BMC 1.5 broken engine mount

[rgriffiths]

I have a BMC engine with a broken mount. Any thoughts on a way forward? 

 

 

[Tracy D'arth]

Its not the mount that's broken but the flywheel casing casting. Looks to have been cracked a while.

 

It is not uncommon.  A good welder should be able to put it back together but you will have to remove the gearbox,  and the housing to take it to them. Aluminium is tricky to weld, it will need building up.

 

You have to ask why it broke, was there a mechanical happening that caused it?

Edited May 6, 2022 by Tracy D'arth

[rgriffiths]

Thanks for the advice. I was wondering if that was the only way. I suspect it has been broken for a while and can  only speculate why it broke. 

 

I was thinking whether it would be better to try and get a replacement bellhousing? 

[Tracy D'arth]

18 minutes ago, rgriffiths said:

Thanks for the advice. I was wondering if that was the only way. I suspect it has been broken for a while and can  only speculate why it broke. 

 

I was thinking whether it would be better to try and get a replacement bellhousing? 

You could try but that looks like the old PRM Delta gearbox and it has some bearings in the housing. Its been many years since they were made. I would guess its a 1.5D engine and not the 1.8D?

 

Properly welded it should be fine but ensure that the mountings are all serviceable and properly set up or it will go again.

[Steve56]

Most probably been running out of alignment and putting excess strain on the casting. It will need removing. You could try to get it welded but if it were me I would try to get a replacement housing.

[Tracy D'arth]

7 hours ago, Steve56 said:

Most probably been running out of alignment and putting excess strain on the casting. It will need removing. You could try to get it welded but if it were me I would try to get a replacement housing.

The big question may be ---- From Where?------

[Steve56]

2 minutes ago, Tracy D'arth said:

The big question may be ---- From Where?------

I'm sure someone must have a second hand one about. In fact I think I remember one being kicked around for years in RW Davis boatyard. May have been scrapped by now. Its the sort of thing you find in boatyard scrap or come in handy piles. But agree it will be one of those things that when you want one it will be impossible to find.

[rgriffiths]

Again thanks. I was about to ask the same question ... where from?

 

While I suspect it must be, does it have to be like for like or are there alternatives that might work? I can't seem to find anything on the net that looks like it.

[Steve56]

There were probably many variations of the gearbox adaptor, depending on who built the engine.

[Slim]

35 minutes ago, Tracy D'arth said:

The big question may be ---- From Where?------

I just looked on Calcutts and they're not listing one. 

[Slim]

3 minutes ago, Slim said:

I just looked on Calcutts and they're not listing one. 

A quick look on E bay just came up with one for £150 + £15 delivery

[Tracy D'arth]

1 minute ago, Slim said:

I just looked on Calcutts and they're not listing one. 

I have not seen any offered for sale since Thornycroft stopped marinizing BMC 1.5 and 1.8 engines. And they were one of the last.

Calcutt may have a used one lying about if you ask but there are several different ones depending on the company.

[StephenA]

12 hours ago, Tracy D'arth said:

Its not the mount that's broken but the flywheel casing casting. Looks to have been cracked a while.

 

It is not uncommon.  A good welder should be able to put it back together but you will have to remove the gearbox,  and the housing to take it to them. Aluminium is tricky to weld, it will need building up.

 

You have to ask why it broke, was there a mechanical happening that caused it?

 

We got our "regular" housing rewelded by Talbot Wharf... ours cracked because the engine was rocking because the bolts on one of the front engine legs had come loose.

[Tony Brooks]

If all else fails and the welding route proves ineffective then if it were mine I would have the housing off and get a length of (say) 6 to 8mm x 75mm  steel strip to a blacksmiths to have it bent arrund the underside of the housing to form a cradle with a horizontal section at each end to fit onto the mounts (assuming you can lose the thickness of the strip in the adjustment. The housing could then be drilled and tapped to accept  several screws to secure it in place.

[rgriffiths]

Thanks all. Sadly the one on ebay is not the same and I am not sure will fit.

 

I will have a trawl around to see if I can find one. Failing that I think a weld plus extra strengthening as you suggest Tony.

 

[Crow]

If your nearLincoln Or Newark I can weld it 

[Tracy D'arth]

1 hour ago, rgriffiths said:

Thanks all. Sadly the one on ebay is not the same and I am not sure will fit.

 

I will have a trawl around to see if I can find one. Failing that I think a weld plus extra strengthening as you suggest Tony.

 

If its welded properly it will be as strong as it ever was.

You need to make sure nothing untoward has caused it to crack in the first place. Check all the other rubber mounts. They sometimes collapse and the centre stud hammers down onto the steel underneath causing shock fracturing.

[Slim]

2 hours ago, rgriffiths said:

Thanks all. Sadly the one on ebay is not the same and I am not sure will fit.

 

I will have a trawl around to see if I can find one. Failing that I think a weld plus extra strengthening as you suggest Tony.

 

Yes, I went back for another look and it appears to use a different casting to mount setup to yours (yours is similar to my 1.8 design ) Also there was no mention of an adaptor plate.

 

I suggest you give Calcutts a call after the weekend.

 

If you go down the welding route make sure sure you find a good one. I had some welding done on my original housing, Not  in so structurally important a position but the welders opinion of the quality of the metal used was X rated

Edited May 7, 2022 by Slim

[rgriffiths]

1 hour ago, Crow said:

If your nearLincoln Or Newark I can weld it 

That's kind of you. We are in London though. 

 

Just out of interest does anyone know what the material is most likely to be? It looks like aluminium but might it be cast iron? 

[Crow]

Just try a magnet on it.  It looks like cast ally to me itl weld fine

[Slim]

11 minutes ago, Crow said:

Just try a magnet on it.  It looks like cast ally to me itl weld fine

It's not the material that gave the welder the problems it was the quality of the material. Full of impurities and "crap" 

[Tracy D'arth]

They are die cast aluminium of rather poor quality because they don't need to have many threads in them and its a big thick casting. I have seen many welded successfully.

[Crow]

Well it’s up to the welder to grind out all the crap, trouble is 90% of them haven’t a clue. 

[Crow]

There not die cast.  Just normal cast aluminium tig weld with  pure argon and use a stainless wire brush and use a proper aluminium grinding wheel. And it will weld easy. 

[bizzard]

4 minutes ago, Crow said:

Well it’s up to the welder to grind out all the crap, trouble is 90% of them haven’t a clue. 

Aluminium welding uses a different technique. You sort of hold off the rod a little from the job and the ally rod sort of sprays on.