Cracked block

[Mike Lloyd]

After succesfully firing the car up for the first time last week the jubilation has sadly been short lived.

After running the engine for a couple of minutes we heard a loud crack as everything cooled down. Slightly curious at the time we thought it a bit strange but were not overly concerned.

Just having a look for the engine no. toight and noticed the lug on the o/s mounting of engine to gearbox has a crack right through it  

I do not understand what has happened  It is a zetec with a MT75 box and raceline shallow (wet) sump. The engine is only fixed to the top half of the bell housing as no fixing is available to the bottom half. It has only been run for 5 mins max and reverse and 1st gear have been engaged but little else

[perksy]

Can We have a Photo    

It may help with diagnosis

[stu999]

Mike - is the engine new or pre-thrashed? If the latter, do you know the history of the engine?

Basically, either the lug is/was under immense strain for some reason (misalignment of engine to gearbox or similar), or the engine has suffered a knock (possibly due to the accident that wrote donor car off?), and the first heat cycle since has opened up the crack...

[Mike Lloyd]

It is a pre-used engine.

Came out of a m plate mondeo with front end damage. Bough the whole car (which still drove) as the engine seemed sweet as a nut

[DIY Si]

Did you connect the cooling system up? If not it can cause all sorts of funny business.

[stu999]

It appears that there is a gap between the majority of the bellhousing and the block, save for the small bit at the bottom of the picture. There shouldnt be. Difficult to say, but that picture suggests that the bellhousing mating face isnt perfectly flat (it should be IIRC).

Do you have the tinplate fitted that usually goes between engine and box?

[Mike Lloyd]

The tin plate is fitted, it looks like a gap in the photo but all surfaces are tight up against each other

The water sytem is all plumbed in and the hoses all apeared to get warm so I assume water was circulating ok.

[perksy]

You thinking the same thing as Me Mate    

The Bolts been Tightened up and the Casting has been Stressed due to being 'un-supported'    

EDIT -   Ahhh ok then    

[Mike Lloyd]

I am a bit baffled if it isn't alignment ( looked OK visually) I'm thinking of other possibilities. The engine was supported by a jack at some point during the build to remove the OS engine mount, although i am fairly sure that the jack was only supporting the weight of the engine and not trying to lift the car IYSWIM . I would be very surprised if this has pre-stressed it but am struggling to think of another reason (faulty casting I guess unlikely but possible).

Any thoughts on welding this to repair

[stu999]

Welding cast is a bit hit and miss to say the least. To weld properly the engine would need to be stripped to the bare block. The block would then be pre-heated prior to welding, to prevent thermal shock and and an even bigger mess occuring . Even then, sadly it would be a bit of a lottery as to wether it would last

[stu999]

Mike, the area roughly circled with yellow appears in the photo to be 'protruding' from the rest of the bellhousing, and would cause such a crack. Is it just an illusion of the photo?

[jeff oakley]

It will be a misalignment at some part of the mating process. Usual casue is when the bolts are done up fully one side to the other, mechanics use air guns and this is common on lighter blocks. The other one I have seen is where a socket which has a thick wall has been used when it was tightened the wall got stuck between the bolt head and the machined pocket again forcing a gap.

A good welder will sort that out, but it is cast so will need someone who is not a hobby welder

[perksy]

A good welder will sort that out, but it is cast so will need someone who is not a hobby welder

Yep

Needs a good Prep' and You'll need to make sure that the Machined mating face doesn't distort during Welding

[nikpro]

Probably fitting of the raceline sump has caused this, it only has to be out of alignment ever so slightly to cause the mating face of the engine/gearbox to not be flat. It is always better to fit the sump after the gearbox has been fitted to the engine to stop this miss alignment.

[Mike Lloyd]

Although I'm gutted about this the only way forward is to take out the engine and box.

In-situ everything looks to be OK with no obvious gaps between the block and bell housing. The picture is a bit misleading with the thin metal plate makink it look as though there is a gap.

With the block and box out hopefully it will be obvious

Welding I think is going to be the preferred option although it may work out easier to replace the engine. Either way it is a complete A*** and doesn't look like SVA is going to happen in the next couple of weeks

Thanks for all thoughts and comments, I'll let you know how it pans out.