posted March 27, 2007 22:27               

Initially I thought that this may have been due to the blocks being bored out for the Super Dexta, but as there is only 0.02mm difference between the outside diameters of the liners, this can be discounted.

Also the cracks on all the engines have occurred in the same place, which suggests that this is a design problem rather than the result of misuse or mal practice. The inference being that the wall thickness in the region of the cracks is insufficient.

No doubt this is aggravated by the fact that anti freeze has not been used in these engines, which not only prevents the cooling water from freezing but also helps to limit corrosion. In only one case is there any evidence of distortion in way of the crack, suggesting that either there were stresses in the casting or the crack has occurred due to frost damage, in this case the crack extended into the core plug aperture.

To date I have not had the oportunity to run these engine under full load conditions, on light load, the leakage from the cracks is minimal and shows as a damp line rather than a severe loss of water. Also the fact that engines for the Home Market do not have a pressurised cooling system helps to limit the rate of leakage.

As a matter of interest, I wonder if this cracking is confined to the Fordson Dexta P3 engine, or do the Perkins P3 engines also suffer cracked blocks?

The method of repairing these cracks has been discussed in a number of previous threads or topics. My own preference is to repair the cracks by metal stiching as once repaired it is unlikely that the crack will return. Whilst this is not the cheapest option, in light of the prices that these tractors are now fetching, coupled with the scarcity of good tractors and parts, it may well be in the long term the only solution.

So be advised, when buying a Dexta have a good look at the block behind the fuel pump between the two core plugs in the block to ensure that it isn't cracked. Scrape away any grease and dirt which may cover up a crack. Any traces of epoxy putty or silicone sealer is a real give away.

Let me hasten to add that I do not have an interest in any Company or individual carrying out Metal Stitching. I am just a p***ed off punter with four defective blocks, who is an advocate of this method of repair and who is fortunate to have the workshop facilites and other resources to limit the overall cost incurred in refurbishing these engines.

Regards.

Gerald

posted March 29, 2007 03:59               

Interesting topic and well presented!

Last fall when I discovered our newly acquired '62 Super Dexta had a hair-line crack in the block, I also searched the forums for other tractors that used the similar A3.152 and AD3.152 Perkins engine.

It has happened to these engines as well but there seemed to be fewer instances.
But this could be that the owners were not as dedicated as we of the Dexta and are not as interested in preserving their tractors!

I have opted to repair my Super Dexta block rather than switch it out with a spare "grey block engine" I have sitting in a shed.
(I looked at them both this afternoon but could not see any external differences in the thickness of the casting.)

Looked at lock-stitching but found it to be ~$900C just for the do-it-yourself kit.
As I was asking for a quicker, more affordable fix, I went with the Belzona (~$250C) as suggested by Brian.
It looks really good but I still have to get the head back on and fire it up.

Curious as to the price of lock-stitching elsewhere?

Just an afterthought.
I believe our tractor has original sleeves and the crack was likely caused by freezing.
But, in other cases, could the outer diameter of some aftermarket liners be a bit oversized and so distort the block when pressed in during a rebuild?

posted March 29, 2007 08:36               

The problem is there on a number of Perkins engines.

The Perkins block fitted in the M-F range is a different block. The Dexta block was made by Ford at Dagenham to different specifications.

There are many tractors out there which have no problems and many Perkins engines of similar design which are OK.

The liners in a Dexta are a far tighter fit than the Perkins ones. These are held in place by a machined rim at the top, the Dexta's are a pressed fit. So I don't think fitting "aftermarket" liners is a problem.

posted March 29, 2007 17:45               

[QUOTE]Originally posted by Tubal Cain:
[B]Out of seven, Dexta and Super Dexta engines in my possession, four of them have cracked cylinder blocks. One Dexta and three Super Dextas.

posted March 29, 2007 21:34               

Now we know where all the Dexta engines have gone, Gerald has them all!!

Regards,

posted March 31, 2007 08:14               

It is reassuring to know that there are only four cracked blocks in existence as that means that the block I have yet to collect will be alright.

But just to inform you that my interest isn’t just restricted to blocks I attach photos of a bell housing.

Any suggestions as to how this happened?

Regards.

Gerald

[This message has been edited by Tubal Cain (edited March 31, 2007).]

[This message has been edited by Tubal Cain (edited March 31, 2007).]

posted April 01, 2007 21:05               

These poor old machines have taken a lot of stick in the past!

Chris

posted April 06, 2007 15:53               

Big loads at the lift and lots of jumpings of the front wheels. Attaching load to the front to prevent nose-lifting....

or in other words : abusing the equipment.

At the end, we may not forget the following, "nothing is eternal"

About the engine : I also have a cracked block on the narrow due to missing anti-freeze. When antifreeze is missing, the block cracs just behind the injection pump at there the material is very thin. The expanding of the ice pushes the material outwards.

This is a picture from Stefan I used to indicate my problem !!

Jos