that maybe someone else had used a stronger grade

Damn him if he did!

 

[penberth3]

....Here, by the way, is an extract from my copy of the BUKH Workshop manual:

View attachment 206332

And they can't spell "Loctite" or specify the actual product. Doesn't fill you with confidence does it? What else have they got wrong in that manual?

 

[Rhylsailer99]

And they can't spell "Loctite" or specify the actual product. Doesn't fill you with confidence does it? What else have they got wrong in that manual?

They are Danish the write the manuals so I would guess it is just a spelling error. Hopefully no critical errors.

 

[Rhylsailer99]

Unbrako socket bolts (Allen type) are marked 12.9 (1200 MPa, YS 90% of UTS). I believe that most Allen bolts are the same grade, although I have come across black painted ones that are almost certainly not. Unbrako claim that theirs are the best but I suspect that any from a reliable source would be as good. Socket Head Cap Screws | Unbrako Socket Head Cap Screws | Unbrako

When I had a Bukh I removed the flywheel several times and used the existing bolts each time, after an inspection for cracks or deformation.

I bought some new bolts from T norris along with a new crank case seal. I have an oil leak and think it is a good idea to change it as I do not want to remove it twice. I have a feeling the flywheel needs to be on for alignment which is a pain as I have limited space.

 

[Poignard]

And they can't spell "Loctite" or specify the actual product. Doesn't fill you with confidence does it? What else have they got wrong in that manual?

Aunty Intelligence says:

"In Denmark,
Loctite (often spelled Locktite or Lock tight colloquially) refers to a well-known brand of anaerobic adhesives and sealants manufactured by Henkel, use...."

 

[vyv_cox]

They are Danish the write the manuals so I would guess it is just a spelling error. Hopefully no critical errors.

It is a remarkably thorough manual but I have come across the occasional omission and error. It's the annoying little things that cause most time loss, one that springs to mind is in the regulator, where a cylindrically wound spring has legs of differing length. It is crucial that these be in the correct positions but the manual says nothing. I wasted hours on this one.

 

[neil_s]

Oil leak from the front crankcase seal? It is worth having a think as to 'why?' I found that my water pump had been leaking and salty water had run down the hand-start/pump drive chain and corroded the crankshaft. Fortunately, you can get a Speedisleeve of the correct size!

 

[Rhylsailer99]

When I first got my boat the water pump was leaking and I replaced it, there was also water dripping in from above the engine from the track screwa. Do I need to check for corrosion around the seal area? I just thought it might be a good idea to change it anyway whilst removing the flywheel.
I do hope I can change the mounts without removing the flywheel, but I have a bad feeling the two front engine bay beds might need work on them. The front right mount is very rusty from the pump leak.

 

[Beneteau381]

I too had thought I'd read that the flywheel bolts should not be re-used, but later came across something (on this forum?) saying otherwise. I also recall reading that they are not standard bolts, but Unbrako ones (branded, extra strong ones). I now don't know what the true situation is.

You definitely do not want your flywheel coming off when the engine is running - likely to make a catastrophic mess of hull and/or bodies.

Replacement bolts from Bukh spares stockists are less than a fiver each, and I would have thought that £30 for the set is probably worth it for peace of mind.

When the Bukh was invented the use of re useable bolts was hardly mainstream! So I doubt they need to be renewed